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1
Wang, Jing Han, Hai Zhen Yang, and Feng Wang. "Potential of Mixotrophic Cultivation of Chlorella sorokiniana for Biodiesel Production." Advanced Materials Research 779-780 (September 2013): 1509–13. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1509.
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Biodiesel from microalgae provides a promising alternative for biofuel production. Microalgal biodiesel can be produced under three major cultivation modes, namely, photoautotrophic, heterotrophic, and mixotrophic cultivation. Studies of biodiesel production from microalgae have been reported mostly focusing on photoautotrophic cultivation, mixotrophic cultivation has rarely been researched. This paper compared the biomass productivity, lipid content, and lipid productivity ofChlorella sorokinianaunder photoautotrophic, heterotrophic, and mixotrophic cultivation. Glucose was adopted as organic carbon source at five concentrations (0.1, 0.5, 1.0, 2.0, 5.0% glucose w/v). Results displayed that microalgal growth was significantly improved in glucose supplied cultures. Synergetic effect of photoautotrophy and heterotrophy existed in mixotrophic cultivation except for 5.0% culture. Highest biomass productivity of 1.178 g·L-1·d-1and highest lipid productivity of 582 mg·L-1·d-1was observed under mixotrophic cultivation with 2.0% (w/v) glucose addition. Lipid content ofC. sorokinianawas mostly higher in stationary phase than in exponential phase. Highest lipid content of 49.37% was observed in 2.0% mixotrophic culture, followed by 47.09% in 2.0% heterotrophic culture.
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Wang, Jing Han, Hai Zhen Yang, and Feng Wang. "Mixotrophic Cultivation of Scenedesmus sp. as Biodiesel Feedstock." Advanced Materials Research 777 (September 2013): 268–73. http://dx.doi.org/10.4028/www.scientific.net/amr.777.268.
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Microalgae are a promising feedstock for biodiesel production. Microalgal biodiesel can be obtained under three major cultivation modes, namely, photoautotrophic, heterotrophic, and mixotrophic cultivation. Reported studies of microalgal biodiesel production are mainly based on photoautotrophic cultivation, mixotrophic cultivation has rarely been researched. This paper compared the biomass productivity, lipid content, and lipid productivity of Scenedesmus sp. under photoautotrophic, heterotrophic, and mixotrophic cultivation. Glucose was added as organic carbon source at five concentrations (0.1, 0.5, 1.0, 2.0, 5.0% glucose w/v). Results displayed that microalgal growth was significantly improved in glucose supplied cultures. Synergetic effect of photoautotrophy and heterotrophy existed in all mixotrophic cultures. Highest biomass productivity of 1.307 g·L-1·d-1 and highest lipid productivity of 316 mg·L-1·d-1 was respectively observed under mixotrophic cultivation with 5.0% and 1.0% (w/v) glucose addition. Lipid content of Scenedesmus sp. under mixotrophic cultivation was mostly higher in stationary phase than in exponential phase. Highest lipid content of 27.73% was observed in 1.0% mixotrophic culture, followed by 24.66% in 1.0% heterotrophic culture.
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Correia, Nádia, Hugo Pereira, Peter S. C. Schulze, Monya M. Costa, Gonçalo E. Santo, Inês Guerra, Mafalda Trovão, et al. "Heterotrophic and Photoautotrophic Media Optimization Using Response Surface Methodology for the Novel Microalga Chlorococcum amblystomatis." Applied Sciences 13, no. 4 (February 6, 2023): 2089. http://dx.doi.org/10.3390/app13042089.
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The nutritional requirements of novel microalgal strains are key for their effective cultivation and metabolite content. Therefore, the optimization of heterotrophic and photoautotrophic culture media is crucial for novel Chlorococcum amblystomatis growth. Heterotrophic and photoautotrophic biomass samples were characterized to identify the differences between their heterotrophic and photoautotrophic biomass composition and their biotechnological potential. Media optimization through surface response methodology led to 44.9 and 51.2% increments in C. amblystomatis-specific growth rates under heterotrophic and photoautotrophic growth, respectively. This microalga registered high protein content (61.49–73.45% dry weight), with the highest value being observed in the optimized photoautotrophic growth medium. The lipid fraction mainly constituted polyunsaturated fatty acids, ranging from 44.47 to 51.41% for total fatty acids (TFA) in cells under heterotrophy. However, these contents became significantly higher (70.46–72.82% TFA) in cultures cultivated under photoautotrophy. An interesting carotenoids content was achieved in the cultures grown in optimized photoautotrophic medium: 5.84 mg·g−1 β-carotene, 5.27 mg·g−1 lutein, 3.66 mg·g−1 neoxanthin, and 0.75 mg·g−1 violaxanthin. Therefore, C. amblystomatis demonstrated an interesting growth performance and nutritional profile for food supplements and feed products that might contribute to meeting the world’s nutritional demand.
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Park, Jeong-Eun, Shan Zhang, Thi Hiep Han, and Sun-Jin Hwang. "The Contribution Ratio of Autotrophic and Heterotrophic Metabolism during a Mixotrophic Culture of Chlorella sorokiniana." International Journal of Environmental Research and Public Health 18, no. 3 (February 2, 2021): 1353. http://dx.doi.org/10.3390/ijerph18031353.
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The contribution ratio of autotrophic and heterotrophic metabolism in the mixotrophic culture of Chlorella sorokiniana (C. sorokiniana) was investigated. At the early stage of mixotrophic growth (day 0–1), autotrophy contributed over 70% of the total metabolism; however, heterotrophy contributed more than autotrophy after day 1 due to the rapid increase in cell density, which had a shading effect in the photo-bioreactor. Heterotrophy continued to have a higher contribution until the available organic carbon was depleted at which point autotrophy became dominant again. Overall, the increase in algal biomass and light conditions in the photo-bioreactor are important factors in determining the contribution of autotrophy and heterotrophy during a mixotrophic culture.
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Cupo, Adelaide, Simone Landi, Salvatore Morra, Genoveffa Nuzzo, Carmela Gallo, Emiliano Manzo, Angelo Fontana, and Giuliana d’Ippolito. "Autotrophic vs. Heterotrophic Cultivation of the Marine Diatom Cyclotella cryptica for EPA Production." Marine Drugs 19, no. 7 (June 23, 2021): 355. http://dx.doi.org/10.3390/md19070355.
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Recently, the marketable value of ω-3 fatty acid, particularly eicosapentaenoic acid (EPA), increased considering their health effects for human consumption. Microalgae are considered a valuable and “green” source of EPA alternative to fish oils, but considerable efforts are necessary for their exploitation at an industrial level. Due to the high operation costs of photoautotrophic microalgae cultivation, heterotrophic growth represents a promising economic solution. Marine diatoms are the major ecological producers of ω-3 fatty acids. Few species of diatoms are capable to grow in the dark using organic carbon sources. The marine diatom Cyclotella cryptica was cultivated for 14 days under photoautotrophic and heterotrophic conditions to define the effects on growth parameters, lipid production, total fatty acids and EPA content. Photoautotrophic conditions led to a total EPA production of 1.6% of dry weight, 12.2 mg L−1 culture and productivity of 0.9 mg L−1 day−1. The heterotrophy cultures reported a total EPA production of 2.7% of dry cell weight, 18 mg L−1 culture, a productivity of 1.3 mg L−1 day−1, which are promising values in the prospective of improving culture parameters for the biotechnological exploitation of dark cultivation. C. cryptica could be a potential candidate for the heterotrophic production of EPA, also considering its robustness, capacity to resist to bacterial contaminations and plasticity of lipid metabolism.
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Wang, Kaixuan, Zhongjie Wang, Yi Ding, Youzhi Yu, Yali Wang, Yahong Geng, Yeguang Li, and Xiaobin Wen. "Optimization of Heterotrophic Culture Conditions for the Algae Graesiella emersonii WBG-1 to Produce Proteins." Plants 12, no. 12 (June 9, 2023): 2255. http://dx.doi.org/10.3390/plants12122255.
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The aim of this study was to improve the protein content and yield of heterotrophic microalgal cultivation and establish a simple, economical, and efficient method for microalgal protein production using the novel green alga, Graesiella emersonii WBG-1, which has not been previously reported for heterotrophic cultivation. Through batch heterotrophic cultivation of this alga, we observed that glucose was the optimal carbon source, while it could not use sucrose as a carbon source. Biomass production and protein content were significantly reduced when sodium acetate was used as the carbon source. Compared with nitrate, protein content increased by 93% when urea was used as the nitrogen source. Cultivation temperature had a significant impact on biomass production and protein content. The optimal conditions were glucose as the carbon source at an initial concentration of 10 g/L, urea as the nitrogen source at an initial concentration of 1.62 g/L, and a culture temperature of 35 °C. On the second day of batch cultivation, the highest protein content (66.14%) was achieved, which was significantly higher than that reported in heterotrophic cultures of Chlorella and much higher than that reported for specially established technologies aimed at increasing the protein content, such as two-stage heterotrophic, heterotrophy–dilution–photoinduction, and mixotrophic processes. These results demonstrate the great potential of the heterotrophic cultivation of G. emersonii WBG-1 for protein production.
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Morris, J. Jeffrey, Robin Kirkegaard, Martin J. Szul, Zackary I. Johnson, and Erik R. Zinser. "Facilitation of Robust Growth of Prochlorococcus Colonies and Dilute Liquid Cultures by “Helper” Heterotrophic Bacteria." Applied and Environmental Microbiology 74, no. 14 (May 23, 2008): 4530–34. http://dx.doi.org/10.1128/aem.02479-07.
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ABSTRACT Axenic (pure) cultures of marine unicellular cyanobacteria of the Prochlorococcus genus grow efficiently only if the inoculation concentration is large; colonies form on semisolid medium at low efficiencies. In this work, we describe a novel method for growing Prochlorococcus colonies on semisolid agar that improves the level of recovery to approximately 100%. Prochlorococcus grows robustly at low cell concentrations, in liquid or on solid medium, when cocultured with marine heterotrophic bacteria. Once the Prochlorococcus cell concentration surpasses a critical threshold, the “helper” heterotrophs can be eliminated with antibiotics to produce axenic cultures. Our preliminary evidence suggests that one mechanism by which the heterotrophs help Prochlorococcus is the reduction of oxidative stress.
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Hršak, Dubravka, and Ana Begonja. "Possible Interactions within a Methanotrophic-Heterotrophic Groundwater Community Able To Transform Linear Alkylbenzenesulfonates." Applied and Environmental Microbiology 66, no. 10 (October 1, 2000): 4433–39. http://dx.doi.org/10.1128/aem.66.10.4433-4439.2000.
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ABSTRACT The relationships and interactions within a methanotrophic-heterotrophic groundwater community were studied in a closed system (shake culture) in the presence of methane as the primary carbon and energy source and with the addition of the pure linear alkylbenzenesulfonate (LAS) congener 2-[4-(sulfophenyl)]decan as a cometabolic substrate. When cultured under different conditions, this community was shown to be a stable association, consisting of one obligate type II methanotroph and four or five heterotrophs possessing different nutritional and physiological characteristics. The results of experiments examining growth kinetics and nutritional relationships suggested that a number of complex interactions existed in the community in which the methanotroph was the only member able to grow on methane and to cometabolically initiate LAS transformation. These growth and metabolic activities of the methanotroph ensured the supply of a carbon source and specific nutrients which sustained the growth of four or five heterotrophs. In addition to the obligatory nutritional relationships between the methanotroph and heterotrophs, other possible interactions resulted in the modification of basic growth parameters of individual populations and a concerted metabolic attack on the complex LAS molecule. Most of these relationships conferred beneficial effects on the interacting populations, making the community adaptable to various environmental conditions and more efficient in LAS transformation than any of the individual populations alone.
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Singh, V., and A. K. Mittal. "Characterization of biofilm of a rotating biological contactor treating synthetic wastewater." Water Science and Technology 66, no. 2 (July 1, 2012): 429–37. http://dx.doi.org/10.2166/wst.2012.221.
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A four-stage rotating biological contactor (RBC) was designed and operated to treat synthetic wastewater containing 1,000 mg/l chemical oxygen demand (COD) and 112 mg/l NH4+-N. A mixed culture bacterial biofilm was developed consisting of a heterotrophic bacterium Paracoccus pantotrophus, nitrifiers and other heterotrophs. Applying the peculiar characteristics of P. pantotrophus of simultaneous heterotrophic nitrification and aerobic denitrification, high simultaneous removal of carbon and nitrogen could be achieved in the fully aerobic RBC. The microbial community structure of the RBC biofilm was categorized based on the nitrate reduction, biochemical reactions, gram staining and morphology. The presence of P. pantotrophus within the RBC biofilm was confirmed with an array of biochemical tests. Isolates from the four stages of RBC were grouped into complete denitrifiers, incomplete denitrifiers and non-denitrifiers. This categorization showed a higher relative abundance of P. pantotrophus in the first stage as compared with subsequent stages, in which other nitrifiers and heterotrophs were significantly present. High total nitrogen removal of upto 68% was in conformity with observations made using microbial categorization and biochemical tests. The high relative abundance of P. pantotrophus in the biofilm revealed that it could successfully compete with other heterotrophs and autotrophic nitrifiers in mixed bacterial biomass.
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Tsuneda, S., S. Park, H. Hayashi, J. Jung, and A. Hirata. "Enhancement of nitrifying biofilm formation using selected EPS produced by heterotrophic bacteria." Water Science and Technology 43, no. 6 (March 1, 2001): 197–204. http://dx.doi.org/10.2166/wst.2001.0374.
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The possibility of enhancing nitrifying biofilm formation rate with the aid of selected EPS produced by heterotrophic bacteria was investigated. When EPS production characteristics were examined for four kinds of heterotrophs isolated from a domestic wastewater treatment reactor, two strains obtained from biofilms (B1, B2) exhibited a higher polysaccharide production rate than those from suspended flocs (A1, A2). Among EPS components, the concentration of uronic acids gave a good correlation with flocculation ability, which suggests that acidic polysaccharides play a major role in bioaggregate formation. Addition of 1g/L D-glucuronic acid as an EPS substitute enhanced the homocoagulation rate of autotrophic Nitrosomonas europaea and altered its zeta potential from ñ30.4mV to +4.3mV, which indicates a possibility that particular EPS components produced by heterotrophs are utilized as neutralising reagents for nitrifying biofilm formation. Moreover, when heterotrophic isolates with Nitrobacter winogradskyi were cultured in batch with fabric supports, biofilm formed on the substratum. These experimental results suggest the application of selected EPS for enhancing nitrifying biofilm formation.
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Sedlacek, Christopher J., Susanne Nielsen, Kenneth D. Greis, Wendy D. Haffey, Niels Peter Revsbech, Tomislav Ticak, Hendrikus J. Laanbroek, and Annette Bollmann. "Effects of Bacterial Community Members on the Proteome of the Ammonia-Oxidizing Bacterium Nitrosomonas sp. Strain Is79." Applied and Environmental Microbiology 82, no. 15 (May 27, 2016): 4776–88. http://dx.doi.org/10.1128/aem.01171-16.
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ABSTRACTMicroorganisms in the environment do not exist as the often-studied pure cultures but as members of complex microbial communities. Characterizing the interactions within microbial communities is essential to understand their function in both natural and engineered environments. In this study, we investigated how the presence of a nitrite-oxidizing bacterium (NOB) and heterotrophic bacteria affect the growth and proteome of the chemolithoautotrophic ammonia-oxidizing bacterium (AOB)Nitrosomonassp. strain Is79. We investigatedNitrosomonassp. Is79 in co-culture withNitrobacter winogradskyi, in co-cultures with selected heterotrophic bacteria, and as a member of the nitrifying enrichment culture G5-7. In batch culture,N. winogradskyiand heterotrophic bacteria had positive effects on the growth ofNitrosomonassp. Is79. An isobaric tag for relative and absolute quantification (iTRAQ) liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics approach was used to investigate the effect ofN. winogradskyiand the co-cultured heterotrophic bacteria from G5-7 on the proteome ofNitrosomonassp. Is79. In co-culture withN. winogradskyi, severalNitrosomonassp. Is79 oxidative stress response proteins changed in abundance, with periplasmic proteins increasing and cytoplasmic proteins decreasing in abundance. In the presence of heterotrophic bacteria, the abundance of proteins directly related to the ammonia oxidation pathway increased, while the abundance of proteins related to amino acid synthesis and metabolism decreased. In summary, the proteome ofNitrosomonassp. Is79 was differentially influenced by the presence of eitherN. winogradskyior heterotrophic bacteria. Together,N. winogradskyiand heterotrophic bacteria reduced the oxidative stress forNitrosomonassp. Is79, which resulted in more efficient metabolism.IMPORTANCEAerobic ammonia-oxidizing microorganisms play an important role in the global nitrogen cycle, converting ammonia to nitrite. In their natural environment, they coexist and interact with nitrite oxidizers, which convert nitrite to nitrate, and with heterotrophic microorganisms. The presence of nitrite oxidizers and heterotrophic bacteria has a positive influence on the growth of the ammonia oxidizers. Here, we present a study investigating the effect of nitrite oxidizers and heterotrophic bacteria on the proteome of a selected ammonia oxidizer in a defined culture to elucidate how these two groups improve the performance of the ammonia oxidizer. The results show that the presence of a nitrite oxidizer and heterotrophic bacteria reduced the stress for the ammonia oxidizer and resulted in more efficient energy generation. This study contributes to our understanding of microbe-microbe interactions, in particular between ammonia oxidizers and their neighboring microbial community.
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Beaver, Rachel C., Katja Engel, W. Jeffrey Binns, and Josh D. Neufeld. "Microbiology of barrier component analogues of a deep geological repository." Canadian Journal of Microbiology 68, no. 2 (February 2022): 73–90. http://dx.doi.org/10.1139/cjm-2021-0225.
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Canada is currently implementing a site selection process to identify a location for a deep geological repository (DGR) for the long-term storage of Canada’s used nuclear fuel, wherein used nuclear fuel bundles will be sealed inside copper-coated carbon steel containers, encased in highly compacted bentonite clay buffer boxes, and sealed deep underground in a stable geosphere. Because a DGR must remain functional for a million years, it is important to examine ancient natural systems that serve as analogues for planned DGR components. Specifically, studying the microbiology of natural analogue components of a DGR is important for developing an understanding of the types of microorganisms that may be able to grow and influence the long-term stability of a DGR. This study explored the abundance, viability, and composition of microorganisms in several ancient natural analogues using a combination of cultivation and cultivation-independent approaches. Samples were obtained from the Tsukinuno bentonite deposit (Japan) that formed ∼10 mya, the Opalinus Clay formation (Switzerland) that formed ∼174 mya, and Canadian shield crystalline rock from Northern Ontario that formed ∼2.7 bya. Analysis of 16S rRNA gene amplicons revealed that three of the ten Tsukinuno bentonite samples analyzed were dominated by putative aerobic heterotrophs and fermenting bacteria from the phylum Actinobacteria, whereas five of the Tsukinuno bentonite samples were dominated by sequences associated with putative acidophilic chemolithoautotrophs capable of sulfur reduction. The remaining Tsukinuno bentonite samples, the Northern Ontario rock samples, and the Opalinus Clay samples generated inconsistent replicate 16S rRNA gene profiles and were associated primarily with contaminant sequences, suggesting that the microbial profiles detected were not sample-specific but spurious. Culturable aerobic heterotroph abundances were relatively low for all Tsukinuno bentonite samples, culturable anaerobic heterotrophs were only detected in half of the Tsukinuno samples, and sulfate-reducing bacteria (SRB) were only detected in one Tsukinuno sample by cultivation. Culture-specific 16S rRNA gene profiles from Tsukinuno clay samples demonstrated the presence of phyla Bacteroidetes, Proteobacteria, Actinobacteria, and Firmicutes among aerobic heterotroph cultures and additional bacteria from the phyla Actinobacteria and Firmicutes from anaerobic heterotroph plate incubations. Only one nucleic acid sequence detected from a culture was also associated with its corresponding clay sample profile, suggesting that nucleic acids from culturable bacteria were relatively rare within the clay samples. Sequencing of DNA extracted from the SRB culture revealed that the taxon present in the culture was affiliated with the genus Desulfosporosinus, which has been found in related bentonite clay analyses. Although the crystalline rock and Opalinus Clay samples were associated with inconsistent, likely spurious 16S rRNA gene profiles, we show evidence for viable and detectable microorganisms within several Tsukinuno natural analogue bentonite samples.
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Blöthe, Marco, and Eric E. Roden. "Composition and Activity of an Autotrophic Fe(II)-Oxidizing, Nitrate-Reducing Enrichment Culture." Applied and Environmental Microbiology 75, no. 21 (September 11, 2009): 6937–40. http://dx.doi.org/10.1128/aem.01742-09.
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ABSTRACT 16S rRNA gene libraries from the lithoautotrophic Fe(II)-oxidizing, nitrate-reducing enrichment culture described by Straub et al. (K. L. Straub, M. Benz, B. Schink, and F. Widdel, Appl. Environ. Microbiol. 62:1458-1460, 1996) were dominated by a phylotype related (95% 16S rRNA gene homology) to the autotrophic Fe(II) oxidizer Sideroxydans lithotrophicus. The libraries also contained phylotypes related to known heterotrophic nitrate reducers Comamonas badia, Parvibaculum lavamentivorans, and Rhodanobacter thiooxidans. The three heterotrophs were isolated and found to be capable of only partial (12 to 24%) Fe(II) oxidation, suggesting that the Sideroxydans species has primary responsibility for Fe(II) oxidation in the enrichment culture.
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Korozi, Evagelina, Vasiliki Tsagou, Io Kefalogianni, Giorgos Markou, Dimitris Antonopoulos, Lambis Chakalis, Yannis Kotzamanis, and Iordanis Chatzipavlidis. "Continuous Culture of Auxenochlorella protothecoides on Biodiesel Derived Glycerol under Mixotrophic and Heterotrophic Conditions: Growth Parameters and Biochemical Composition." Microorganisms 10, no. 3 (February 28, 2022): 541. http://dx.doi.org/10.3390/microorganisms10030541.
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As crude glycerol comprises a potential substrate for microalga fermentation and value added products’ biosynthesis, Auxenochlorella protothecoides was grown on it under heterotrophic and mixotrophic conditions and its growth kinetics were evaluated in a continuous system under steady state conditions. Increasing initial glycerol concentration (from 30 to 50 g/L) in the heterotrophic culture led to reduced biomass yield (Yx/S) and productivity (Px), but favored lipid accumulation. Under heterotrophic conditions, the microalga was found to grow better (biomass up to 7.888 g/L) and faster (higher growth rates), the system functioned more effectively (higher Px) and crude glycerol was exploited more efficiently. Heterotrophy also favored proteins synthesis (up to 53%), lipids (up to 9.8%), and carbohydrates (up to 44.6%) accumulation. However, different trophic modes had no significant impact on the consistency of proteins and lipids. Oleic acid was the most abundant fatty acid detected (55–61.2% of the total lipids). The algal biomass contained many essential and non-essential amino acids, especially arginine, glutamic acid, lysine, aspartic acid, leucine, and alanine. In all the experimental trials, the protein contents in the microalgal biomass increased with the increasing dilution rate (D), with a concomitant decrease in the lipids and carbohydrates fractions.
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Le, Thanh Tung, Amélie Corato, Thomas Gerards, Stéphanie Gérin, Claire Remacle, and Fabrice Franck. "Heterotrophy Compared to Photoautotrophy for Growth Characteristics and Pigment Compositions in Batch Cultures of Four Green Microalgae." Plants 13, no. 9 (April 24, 2024): 1182. http://dx.doi.org/10.3390/plants13091182.
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Four strains of green microalgae (Scenedesmus acutus, Scenedesmus vacuolatus, Chlorella sorokiniana, and Chlamydomonas reinhardtii) were compared to determine growth and pigment composition under photoautotrophic or heterotrophic conditions. Batch growth experiments were performed in multicultivators with online monitoring of optical density. For photoautotrophic growth, light-limited (CO2-sufficient) growth was analyzed under different light intensities during the exponential and deceleration growth phases. The specific growth rate, measured during the exponential phase, and the maximal biomass productivity, measured during the deceleration phase, were not related to each other when different light intensities and different species were considered. This indicates species-dependent photoacclimation effects during cultivation time, which was confirmed by light-dependent changes in pigment content and composition when exponential and deceleration phases were compared. Except for C. reinhardtii, which does not grow on glucose, heterotrophic growth was promoted to similar extents by acetate and by glucose; however, these two substrates led to different pigment compositions. Weak light increased the pigment content during heterotrophy in the four species but was efficient in promoting growth only in S. acutus. C. sorokiniana, and S. vacuolatus exhibited the best potential for heterotrophic biomass productivities, both on glucose and acetate, with carotenoid (lutein) content being the highest in the former.
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Khanichaidecha, W., A. Nakaruk, K. Ratananikom, R. Eamrat, and F. Kazama. "Heterotrophic nitrification and aerobic denitrification using pure-culture bacteria for wastewater treatment." Journal of Water Reuse and Desalination 9, no. 1 (February 9, 2018): 10–17. http://dx.doi.org/10.2166/wrd.2018.064.
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Abstract Due to the high water demand and unsustainable water resource, wastewater reclamation and wastewater treatment prior to discharge have become current important issues. Various treatment technologies, such as biological processes, have been improved as alternatives. In this study, the biological nitrogen removal system using pure-culture Bacillus licheniformis was developed and used as an internal treatment unit in an aquarium to improve the effluent quality for water reuse. The efficiencies for NH4-N and total nitrogen (TN) removal and the quality of treated water verified the occurrence of heterotrophic nitrification and aerobic denitrification; the nitrification rate was 0.84 mg/L-h and the denitrification rate was 0.62 mg/L-h. The maximal NH4-N and TN removal efficiencies were approximately 73% at the influent NH4-N of 30 mg/L. However, the other competitive heterotroph of Pseudomonas sp. was observed, which resulted in dramatically decreasing efficiencies and an enlarged ratio of carbon consumption and nitrogen removal. Although the overall performance of the B. licheniformis system was lower than the system using mixed-culture nitrifying and heterotrophic denitrifying microorganisms, the advantages of the B. licheniformis system were ease of operation and the fact that it is a land-limited treatment system. The research is ongoing to enhance performance and maintain excellent efficiency in a long-term operation.
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Obayagbona, O. N., A. Dunkwu-Okafor, O. Odigie, and J. U. Oghene. "Biodegradation potentials of edaphic bacterial isolates cultured on Haloxyfop R Methyl ester herbicide-mineral salt medium." Nigerian Journal of Biotechnology 40, no. 2 (January 31, 2024): 1–10. http://dx.doi.org/10.4314/njb.v40i2.1.
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The heterotrophic and haloxyfop-R methyl ester utilizing bacterial counts associated with top soil samples was evaluated. Three (3) bacterial isolates; Bacillus sp., Micrococcus sp. and Staphylococcus sp. were cultured and screened for their ability to utilize haloxyfop-R methyl ester as sole source of carbon and energy using the turbidimeteric procedure. The growth profiles of two axenic cultures; Bacillus sp. and Micrococcus sp. were determined using the shake flask test. Parameters which included pH, mean viable bacterial counts, optical density and dissolved CO2 were determined during growth profiling using relevant procedures and equipment. The pH of the soil samples was 5.08 ± 0.02 for sample A and 4.62 ± 0.02 for sample B. The total heterotrophic bacterial count was 2.8 × 104 cfu/g ± 849 for A and 4.62 × 104 cfu/g ± 989 for B. The mean dissolved CO2 data for Micrococcus sp. during the growth profile study ranged from 1.1 mg/l ± 0.1 to 6.8 mg/l ± 0.2. Axenic Micrococcus sp. was the most effective amongst the growth profile cultures in mineralizing the herbicide content of the culture medium.
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Fruhen, M., E. Christan, W. Gujer, and O. Wanner. "Significance of Spatial Distribution of Microbial Species in Mixed Culture Biofilms." Water Science and Technology 23, no. 7-9 (April 1, 1991): 1365–74. http://dx.doi.org/10.2166/wst.1991.0589.
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Experimental data from a biofilm reactor, in which two groups of organisms (Nitrifiers and Heterotrophs) compete for dissolved oxygen, were analyzed by a Mixed Culture Biofilm Model. The objective was to investigate to what extent and how fast relative abundance and spatial distribution of microbial species in a mixed culture biofilm changed upon variations of the bulk fluid substrate composition, and what the consequences of these changes were for substrate removal. Experimental results showed that within nine days the nitrification rate in a biofilm of constant thickness could change by a factor of five. Model predictions indicated that these changes must be due to a significant shift of the biofilm population. The distribution of the autotrophic and heterotrophic species over the depth of the biofilm turned out to be an important aspect of mixed culture biofilm behavior. Since it is difficult to observe the microbial population and its spatial distribution experimentally, the Mixed Culture Biofilm Model has proved to be a valuable tool for the interpretation of the observed phenomena.
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Bacelar-Nicolau, Paula, and D. Barrie Johnson. "Leaching of Pyrite by Acidophilic Heterotrophic Iron-Oxidizing Bacteria in Pure and Mixed Cultures." Applied and Environmental Microbiology 65, no. 2 (February 1, 1999): 585–90. http://dx.doi.org/10.1128/aem.65.2.585-590.1999.
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ABSTRACT Seven strains of heterotrophic iron-oxidizing acidophilic bacteria were examined to determine their abilities to promote oxidative dissolution of pyrite (FeS2) when they were grown in pure cultures and in mixed cultures with sulfur-oxidizingThiobacillus spp. Only one of the isolates (strain T-24) oxidized pyrite when it was grown in pyrite-basal salts medium. However, when pyrite-containing cultures were supplemented with 0.02% (wt/vol) yeast extract, most of the isolates oxidized pyrite, and one (strain T-24) promoted rates of mineral dissolution similar to the rates observed with the iron-oxidizing autotroph Thiobacillus ferrooxidans. Pyrite oxidation by another isolate (strain T-21) occurred in cultures containing between 0.005 and 0.05% (wt/vol) yeast extract but was completely inhibited in cultures containing 0.5% yeast extract. Ferrous iron was also needed for mineral dissolution by the iron-oxidizing heterotrophs, indicating that these organisms oxidize pyrite via the “indirect” mechanism. Mixed cultures of three isolates (strains T-21, T-23, and T-24) and the sulfur-oxidizing autotroph Thiobacillus thiooxidans promoted pyrite dissolution; since neither strains T-21 and T-23 nor T. thiooxidans could oxidize this mineral in yeast extract-free media, this was a novel example of bacterial synergism. Mixed cultures of strains T-21 and T-23 and the sulfur-oxidizing mixotrophThiobacillus acidophilus also oxidized pyrite but to a lesser extent than did mixed cultures containing T. thiooxidans. Pyrite leaching by strain T-23 grown in an organic compound-rich medium and incubated either shaken or unshaken was also assessed. The potential environmental significance of iron-oxidizing heterotrophs in accelerating pyrite oxidation is discussed.
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Aislabie, J., J. Ryburn, and A. Sarmah. "Culturable microbes in shallow groundwater underlying ornithogenic soil of Cape Hallett, AntarcticaThis article is one of a selection of papers in the Special Issue on Polar and Alpine Microbiology." Canadian Journal of Microbiology 55, no. 1 (January 2009): 12–20. http://dx.doi.org/10.1139/w08-118.
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The objective of this study was to investigate the culturable psychrotolerant microbial community in groundwater from Seabee Hook, Antarctica. Shallow groundwater can be present in coastal regions at higher latitudes during the Antarctic summer. Perched groundwater atop ice-cemented permafrost occurs on Seabee Hook, Cape Hallett, at depths from 5 to 80 cm below the soil surface. Compared with terrestrial water from other sites in Antarctica, the groundwater was high in salt and nutrients, reflecting proximity to the sea and ornithogenic soil. Microbial communities in groundwater samples from Seabee Hook exhibited aerobic metabolism of14C-acetate at 5 °C. Numbers of culturable aerobic heterotrophs in the samples ranged from <10 to ca. 1 × 106 colony-forming units·mL–1, and similar numbers of microaerophiles and nitrate reducers were detected. In contrast, numbers of nitrifiers, sulfate reducers, and iron reducers were up to 1000-fold lower. All cultures were incubated at 5 °C. Aerobic heterotrophic bacteria isolated from the groundwater were assigned to Actinobacteria, Proteobacteria, or Bacteroidetes. The isolates were most similar to cultured bacteria from Antarctic soil or sediment and were cold, salt, and alkaline pH tolerant, indicating they are adapted to in situ conditions.
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Gao, Yifan, Yuan Li, Yan Yang, Jia Feng, Li Ji, and Shulian Xie. "Effects of Trophic Modes on the Lipid Accumulation of Parachlorella kessleri TY." Fermentation 9, no. 10 (October 3, 2023): 891. http://dx.doi.org/10.3390/fermentation9100891.
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Microalgae are considered to have great potential as a source of biodiesel. Currently, algae culture has three different trophic modes, i.e., autotrophic, heterotrophic, and mixotrophic, but not all kinds of algae are suitable for heterotrophic and mixotrophic cultivation. In this study, Parachlorella kessleri TY, screened from the soil of Shanxi Province, was heterotrophically and mixotrophically treated with glucose as an organic carbon source, and the physiological and biochemical levels of its growth and lipid accumulation were measured. The results showed that the highest biomass and biomass productivity (1.53 g·L−1 and 218.57 mg·L−1d−1) were attained by P. kessleri TY under mixotrophic cultivation. In comparison, the lowest (0.55 g·L−1 and 78.57 mg·L−1d−1) were attained under heterotrophic culture. Furthermore, heterotrophic and mixotrophic conditions could accumulate more lipids (total lipid contents: 39.85% and 42.92%, respectively), especially the neutral lipids. Additionally, the contents of fatty acids suitable for use as biodiesel raw materials in both heterotrophic and mixotrophic cultures increased, especially the content of C18:1. Moreover, due to the lower biomass of heterotrophic cultivation compared with that from mixotrophic cultivation, the total lipid productivity of heterotrophic conditions decreased. In summary, the conditions of mixotrophic cultivation are more conducive to the accumulation of lipids in P. kessleri TY.
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Nicodemou, Andonia, Michalis Kallis, Anastasia Agapiou, Androulla Markidou, and Michalis Koutinas. "The Effect of Trophic Modes on Biomass and Lipid Production of Five Microalgal Strains." Water 14, no. 2 (January 14, 2022): 240. http://dx.doi.org/10.3390/w14020240.
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Five microalgae strains, namely Isochrysis galbana, Microchloropsis gaditana, Scenedesmus obliquus, Nannochloropsis oculata and Tetraselmis suecica, were selected as potential candidates for polyunsaturated fatty acids’ production, evaluating biomass productivity and their capacity to accumulate high lipid contents under different trophic modes. Microalgae strains were cultivated in the presence of 1% glucose using mixotrophic and heterotrophic conditions, while autotrophic cultures served as control experiments. The results demonstrate that S. obliquus performed the highest biomass productivity that reached 0.13 and 0.14 g L−1 d−1 under mixotrophic and heterotrophic conditions, respectively. I. galbana and S. obliquus utilized elevated contents of glucose in mixotrophy, removing 55.9% and 95.6% of the initial concentration of the carbohydrate, respectively, while glucose consumption by the aforementioned strains also remained high under heterotrophic cultivation. The production of lipids was maximal for I. galbana in mixotrophy and S. obliquus in heterotrophy, performing lipid productivities of 24.85 and 22.77 mg L−1 d−1, respectively. The most abundant saturated acid detected for all microalgae strains evaluated was palmitic acid (C16:0), while oleic and linolenic acids (C18:1n9c/C18:3n3) comprised the most abundant unsaturated fatty acids. I. galbana performed the highest linoleic acid (C18:2n6c) content under heterotrophic nutrition, which reached 87.9 mg g−1 of ash-free dry weight. Among the microalgae strains compared, the biomass and lipid production monitored for I. galbana and S. obliquus confirm that both strains could serve as efficient bioproducers for application in algal biorefineries.
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Puzanskiy, Roman K., Daria A. Romanyuk, Anastasia A. Kirpichnikova, Vladislav V. Yemelyanov, and Maria F. Shishova. "Plant Heterotrophic Cultures: No Food, No Growth." Plants 13, no. 2 (January 17, 2024): 277. http://dx.doi.org/10.3390/plants13020277.
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Plant cells are capable of uptaking exogenous organic substances. This inherited trait allows the development of heterotrophic cell cultures in various plants. The most common of them are Nicotiana tabacum and Arabidopsis thaliana. Plant cells are widely used in academic studies and as factories for valuable substance production. The repertoire of compounds supporting the heterotrophic growth of plant cells is limited. The best growth of cultures is ensured by oligosaccharides and their cleavage products. Primarily, these are sucrose, raffinose, glucose and fructose. Other molecules such as glycerol, carbonic acids, starch, and mannitol have the ability to support growth occasionally, or in combination with another substrate. Culture growth is accompanied by processes of specialization, such as elongation growth. This determines the pattern of the carbon budget. Culture ageing is closely linked to substrate depletion, changes in medium composition, and cell physiological rearrangements. A lack of substrate leads to starvation, which results in a decrease in physiological activity and the mobilization of resources, and finally in the loss of viability. The cause of the instability of cultivated cells may be the non-optimal metabolism under cultural conditions or the insufficiency of internal regulation.
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Şentürk, Tuğba. "Effect of different trophic cultures on the amount of total carbohydrate and chlorophyll of Oscillatoria sp." Aquatic Research 7, no. 3 (2024): 144–54. http://dx.doi.org/10.3153/ar24013.
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Cyanobacteria (blue-green microalgae) is a gram-negative prokaryotic autotroph found in natural waters that plays a pivotal role in biochemical cycles. The present investigation proposed to study the potential of using different concentrations of glucose as the carbon substrate to produce microalgal biomass and biochemical components, such as photosynthetic pigments and total carbohydrates (CH) by Oscillatoria sp. The cyanobacteria were collected, and the isolated colony was found to be Oscillatoria sp., and it was grown in BG-11 medium for mass cultivation. Then, the centrifuged biomass was weighed and used to extract bioactive compounds. Oscillatoria sp. cells were cultured in three different tropic cultures (phototrophic, heterotrophic and mixotrophic) under controlled laboratory conditions with continuous light illumination or unillumination and aeration. Chl–a and total C.H. contents were also evaluated after 120 hrs. The recorded optical density of Oscillatoria was increased from 0.6798 ±0.01 at 660 nm and 0.5847 ±0.01 at 750 nm after 24 hrs to 1.2174±0.002 at 680nm and 1.0243±0.01 at 730nm at the end of 120hrs of the experiment. According to analysis results, the mean amount of Chl-a and Total C.H. of Oscillatoria sp. biomass was determined as 0.5132 µg L-1 and 3.5715 mg mL-1 under the phototrophic culture (absence of glucose), respectively. Under the mixotrophic culture (presence of light), the experimental results showed that the chl-a content was calculated as 0.1770, 0.3380 and 0.7098 µg L-1. In contrast, the total C.H. was calculated as 3.6150, 7.9129 and 11.3191 mg mL-1 in the presence of 2.5, 5 and 10 g L-1 glucose, respectively. Under the heterotrophic culture (absence of light), the results showed that the chl-a content was 0.2366, 0.2456 and 0.2346 µg L-1 while the total C.H. was 4.2969, 8.0990 and 11.5861 mg m L-1 in the presence of 2.5, 5 and 10 g L-1 glucose, respectively. The experimental results showed that the total C.H. content was increased from 3.5715 to 11.58 61 mg mL-1 in the heterotrophic (the absence of light and the presence of 10 g L-1 glucose) BG-11 culture conditions. The chlorophyll-a content was increased from 0.1770 µg L-1 to 0.7098 µg L-1 in the mixotrophic (the presence of glucose and light) BG-11 culture conditions. As a result of the experiment, it was determined that the most suitable culture in terms of total carbohydrate and growth rate was mixotrophic and heterotrophic BG-11 (10 g L-1 glucose) culture condition, and in terms of chl-a was mixotrophic culture (10 g L-1 glucose).
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Dong, Kaiyi, Ying Wang, Wenjing Zhang, and Qian Li. "Prevalence and Preferred Niche of Small Eukaryotes with Mixotrophic Potentials in the Global Ocean." Microorganisms 12, no. 4 (April 8, 2024): 750. http://dx.doi.org/10.3390/microorganisms12040750.
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Unicellular eukaryotes that are capable of phago-mixotrophy in the ocean compete for inorganic nutrients and light with autotrophs, and for bacterial prey with heterotrophs. In this study, we ask what the overall prevalence of eukaryotic mixotrophs in the vast open ocean is, and how the availability of inorganic nutrients, light, and prey affects their relative success. We utilized the Tara Oceans eukaryotic 18S rRNA gene and environmental context variables dataset to conduct a large-scale field analysis. We also performed isolate-based culture experiments to verify growth and nutritional resource relationships for representative mixotrophic taxa. The field analysis suggested that the overall prevalence of mixotrophs were negatively correlated with nutrient concentrations and positively associated with light availability. Concentrations of heterotrophic bacteria as a single variable also presented a positive correlation with mixotrophic prevalence, but to a lesser extent. On the other hand, the culture experiments demonstrated a taxa-specific relationship between mixotrophic growth and nutrition resources, i.e., the growth of one group was significantly dependent on light availability, while the other group was less affected by light when they received sufficient prey. Both groups were capable of growing efficiently with low inorganic nutrients when receiving sufficient prey and light. Therefore, our field analysis and culture experiments both suggest that phago-mixotrophy for ocean eukaryotes is seemingly an efficient strategy to compensate for nutrient deficiency but unnecessary to compensate for light scarcity. This study collectively revealed a close relationship between abiotic and biotic nutritional resources and the prevalence of trophic strategies, shedding light on the importance of light and nutrients for determining the competitive success of mixotrophs versus autotrophic and heterotrophic eukaryotes in the ocean.
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Childress, H., B. Sullivan, J. Kaur, and R. Karthikeyan. "Effects of ultraviolet light disinfection on tetracycline-resistant bacteria in wastewater effluents." Journal of Water and Health 12, no. 3 (December 24, 2013): 404–9. http://dx.doi.org/10.2166/wh.2013.257.
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The ubiquitous use of antibiotics has led to an increasing number of antibiotic-resistant bacterial strains, including strains that are multidrug-resistant, pathogenic, or both. There is also evidence to suggest that antibiotic resistance genes (ARGs) spread to the environment, humans, and animals through wastewater effluents. The overall objective of this study was to investigate the effect of ultraviolet (UV) light disinfection on antibiotic-resistant bacteria. Wastewater effluent samples from a wastewater treatment plant (WWTP) in Texas were evaluated for differences in tetracycline-resistant bacteria before and after UV treatment. The effects of photoreactivation or dark repair on the reactivation of bacteria present in WWTP effluent after UV disinfection were also examined. Culture-based methods were used to characterize viable heterotrophic, tetracycline-resistant heterotrophic, Escherichia coli, and tetracycline-resistant E. coli bacteria present before and after UV treatment. UV disinfection was found to be as effective at reducing concentrations of resistant heterotrophs and E. coli, as it was at reducing total bacterial concentrations. The lowest survival ratio following UV disinfection was observed in tetracycline-resistant E. coli showing particular susceptibility to UV treatment. Photoreactivation and dark repair rates were found to be comparable to each other for all bacterial populations.
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Lehman, R. Michael, Francisco F. Roberto, Drummond Earley, Debby F. Bruhn, Susan E. Brink, Sean P. O'Connell, Mark E. Delwiche, and Frederick S. Colwell. "Attached and Unattached Bacterial Communities in a 120-Meter Corehole in an Acidic, Crystalline Rock Aquifer." Applied and Environmental Microbiology 67, no. 5 (May 1, 2001): 2095–106. http://dx.doi.org/10.1128/aem.67.5.2095-2106.2001.
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ABSTRACT The bacteria colonizing geologic core sections (attached) were contrasted with those found suspended in the groundwater (unattached) by examining the microbiology of 16 depth-paired core and groundwater samples using a suite of culture-independent and culture-dependent analyses. One hundred twenty-two meters was continuously cored from a buried chalcopyrite ore hosted in a biotite-quartz-monzonite porphyry at the Mineral Park Mine near Kingman, Ariz. Every fourth 1.5-m core was acquired using microbiologically defensible methods, and these core sections were aseptically processed for characterization of the attached bacteria. Groundwater samples containing unattached bacteria were collected from the uncased corehole at depth intervals corresponding to the individual cores using an inflatable straddle packer sampler. The groundwater was acidic (pH 2.8 to 5.0), with low levels of dissolved oxygen and high concentrations of sulfate and metals, including ferrous iron. Total numbers of attached cells were less than 105 cells g of core material−1 while unattached cells numbered about 105 cells ml of groundwater−1. Attached and unattached acidophilic heterotrophs were observed throughout the depth profile. In contrast, acidophilic chemolithotrophs were not found attached to the rock but were commonly observed in the groundwater. Attached communities were composed of low numbers (<40 CFU g−1) of neutrophilic heterotrophs that exhibited a high degree of morphologic diversity, while unattached communities contained higher numbers (ca. 103 CFU ml−1) of neutrophilic heterotrophs of limited diversity. Sulfate-reducing bacteria were restricted to the deepest samples of both core and groundwater. 16S ribosomal DNA sequence analysis of attached, acidophilic isolates indicated that organisms closely related to heterotrophic, acidophilic mesophiles such as Acidiphilium organovorum and, surprisingly, to the moderately thermophilic Alicyclobacillus acidocaldariuswere present. The results indicate that viable (but possibly inactive) microorganisms were present in the buried ore and that there was substantial distinction in biomass and physiological capabilities between attached and unattached populations.
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Wu, Kangping, Yilin Fang, Biyuan Hong, Yihui Cai, Honglei Xie, Yunpu Wang, Xian Cui, et al. "Enhancement of Carbon Conversion and Value-Added Compound Production in Heterotrophic Chlorella vulgaris Using Sweet Sorghum Extract." Foods 11, no. 17 (August 25, 2022): 2579. http://dx.doi.org/10.3390/foods11172579.
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High-cost carbon sources are not economical or sustainable for the heterotrophic culture of Chlorella vulgaris. In order to reduce the cost, this study used sweet sorghum extract (SE) and its enzymatic hydrolysate (HSE) as alternative carbon sources for the heterotrophic culture of Chlorella vulgaris. Under the premise of the same total carbon concentration, the value-added product production performance of Chlorella vulgaris cultured in HSE (supplemented with nitrogen sources and minerals) was much better than that in the glucose medium. The conversion rate of the total organic carbon and the utilization rate of the total nitrogen were both improved in the HSE system. The biomass production and productivity using HSE reached 2.51 g/L and 0.42 g/L/d, respectively. The production of proteins and lipids using HSE reached 1.17 and 0.35 g/L, respectively, and the production of chlorophyll-a, carotenoid, and lutein using HSE reached 30.42, 10.99, and 0.88 mg/L, respectively. The medium cost using HSE decreased by 69.61% compared to glucose. This study proves the feasibility and practicability of using HSE as a carbon source for the low-cost heterotrophic culture of Chlorella vulgaris.
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Jia, Shi Ru, Zhen Ding, Ning Tan, Nan Wang, Pei Pei Han, and Nan Nan Yuan. "Heterotrophic Fed-Batch Cultures of Nostoc flagelliforme and Production of Extracellular Polysaccharides." Advanced Materials Research 518-523 (May 2012): 5468–71. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.5468.
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Nostoc flagelliforme is a kind of terrestrial cyanobacterium with high economic value. Dissociated cells, which separated from a natural colony of N. flagelliforme, could be cultivated heterotrophically in the darkness on xylose and glucose under fed-batch culture conditions. Growth and extracellular polysaccharides (EPS) production in different cultures are investigated. At harvest time, the cultures contain 1.215 g•L-1 of biomass and 122.5 mg•L-1 of EPS respectively. The gravimetric EPS production rate is 17.5 mg•g-1•day-1, which is 1.65 times higher than previously reported results for heterotrophic Nostoc flagelliforme grown on xylose batch culture.
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Tisserat, Brent, and Robert Silman. "Growth of Plant Tissue Cultures in Ultra-high Levels of Carbon Dioxide under Autotrophic and Heterotrophic Conditions." HortScience 31, no. 4 (August 1996): 587e—587. http://dx.doi.org/10.21273/hortsci.31.4.587e.
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A comparative study was undertaken to determine the influence of lighting, carbohydrate concentrations and ultra-high levels of CO2, i.e., >10,000 ppm, on sterile culture growth. Past CO2-sterile studies have confirmed that elevation of CO2 to as high as 1000 ppm resulted in beneficial growth. Within special constructed chambers, tissue cultures were given a variety of CO2 levels for 12–16 hours/day using artificial lighting and natural sunlight. Several different plants (lettuce, beans, pine) and plant culture types were grown in CO2-enriched environments, ranging from 350 to 50,000 ppm. In almost all cases, plant tissue cultures not only tolerated but exhibited enhanced growth using ultra-high levels of CO2. For example, lettuce cultures were found to grow 2 to 4 times faster under ultra-high CO2. levels than under normal atmospheric CO2 levels, i.e., 350 ppm. Natural sunlight was found to be suitable for sterile culture growth. Modes of administration of CO2 in vitro and gas permeability of various culture vessels are presented.
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Inamori, Yuhei, Xiao-Lei Wu, and Motoyuki Mizuochi. "N2O producing capability of nitrosomonas europaea, nitrobacter winogradskyi and alcaligenes faecalis." Water Science and Technology 36, no. 10 (November 1, 1997): 65–72. http://dx.doi.org/10.2166/wst.1997.0360.
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Nitrosomonas europaea, Nitrobacter winogradskyi and Alcaligenes faecalis—typical ammonia-oxidizer, nitrite-oxidizer and heterotrophic nitrifier were immobilized in PVA gel and employed in the study. Continuous experiments were conducted in their pure and mixed cultures with DO concentrations in the cultures kept at 4, 2, 0.5 mg·l−1. Comparisons among N2O emission from different cultures were made to show their N2O producing capabilities. Results showed that: compared with N. europaea and A. faecalis, N. winogradskyi produced negligible N2O. On the other hand, N. europaea had the highest N2O producing ability. Unit N. europaea produced N2O 18–53 times higher than unit A. faecalis did. However, due to the higher population of A. faecalis, N2O production of the A. faecalis culture was higher than that of the N. europaea culture when DO concentration in the cultures was 2 mg·l−1; whereas, N2O yields of the A. faecalis culture were smaller than those of the N. europaea culture at DO concentrations of 4 and 0.5 mg·l−1. N2O emitted from most the mixed cultures was lower than that from pure cultures under the experimental conditions.
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Sorokin, Dimitry Y., Tatyana P. Tourova, Anatoly M. Lysenko, and J. Gijs Kuenen. "Microbial Thiocyanate Utilization under Highly Alkaline Conditions." Applied and Environmental Microbiology 67, no. 2 (February 1, 2001): 528–38. http://dx.doi.org/10.1128/aem.67.2.528-538.2001.
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ABSTRACT Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS−) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate. The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source. Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (theHalomonas group for the heterotrophs and the genusThioalkalivibrio for autotrophs). The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy. These bacteria could be enriched on mineral medium with thiocyanate at pH 10. Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher. Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio. The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide. Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genusThioalkalivibrio according to a phylogenetic analysis. The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase activity which converted cyanate (CNO−) to ammonia and CO2. On the other hand, cyanase activity either was absent or was present at very low levels in the autotrophic strains grown on thiocyanate as the sole energy and N source. As a result, large amounts of cyanate were found to accumulate in the media during utilization of thiocyanate at pH 10 in batch and thiocyanate-limited continuous cultures. This is a first direct proof of a “cyanate pathway” in pure cultures of thiocyanate-degrading bacteria. Since it is relatively stable under alkaline conditions, cyanate is likely to play a role as an N buffer that keeps the alkaliphilic bacteria safe from inhibition by free ammonia, which otherwise would reach toxic levels during dissimilatory degradation of thiocyanate.
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Bhattacharyya, Saswati, B. K. Chakrabarty, A. Das, P. N. Kundu, and P. C. Banerjee. "Acidiphilium symbioticum sp.nov., an acidophilic heterotrophic bacterium from Thiobacillus ferrooxidans cultures isolated from Indian mines." Canadian Journal of Microbiology 37, no. 1 (January 1, 1991): 78–85. http://dx.doi.org/10.1139/m91-012.
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Two cultures of Thiobacillus ferrooxidans enriched from Indian mine samples and grown autotrophically on FeSO4 – basal salts medium for periods ranging from several months to years contained acidophilic, heterotrophic bacterial contaminants. The heterotrophs (strains KM2 and H8) were isolated by selective growth in a mineral salts – glucose – yeast extract medium of pH 3 and were purified as single colonies on an agarose medium. Mannose, galactose, sucrose, lactose, citrate, mannitol, and glycerol supported the growth of these strains in the presence of yeast extract. The heterotrophs grew poorly or failed to grow in media without yeast extract. They could not grow autotrophically with Fe2+, or with sulfur and its oxidizable derivatives, as the sole source of energy. Although they exhibited many characteristics of the genus Acidiphilium, they differed from Acidiphilium cryptum and other species of this genus in some physiological properties, notably in their ability to grow at higher glucose (5%, w/v) and Mn2+ (20 mM) concentrations. The G+C mol% contents (58.8 and 60.2) of strains KM2 and H8, respectively, determined from melting temperature (Tm) values were close to that of A. cryptum (62.7%). Strains KM2 and H8 showed 70–80% DNA homology with each other and about 60% with A. cryptum. All of the strains, including A. cryptum, responded similarly to several metal ions and antibiotics. SDS–PAGE of whole-cell proteins exhibited striking similarity between these two isolated strains, which were unlike that of A. cryptum. The strains were also agglutinated with a few common lectins and differed strongly from A. cryptum in respect to wheat-germ agglutinin and concanavalin A. Considering all these characteristics, we propose that strains KM2 and H8 be designated as a new species: Acidiphilium symbioticum. The type strain of A. symbioticum is strain KM2 (= MTCC 566). Key words: Acidiphilium symbioticum, Acidiphilium cryptum, Thiobacillus ferrooxidans, acidophilic bacteria.
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Ronan, Patrick, Otini Kroukamp, Steven N. Liss, and Gideon Wolfaardt. "Interaction between CO2-consuming autotrophy and CO2-producing heterotrophy in non-axenic phototrophic biofilms." PLOS ONE 16, no. 6 (June 15, 2021): e0253224. http://dx.doi.org/10.1371/journal.pone.0253224.
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As the effects of climate change become increasingly evident, the need for effective CO2 management is clear. Microalgae are well-suited for CO2 sequestration, given their ability to rapidly uptake and fix CO2. They also readily assimilate inorganic nutrients and produce a biomass with inherent commercial value, leading to a paradigm in which CO2-sequestration, enhanced wastewater treatment, and biomass generation could be effectively combined. Natural non-axenic phototrophic cultures comprising both autotrophic and heterotrophic fractions are particularly attractive in this endeavour, given their increased robustness and innate O2-CO2 exchange. In this study, the interplay between CO2-consuming autotrophy and CO2-producing heterotrophy in a non-axenic phototrophic biofilm was examined. When the biofilm was cultivated under autotrophic conditions (i.e. no organic carbon), it grew autotrophically and exhibited CO2 uptake. After amending its growth medium with organic carbon (0.25 g/L glucose and 0.28 g/L sodium acetate), the biofilm rapidly toggled from net-autotrophic to net-heterotrophic growth, reaching a CO2 production rate of 60 μmol/h after 31 hours. When the organic carbon sources were provided at a lower concentration (0.125 g/L glucose and 0.14 g/L sodium acetate), the biofilm exhibited distinct, longitudinally discrete regions of heterotrophic and autotrophic metabolism in the proximal and distal halves of the biofilm respectively, within 4 hours of carbon amendment. Interestingly, this upstream and downstream partitioning of heterotrophic and autotrophic metabolism appeared to be reversible, as the position of these regions began to flip once the direction of medium flow (and hence nutrient availability) was reversed. The insight generated here can inform new and important research questions and contribute to efforts aimed at scaling and industrializing algal growth systems, where the ability to understand, predict, and optimize biofilm growth and activity is critical.
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Amaral, J. A., A. Ekins, S. R. Richards, and R. Knowles. "Effect of Selected Monoterpenes on Methane Oxidation, Denitrification, and Aerobic Metabolism by Bacteria in Pure Culture." Applied and Environmental Microbiology 64, no. 2 (February 1, 1998): 520–25. http://dx.doi.org/10.1128/aem.64.2.520-525.1998.
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ABSTRACT Selected monoterpenes inhibited methane oxidation by methanotrophs (Methylosinus trichosporium OB3b, Methylobacter luteus), denitrification by environmental isolates, and aerobic metabolism by several heterotrophic pure cultures. Inhibition occurred to various extents and was transient. Complete inhibition of methane oxidation by Methylosinus trichosporium OB3b with 1.1 mM (−)-α-pinene lasted for more than 2 days with a culture of optical density of 0.05 before activity resumed. Inhibition was greater under conditions under which particulate methane monooxygenase was expressed. No apparent consumption or conversion of monoterpenes by methanotrophs was detected by gas chromatography, and the reason that transient inhibition occurs is not clear. Aerobic metabolism by several heterotrophs was much less sensitive than methanotrophy was;Escherichia coli (optical density, 0.01), for example, was not affected by up to 7.3 mM (−)-α-pinene. The degree of inhibition was monoterpene and species dependent. Denitrification by isolates from a polluted sediment was not inhibited by 3.7 mM (−)-α-pinene, γ-terpinene, or β-myrcene, whereas 50 to 100% inhibition was observed for isolates from a temperate swamp soil. The inhibitory effect of monoterpenes on methane oxidation was greatest with unsaturated, cyclic hydrocarbon forms [e.g., (−)-α-pinene, (S)-(−)-limonene, (R)-(+)-limonene, and γ-terpinene]. Lower levels of inhibition occurred with oxide and alcohol derivatives [(R)-(+)-limonene oxide, α-pinene oxide, linalool, α-terpineol] and a noncyclic hydrocarbon (β-myrcene). Isomers of pinene inhibited activity to different extents. Given their natural sources, monoterpenes may be significant factors affecting bacterial activities in nature.
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Nishimura, Takao, Raghunath Ramu Pachpande, and Tatsuichi Iwamura. "A heterotrophic synchronous culture of Chlorella." Cell Structure and Function 13, no. 3 (1988): 207–15. http://dx.doi.org/10.1247/csf.13.207.
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Charria-Girón, Esteban, Vanessa Amazo, Daniela De Angulo, Eliana Hidalgo, María Francisca Villegas-Torres, Frank Baganz, and Nelson H. Caicedo Ortega. "Strategy for Managing Industrial Anaerobic Sludge through the Heterotrophic Cultivation of Chlorella sorokiniana: Effect of Iron Addition on Biomass and Lipid Production." Bioengineering 8, no. 6 (June 10, 2021): 82. http://dx.doi.org/10.3390/bioengineering8060082.
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Microalgae provides an alternative for the valorization of industrial by-products, in which the nutritional content varies substantially and directly affects microalgae system performance. Herein, the heterotrophic cultivation of Chlorella sorokiniana was systematically studied, allowing us to detect a nutritional deficiency other than the carbon source through assessing the oxygen transfer rate for glucose or acetate fermentation. Consequently, a mathematical model of the iron co-limiting effect on heterotrophic microalgae was developed by exploring its ability to regulate the specific growth rate and yield. For instance, higher values of the specific growth rate (0.17 h−1) compared with those reported for the heterotrophic culture of Chlorella were obtained due to iron supplementation. Therefore, anaerobic sludge from an industrial wastewater treatment plant (a baker’s yeast company) was pretreated to obtain an extract as a media supplement for C. sorokiniana. According to the proposed model, the sludge extract allowed us to supplement iron values close to the growth activation concentration (KFe ~12 mg L−1). Therefore, a fed-batch strategy was evaluated on nitrogen-deprived cultures supplemented with the sludge extract to promote biomass formation and fatty acid synthesis. Our findings reveal that nitrogen and iron in sludge extract can supplement heterotrophic cultures of Chlorella and provide an alternative for the valorization of industrial anaerobic sludge.
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Fu, Yunlei, Lanbo Yi, Shufang Yang, Xue Lu, Bin Liu, Feng Chen, Junchao Huang, Kawing Cheng, Han Sun, and Xiaolei Wu. "Light Induction of Seed Culture Accelerates Lutein Accumulation in Heterotrophic Fermentation of Chlorella protothecoides CS-41." Fermentation 9, no. 8 (August 18, 2023): 768. http://dx.doi.org/10.3390/fermentation9080768.
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Microalgae are recognized as a promising and valuable source of lutein. However, the current two-stage method for lutein production has drawbacks, such as complex operations and a long cultivation time. Additionally, utilizing heterotrophic fermentation to cultivate microalgae for lutein production leads to low lutein content due to the absence of light. In this study, we proposed a novel cultivation method that involves light induction of the seed culture to enhance lutein production during the heterotrophic cultivation phase of Chlorella protothecoides CS-41. To gain comprehensive insights into the underlying mechanisms of this method, we conducted qualitative and quantitative analyses of specific metabolites related to central carbon metabolism. The results revealed that low-light induction of seeds exhibited higher carbon efficiency compared to cells continuously subjected to heterotrophic cultivation, which may explain the observed increase in biomass and lutein content in cultures. Cultures after low-light induction of seed exhibited significantly higher lutein content (2.71 mg/g), yield (66.49 mg/L) and productivity (8.59 mg/L/d) compared to those consistently cultivated under heterotrophic conditions (2.37 mg/g, 37.45 mg/L, 4.68 mg/L/d). This cultivation strategy effectively enhances lutein yields, reduces production costs and holds the potential for broader application in other algal species for pigment production.
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Zhang, Han, Jiaxin Shi, Cuibai Chen, Meng Yang, Jianping Lu, and Baogang Zhang. "Heterotrophic Bioleaching of Vanadium from Low-Grade Stone Coal by Aerobic Microbial Consortium." International Journal of Environmental Research and Public Health 19, no. 20 (October 17, 2022): 13375. http://dx.doi.org/10.3390/ijerph192013375.
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Bioleaching is a viable method that assists in increasing the vanadium output in an economical and environmentally friendly manner. Most bioleaching is conducted by pure cultures under autotrophic conditions, which frequently require strong acidity and produce acid wastewater. However, little is known about heterotrophic bioleaching of vanadium by mixed culture. This study investigated the bioleaching of vanadium from low-grade stone coal by heterotrophic microbial consortium. According to the results, vanadium was efficiently extracted by the employed culture, with the vanadium recovery percentage in the biosystem being 7.24 times greater than that in the control group without inoculum. The average vanadium leaching concentration reached 680.7 μg/L in the first three cycles. The kinetic equation indicated that the main leaching process of vanadium was modulated by a diffusion process. Scanning electron microscopy revealed traces of bacterial erosion with fluffy structures on the surface of the treated stone coal. X-ray photoelectron spectroscopy confirmed the reduction of the vanadium content in the stone coal after leaching. Analysis of high-throughput 16S rRNA gene sequencing revealed that the metal-oxidizing bacteria, Acidovorax and Delftia, and the heterotrophic-metal-resistant Pseudomonas, were significantly enriched in the bioleaching system. Our findings advance the understanding of bioleaching by aerobic heterotrophic microbial consortium and offer a promising technique for vanadium extraction from low-grade stone coals.
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Xie, Weiying, Xiaojie Li, Huo Xu, Feng Chen, Ka-Wing Cheng, Hongbin Liu, and Bin Liu. "Optimization of Heterotrophic Culture Conditions for the Microalgae Euglena gracilis to Produce Proteins." Marine Drugs 21, no. 10 (September 29, 2023): 519. http://dx.doi.org/10.3390/md21100519.
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Euglena gracilis is one of the few permitted edible microalgae. Considering consumer acceptance, E. gracilis grown heterotrophically with yellow appearances have wider food industrial applications such as producing meat analogs than green cells. However, there is much room to improve the protein content of heterotrophic culture cells. In this study, the effects of nitrogen sources, temperature, initial pH, and C/N ratios on the protein production of E. gracilis were evaluated under heterotrophic cultivation. These results indicated that ammonium sulfate was the optimal nitrogen source for protein production. The protein content of E. gracilis cultured by ammonium sulfate increased by 113% and 44.7% compared with that cultured by yeast extract and monosodium glutamate, respectively. The manipulation of the low C/N ratio further improved E. gracilis protein content to 66.10% (w/w), which was 1.6-fold of that in the C/N = 25 group. Additionally, amino acid analysis revealed that the nitrogen-to-protein conversion factor (NTP) could be affected by nitrogen sources. A superior essential amino acid index (EAAI) of 1.62 and a balanced amino acid profile further confirmed the high nutritional value of E. gracilis protein fed by ammonium sulfate. This study highlighted the vast potency of heterotrophic cultured E. gracilis as an alternative dietary protein source.
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De la Hoz, H., A. Ben-Zvi, R. Burrell, and W. McCaffrey. "Optimization of Heterotrophic Microalgal Cultures." Journal of Biotechnology 150 (November 2010): 17. http://dx.doi.org/10.1016/j.jbiotec.2010.08.058.
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Alongi, Deborah A., Jeffrey P. Hill, and Matthew J. Germino. "Opportunistic heterotrophy in gametophytes of the homosporous fern Ceratopteris richardii." Botany 87, no. 8 (August 2009): 799–806. http://dx.doi.org/10.1139/b09-039.
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Fern gametophytes are extremely shade-tolerant, potentially existing for long periods under conditions of extreme light limitation. Many previous studies have demonstrated an increase in gametophyte growth and incidence of spontaneous transition to sporophyte morphology (apogamy) under culture on media containing exogenous sugar. However, these studies did not verify sugar uptake or quantify relative growth on media containing different sugar types. Here, we examine the extent of heterotrophy and underlying mechanisms of sugar transport in photosynthetic gametophytes of the fern Ceratopteris richardii Brongn. Exogenous sugar uptake, growth, and sugar transport were evaluated with assays of exogenous glucose depletion, experimental culture of gametophytes under different sugar and light conditions, and bioinformatic approaches. The glucose from the growth media was significantly depleted by gametophytes growing under all conditions, especially those in the dark compared with those exposed to higher light. Gametophyte area increased similarly when cultured on equimolar concentrations of either glucose or the disaccharide sucrose, likely due to preferential uptake of one of the monomers of sucrose. Although at least one gene with similarity to sucrose transporters is expressed in germinating spores, our results suggest a reliance on monosaccharide transport for exogenous sugar uptake. Glucose assimilation in both light and dark conditions constitutes nutritional opportunism and may enhance gametophyte survival in very low light.
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Santo, Gonçalo Espírito, Ana Barros, Margarida Costa, Hugo Pereira, Mafalda Trovão, Helena Cardoso, Bernardo Carvalho, et al. "Scenedesmus rubescens Heterotrophic Production Strategies for Added Value Biomass." Marine Drugs 21, no. 7 (July 19, 2023): 411. http://dx.doi.org/10.3390/md21070411.
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Microalgae attract interest worldwide due to their potential for several applications. Scenedesmus is one of the first in vitro cultured algae due to their rapid growth and handling easiness. Within this genus, cells exhibit a highly resistant wall and propagate both auto- and heterotrophically. The main goal of the present work is to find scalable ways to produce a highly concentrated biomass of Scenedesmus rubescens in heterotrophic conditions. Scenedesmus rubescens growth was improved at the lab-scale by 3.2-fold (from 4.1 to 13 g/L of dry weight) through medium optimization by response surface methodology. Afterwards, scale-up was evaluated in 7 L stirred-tank reactor under fed-batch operation. Then, the optimized medium resulted in an overall productivity of 8.63 g/L/day and a maximum biomass concentration of 69.5 g/L. S. rubescens protein content achieved approximately 31% of dry weight, similar to the protein content of Chlorella vulgaris in heterotrophy.
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Jehlička, Jan, Howell G. M. Edwards, Kateřina Osterrothová, Julie Novotná, Linda Nedbalová, Jiří Kopecký, Ivan Němec, and Aharon Oren. "Potential and limits of Raman spectroscopy for carotenoid detection in microorganisms: implications for astrobiology." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2030 (December 13, 2014): 20140199. http://dx.doi.org/10.1098/rsta.2014.0199.
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In this paper, it is demonstrated how Raman spectroscopy can be used to detect different carotenoids as possible biomarkers in various groups of microorganisms. The question which arose from previous studies concerns the level of unambiguity of discriminating carotenoids using common Raman microspectrometers. A series of laboratory-grown microorganisms of different taxonomic affiliation was investigated, such as halophilic heterotrophic bacteria, cyanobacteria, the anoxygenic phototrophs, the non-halophilic heterotrophs as well as eukaryotes (Ochrophyta, Rhodophyta and Chlorophyta). The data presented show that Raman spectroscopy is a suitable tool to assess the presence of carotenoids of these organisms in cultures. Comparison is made with the high-performance liquid chromatography approach of analysing pigments in extracts. Direct measurements on cultures provide fast and reliable identification of the pigments. Some of the carotenoids studied are proposed as tracers for halophiles, in contrast with others which can be considered as biomarkers of other genera. The limits of application of Raman spectroscopy are discussed for a few cases where the current Raman spectroscopic approach does not allow discriminating structurally very similar carotenoids. The database reported can be used for applications in geobiology and exobiology for the detection of pigment signals in natural settings.
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Steen, R. G. "Evidence for facultative heterotrophy in cultured zooxanthellae." Marine Biology 95, no. 1 (June 1987): 15–23. http://dx.doi.org/10.1007/bf00447480.
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León, María José, Ana B. Fernández, Rohit Ghai, Cristina Sánchez-Porro, Francisco Rodriguez-Valera, and Antonio Ventosa. "From Metagenomics to Pure Culture: Isolation and Characterization of the Moderately Halophilic Bacterium Spiribacter salinus gen. nov., sp. nov." Applied and Environmental Microbiology 80, no. 13 (April 18, 2014): 3850–57. http://dx.doi.org/10.1128/aem.00430-14.
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ABSTRACTRecent metagenomic studies on saltern ponds with intermediate salinities have determined that their microbial communities are dominated by bothEuryarchaeotaand halophilic bacteria, with a gammaproteobacterium closely related to the generaAlkalilimnicolaandArhodomonasbeing one of the most predominant microorganisms, making up to 15% of the total prokaryotic population. Here we used several strategies and culture media in order to isolate this organism in pure culture. We report the isolation and taxonomic characterization of this new, never before cultured microorganism, designated M19-40T, isolated from a saltern located in Isla Cristina, Spain, using a medium with a mixture of 15% salts, yeast extract, and pyruvic acid as the carbon source. Morphologically small curved cells (young cultures) with a tendency to form long spiral cells in older cultures were observed in pure cultures. The organism is a Gram-negative, nonmotile bacterium that is strictly aerobic, non-endospore forming, heterotrophic, and moderately halophilic, and it is able to grow at 10 to 25% (wt/vol) NaCl, with optimal growth occurring at 15% (wt/vol) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence comparison showed that strain M19-40Thas a low similarity with other previously described bacteria and shows the closest phylogenetic similarity with species of the generaAlkalilimnicola(94.9 to 94.5%),Alkalispirillum(94.3%), andArhodomonas(93.9%) within the familyEctothiorhodospiraceae. The phenotypic, genotypic, and chemotaxonomic features of this new bacterium showed that it constitutes a new genus and species, for which the nameSpiribacter salinusgen. nov., sp. nov., is proposed, with strain M19-40T(= CECT 8282T= IBRC-M 10768T= LMG 27464T) being the type strain.
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De la Hoz Siegler, H., A. Ben-Zvi, R. E. Burrell, and W. C. McCaffrey. "The dynamics of heterotrophic algal cultures." Bioresource Technology 102, no. 10 (May 2011): 5764–74. http://dx.doi.org/10.1016/j.biortech.2011.01.081.
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Azma, Mojtaba, Rosfarizan Mohamad, Raha Abdul Rahim, and Arbakariya B. Ariff. "Improved Protocol for the Preparation of Axenic Culture and Adaptation to Heterotrophic Cultivation." Open Biotechnology Journal 4, no. 1 (July 8, 2010): 36–46. http://dx.doi.org/10.2174/1874070701004010036.
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The effectiveness of various physical and chemical methods for the removal of contaminants from the microalgae, Tetraselmis suecica, culture was investigated. The information obtained was used as the basis for the development of improved protocol for the preparation of axenic culture to be adapted to heterotrophic cultivation. Repeated centrifugation and rinsing effectively removed the free bacterial contaminants from the microalgae culture while sonication helped to loosen up the tightly attached bacterial contaminants on the microalgae cells. Removal of bacterial spores was accomplished using a mixture of two antibiotics, 5 mg/mL vancomycine and 10 mg/mL neomycine. Walne medium formulation with natural seawater was preferred for the enhancement of growth of T. suecica. Adaptation of growth from photoautotrophic to heterotrophic conditions was achieved by the repeated cultivation of photoautotrophic culture with sequential reduction in illumination time, and finally the culture was inoculated into the medium containing 10 g/L glucose, incubated in total darkness to obtain heterotrophic cells. Changes in the morphology and composition of T. suecica cells during the adaptation from photoautotrophic to heterotrophic condition, as examined under Transmission Electron Microscope, were also reported.
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Xiao, Yibo, Xi He, Qi Ma, Yue Lu, Fan Bai, Junbiao Dai, and Qingyu Wu. "Photosynthetic Accumulation of Lutein in Auxenochlorella protothecoides after Heterotrophic Growth." Marine Drugs 16, no. 8 (August 16, 2018): 283. http://dx.doi.org/10.3390/md16080283.
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In order to enhance lutein accumulation and to explain the reasons for the difference in lutein accumulation under photoautotrophic and heterotrophic conditions, different culture modes and the associated transcriptome profiles were investigated in Auxenochlorella protothecoides. The heterotrophic-photoautotrophic transition culture mode was investigated for lutein accumulation, changing from organic carbon to increase biomass in dark fermentation to irradiation under nitrogen rich conditions. This strategy increased the lutein content 10 times along with chloroplast regeneration and little biomass loss in 48 h. The highest lutein productivity and production in the heterotrophic-photoautotrophic transition culture reached 12.36 mg/L/day and 34.13 mg/L respectively within seven days. Furthermore, compared to the photoautotrophic conditions, most genes involved in lutein biosynthesis and photosystem generation were down-regulated during heterotrophic growth. By contrast, two β-ring hydroxylases were transiently upregulated, while violaxanthin de-epoxidase and zeaxanthin epoxidase were mostly downregulated, which explained the extremely low lutein content of heterotrophic cells. Nevertheless, the lutein proportion in total carotenoids reached nearly 100%. This study is the first to our knowledge to report on a comparative transcriptome analysis of lutein biosynthesis, and it provides a promising strategy to boost lutein production in A. protothecoides.
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Mozumder, Md Salatul Islam, Laurens Goormachtigh, Linsey Garcia-Gonzalez, Heleen De Wever, and Eveline I. P. Volcke. "Modeling pure culture heterotrophic production of polyhydroxybutyrate (PHB)." Bioresource Technology 155 (March 2014): 272–80. http://dx.doi.org/10.1016/j.biortech.2013.12.103.
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