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Journal articles on the topic 'Exogenous source of carbon'

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Published: 4 June 2021
Last updated: 6 February 2022

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1

PEN˜UELAS, JOSEP. "HCO−3as an Exogenous Carbon Source for Aquatic BryophytesFontinalis antipyreticaandFissidens grandifrons." Journal of Experimental Botany 36, no. 3 (1985): 441–48. http://dx.doi.org/10.1093/jxb/36.3.441.

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2

Sun, Caili, Aabid Manzoor Shah, Junhuan Yang, Zongmin Wang, Lanlan Zhu, and Yuanda Song. "Transcriptome Analysis of Oleaginous Fungus Mucor circinelloides WJ11 in Response to Exogenous Soybean Oil as Carbon Source." Natural Product Communications 16, no. 6 (June 2021): 1934578X2110233. http://dx.doi.org/10.1177/1934578x211023366.

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Mucor circinelloides is an oleaginous fungus that utilizes a wide variety of carbon substrates for its growth. The different sources of carbon strongly influence the total lipid content of the fungus. These different carbon substrates are assimilated and dissimilated through different metabolic pathways before entering into the TAG synthesis pathway. In the present study, we attempted to explore the mechanism of ex-novo lipid biosynthesis in M. circinelloides WJ11 in response to exogenous plant oil as a carbon source through transcriptomic analysis. The lipid content of WJ11 grown in a media containing mixed soybean oil with glucose as a carbon source was up to 43.8%, an increase of 13.9% as compared to glucose alone as the carbon source. RNA-Seq analysis was performed to investigate global gene expression patterns in the oil-treated WJ11. Based on RNA-seq analysis, among the 4646 differentially expressed genes (DEGs), 2379 were up-regulated and 2267 down-regulated. The expression of acetyl-CoA synthetase, 6-phosphofructokinase, alcohol dehydrogenase (NADP+), fructose-bisphosphate aldolase, and pyruvate kinase was down-regulated while genes related to triglyceride synthesis were up-regulated. The majority of genes and pathways related to lipid biosynthesis were up-regulated indicating a diversion of metabolic pathways towards lipid biosynthesis. The data generated advance the genomic resources and provide insights into the mechanisms of ex-novo lipid accumulation in fungi that use exogenous oil as a carbon source.
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3

Francisco, Érika Cristina, Telma Teixeira Franco, Roger Wagner, and Eduardo Jacob-Lopes. "Assessment of different carbohydrates as exogenous carbon source in cultivation of cyanobacteria." Bioprocess and Biosystems Engineering 37, no. 8 (January 21, 2014): 1497–505. http://dx.doi.org/10.1007/s00449-013-1121-1.

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4

Francisco, E. C., E. Jacob-Lopes, and T. T. Franco. "Assessing the potential of disaccharides as exogenous carbon source in cultivation of cyanobacteria." New Biotechnology 29 (September 2012): S66. http://dx.doi.org/10.1016/j.nbt.2012.08.185.

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5

Suner, Selim. "Reply: Elevated SpCO is Most Commonly from an Exogenous Source of Carbon Monoxide." Journal of Emergency Medicine 37, no. 3 (October 2009): 310. http://dx.doi.org/10.1016/j.jemermed.2008.06.035.

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6

Ramírez-Godínez, Juan, Icela Beltrán-Hernández, Alejandro Álvarez-Hernández, Claudia Coronel-Olivares, Elizabeth Contreras-López, Maribel Quezada-Cruz, and Gabriela Vázquez-Rodríguez. "Evaluation of Natural Materials as Exogenous Carbon Sources for Biological Treatment of Low Carbon-to-Nitrogen Wastewater." BioMed Research International 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/754785.

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In the bacterial processes involved in the mitigation of nitrogen pollution, an adequately high carbon-to-nitrogen (C : N) ratio is key to sustain denitrification. We evaluated three natural materials (woodchips, barley grains, and peanut shells) as carbon sources for low C : N wastewater. The amount of organic matter released from these materials to aqueous media was evaluated, as well as their pollution swapping potential by measuring the release of total Kjeldahl nitrogen, N-NH4+,NO2-, andNO3-, and total phosphorous. Barley grains yielded the highest amount of organic matter, which also showed to be the most easily biodegradable. Woodchips and peanut shells released carbon rather steadily and so they would not require frequent replenishment from biological reactors. These materials produced eluates with lower concentrations of nutrients than the leachates from barley grains. However, as woodchips yielded lower amounts of suspended solids, they constitute an adequate exogenous source for the biological treatment of carbon-deficient effluents.
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7

Farrugia, G., S. M. Miller, A. Rich, X. Liu, M. D. Maines, J. L. Rae, and J. H. Szurszewski. "Distribution of heme oxygenase and effects of exogenous carbon monoxide in canine jejunum." American Journal of Physiology-Gastrointestinal and Liver Physiology 274, no. 2 (February 1, 1998): G350—G358. http://dx.doi.org/10.1152/ajpgi.1998.274.2.g350.

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Carbon monoxide (CO) has been postulated to be a messenger in the gastrointestinal tract. The aims of this study were to determine the distribution of heme oxygenase (HO), the source for endogenous CO in the canine jejunum, and to determine the effects of CO on jejunal circular smooth muscle cells. HO-2 isoform was present in a population of myenteric and submucosal neuronal cell bodies, in nerve fibers innervating the muscle layers, and in smooth muscle cells. HO-1 isozyme was not detected in the canine jejunum. Exogenous CO increased whole cell current by 285 ± 86%, hyperpolarized the membrane potential by 8.5 ± 2.9 mV, and increased guanosine 3′,5′-cyclic monophosphate (cGMP) levels in smooth muscle cells. 8-Bromo- cGMP also increased the whole cell current. The data suggest that endogenous activity of HO-2 may be a source of CO in the canine jejunum and that exogenously applied CO can modulate intestinal smooth muscle electrical activity. It is therefore reasonable to suggest a role for endogenously produced CO as a messenger in the canine jejunum.
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8

González-Hernández, Ana Isabel, Loredana Scalschi, Pilar García-Agustín, and Gemma Camañes. "Exogenous Carbon Compounds Modulate Tomato Root Development." Plants 9, no. 7 (July 3, 2020): 837. http://dx.doi.org/10.3390/plants9070837.

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NO3− is not only a nutrient, but also a signaling compound that plays an important role in several plant processes, like root development. The present study aimed to investigate the effect of three different exogenous C compounds (sucrose, glucose, 2-oxoglutarate) added to NO3− nutrition on C/N, auxin and antioxidant metabolisms in 10-day-old tomato seedlings. Sucrose and glucose supplementation enhanced primary root (PR) length, lateral root number and root density, while 2-oxoglutarate negatively affected them. This phenomenon was accompanied by a slight increase in NRT2.1 and GS1 gene expression, together with an increase in LAX2 and LAX3 and a decrease in LAX4 in the roots growing under sucrose and glucose sources. The addition of 2-oxoglutarate enhanced the expression of NiR, GDH, PEPC1, LAX1, LAX3 and the antioxidant gene SOD Cl. Taken together, these findings contribute to a better understanding of how these C sources can modulate N uptake and C/N, auxin and antioxidant gene expression, which could be useful for improving nitrogen use efficiency.
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9

Kowallik, Wolfgang, Meinolf Thiemann, Yi Huang, Gerard Mutumba, Lisa Beermann, Dagmar Broer, and Norbert Grotjohann. "Complete Sequence of Glycolytic Enzymes in the Mycorrhizal Basidiomycete, Suillus bovinus." Zeitschrift für Naturforschung C 53, no. 9-10 (October 1, 1998): 818–27. http://dx.doi.org/10.1515/znc-1998-9-1007.

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Axenic cultures of Suillus bovinus were cultivated in inorganic liquid medium with glucose as a carbon source at 25 °C and continuous supply of oxygen by aeration with compressed air in the dark. Exogenous fructose as sole carbon source yielded about 50% less increase in dry weight than glucose. This resulted from different uptake velocities. Sucrose as sole exogenous carbon source yielded no measurable increase in dry weight. In glucose cultures, activities of all glycolytic enzymes were found. Maximum specific activities varied largely (from about 60 [fructose 6-phosphate kinase] to about 20 000 [triosephosphate isomerase] nmoles · mg protein-1 · min-1). Apparent Km-values also varied over more than two orders of magnitude (0.035 mᴍ [pyruvate kinase] to 6.16 mᴍ [triosephosphate isomerase]). Fructose 6-phosphate kinase proved to be the fructose 2,6-bisphosphate-regulated type, aldolase the divalent cation-dependent (class II) type and glyceratephosphate mutase the glycerate 2,3-phosphate-independent type of the respective enzymes. Eight of the 10 enzymes exhibited pʜ-optima′ between 7.5-8.0. Triosephosphate isomerase and pyruvate kinase showed highest activities at pʜ 6.5. Regulatory sites within the glycolytic pathway of Suillus bovinus are discussed; fructose 6-phosphate kinase appears to be its main bottle neck.
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10

Tsai, C. Stan, Antonio J. Aveledo, Ian J. McDonald, and Byron F. Johnson. "Diauxic growth of the fission yeast Schizosaccharomyces pombe in mixtures of D-glucose and ethanol or acetate." Canadian Journal of Microbiology 33, no. 7 (July 1, 1987): 593–97. http://dx.doi.org/10.1139/m87-103.

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The fission yeast Schizosaccharomyces pombe was unable to utilize ethanol or acetate as its sole carbon source for growth. However, ethanol and acetate were utilized in the presence of D-glucose during diauxic growth. No mutants capable of utilizing ethanol or acetate as sole carbon source were isolated from cultures grown in glucose together with ethanol or acetate. Low concentrations of acetate facilitated growth with glucose, whereas high concentrations of ethanol or acetate were inhibitory. Growing cells readily took up [1-14C]ethanol and [1-14C]acetate. The exogenous [1-14C]acetate was initially incorporated into biomacromolecules which were subsequently catabolized.
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11

Maberly, Stephen C. "EXOGENOUS SOURCES OF INORGANIC CARBON FOR PHOTOSYNTHESIS BY MARINE MACROALGAE1." Journal of Phycology 26, no. 3 (September 1990): 439–49. http://dx.doi.org/10.1111/j.0022-3646.1990.00439.x.

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12

Zhong, Yuming, Hui Liu, Huankai Li, Qian Lu, and Yan Sun. "Does exogenous carbon source always promote algal biomass and nutrients removal in algal-bacterial wastewater remediation?" Journal of Cleaner Production 281 (January 2021): 125371. http://dx.doi.org/10.1016/j.jclepro.2020.125371.

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13

Sengmee, Dennapa, Benjamas Cheirsilp, Thanwadee Tachapattaweawrakul Suksaroge, and Poonsuk Prasertsan. "Biophotolysis-based hydrogen and lipid production by oleaginous microalgae using crude glycerol as exogenous carbon source." International Journal of Hydrogen Energy 42, no. 4 (January 2017): 1970–76. http://dx.doi.org/10.1016/j.ijhydene.2016.10.089.

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14

Park, S. K., S. C. Choi, and Y. K. Kim. "The rate of iron corrosion for different organic carbon sources during biofilm formation." Water Science and Technology 55, no. 8-9 (April 1, 2007): 489–97. http://dx.doi.org/10.2166/wst.2007.295.

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The effects of total organic carbon and biofilm on microbial corrosion were quantified using serum bottles in a 2×2 factorial design. Both organic carbon and biofilm bacteria had a significant effect on the iron corrosion rate, irrespective of the levels of the other variable (p=0.05). There was no evidence of interaction between organic carbon and biofilm bacteria. Within the tested levels, the addition of exogenous organic carbon increased the corrosion rate by an average of 3.838 mg dm−2 day−1 (mdd), but the presence of biofilm bacteria decreased the rate by an average of 2.305 mdd. More iron was released from the coupon in response to organic carbon. Powder x-ray diffractometry indicated that the scales deposited on the corroded iron surface consisted primarily of lepidocrocite (γ-FeOOH), magnetite (Fe3O4) and hematite (α-Fe2O3). Corrosion rates by different organic carbon sources, i.e. acetate, glucose and humic substances, were compared using an annular biofilm reactor. One-way ANOVA suggested that the effect of each carbon source on corrosion was not the same, with the iron corrosion rate highest for glucose, followed by acetate, humic substances and the control. Magnetite was a major constituent of the corrosion products scraped from iron slides. Examination of community-level physiological profile patterns on the biofilms indicated that acetate was a carbon source that could promote the metabolic and functional potentials of biofilm communities.
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15

Dongmei, Lang, Zhu Zitan, Qin Sijun, and Lyu Deguo. "Root architecture and nitrogen metabolism in roots of apple rootstock respond to exogenous glucose supply in low carbon soil." Plant, Soil and Environment 64, No. 5 (May 14, 2018): 240–46. http://dx.doi.org/10.17221/15/2018-pse.

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To investigate the response of root architecture and nitrogen metabolism of apple rootstock to glucose supply in low-carbon (C) soil, Malus baccata (L.) Borkh. in gravel soil was treated with glucose C equal to the soil microbial biomass carbon (MBC)-C value (G<sub>1</sub>), five times the soil MBC value (G<sub>2</sub>), or with no glucose (CK). The roots samples were harvested after treatments for 7, 15 and 30 days. The roots tended to become larger, more dichotomous and showed a larger link branching angle in G<sub>1</sub> and G<sub>2</sub> than in CK, especially in the G<sub>1</sub> treatment for 30 days. Plant height and biomass were increased by G1. Nitrate (NO<sub>3</sub><sup>–</sup>-N) and nitrite (NO<sub>2</sub><sup>–</sup>-N) contents were increased, but ammonium (NH<sub>4</sub><sup>+</sup>-N) concentration was decreased in the roots treated with G<sub>1</sub> and G<sub>2</sub> in all treatment periods. Also, the activities and transcript levels of nitrate reductase, glutamine synthetase, glutamate dehydrogenase, glutamate synthase were generally increased in roots treated with glucose, especially under G<sub>1</sub>. The activities of glutamic oxalacetic transaminases and glutamic-pyruvic transaminase were higher under G<sub>1</sub> than under either G<sub>2</sub> or CK. Exogenous carbon source that equals to the native MBC effectively regulated the root architecture and supported increasing nitrogen absorption and metabolism in plants growing under carbon-restricted conditions.
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16

Braga, Gilberto U. L., Ricardo H. R. Destéfano, and Claudio L. Messias. "Protease production during growth and autolysis of submerged Metarhizium anisopliae cultures." Revista de Microbiologia 30, no. 2 (April 1999): 107–13. http://dx.doi.org/10.1590/s0001-37141999000200004.

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The growth and autolysis of two strains of the entomopathogenic deuteromycete fungus Metarhizium anisopliae var. anisopliae were evaluated in medium containing casein or glucose as carbon source. Parameters such as economic coefficient and degree of autolysis were determined for each strain. Protease production was determined throughout the growth and autolysis phases of the cultures on medium under conditions of protease induction (in the presence of casein as sole source of carbon and nitrogen). The fungus was shown to utilize casein as a carbon/energy source in a more efficient manner than glucose. The autolysis shown by the strains was intense under both types of growth conditions, reaching up to 62.7% of the dry mass produced and started soon after the depletion of the exogenous carbon source. The relationship between the proteolytic activities of the two strains evaluated varied significantly (a maximum of 19.78 on the 5th day and a minimum of 2.03 on the 16th day of growth) during the various growth and autolysis phases, clearly showing that the difference between the growth curves and the difference in the kinetics of enzyme production may decisively affect the process of strain selection for protease production.
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17

Lear, Gavin, Susan J. Turner, and Gillian D. Lewis. "Effect of light regimes on the utilisation of an exogenous carbon source by freshwater biofilm bacterial communities." Aquatic Ecology 43, no. 2 (May 22, 2008): 207–20. http://dx.doi.org/10.1007/s10452-008-9193-8.

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18

Wang, Mo, Dongqing Zhang, Yong Li, Qinghe Hou, Yuying Yu, Jinda Qi, Weicong Fu, Jianwen Dong, and Yuning Cheng. "Effect of a Submerged Zone and Carbon Source on Nutrient and Metal Removal for Stormwater by Bioretention Cells." Water 10, no. 11 (November 12, 2018): 1629. http://dx.doi.org/10.3390/w10111629.

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A bioretention system is a low-impact and sustainable treatment facility for treating urban stormwater runoff. To meet or maintain a consistently satisfactory performance, especially in terms of increasing nitrogen removal efficiency, the introduction of a submerged (anoxic) zone (SZ) combined with a module-based carbon source (C) has been recommended. This study investigated the removal of nitrogen (N), phosphorus (P) and heavy metals with a retrofitted bioretention system. A significant (p < 0.05) removal enhancement of N as well as total phosphorus (TP) was observed, in the mesocosms with additions of exogenous carbon as opposed to those without such condition. However, even in the mesocosm with SZ alone (without exogenous C), TP removal showed significant enhancement. With regard to the effects of SZ depth on nutrient removal, the results showed that the removal of both N and P in module with a shallow SZ (200 mm) showed significant enhancement compared to that in module with a deep SZ (300 mm). Removal efficiencies greater than 93% were observed for all three heavy metals tested (Cu, Pb, and Zn) in all mesocosms, even in the bioretention module without an SZ or plants, and it indicated that adsorption by the filtration media itself is probably the most important removal mechanism. Only Cu (but not Pb or Zn) showed significantly enhanced removal in module with an SZ as compared to those without an SZ. Carbon source played a minor role in metal removal as no significant (p > 0.05) improvement was observed in module with C as compared to that without C. Based on these results, the incorporation of SZ with C in stormwater biofilters is recommended.
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19

Wolfaardt, G. M., J. R. Lawrence, R. D. Robarts, and D. E. Caldwell. "The role of interactions, sessile growth, and nutrient amendments on the degradative efficiency of a microbial consortium." Canadian Journal of Microbiology 40, no. 5 (May 1, 1994): 331–40. http://dx.doi.org/10.1139/m94-055.

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A degradative microbial consortium consisting of at least nine bacterial and one algal species was isolated from soil with diclofop methyl as the sole carbon source. In continuous flow culture, the presence of the algae increased diclofop methyl degradation and removal by 36%. Batch culture experiments with 14C-labeled diclofop methyl confirmed algal involvement in the mineralization of diclofop methyl as there was no significant difference in the amount of 14CO2 evolved by the bacterial consortium with and without the algal activity when the consortium was cultivated in the dark to inhibit algal growth, while 11% more 14CO2 was produced in the light by the algal–bacterial consortium. Pure cultures isolated from the bacterial consortium could not individually mineralize diclofop methyl as the sole carbon source. However, when supplied with an additional carbon source, two strains could mineralize diclofop methyl. Addition of either the complex growth medium, or a cell-free filtrate from the algal–bacterial consortium to batch systems containing 14C-labeled diclofop methyl resulted in a significant increase in the production of 14CO2 by the bacterial consortium, suggesting co-metabolism of diclofop methyl in the presence of a labile carbon source. Removal of diclofop methyl by the bacterial consortium was increased by 36% when a larger surface to volume ratio was provided by glass beads that allowed extensive biofilm formation. The requirement for exogenous carbon sources and the inability of isolated pure cultures to degrade diclofop methyl indicated that interspecies interactions are necessary for degradation. The positive effect of sessile growth suggested that spatial organization of cells may also be important for degradation.Key words: consortium, degradation, herbicide, microbial interactions.
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20

Li, Weina, and Fei He. "Infusion of Kupffer Cells Expanded in Vitro Ameliorated Liver Fibrosis in a Murine Model of Liver Injury." Cell Transplantation 30 (January 1, 2021): 096368972110040. http://dx.doi.org/10.1177/09636897211004090.

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Transfer of exogenous macrophages represents an alternative technique to treat liver fibrosis. At present, bone marrow-derived monocytes and stem cells are the main sources for exogenous macrophages. Kupffer cells (KCs) are the resident macrophages in the liver and play a critical role in the liver homeostasis and diseases. It is unclear whether infusion of KCs can treat liver fibrosis. In this study, we observed that granulocyte-macrophage colony stimulating factor (GM-CSF) could improve the purity of cultured KCs and significantly up-regulate the expression of Cluster of Differentiation 11b (CD11b). The most important point is that GM-CSF could significantly promote the proliferation of KCs in vitro. KCs expanded in vitro still had the potential of M1/M2 polarization and phagocytosis. Furthermore, infusion of these KCs could ameliorate liver fibrosis induced by carbon tetrachloride (CCl4) in mice. Together, our results suggest that KCs are likely to be another source for macrophage therapy.
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21

Munksgaard, Niels C., Anna V. McBeath, Philippa L. Ascough, Vladimir A. Levchenko, Alan Williams, and Michael I. Bird. "Partitioning of Microbially Respired CO2 Between Indigenous and Exogenous Carbon Sources During Biochar Degradation Using Radiocarbon and Stable Carbon Isotopes." Radiocarbon 61, no. 2 (November 5, 2018): 573–86. http://dx.doi.org/10.1017/rdc.2018.128.

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ABSTRACTPyrolized carbon in biochar can sequester atmospheric CO2 into soil to reduce impacts of anthropogenic CO2 emissions. When estimating the stability of biochar, degradation of biochar carbon, mobility of degradation products, and ingress of carbon from other sources must all be considered. In a previous study we tracked degradation in biochars produced from radiocarbon-free wood and subjected to different physico-chemical treatments over three years in a rainforest soil. Following completion of the field trial, we report here a series of in-vitro incubations of the degraded biochars to determine CO2 efflux rates, 14C concentration and δ13C values in CO2 to quantify the contributions of biochar carbon and other sources of carbon to the CO2 efflux. The 14C concentration in CO2 showed that microbial degradation led to respiration of CO2 sourced from indigenous biochar carbon (≈0.5–1.4 μmoles CO2/g biochar C/day) along with a component of carbon closely associated with the biochars but derived from the local environment. Correlations between 14C concentration, δ13C values and Ca abundance indicated that Ca2+ availability was an important determinant of the loss of biochar carbon.
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22

Pompei, Anna, Lisa Cordisco, Alberto Amaretti, Simona Zanoni, Diego Matteuzzi, and Maddalena Rossi. "Folate Production by Bifidobacteria as a Potential Probiotic Property." Applied and Environmental Microbiology 73, no. 1 (October 27, 2006): 179–85. http://dx.doi.org/10.1128/aem.01763-06.

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ABSTRACT The ability of 76 Bifidobacterium strains to produce folate was investigated. In order to evaluate folic acid productivity, bifidobacteria were cultivated in the folate-free semisynthetic medium SM7. Most of the tested strains needed folate for growth. The production and the extent of vitamin accumulation were not a function of species but were distinctive features of individual strains. Six strains among the 17 that grew without folate produced significantly higher concentrations of vitamin (between 41 and 82 ng ml−1). The effects of exogenous folate and p-aminobenzoic acid (PABA) concentrations on folate production were evaluated. In contrast to most of the other strains, the folate yield of B. adolescentis MB 239 was not negatively affected by either PABA or exogenous folic acid. Folate production by B. adolescentis MB 239 was studied in the pH range of the colonic environment, and a comparison of folate production on raffinose, lactose, and fructo-oligosaccharides, which belong to three important groups of fermentable intestinal carbon sources, was established. Differences in folate biosynthesis by B. adolescentis MB 239 were not observed as a function either of the pH or of the carbon source. Fecal culture experiments demonstrated that the addition of B. adolescentis MB 239 may increase the folate concentration in the colonic environment.
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23

Novak, Ryan T., Rachel F. Gritzer, Edward R. Leadbetter, and Walter Godchaux. "Phototrophic utilization of taurine by the purple nonsulfur bacteria Rhodopseudomonas palustris and Rhodobacter sphaeroides." Microbiology 150, no. 6 (June 1, 2004): 1881–91. http://dx.doi.org/10.1099/mic.0.27023-0.

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Taurine metabolism by two phototrophically grown purple nonsulfur bacteria enrichment isolates has been examined. Rhodopseudomonas palustris (strain Tau1) grows with taurine as a sole electron donor, sulfur and nitrogen source during photoautotrophic growth. Rhodobacter sphaeroides (strain Tau3) grows on the compound as sole electron donor, sulfur and nitrogen source, and partial carbon source, in the presence of CO2 during photoheterotrophic growth. Both organisms utilize an inducible taurine–pyruvate aminotransferase and a sulfoacetaldehyde acetyltransferase. The products of this metabolism are bisulfite and acetyl phosphate. Bisulfite ultimately was oxidized to sulfate, but this was not an adequate source of electrons for photometabolism. Experiments using either [U-14C]taurine or 14CO2 demonstrated that Rb. sphaeroides Tau3 assimilated the carbon from approximately equimolar amounts of taurine and exogenous CO2. The taurine-carbon assimilation was not diminished by excess non-radioactive bicarbonate. Malate synthase (but not isocitrate lyase) was induced in these taurine-grown cells. It is concluded that assimilation of taurine carbon occurs through an intermediate other than CO2. Similar labelling experiments with Rp. palustris Tau1 determined that taurine is utilized only as an electron donor for the reduction of CO2, which contributes all the cell carbon. Photoautotrophic metabolism was confirmed in this organism by the absence of either malate synthase or isocitrate lyase in taurine+CO2-grown cells. Culture collection strains of these two bacteria did not utilize taurine in these fashions.
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24

Vijay, Aravind K., Said Ali M. Salim, Syama Prabha, and Basil George. "Exogenous carbon source and phytohormone supplementation enhanced growth rate and metabolite production in freshwater microalgae Scenedesmus obtusus Meyen." Bioresource Technology Reports 14 (June 2021): 100669. http://dx.doi.org/10.1016/j.biteb.2021.100669.

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25

Gorkovenko, Alexander, Jinwen Zhang, Richard A. Gross, Alfred L. Allen, and David L. Kaplan. "Bioengineering of emulsifier structure: emulsan analogs." Canadian Journal of Microbiology 43, no. 4 (April 1, 1997): 384–90. http://dx.doi.org/10.1139/m97-053.

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Strategies were investigated to modulate the side chain structure of emulsans formed by Acinetobacter calcoaceticus RAG-1. Analysis of emulsan fatty acid side chain groups by gas chromatography – mass spectrometry (GC–MS) revealed that by providing the exogenous n-alkanoic fatty acids 15:0, 16:0, and 17:0, emulsan analogs were formed with 53, 46, and 44 mol%, respectively, of fatty acid substituents with chain lengths equal to that of the carbon source. In contrast, the increase in emulsan fatty acids of chain lengths less than 15 or greater than 17 by providing corresponding shorter and longer chain length fatty acids as carbon sources was not substantial. When [1-13C]-labeled (99% enriched) palmitic acid was used as a carbon source along with acetate, analysis of m/z 75/14 and 87/88 isotopomer ratios by GC-MS indicated that 84 and 86% of the 16:0 and 16:1 (9-cis) side groups, respectively, were incorporated intact from the 16:0 carbon source. The percentage of 14-, 15-, 16-, 17-, and 18-carbon chain length fatty acid esters that were monounsaturated were 11, 26, 50, 70, and 85%, respectively. Based on the observed percentage of unsaturated chain length dependence and almost identical enrichment at C-1 of 16:0 and 16:1 (9-cis) side groups from [1-13C]-labeled experiments, it was concluded that desaturation of preformed n-alkanoic acids was the predominant mechanism of their formation. Further work established correlations between side chain structure and product emulsification specificity/activity, so that bioengineered emulsans with improved selectivity can now be formed.Key words: emulsan, Acinetobacter calcoaceticus RAG-1, fatty acids, direct incorporation, emulsification activity.
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26

Santos, Eliana de Oliveira, and Meire Lelis Leal Martins. "Effect of the medium composition on formation of amylase by Bacillus sp." Brazilian Archives of Biology and Technology 46, no. 1 (January 2003): 129–34. http://dx.doi.org/10.1590/s1516-89132003000100018.

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Studies on the alpha -amylase synthesis was carried out with a moderately thermophilic, facultatively anaerobic Bacillus sp, isolated from soil samples. The cells were cultivated in a complex medium containing soluble starch or maltose as carbon source. The levels of the alpha -amylaseactivity detected in culture supernatants varied greatly with the type of carbon source used. Maltose, soluble starch and citrate stimulated alpha -amylaseformation. Addition of exogenous glucose repressed formation of alpha -amylase, demonstrating that a classical glucose effect was operative in this organism. The concentration of yeast extract was found to be important factor in the alpha -amylase synthesis bythe isolate.The activity of the enzyme increased between 2 and 5 g/L yeast extract concentration and then fell very rapidly beyond this point. The best concentration of peptone to alpha-amylase formation was found to be around 10g/L.
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Bastías, Marcela, and J. C. Gentina. "Effect of the Energy and Carbon Source Limitations and Ferric Inhibition on Metabolic Parameters of Leptospirillum Ferrooxidans Growing in Chemostat." Advanced Materials Research 71-73 (May 2009): 267–70. http://dx.doi.org/10.4028/www.scientific.net/amr.71-73.267.

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L. ferrooxidans plays a significant role in bioleaching process of ores. Being a chemoautotrophic bacterium, its sources of carbon and energy are independent. In this study were measured separately in a chemostat, the effect of growth limited by each source (CO2 and Fe(II)), and under conditions of inhibition (Fe(III)) on metabolic parameters of the cell. The runs were carried out in a bioreactor with 1.25 liter of KJ culture medium at 33.5 °C, pH 1.8, agitation rate of 300 rpm and aeration rate of 2 VVM. Using only air as CO2 source, it was established that the cells suffer simultaneous limitation of carbon and energy. It was determined that these limitations are released separately when enriching the air with 4% CO2 in one case and when doubling concentration of Fe(II) in the feed stream in the other. Under double limitation maximum yield (YºX/S) and maintenance coefficient (m) were 6.0•10-3 gcel/gFe(II) and 2.48 gFe(III)/gcel•h respectively. Growth limited only by carbon source and only by energy source gave YºX/S 11.5•10-3 and 21.9•10-3 gcel/gFe(II), whereas m was 1.23 and 0.11 gFe(II)/gcel•h respectively. On the other hand, the lower specific Fe(III) production rate (qP) was obtained when cell growth was limited by the energy source and the higher value was observed during growth in presence of 15 g/L exogenous Fe(III). The qP values at D = 0.04 h-1 were 1.93 and 14.04 gFe(III)/gcel•h respectively. In general, the worse the culture conditions the highest the specific rate of Fe(III) production. The bacterium varied its metabolic parameters quite broadly depending on the growth limiting nutrient and presence of Fe(III).
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Revelles, Olga, Manuel Espinosa-Urgel, Soeren Molin, and Juan L. Ramos. "The davDT Operon of Pseudomonas putida, Involved in Lysine Catabolism, Is Induced in Response to the Pathway Intermediate δ-Aminovaleric Acid." Journal of Bacteriology 186, no. 11 (June 1, 2004): 3439–46. http://dx.doi.org/10.1128/jb.186.11.3439-3446.2004.

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ABSTRACT Pseudomonas putida KT2440 is a soil microorganism that attaches to seeds and efficiently colonizes the plant's rhizosphere. Lysine is one of the major compounds in root exudates, and P. putida KT2440 uses this amino acid as a source of carbon, nitrogen, and energy. Lysine is channeled to δ-aminovaleric acid and then further degraded to glutaric acid via the action of the davDT gene products. We show that the davDT genes form an operon transcribed from a single σ70-dependent promoter. The relatively high level of basal expression from the davD promoter increased about fourfold in response to the addition of exogenous lysine to the culture medium. However, the true inducer of this operon seems to be δ-aminovaleric acid because in a mutant unable to metabolize lysine to δ-aminovaleric acid, this compound, but not lysine, acted as an effector. Effective induction of the P. putida P davD promoter by exogenously added lysine requires efficient uptake of this amino acid, which seems to proceed by at least two uptake systems for basic amino acids that belong to the superfamily of ABC transporters. Mutants in these ABC uptake systems retained basal expression from the davD promoter but exhibited lower induction levels in response to exogenous lysine than the wild-type strain.
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Jan, Ponert, and Lipavská Helena. "Utilization of exogenous saccharides by protocorms of two terrestrial orchids." Plant, Soil and Environment 63, No. 4 (April 25, 2017): 152–58. http://dx.doi.org/10.17221/71/2017-pse.

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Orchid protocorms are completely mycoheterotrophic structures. Although saccharides are proposed as the main energy and carbon (C) sources provided by fungi, there is only limited knowledge on their effects. For the first time, utilization of a wide range of saccharides by in vitro axenic protocorms of two terrestrial orchids from two subfamilies, Ophrys iricolor subsp. lojaconoi and Oeceoclades, was tested. Protocorm size and, in the first of these also rhizoid length and soluble saccharide contents, were analysed. The endogenous saccharide spectra reflected the supplied saccharides and their metabolism. In both species, sucrose supported protocorm growth best. Surprisingly, fructose inhibited O. iricolor subsp. lojaconoi protocorm growth while O. decaryana ones grew well on it. Interestingly, mannitol abundant in mycorrhizal fungi was not utilized while sorbitol not found in fungi was usable. Galactose was toxic at pre-germination stage. Protocorm rhizoid length correlated with protocorm size but revealed several signalling effects of some saccharides. In conclusion, the orchid’s ability to utilize various saccharides reflects more likely species life strategy rather than phylogenetic relations or saccharide abundance in mycorrhizal fungi.
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30

Voigt, Christian C., Karin Sörgel, Jurģis Šuba, Oskars Keišs, and Gunārs Pētersons. "The insectivorous bat Pipistrellus nathusii uses a mixed-fuel strategy to power autumn migration." Proceedings of the Royal Society B: Biological Sciences 279, no. 1743 (June 20, 2012): 3772–78. http://dx.doi.org/10.1098/rspb.2012.0902.

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In contrast to birds, bats are possibly limited in their capacity to use body fat as an energy source for long migrations. Here, we studied the fuel choice of migratory Pipistrellus nathusii (approximate weight: 8 g) by analysing the stable carbon isotope ratio ( δ 13 C V-PDB ) of breath and potential energy sources. Breath δ 13 C V-PDB was intermediate between δ 13 C V-PDB of insect prey and adipocyte triacylglycerols, suggesting a mixed-fuel use of P. nathusii during autumn migration. To clarify the origin of oxidized fatty acids, we performed feeding experiments with captive P. nathusii . After an insect diet, bat breath was enriched in 13 C relative to the bulk and fat portion of insects, but not deviating from the non-fat portion of insects, suggesting that bats oxidized exogenous proteins and carbohydrates, but not exogenous fatty acids. A feeding experiment with 13 C-labelled substrates confirmed these findings. In conclusion, migratory P. nathusii oxidized dietary proteins directly from insects captured en route in combination with endogenous fatty acids from adipocytes, and replenished their body reserves by routing dietary fatty acids to their body reserves.
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31

Davey, Matthew P., Irmtraud Horst, Giang-Huong Duong, Eleanor V. Tomsett, Alexander C. P. Litvinenko, Christopher J. Howe, and Alison G. Smith. "Triacylglyceride Production and Autophagous Responses in Chlamydomonas reinhardtii Depend on Resource Allocation and Carbon Source." Eukaryotic Cell 13, no. 3 (January 10, 2014): 392–400. http://dx.doi.org/10.1128/ec.00178-13.

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ABSTRACT To improve the economic viability of microalgal biodiesel, it will be essential to optimize the productivity of fuel molecules such as triacylglyceride (TAG) within the microalgal cell. To understand some of the triggers required for the metabolic switch to TAG production, we studied the effect of the carbon supply (acetate or CO 2 ) in Chlamydomonas reinhardtii (wild type and the starchless sta6 mutant) grown under low N availability. As expected, initial rates of TAG production were much higher when acetate was present than under strictly photosynthetic conditions, particularly for the sta6 mutant, which cannot allocate resources to starch. However, in both strains, TAG production plateaued after a few days in mixotrophic cultures, whereas under autotrophic conditions, TAG levels continued to rise. Moreover, the reduced growth of the sta6 mutant meant that the greatest productivity (measured as mg TAG liter −1 day −1 ) was found in the wild type growing autotrophically. Wild-type cells responded to low N by autophagy, as shown by degradation of polar (membrane) lipids and loss of photosynthetic pigments, and this was less in cells supplied with acetate. In contrast, little or no autophagy was observed in sta6 mutant cells, regardless of the carbon supply. Instead, very high levels of free fatty acids were observed in the sta6 mutant, suggesting considerable alteration in metabolism. These measurements show the importance of carbon supply and strain selection for lipid productivity. Our findings will be of use for industrial cultivation, where it will be preferable to use fast-growing wild-type strains supplied with gaseous CO 2 under autotrophic conditions rather than require an exogenous supply of organic carbon.
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32

LINE, J. E., and R. E. BRACKETT. "Role of Toxin Concentration and Second Carbon Source in Microbial Transformation of Aflatoxin B1 by Flavobacterium aurantiacum." Journal of Food Protection 58, no. 9 (September 1, 1995): 1042–44. http://dx.doi.org/10.4315/0362-028x-58.9.1042.

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The aflatoxins are toxic and carcinogenic mycotoxins which contaminate a variety of foods and feeds. The bacterium Flavobacterium aurantiacum NRRL B-184 has been previously shown to be effective in degrading aflatoxin B1) in liquid test medium as well as in several food types. The purpose of this study was to investigate the effects of an added nutrient source and added aflatoxin on the ability of F. aurantiacum to degrade aflatoxin B1. Radioactively labeled aflatoxin B1 was added to test solutions containing cells in phosphate buffer or tryptic soy broth. Nonlabeled aflatoxin B1 was also added to similar flasks. Analysis of radioactive CO2 and water- and chloroform-soluble portions of the cell supernatant fluids revealed that neither added nutrients nor added nonlabeled toxin had a significant influence on the microbial transformation of aflatoxin B1 These results suggest that the microbial degradation of aflatoxin by F. aurantiacum is probably a mineralization phenomenon and not a co-metabolism. The ability of this organism to detoxify aflatoxin without the need for exogenous energy sources could be important to future endeavors attempting to use the organism, or the mechanisms responsible, in fermentation reactions.
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Gonzalez-Garcia, R. Axayacatl, Lars K. Nielsen, and Esteban Marcellin. "Heterologous Production of 6-Deoxyerythronolide B in Escherichia coli through the Wood Werkman Cycle." Metabolites 10, no. 6 (June 1, 2020): 228. http://dx.doi.org/10.3390/metabo10060228.

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Polyketides are a remarkable class of natural products with diverse functional and structural diversity. The class includes many medicinally important molecules with antiviral, antimicrobial, antifungal and anticancer properties. Native bacterial, fungal and plant hosts are often difficult to cultivate and coax into producing the desired product. As a result, Escherichia coli has been used for the heterologous production of polyketides, with the production of 6-deoxyerythronolide B (6-dEB) being the first example. Current strategies for production in E. coli require feeding of exogenous propionate as a source for the precursors propionyl-CoA and S-methylmalonyl-CoA. Here, we show that heterologous polyketide production is possible from glucose as the sole carbon source. The heterologous expression of eight genes from the Wood-Werkman cycle found in Propionibacteria, in combination with expression of the 6-dEB synthases DEBS1, DEBS2 and DEBS3 resulted in 6-dEB formation from glucose as the sole carbon source. Our results show that the Wood-Werkman cycle provides the required propionyl-CoA and the extender unit S-methylmalonyl-CoA to produce up to 0.81 mg/L of 6-dEB in a chemically defined media.
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34

Nobre, M. Fernanda, and Milton S. da Costa. "Factors favouring the accumulation of arabinitol in the yeast Debaryomyces hansenii." Canadian Journal of Microbiology 31, no. 5 (May 1, 1985): 467–71. http://dx.doi.org/10.1139/m85-087.

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Culture conditions which lead to the intracellular accumulation of arabinitol were investigated in Debaryomyces hansenii. Arabinitol, detected in very low concentrations during the exponential phase of growth, accumulated during the stationary phase of growth in yeast extract – peptone – 1% (w/v) glucose medium. This polyol was retained intracellularly even after depletion of exogenous glucose, but was rapidly depleted during regrowth in fresh glucose medium. The accumulation of arabinitol was also favoured in media containing 1% (w/v) D-fructose, sucrose, L-arabinose, glycerol, and sodium acetate. High mannitol levels accumulated in stationary phase cells derived from growth in 1% (w/v) D-mannitol, and in these cultures only traces of arabinitol were detectable. Intracellular mannitol was also retained after the extracellular mannitol had been consumed, and was rapidly depleted during regrowth in glucose medium. Arabinitol did not accumulate in basal medium with no added carbon source, nor in media with nonmetabolizable carbon sources (D-arabinose or D-ribose). On the other hand, arabinitol accumulation was independent of the initial glucose concentration between 1% (w/v) and about 9% (w/v).
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35

Huertas, I. Emma, and Luis M. Lubián. "Comparative study of dissolved inorganic carbon utilization and photosynthetic responses in Nannochloris (Chlorophyceae) and Nannochloropsis (Eustigmatophyceae) species." Canadian Journal of Botany 76, no. 6 (June 1, 1998): 1104–8. http://dx.doi.org/10.1139/b98-068.

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Four species of marine microalgae with similar morphology and life cycle, namely Nannochloris atomus Butcher, Nannochloris maculata Butcher, Nannochloropsis gaditana Lubian, and Nannochloropsis oculata (Droop) Hibberd, have been examined with respect to their affinity for different sources of dissolved inorganic carbon. External carbonic anhydrase activity was not found in any of these species, but the cell affinity for dissolved inorganic carbon (DIC) in Nannochloris species was affected by the inhibitor acetazolamide at a concentration of 400 µM. Measurement of photosynthetic rates and CO2 compensation points at different pH values showed that the Nannochloris species had a greater capacity for CO2 rather than HCO3- utilization. In contrast, the observed rates of photosynthetic oxygen evolution in Nannochloropsis species were greater than could be accounted for by the theoretical rate of CO2 supply from the spontaneous dehydration of bicarbonate in the external medium. This indicates that these algae were able to transport bicarbonate across the plasmalemma. Furthermore, the K0.5 (DIC) value at acidic pH showed that Nannochloropsis oculata could also use CO2 as an exogenous carbon source for photosynthesis. Although the species of marine phytoplankton used in this study possess similar morphological characteristics and life cycle, there exist many differences in the mode of inorganic carbon utilization between these microalgae.Key words: Nannochloris, Nannochloropsis, inorganic carbon utilization, bicarbonate transport, CO2 compensation point, photosynthesis.
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36

Li, Liande, and Katherine A. Borkovich. "GPR-4 Is a Predicted G-Protein-Coupled Receptor Required for Carbon Source-Dependent Asexual Growth and Development in Neurospora crassa." Eukaryotic Cell 5, no. 8 (August 2006): 1287–300. http://dx.doi.org/10.1128/ec.00109-06.

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ABSTRACT The filamentous fungus Neurospora crassa is able to utilize a wide variety of carbon sources. Here, we examine the involvement of a predicted G-protein-coupled receptor (GPCR), GPR-4, during growth and development in the presence of different carbon sources in N. crassa. Δgpr-4 mutants have reduced mass accumulation compared to the wild type when cultured on high levels of glycerol, mannitol, or arabinose. The defect is most severe on glycerol and is cell density dependent. The genetic and physical relationship between GPR-4 and the three N. crassa Gα subunits (GNA-1, GNA-2, and GNA-3) was explored. All three Gα mutants are defective in mass accumulation when cultured on glycerol. However, the phenotypes of Δgna-1 and Δgpr-4 Δgna-1 mutants are identical, introduction of a constitutively activated gna-1 allele suppresses the defects of the Δgpr-4 mutation, and the carboxy terminus of GPR-4 interacts most strongly with GNA-1 in the yeast two-hybrid assay. Although steady-state cyclic AMP (cAMP) levels are normal in Δgpr-4 strains, exogenous cAMP partially remediates the dry mass defects of Δgpr-4 mutants on glycerol medium and Δgpr-4 strains lack the transient increase in cAMP levels observed in the wild type after addition of glucose to glycerol-grown liquid cultures. Our results support the hypothesis that GPR-4 is coupled to GNA-1 in a cAMP signaling pathway that regulates the response to carbon source in N. crassa. GPR-4-related GPCRs are present in the genomes of several filamentous ascomycete fungal pathogens, raising the possibility that a similar pathway regulates carbon sensing in these organisms.
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Sun, Dongchang, Xuewu Zhang, Lingyu Wang, Marc Prudhomme, Zhixiong Xie, Bernard Martin, and Jean-Pierre Claverys. "Transforming DNA Uptake Gene Orthologs Do Not Mediate Spontaneous Plasmid Transformation in Escherichia coli." Journal of Bacteriology 191, no. 3 (November 14, 2008): 713–19. http://dx.doi.org/10.1128/jb.01130-08.

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ABSTRACT Spontaneous plasmid transformation of Escherichia coli occurs on nutrient-containing agar plates. E. coli has also been reported to use double-stranded DNA (dsDNA) as a carbon source. The mechanism(s) of entry of exogenous dsDNA that allows plasmid establishment or the use of DNA as a nutrient remain(s) unknown. To further characterize plasmid transformation, we first documented the stimulation of transformation by agar and agarose. We provide evidence that stimulation is not due to agar contributing a supplement of Ca2+, Fe2+, Mg2+, Mn2+, or Zn2+. Second, we undertook to inactivate the E. coli orthologues of Haemophilus influenzae components of the transformation machine that allows the uptake of single-stranded DNA (ssDNA) from exogenous dsDNA. The putative outer membrane channel protein (HofQ), transformation pseudopilus component (PpdD), and transmembrane pore (YcaI) are not required for plasmid transformation. We conclude that plasmid DNA does not enter E. coli cells as ssDNA. The finding that purified plasmid monomers transform E. coli with single-hit kinetics supports this conclusion; it establishes that a unique monomer molecule is sufficient to give rise to a transformant, which is not consistent with the reconstitution of an intact replicon through annealing of partially overlapping complementary ssDNA, taken up from two independent monomers. We therefore propose that plasmid transformation involves internalization of intact dsDNA molecules. Our data together, with previous reports that HofQ is required for the use of dsDNA as a carbon source, suggest the existence of two routes for DNA entry, at least across the outer membrane of E. coli.
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38

Pech-Canul, Ángel de la Cruz, Geovanny Rivera-Hernández, Joaquina Nogales, Otto Geiger, María J. Soto, and Isabel M. López-Lara. "Role of Sinorhizobium meliloti and Escherichia coli Long-Chain Acyl-CoA Synthetase FadD in Long-Term Survival." Microorganisms 8, no. 4 (March 26, 2020): 470. http://dx.doi.org/10.3390/microorganisms8040470.

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FadD is an acyl-coenzyme A (CoA) synthetase specific for long-chain fatty acids (LCFA). Strains mutated in fadD cannot produce acyl-CoA and thus cannot grow on exogenous LCFA as the sole carbon source. Mutants in the fadD (smc02162) of Sinorhizobium meliloti are unable to grow on oleate as the sole carbon source and present an increased surface motility and accumulation of free fatty acids at the entry of the stationary phase of growth. In this study, we found that constitutive expression of the closest FadD homologues of S. meliloti, encoded by sma0150 and smb20650, could not revert any of the mutant phenotypes. In contrast, the expression of Escherichia coli fadD could restore the same functions as S. meliloti fadD. Previously, we demonstrated that FadD is required for the degradation of endogenous fatty acids released from membrane lipids. Here, we show that absence of a functional fadD provokes a significant loss of viability in cultures of E. coli and of S. meliloti in the stationary phase, demonstrating a crucial role of fatty acid degradation in survival capacity.
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39

Demain, Arnold L., and Spyridon N. Agathos. "Studies on in vivo inactivation of gramicidin S synthetase and its retardation." Canadian Journal of Microbiology 32, no. 3 (March 1, 1986): 208–14. http://dx.doi.org/10.1139/m86-042.

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The oxygen-dependent in vivo inactivation of gramicidin S synthetase was investigated in Bacillus brevis ATCC 9999. Inhibitors of energy metabolism and of protein synthesis added to aerated cell suspensions did not provide any protection against inactivation, thus indicating that the process does not depend on energy-yielding metabolism nor on de novo protein synthesis. Organic thiols added to anaerobic long-term incubations retarded synthetase inactivation for several hours, whereas in short-term incubations of previously air-exposed cells they resulted in partial restoration of activity. The in vivo inactivation of the enzyme was found to be accompanied by a parallel drop in intracellular thiols. These results implicate enzyme SH oxidation as a mechanism of in vivo inactivation. Retardation of inactivation was achieved upon addition of utilizable carbon sources (glycerol, fructose, inositol) to aerated cell suspensions in buffer, the degree of stabilization being proportional to the ease of uptake and to the concentration of C source. This effect involves actual consumption of the exogenous C source and is accompanied by lower dissolved oxygen levels in the cell suspension. Pulsed additions of C source could retard inactivation but could not restore partly or fully lost activity. The C-source effect was blocked by the uncoupler dinitrophenol, while dissolved oxygen levels in the suspension remained low. C-source-supplemented cell suspensions incubated under air had a decreased intracellular redox state, as revealed by intracellular SH concentration.
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40

Wright, Lesley C., Rosemary M. Santangelo, Ranjini Ganendren, Jackie Payne, Julianne T. Djordjevic, and Tania C. Sorrell. "Cryptococcal Lipid Metabolism: Phospholipase B1 Is Implicated in Transcellular Metabolism of Macrophage-Derived Lipids." Eukaryotic Cell 6, no. 1 (November 10, 2006): 37–47. http://dx.doi.org/10.1128/ec.00262-06.

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ABSTRACT Cryptococci survive and replicate within macrophages and can use exogenous arachidonic acid for the production of eicosanoids. Phospholipase B1 (PLB1) has a putative, but uninvestigated, role in these processes. We have shown that uptake and esterification of radiolabeled arachidonic, palmitic, and oleic acids by the Cryptococcus neoformans var. grubii H99 wild-type strain and its PLB1 deletion mutant strain (the Δplb1 strain) are independent of PLB1, except under hyperosmolar stress. Similarly, PLB1 was required for metabolism of 1-palmitoyl lysophosphatidylcholine (LysoPC), which is toxic to eukaryotic cell membranes, under hyperosmolar conditions. During both logarithmic and stationary phases of growth, the physiologically relevant phospholipids, dipalmitoyl phosphatidylcholine (DPPC) and dioleoyl phosphatidylcholine, were taken up and metabolized via PLB1. Exogenous DPPC did not enhance growth in the presence of glucose as a carbon source but could support it for at least 24 h in glucose-free medium. Detoxification of LysoPC by reacylation occurred in both the H99 wild-type and the Δplb1 strains in the presence of glucose, but PLB1 was required when LysoPC was the sole carbon source. This indicates that both energy-independent (via PLB1) and energy-dependent transacylation pathways are active in cryptococci. Phospholipase A1 activity was identified by PLB1-independent degradation of 1-palmitoyl-2-arachidonoyl phosphatidylcholine, but the arachidonoyl LysoPC formed was not detoxified by reacylation. Using the human macrophage-like cell line THP-1, we demonstrated the PLB1-dependent incorporation of macrophage-derived arachidonic acid into cryptococcal lipids during cryptococcus-phagocyte interaction. This pool of arachidonate can be sequestered for eicosanoid production by the fungus and/or suppression of host phagocytic activity, thus diminishing the immune response.
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41

Fox, Calum P., Xingqian Cui, Jessica H. Whiteside, Paul E. Olsen, Roger E. Summons, and Kliti Grice. "Molecular and isotopic evidence reveals the end-Triassic carbon isotope excursion is not from massive exogenous light carbon." Proceedings of the National Academy of Sciences 117, no. 48 (November 16, 2020): 30171–78. http://dx.doi.org/10.1073/pnas.1917661117.

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The negative organic carbon isotope excursion (CIE) associated with the end-Triassic mass extinction (ETE) is conventionally interpreted as the result of a massive flux of isotopically light carbon from exogenous sources into the atmosphere (e.g., thermogenic methane and/or methane clathrate dissociation linked to the Central Atlantic Magmatic Province [CAMP]). Instead, we demonstrate that at its type locality in the Bristol Channel Basin (UK), the CIE was caused by a marine to nonmarine transition resulting from an abrupt relative sea level drop. Our biomarker and compound-specific carbon isotopic data show that the emergence of microbial mats, influenced by an influx of fresh to brackish water, provided isotopically light carbon to both organic and inorganic carbon pools in centimeter-scale water depths, leading to the negative CIE. Thus, the iconic CIE and the disappearance of marine biota at the type locality are the result of local environmental change and do not mark either the global extinction event or input of exogenous light carbon into the atmosphere. Instead, the main extinction phase occurs slightly later in marine strata, where it is coeval with terrestrial extinctions and ocean acidification driven by CAMP-induced increases inPco2; these effects should not be conflated with the CIE. An abrupt sea-level fall observed in the Central European basins reflects the tectonic consequences of the initial CAMP emplacement, with broad implications for all extinction events related to large igneous provinces.
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42

Palchevskiy, Vyacheslav, and Steven E. Finkel. "Escherichia coli Competence Gene Homologs Are Essential for Competitive Fitness and the Use of DNA as a Nutrient." Journal of Bacteriology 188, no. 11 (June 1, 2006): 3902–10. http://dx.doi.org/10.1128/jb.01974-05.

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ABSTRACT Natural genetic competence is the ability of cells to take up extracellular DNA and is an important mechanism for horizontal gene transfer. Another potential benefit of natural competence is that exogenous DNA can serve as a nutrient source for starving bacteria because the ability to “eat” DNA is necessary for competitive survival in environments containing limited nutrients. We show here that eight Escherichia coli genes, identified as homologs of com genes in Haemophilus influenzae and Neisseria gonorrhoeae, are necessary for the use of extracellular DNA as the sole source of carbon and energy. These genes also confer a competitive advantage to E. coli during long-term stationary-phase incubation. We also show that homologs of these genes are found throughout the proteobacteria, suggesting that the use of DNA as a nutrient may be a widespread phenomenon.
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43

TAM, N., Y. WONG, and G. LEUNG. "Effect of exogenous carbon sources on removal of inorganic nutrient by the nitrification-denitrification process." Water Research 26, no. 9 (September 1992): 1229–36. http://dx.doi.org/10.1016/0043-1354(92)90183-5.

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44

Chang, Junjun, Wei Jia, Ying Qu, Liangjie Wang, and Jinquan Chen. "Improving treatment performance of biofilters for heavily polluted surface water using combined organic/inorganic substrates and exogenous carbon source of wood pieces." DESALINATION AND WATER TREATMENT 169 (2019): 191–97. http://dx.doi.org/10.5004/dwt.2019.24713.

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45

Chang, Jun-jun, Yi-Feng Lu, Jin-quan Chen, Xiao-yun Wang, Tong Luo, and Hu Liu. "Simultaneous removals of nitrate and sulfate and the adverse effects of gravel-based biofilters with flower straws added as exogenous carbon source." Ecological Engineering 95 (October 2016): 189–97. http://dx.doi.org/10.1016/j.ecoleng.2016.06.032.

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46

Wilson, R. B., and K. Tatchell. "SRA5 encodes the low-Km cyclic AMP phosphodiesterase of Saccharomyces cerevisiae." Molecular and Cellular Biology 8, no. 1 (January 1988): 505–10. http://dx.doi.org/10.1128/mcb.8.1.505.

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sra5 mutations in Saccharomyces cerevisiae were previously shown to suppress the inefficient growth of ras2 strains on nonfermentable carbon sources and to result in deficient low-Km cyclic AMP (cAMP) phosphodiesterase activity. We have cloned SRA5 by complementation. It maps to the right arm of chromosome XV, tightly linked to PRT1, and its sequence matches the sequence of PDE2, encoding the low-Km cAMP phosphodiesterase. Disruptions of SRA5 allowed ras1 ras2 strains to grow either on rich media supplemented with cAMP or on minimal media without exogenous cAMP. sra5 strains failed to survive prolonged nitrogen starvation in the presence of exogenous cAMP.
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47

Wilson, R. B., and K. Tatchell. "SRA5 encodes the low-Km cyclic AMP phosphodiesterase of Saccharomyces cerevisiae." Molecular and Cellular Biology 8, no. 1 (January 1988): 505–10. http://dx.doi.org/10.1128/mcb.8.1.505-510.1988.

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sra5 mutations in Saccharomyces cerevisiae were previously shown to suppress the inefficient growth of ras2 strains on nonfermentable carbon sources and to result in deficient low-Km cyclic AMP (cAMP) phosphodiesterase activity. We have cloned SRA5 by complementation. It maps to the right arm of chromosome XV, tightly linked to PRT1, and its sequence matches the sequence of PDE2, encoding the low-Km cAMP phosphodiesterase. Disruptions of SRA5 allowed ras1 ras2 strains to grow either on rich media supplemented with cAMP or on minimal media without exogenous cAMP. sra5 strains failed to survive prolonged nitrogen starvation in the presence of exogenous cAMP.
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48

Chelius, Marisa K., and Eric W. Triplett. "Immunolocalization of Dinitrogenase Reductase Produced by Klebsiella pneumoniae in Association withZea mays L." Applied and Environmental Microbiology 66, no. 2 (February 1, 2000): 783–87. http://dx.doi.org/10.1128/aem.66.2.783-787.2000.

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ABSTRACT The endophytic lifestyle of Klebsiella pneumoniae is described, including the production of dinitrogenase reductase by bacteria residing in maize root tissue. The green fluorescent protein (GFP) was used to detect the colonization of maize by K. pneumoniae strains 2028 and 342. These strains were found to reside in intercortical layers of the stem and within the region of maturation in the root. The production of dinitrogenase reductase by GFP-tagged bacteria was visualized using immunolocalization. This activity was only apparent when bacteria were supplied with an exogenous carbon source. The results suggest that maize provides a suitable habitat for K. pneumoniae and that this species is capable of producing nitrogenase under the appropriate plant cultivation conditions.
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49

Amoah-Buahin, Evelyn, Neil Bone, and John Armstrong. "Hyphal Growth in the Fission Yeast Schizosaccharomyces pombe." Eukaryotic Cell 4, no. 7 (July 2005): 1287–97. http://dx.doi.org/10.1128/ec.4.7.1287-1297.2005.

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ABSTRACT The fission yeast Schizosaccharomyces pombe grows in a single-celled form or can mate and undergo meiosis and sporulation. Here we show that wild-type S. pombe can also differentiate to form elaborately branched hyphae which invade deep into solid medium. Branches appear in the hyphae adjacent to unseparated septa. Electron microscopy reveals unusual multivesicular structures within the hyphae. Nitrogen deprivation appears to be the main stimulus for hyphal growth. No mitogen-activated protein kinase is necessary for the response. Inhibition of cyclic AMP (cAMP) production or signaling prevents the response, and exogenous cAMP promotes it, suggesting that detection of a good carbon source is required for hyphal growth but not for mating.
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50

Handrick, René, Simone Reinhardt, and Dieter Jendrossek. "Mobilization of Poly(3-Hydroxybutyrate) inRalstonia eutropha." Journal of Bacteriology 182, no. 20 (October 15, 2000): 5916–18. http://dx.doi.org/10.1128/jb.182.20.5916-5918.2000.

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ABSTRACT Ralstonia eutropha H16 degraded (mobilized) previously accumulated poly(3-hydroxybutyrate) (PHB) in the absence of an exogenous carbon source and used the degradation products for growth and survival. Isolated native PHB granules of mobilized R. eutropha cells released 3-hydroxybutyrate (3HB) at a threefold higher rate than did control granules of nonmobilized bacteria. No 3HB was released by native PHB granules of recombinant Escherichia coli expressing the PHB biosynthetic genes. Native PHB granules isolated from chromosomal knockout mutants of an intracellular PHB (i-PHB) depolymerase gene of R. eutropha H16 and HF210 showed a reduced but not completely eliminated activity of 3HB release and indicated the presence of i-PHB depolymerase isoenzymes.
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