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1
Nakamura, K., M. Shibata et Y. Miyaji. « Substrate Affinity of Oligotrophic Bacteria in Biofilm Reactors ». Water Science and Technology 21, no 8-9 (1 août 1989) : 779–90. http://dx.doi.org/10.2166/wst.1989.0281.
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Several biofilm reactors were operated to investigate the substrate affinity of oligotrophic bacteria in the biofilm reactor. The attached oligotrophs were removed from reactors, and substrate affinity was determined in dispersed form. The saturation constant (Ks) of attached oligotrophs for acetate was less than 10 µg-C/l. The apparent Ks (Ksa) values of reactors were also determined to evaluate the performance of reactors,and the effect of specific surface area of packed media on Ksa was investigated at a loading of 0.006 mg-C per cm3-apparent media volume per hour. Larger specific surface area led to smaller Ksa, and 6.9 µg-C/l of Ksa for acetate was obtained with the media having 340 cm2 -surface area per cm -apparent media volume of specific surface area. The bacterial flora in the oligotrophic biofilm was examined, and Pseudomonas was found to be dominant.
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Cottrell, Matthew T., et David L. Kirchman. « Transcriptional Control in Marine Copiotrophic and Oligotrophic Bacteria with Streamlined Genomes ». Applied and Environmental Microbiology 82, no 19 (29 juillet 2016) : 6010–18. http://dx.doi.org/10.1128/aem.01299-16.
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ABSTRACTBacteria often respond to environmental stimuli using transcriptional control, but this may not be the case for marine bacteria such as “CandidatusPelagibacter ubique,” a cultivated representative of the SAR11 clade, the most abundant organism in the ocean. This bacterium has a small, streamlined genome and an unusually low number of transcriptional regulators, suggesting that transcriptional control is low inPelagibacterand limits its response to environmental conditions. Transcriptome sequencing during batch culture growth revealed that only 0.1% of protein-encoding genes appear to be under transcriptional control inPelagibacterand in another oligotroph (SAR92) whereas >10% of genes were under transcriptional control in the copiotrophsPolaribactersp. strain MED152 andRuegeria pomeroyi. When growth levels changed, transcript levels remained steady inPelagibacterand SAR92 but shifted in MED152 andR. pomeroyi. Transcript abundances per cell, determined using an internal RNA sequencing standard, were low (<1 transcript per cell) for all but a few of the most highly transcribed genes in all four taxa, and there was no correlation between transcript abundances per cell and shifts in the levels of transcription. These results suggest that low transcriptional control contributes to the success ofPelagibacterand possibly other oligotrophic microbes that dominate microbial communities in the oceans.IMPORTANCEDiverse heterotrophic bacteria drive biogeochemical cycling in the ocean. The most abundant types of marine bacteria are oligotrophs with small, streamlined genomes. The metabolic controls that regulate the response of oligotrophic bacteria to environmental conditions remain unclear. Our results reveal that transcriptional control is lower in marine oligotrophic bacteria than in marine copiotrophic bacteria. Although responses of bacteria to environmental conditions are commonly regulated at the level of transcription, metabolism in the most abundant bacteria in the ocean appears to be regulated by other mechanisms.
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Lami, Raphaël, Matthew T. Cottrell, Joséphine Ras, Osvaldo Ulloa, Ingrid Obernosterer, Hervé Claustre, David L. Kirchman et Philippe Lebaron. « High Abundances of Aerobic Anoxygenic Photosynthetic Bacteria in the South Pacific Ocean ». Applied and Environmental Microbiology 73, no 13 (11 mai 2007) : 4198–205. http://dx.doi.org/10.1128/aem.02652-06.
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ABSTRACT Little is known about the abundance, distribution, and ecology of aerobic anoxygenic phototrophic (AAP) bacteria, particularly in oligotrophic environments, which represent 60% of the ocean. We investigated the abundance of AAP bacteria across the South Pacific Ocean, including the center of the gyre, the most oligotrophic water body of the world ocean. AAP bacteria, Prochlorococcus, and total prokaryotic abundances, as well as bacteriochlorophyll a (BChl a) and divinyl-chlorophyll a concentrations, were measured at several depths in the photic zone along a gradient of oligotrophic conditions. The abundances of AAP bacteria and Prochlorococcus were high, together accounting for up to 58% of the total prokaryotic community. The abundance of AAP bacteria alone was up to 1.94 × 105 cells ml−1 and as high as 24% of the overall community. These measurements were consistent with the high BChl a concentrations (up to 3.32 × 10−3 μg liter−1) found at all stations. However, the BChl a content per AAP bacterial cell was low, suggesting that AAP bacteria are mostly heterotrophic organisms. Interestingly, the biovolume and therefore biomass of AAP bacteria was on average twofold higher than that of other prokaryotic cells. This study demonstrates that AAP bacteria can be abundant in various oligotrophic conditions, including the most oligotrophic regime of the world ocean, and can account for a large part of the bacterioplanktonic carbon stock.
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Feng, Cui, Jingyi Jia, Chen Wang, Mengqi Han, Chenchen Dong, Bin Huo, Dapeng Li et Xiangjiang Liu. « Phytoplankton and Bacterial Community Structure in Two Chinese Lakes of Different Trophic Status ». Microorganisms 7, no 12 (27 novembre 2019) : 621. http://dx.doi.org/10.3390/microorganisms7120621.
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Phytoplankton are the primary producers at the basis of aquatic food webs, and bacteria play an important role in energy flow and biochemical cycling in aquatic ecosystems. In this study, both the bacterial and phytoplankton communities were examined in the oligotrophic Lake Basomtso and the eutrophic Lake South (China). The results of this study showed that the phytoplankton density and diversity in the eutrophic lake were higher than those in the oligotrophic lake. Furthermore, Chlorophyta (68%) and Cryptophyta (24%) were the dominant groups in the eutrophic lake, while Bacillariophyta (95%) dominated in the oligotrophic lake. The bacterial communities in the waters and sediments of the two lakes were mainly composed of Proteobacteria (mean of 32%), Actinobacteria (mean of 25%), Bacteroidetes (mean of 12%), and Chloroflexi (mean of 6%). Comparative analysis showed that the abundance of bacteria in the eutrophic lake was higher than that in the oligotrophic lake (p < 0.05), but the bacterial diversity in the oligotrophic lake was higher than that in the eutrophic lake (p < 0.05). Finally, the bacterial abundance and diversity in the sediments of the two lakes were higher than those in the water samples (p < 0.05), and the Latescibacteria and Nitrospinae groups were identified only in the sediments. These results suggest that both the phytoplankton and bacterial communities differed considerably between the oligotrophic lake and the eutrophic lake.
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Lamy, D., C. Jeanthon, J. Ras, F. Van Wambeke, O. Dahan, M. T. Cottrell, D. L. Kirchman et P. Lebaron. « Ecology of aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea ». Biogeosciences Discussions 8, no 1 (12 janvier 2011) : 323–54. http://dx.doi.org/10.5194/bgd-8-323-2011.
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Abstract. Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use both light and organic substrates for energy production. They are widely distributed in coastal and oceanic environments and may contribute significantly to the carbon cycle in the upper ocean. To better understand questions regarding links between the ecology of these photoheterotrophic bacteria and the trophic status of water masses, we examined their horizontal and vertical distribution and the effects of nutrient additions on their growth along an oligotrophic gradient in the Mediterranean Sea. Concentrations of bacteriochlorophyll-a (BChl-a) and AAP bacterial abundance decreased from the western to the eastern basins of the Mediterranean Sea and were linked with concentrations of chlorophyll-a, nutrient and dissolved organic carbon. Inorganic nutrient and glucose additions to surface seawater samples along the oligotrophic gradient revealed that AAP bacteria were nitrogen- and carbon-limited in the ultra-oligotrophic eastern basin. The intensity of the AAP bacterial growth response generally differed from that of the total bacterial growth response. BChl-a quota of AAP bacterial communities was significantly higher in the eastern basin than in the western basin, suggesting that reliance on phototrophy varied along the oligotrophic gradient and that nutrient and/or carbon limitation favors BChl-a synthesis.
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Lauro, Federico M., Diane McDougald, Torsten Thomas, Timothy J. Williams, Suhelen Egan, Scott Rice, Matthew Z. DeMaere et al. « The genomic basis of trophic strategy in marine bacteria ». Proceedings of the National Academy of Sciences 106, no 37 (8 septembre 2009) : 15527–33. http://dx.doi.org/10.1073/pnas.0903507106.
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Many marine bacteria have evolved to grow optimally at either high (copiotrophic) or low (oligotrophic) nutrient concentrations, enabling different species to colonize distinct trophic habitats in the oceans. Here, we compare the genome sequences of two bacteria,Photobacterium angustumS14 andSphingopyxis alaskensisRB2256, that serve as useful model organisms for copiotrophic and oligotrophic modes of life and specifically relate the genomic features to trophic strategy for these organisms and define their molecular mechanisms of adaptation. We developed a model for predicting trophic lifestyle from genome sequence data and tested >400,000 proteins representing >500 million nucleotides of sequence data from 126 genome sequences with metagenome data of whole environmental samples. When applied to available oceanic metagenome data (e.g., the Global Ocean Survey data) the model demonstrated that oligotrophs, and not the more readily isolatable copiotrophs, dominate the ocean's free-living microbial populations. Using our model, it is now possible to define the types of bacteria that specific ocean niches are capable of sustaining.
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Weisse, Thomas, et Erland MacIsaac. « Significance and fate of bacterial production in oligotrophic lakes in British Columbia ». Canadian Journal of Fisheries and Aquatic Sciences 57, no 1 (1 janvier 2000) : 96–105. http://dx.doi.org/10.1139/f99-187.
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We measured bacterial abundance, biomass, production rates, and grazing losses to protozoans in three oligotrophic British Columbia lakes and analyzed bacteria abundance and lake productivity data from 11 other lakes, most fertilized with inorganic nutrients to increase their productivity for juvenile salmon. Bacteria contributed about 24% to the phytoplankton-bacteria carbon biomass in the most ultraoligotrophic lakes, and their relative contribution declined to <11% with increasing lake productivity. At increasingly high nutrient loadings to the lakes, bacteria abundance increased and was closely correlated with phytoplankton biomass and productivity. Heterotrophic nanoflagellate (HNF) abundance was positively correlated with bacterial numbers. Grazing experiments revealed that HNF were the primary pathway for moving bacterial production to higher trophic levels in oligotrophic British Columbia lakes, and predation by the ciliate and rotifer microzooplankton community appeared to exert top-down control over the abundance of HNF and the transfer of carbon from bacteria. The HNF and microzooplankton, in turn, were affected by the abundance of crustacean mesozooplankton, principally copepods in our experiments.
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Kim, Mikyeong, et Mooyoung Han. « Composition and distribution of bacteria in an operating rainwater harvesting tank ». Water Science and Technology 63, no 7 (1 avril 2011) : 1524–30. http://dx.doi.org/10.2166/wst.2011.410.
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In this study, we investigated the phylogenetic distribution of the bacteria present in an operating rainwater tank by denaturing gradient gel electrophoresis (DGGE), and compared the bacterial composition in rainwater and biofilm from the inlet and outlet of the tank. Seventeen species were identified, the DGGE profiles of which showed a clear difference between the planktonic bacterial community and the community in the biofilm. Most of the bacteria were closely related to fresh water, soil, and biofilm bacteria found in natural environments. The high proportion of Proteobacteria indicates the generally clean oligotrophic nature of the tank water. Biofilm formation is an advantage for bacteria that exist in oligotrophic environments. The groups identified in the biofilm, such as Sphingomonas, Bacillus, and Sphingophyxis, have been demonstrated to degrade certain contaminants and to act as bio-control agents. Thus, biofilm formation in rainwater tanks not only represents a survival strategy for bacteria, but also serves as a natural filter by removing contaminants and bacteria from rainwater.
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Chiba, Akane, Yoshitaka Uchida, Susanne Kublik, Gisle Vestergaard, Franz Buegger, Michael Schloter et Stefanie Schulz. « Soil Bacterial Diversity Is Positively Correlated with Decomposition Rates during Early Phases of Maize Litter Decomposition ». Microorganisms 9, no 2 (11 février 2021) : 357. http://dx.doi.org/10.3390/microorganisms9020357.
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This study aimed to investigate the effects of different levels of soil- and plant-associated bacterial diversity on the rates of litter decomposition, and bacterial community dynamics during its early phases. We performed an incubation experiment where soil bacterial diversity (but not abundance) was manipulated by autoclaving and reinoculation. Natural or autoclaved maize leaves were applied to the soils and incubated for 6 weeks. Bacterial diversity was assessed before and during litter decomposition using 16S rRNA gene metabarcoding. We found a positive correlation between litter decomposition rates and soil bacterial diversity. The soil with the highest bacterial diversity was dominated by oligotrophic bacteria including Acidobacteria, Nitrospiraceae, and Gaiellaceae, and its community composition did not change during the incubation. In the less diverse soils, those taxa were absent but were replaced by copiotrophic bacteria, such as Caulobacteraceae and Beijerinckiaceae, until the end of the incubation period. SourceTracker analysis revealed that litter-associated bacteria, such as Beijerinckiaceae, only became part of the bacterial communities in the less diverse soils. This suggests a pivotal role of oligotrophic bacteria during the early phases of litter decomposition and the predominance of copiotrophic bacteria at low diversity.
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Lamy, D., C. Jeanthon, M. T. Cottrell, D. L. Kirchman, F. Van Wambeke, J. Ras, O. Dahan et al. « Ecology of aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea ». Biogeosciences 8, no 4 (20 avril 2011) : 973–85. http://dx.doi.org/10.5194/bg-8-973-2011.
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Abstract. Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use both light and organic substrates for energy production. They are widely distributed in coastal and oceanic environments and may contribute significantly to the carbon cycle in the upper ocean. To better understand questions regarding links between the ecology of these photoheterotrophic bacteria and the trophic status of water masses, we examined their horizontal and vertical distribution and the effects of nutrient additions on their growth along an oligotrophic gradient in the Mediterranean Sea. Concentrations of bacteriochlorophyll-a (BChl-a) and AAP bacterial abundance decreased from the western to the eastern basin of the Mediterranean Sea and were linked with concentrations of chlorophyll-a, nutrient and dissolved organic carbon. Inorganic nutrient and glucose additions to surface seawater samples along the oligotrophic gradient revealed that AAP bacteria were nitrogen- and carbon-limited in the ultraoligotrophic eastern basin. The intensity of the AAP bacterial growth response generally differed from that of the total bacterial growth response. BChl-a quota of AAP bacterial communities was significantly higher in the eastern basin than in the western basin, suggesting that reliance on phototrophy varied along the oligotrophic gradient and that nutrient and/or carbon limitation favors BChl-a synthesis.
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Tada, Y., M. Ihmori et J. Yamaguchi. « Oligotrophic bacteria isolated from clinical materials. » Journal of clinical microbiology 33, no 2 (1995) : 493–94. http://dx.doi.org/10.1128/jcm.33.2.493-494.1995.
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Slabova, O. I., et D. I. Nikitin. « Relations of Oligotrophic Bacteria to Oxygen ». Biology Bulletin 32, no 5 (septembre 2005) : 515–17. http://dx.doi.org/10.1007/s10525-005-0134-y.
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Whang, Kyungsook, et Tsutomu Hattori. « Oligotrophic bacteria from rendzina forest soil ». Antonie van Leeuwenhoek 54, no 1 (1988) : 19–36. http://dx.doi.org/10.1007/bf00393955.
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Duarte, C. M., et S. Agustí. « Rapid carbon cycling in the oligotrophic ocean ». Biogeosciences Discussions 8, no 6 (7 décembre 2011) : 11661–87. http://dx.doi.org/10.5194/bgd-8-11661-2011.
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Abstract. The dynamics of organic carbon production, release and bacterial use was examined across a range of communities spanning from highly oligotrophic ones in the Subtropical Atlantic Ocean, mesotrophic ones in the Mediterranean Sea and productive ones in the Northern African upwelling and the Southern Ocean. A comparative analysis of experiments examining total and particulate organic carbon production across a range of time scales (15 min to 24 h) for 20 communities with contrasting phytoplankton cell status, as assessed by cell lysis rates, and the use of a simple inverse model was used to resolve patterns of carbon flow in the microbial food web. Communities in productive ocean waters accumulated organic carbon over hourly time scales, whereas only a small fraction of net primary production accumulated in communities from oligotrophic waters. These communities supported high phytoplankton cell lysis rates leading to a rapid flux of organic carbon to bacteria, which had high affinity for phytoplankton-derived carbon, much of which was rapidly respired. Conventional assessments of primary production in the oligotrophic ocean severely underestimate net phytoplankton production, as carbon flow in microbial communities from oligotrophic ocean waters occurs within short (minutes) time scales. This explains difficulties to reconcile estimates of primary production with independent estimates of carbon use by bacteria in oligotrophic marine ecosystems.
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Jiang, Deng Ling, Guo Wei Ni et Yu Min Zhang. « Effects of AOC and Phosphorus on Bacterial Growth under Oligotrophic Condition (1) ». Applied Mechanics and Materials 138-139 (novembre 2011) : 981–87. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.981.
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The effects of phosphorus and organic carbon on bacterial growth were investigated in the laboratory. The bacteria sampled from the drinking water network of Tianjin were inoculated into water samples with different content of phosphorus (0～15µg PO43--P/L) and assimilable organic carbon (10～200µgAOC/L). The inoculated water samples were incubated at 20°C. Bacterial growth was monitored in every 2 days in the beginning of cultivation and in every 4 days or more in the later of the cultivation. Results showed that Phosphorus had obvious promotion on bacterial growth, which included shortening the lag phase evidently, increasing the growth rate and the maximum cell count in stationary phase. Carbon can only increase bacterial number. Under oligotrophic condition，when ratio of AOC: P in nutrients of water was more than 100:5, phosphorus was the limiting factor of bacterial growth. The bacterial yield factors against phosphorus and AOC were 1.1×109CFU/µgP and 9.0×107CFU/µgAOC respectively. Phosphorus was more sensitive than AOC. When the phosphorus concentration was less than 0.7µg/L in water samples, it was very difficult for bacteria to obtain phosphorus, and then growth of bacteria was very slowly or in lag phase in the first nine days of incubation time. In drinking water with low concentration of phosphorus (<0.7µg/L) and disinfectants, bacterial regrowth may be controlled. The paper will be Narrated in two parts, “Effects of AOC and Phosphorus on Bacterial Growth under Oligotrophic Condition (1)” and “Effects of AOC and Phosphorus on Bacterial Growth under Oligotrophic Condition (2)”.
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Jiang, Deng Ling, Yu Min Zhang et Guo Wei Ni. « Effects of AOC and Phosphorus on Bacterial Growth under Oligotrophic Condition (2) ». Applied Mechanics and Materials 138-139 (novembre 2011) : 988–94. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.988.
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The effects of phosphorus and organic carbon on bacterial growth were investigated in the laboratory. The bacteria sampled from the drinking water network of Tianjin were inoculated into water samples with different content of phosphorus (0～15µg PO43--P/L) and assimilable organic carbon (10～200µgAOC/L). The inoculated water samples were incubated at 20°C. Bacterial growth was monitored in every 2 days in the beginning of cultivation and in every 4 days or more in the later of the cultivation. Results showed that Phosphorus had obvious promotion on bacterial growth, which included shortening the lag phase evidently, increasing the growth rate and the maximum cell count in stationary phase. Carbon can only increase bacterial number. Under oligotrophic condition，when ratio of AOC: P in nutrients of water was more than 100:5, phosphorus was the limiting factor of bacterial growth. The bacterial yield factors against phosphorus and AOC were 1.1×109CFU/µgP and 9.0×107CFU/µgAOC respectively. Phosphorus was more sensitive than AOC. When the phosphorus concentration was less than 0.7µg/L in water samples, it was very difficult for bacteria to obtain phosphorus, and then growth of bacteria was very slowly or in lag phase in the first nine days of incubation time. In drinking water with low concentration of phosphorus (<0.7µg/L) and disinfectants, bacterial regrowth may be controlled. The paper will be Narrated in two parts, “Effects of AOC and Phosphorus on Bacterial Growth under Oligotrophic Condition (1)” and “Effects of AOC and Phosphorus on Bacterial Growth under Oligotrophic Condition (2)”.
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Wainwright, M., K. Al-Wajeeh, N. C. Wickramasinghe et J. V. Narlikar. « Did silicon aid in the establishment of the first bacterium ? » International Journal of Astrobiology 2, no 3 (juillet 2003) : 227–29. http://dx.doi.org/10.1017/s1473550403001587.
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Silicic acid increased numbers of both aerobic and facultatively anaerobic bacteria in ultrapure water incubated under strict oligotrophic conditions; soil extracts acted as the bacterial inoculum. The results are discussed in relation to the possibility that silicic acid, produced by the hydrolysis of silicates on the early Earth, could have stimulated the growth of the first bacterium, thereby allowing it to become established in the then prevailing conditions (presumed to be oligotrophic).
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Wyszkowska, J., J. Kucharski et E. Wałdowska. « The influence of diesel oil contamination on soil microorganisms and oat growth ». Plant, Soil and Environment 48, No. 2 (21 décembre 2011) : 51–57. http://dx.doi.org/10.17221/4359-pse.
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The effect of diesel oil applied at 0, 2.4, 4.8 and 7.2 ml/kg of soil on yield of oat and number of oligotrophic, eutrophic, nitrogen immobilising, ammonifying and cellulolytic bacteria and Azotobacter sp., actinomyces and fungi was studied in a pot experiment. Inoculation with Streptomyces intermedius spores was used for soil detoxication. The experiment was performed in Eutric Cambisol soil derived from light clay sand. Diesel oil was found to have a negative effect on the growth and development of oat. Inoculation did not attenuate the response of oat to soil contamination with diesel oil, but it had a positive effect on oligotrophic and eutrophic bacteria as well as Azotobacter sp., nitrogen immobilising bacteria and fungi. Regardless of sown and unsown soil and inoculation with S. intermedius spores, diesel oil stimulated the number of oligotrophic, eutrophic, nitrogen immobilising bacteria and actinomyces. Sowing of oat positively affected microbiological properties of soil, because it had a positive influence on the relation of oligotrophic bacteria and actinomyces to fungi. This positive effect, however, was weakened by diesel oil.
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YANG, RUILAN, JING LI, LUYAO WEI-XIE et LIN SHAO. « Oligotrophic Nitrification and Denitrification Bacterial Communities in a Constructed Sewage Treatment Ecosystem and Nitrogen Removal of Delftia tsuruhatensis NF4 ». Polish Journal of Microbiology 69, no 1 (11 mars 2020) : 99–108. http://dx.doi.org/10.33073/pjm-2020-013.
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Oligotrophic nitrifiers and denitrifiers play important roles in the removal of nitrogen from wastewater. Here, we studied the dominant bacterial populations of the sewage treatment ecosystem (STE) water from different processes and those of culture on oligotrophic heterotrophic nitrification (OHN) medium and oligotrophic aerobic denitrification (OAD) medium, using co-analysis of Illumina HiSeq DNA sequencing and traditional culture methods. The results showed that the STE water had no dominant population of oligotrophic nitrifiers or oligotrophic denitrifiers. However, after culturing on OHN medium and OAD medium, the core genera Pseudomonas, Aeromonas, and Acinetobacter that have the nitrogen removal capacity in oligotrophic environments, dominated in the bacterial community. The principal component analysis (PCA) showed that the bacterial community in the constructed rapid infiltration (CRI) effluent water of STE had high similarity with those of cultures on OHN medium and OAD medium, which prompt the special purification role of nitrogen in the CRI system. The sodium alginate immobilized OAD bacteria strain Delftia tsuruhatensis NF4 was isolated from the CRI system, with total nitrogen (TN) removal efficiency of 43.3% in sterilized STE influent water, and 60.1% in OAD medium on day three. The immobilization significantly influenced the TN and nitrate removal efficiency in OAD medium (p < 0.05), but not in sterilized STE influent water (p > 0.05). This study would lay the foundation for resource discovery of oligotrophic heterotrophic nitrifiers and aerobic denitrifiers in STE and further functional application of them on the bioremediation of wastewater.
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Tomkiel, Monika, Małgorzata Baćmaga, Jadwiga Wyszkowska, Jan Kucharski et Agata Borowik. « The effect of carfentrazone-ethyl on soil microorganisms and soil enzymes activity / Wpływ karfentrazonu etylu na mikroorganizmy i aktywność enzymów glebowych ». Archives of Environmental Protection 41, no 3 (1 septembre 2015) : 3–10. http://dx.doi.org/10.1515/aep-2015-0025.
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Abstract The aim of this study was to determine the effect of carfentrazone-ethyl (CE) doses of 0.265, 5.280, 10.560, 21.180, 42.240 μg kg-1 soil DM on fungi, Acnomycetes, organotrophic bacteria, total oligotrophic bacteria and spore-forming oligotrophic bacteria, and on the activity of dehydrogenases, catalase, urease, alkaline phosphatase, acid phosphatase, arylsulfatase and β-glucosidase. Carfentrazone-ethyl had a stimulating effect on total oligotrophic bacteria and organotrophic bacteria, but it inhibited the growth of Azotobacter, fungi, spore-forming oligotrophic bacteria and Actinomycetes. The analyzed substance modified the structure of soil microbial communities, and it induced the most profound changes in fungi. The highest values of the colony development (CD) index and the eco-physiological (EP) index were observed in organotrophic bacteria. The optimal dose of carfentrazone-ethyl stimulated the activity of dehydrogenases, catalase, urease, alkaline phosphatase, acid phosphatase and β-glucosidase, but it had no effect on arylsulfatase. The highest doses of the analyzed substance inhibited the activity of dehydrogenases (reduction from 11.835 to 11.381 μmol TPF), urease (reduction from 0.545 to 0.500 mmol N-NH4) and arylosulfatase (reduction from 0.210 to 0.168 mmol PNP). Dehydrogenases were most resistant to CE, whereas acid phosphatase and arylsulfatase were least resistant to the analyzed compound
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Lasternas, S., et S. Agustí. « Bacterial survival governed by organic carbon release from senescent oceanic phytoplankton ». Biogeosciences Discussions 10, no 10 (30 octobre 2013) : 16973–99. http://dx.doi.org/10.5194/bgd-10-16973-2013.
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Abstract. Bacteria recycle vast amounts of organic carbon, playing key biogeochemical and ecological roles in the ocean. Bacterioplankton dynamics are expected to be dependent on phytoplankton primary production, but there is a high diversity of processes (e.g. sloppy feeding, cell exudation, viral lysis) involved in the transference of primary production to dissolved organic carbon available to bacteria. Here we show cell survival of heterotrophic bacterioplankton in the subtropical Atlantic Ocean to be determined by phytoplankton extracellular carbon release (PER). PER represents the fraction of primary production released as dissolved organic carbon, and changes in the PER variability was explained by phytoplankton cell death, with the communities experiencing the highest phytoplankton cell mortality showing a larger proportion of extracellular carbon release. Both PER and the percent of dead phytoplankton cells increased from eutrophic to oligotrophic waters, while heterotrophic bacteria communities, including 60 to 95% of living cells (%LC), increased from the productive to the most oligotrophic waters. The percentage of living heterotrophic bacterial cells increased with increasing phytoplankton extracellular carbon release, across oligotrophic to productive waters in the NE Atlantic, where lower PER have resulted in a decrease in the flux of phytoplankton DOC per bacterial cell. The results highlight phytoplankton cell death as a process influencing the flow of dissolved photosynthetic carbon in the NE Atlantic Ocean, and demonstrated a close coupling between the fraction of primary production released and heterotrophic bacteria survival.
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Hewson, Ian, Danielle M. Winget, Kurt E. Williamson, Jed A. Fuhrman et K. Eric Wommack. « Viral and bacterial assemblage covariance in oligotrophic waters of the West Florida Shelf (Gulf of Mexico) ». Journal of the Marine Biological Association of the United Kingdom 86, no 3 (10 avril 2006) : 591–603. http://dx.doi.org/10.1017/s0025315406013506.
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Viruses are hypothesized to cause enhanced diversity in bacterial communities by regulating the outcome of intertaxon competition. However, concomitant documentation of viral and bacterial assemblage composition in oligotrophic waters are rare, particularly in situ over time, and there is almost no information on the temporal variability in virioplankton assemblage composition in oligotrophic water masses. Assemblage composition of viruses (via pulsed-field gel electrophoresis, PFGE) and bacteria (via automated rRNA intergenic spacer analysis, ARISA) was compared during surface lagrangian drifter deployments in the oligotrophic Gulf of Mexico during summer 2001, 2002, and 2003. In vertical profile, viruses and bacteria both had maximum abundances in surface waters, which decreased with depth; however, the richness of their assemblages was not significantly different between depths, suggesting independence of biomass and diversity. Viral assemblages changed rapidly (0.17–0.32 Jaccard index d−1), which was similar to the rate of change in bacterial assemblages reported in surface waters. Patterns of viral and bacterial assemblage composition were significantly related (P<0.001, r=0.58 between node ranks), and both assemblages clustered primarily by year and then by depth. These cultivation-independent observations demonstrate relationships between viral and bacterial assemblages, which are dynamic in patches of open ocean water. Even at the relatively low phylogenetic resolution of the ARISA and PFGE methods, the results support the idea that viruses may influence the species composition of host assemblages.
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Ducklow, Hugh. « Bacteria in oligotrophic environments : Starvation-survival lifestyle ». Limnology and Oceanography 43, no 5 (juillet 1998) : 1021–22. http://dx.doi.org/10.4319/lo.1998.43.5.1021.
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OHTA, HIROYUKI, et SHIGEHIKO TANIGUCHI. « Respiratory characteristics of two oligotrophic bacteria : Agromonas oligotrophica JCM 1494 and Aeromonas hydrophila 315. » Journal of General and Applied Microbiology 34, no 4 (1988) : 355–65. http://dx.doi.org/10.2323/jgam.34.355.
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Pulido-Villena, E., A. C. Baudoux, I. Obernosterer, M. Landa, J. Caparros, P. Catala, C. Georges, J. Harmand et C. Guieu. « Microbial food web dynamics in response to a Saharan dust event : results from a mesocosm study in the oligotrophic Mediterranean Sea ». Biogeosciences Discussions 11, no 1 (7 janvier 2014) : 337–71. http://dx.doi.org/10.5194/bgd-11-337-2014.
Texte intégralRésumé :
Abstract. The significant impact of dust deposition on heterotrophic bacterial dynamics in the surface oligotrophic ocean has recently been evidenced. Considering the central role of bacteria in the microbial loop, it is likely that dust deposition also affects the structure and the functioning of the whole microbial food web. In the frame of the DUNE project, aiming to estimate the impact of dust deposition on the oligotrophic Mediterranean Sea through mesocosm experiments, the main goal of the present paper was to assess how two successive dust deposition events affect the dynamics of the microbial food web. The first dust seeding delivered new P and N to the amended mesocosms and resulted in a pronounced stimulation of bacterial respiration. It also induced pronounced, but transient, changes in the bacterial community composition. No significant effects were observed on the abundances of viruses and heterotrophic nanoflagellates. The second dust seeding also delivered new P and N to the amended mesocosms but the effect on the microbial food web was very different. Bacterial respiration remained constant and bacterial abundance decreased. Compositional changes following the second seeding were minor compared to the first one. The decrease in bacterial abundance coincided with an increase in virus abundance, resulting in higher virus: bacteria ratios throughout the second seeding period. Our study shows that dust deposition to the surface oligotrophic ocean may involve important modifications of the trophic links among the components of the microbial food web with presumed consequences on C and nutrient cycling.
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Norris, Noele, Naomi M. Levine, Vicente I. Fernandez et Roman Stocker. « Mechanistic model of nutrient uptake explains dichotomy between marine oligotrophic and copiotrophic bacteria ». PLOS Computational Biology 17, no 5 (19 mai 2021) : e1009023. http://dx.doi.org/10.1371/journal.pcbi.1009023.
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Marine bacterial diversity is immense and believed to be driven in part by trade-offs in metabolic strategies. Here we consider heterotrophs that rely on organic carbon as an energy source and present a molecular-level model of cell metabolism that explains the dichotomy between copiotrophs—which dominate in carbon-rich environments—and oligotrophs—which dominate in carbon-poor environments—as the consequence of trade-offs between nutrient transport systems. While prototypical copiotrophs, like Vibrios, possess numerous phosphotransferase systems (PTS), prototypical oligotrophs, such as SAR11, lack PTS and rely on ATP-binding cassette (ABC) transporters, which use binding proteins. We develop models of both transport systems and use them in proteome allocation problems to predict the optimal nutrient uptake and metabolic strategy as a function of carbon availability. We derive a Michaelis–Menten approximation of ABC transport, analytically demonstrating how the half-saturation concentration is a function of binding protein abundance. We predict that oligotrophs can attain nanomolar half-saturation concentrations using binding proteins with only micromolar dissociation constants and while closely matching transport and metabolic capacities. However, our model predicts that this requires large periplasms and that the slow diffusion of the binding proteins limits uptake. Thus, binding proteins are critical for oligotrophic survival yet severely constrain growth rates. We propose that this trade-off fundamentally shaped the divergent evolution of oligotrophs and copiotrophs.
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Borrero, Celia, M. Isabel Trillas, José Ordovás, Julio C. Tello et Manuel Avilés. « Predictive Factors for the Suppression of Fusarium Wilt of Tomato in Plant Growth Media ». Phytopathology® 94, no 10 (octobre 2004) : 1094–101. http://dx.doi.org/10.1094/phyto.2004.94.10.1094.
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Fusarium wilts are economically important diseases for which there are no effective chemical control measures. However, biological control and fertility management are becoming efficient alternatives for controlling this disease. Growth media formulated with composts that are able to suppress Fusarium wilt of tomato provide a control system that integrates both strategies. The aim of this study was to predict Fusarium wilt suppression of growth media using abiotic and biotic variables. Grape marc compost was the most effective medium used to suppress Fusarium wilt. Cork compost was intermediate, and light peat and expanded vermiculite were the most conducive growth media. The growth media evaluated were in a pH range of 6.26 to 7.97. Both composts had high β-glucosidase activity. When pH and β-glucosidase activity were taken into account as predictive variables, more than 91% of the variation in severity of Fusarium wilt was explained. This relationship illustrates the effect of nutrient availability and the degree of microbiostasis, two key factors in this pathosystem. Microbial populations involved in suppressiveness were cellulolytic and oligotrophic actinomycetes, fungi, and the ratios cellulolytic actinomycetes/cellulolytic bacteria, oligotrophic bacteria/copiotrophic bacteria, and oligotrophic actinomycetes/oligotrophic bacteria. Based on community level physiological profiles, different community structures were evident among growth media evaluated.
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Marshall, Kevin C. « Adhesion and growth of bacteria at surfaces in oligotrophic habitats ». Canadian Journal of Microbiology 34, no 4 (1 avril 1988) : 503–6. http://dx.doi.org/10.1139/m88-086.
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In an extension of our previous studies demonstrating the ability of reversibly and irreversibly adhering bacteria to metabolize surface-bound organic substrates, we have directly demonstrated cellular growth and reproduction by previously starved bacteria in association with surface-bound substrates. The mode of cell attachment and division varies with the organisms involved, ranging from a continuous release of daughter cells from a perpendicularly attached mother cell of Vibrio DW1, to normal binary fission and a slow surface migration of face to face attached daughter cells of Pseudomonas JD8, with extensive detachment of cells late in the growth cycle, to normal binary fission in the aqueous phase following surface association of reversibly attached cells of Vibrio MH3. These studies indicate a range of strategies of bacterial growth and development at surfaces.
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Shoji, Tadashi, Shuichi Ochi et Masaaki Ozaki. « Characterization of bacterial biofilm communities in tertiary treatment processes for wastewater reclamation and reuse ». Water Science and Technology 58, no 5 (1 septembre 2008) : 1023–30. http://dx.doi.org/10.2166/wst.2008.457.
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The concern with wastewater reuse as a sustainable water resource in urban areas has been growing. For the reclamation and distribution of wastewater, biofilm development deserves careful attention from the point of view of its promotion (e.g. biofiltration) and inhibition (e.g. clogging and hygiene problems). As the first step to control biofilm development, bacterial biofilm communities in tertiary treatment processes were characterized by using molecular biological methods. The result of clone library analysis showed that Nitrospirae-related (nitrite-oxydizing bacteria) and Acidobacteria-related (probably oligotrophic bacteria) groups were dominant. The ratio of the Nitrospirae-related group to the Acidobacteria-related group was associated with ammonia load, whereas other operational conditions (process, media, temperature, salt) did not clearly affect the phylum-level community or the dominant sequence of nitrifying bacteria. The result of real-time PCR also indicated that high ammonia load promotes the proliferation of nitrite- and ammonia-oxidizing bacteria. Regarding water supply systems, some researchers also have suggested the dominance of Nitrospirae- and Acidobacteria-related groups in biofilm formed on water distribution pipes. In tertiary wastewater treatment, therefore, it is concluded that oligotrophic and autotrophic bacteria are the dominant groups in biofilm samples because assimilable organic carbon is too poor to proliferate various heterotrophic bacteria.
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Luo, Haiwei. « Predicted Protein Subcellular Localization in Dominant Surface Ocean Bacterioplankton ». Applied and Environmental Microbiology 78, no 18 (6 juillet 2012) : 6550–57. http://dx.doi.org/10.1128/aem.01406-12.
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ABSTRACTBacteria consume dissolved organic matter (DOM) through hydrolysis, transport and intracellular metabolism, and these activities occur in distinct subcellular localizations. Bacterial protein subcellular localizations for several major marine bacterial groups were predicted using genomic, metagenomic and metatranscriptomic data sets following modification of MetaP software for use with partial gene sequences. The most distinct pattern of subcellular localization was found forBacteroidetes, whose genomes were substantially enriched with outer membrane and extracellular proteins but depleted of inner membrane proteins compared with five other taxa (SAR11, Roseobacter,Synechococcus,Prochlorococcus, oligotrophic marineGammaproteobacteria). When subcellular localization patterns were compared between genes and transcripts, three taxa had expression biased toward proteins localized to cell locations outside of the cytosol (SAR11, Roseobacter, andSynechococcus), as expected based on the importance of carbon and nutrient acquisition in an oligotrophic ocean, but two taxa did not (oligotrophic marineGammaproteobacteriaandBacteroidetes). Diel variations in the fraction and putative gene functions of transcripts encoding inner membrane and periplasmic proteins compared to cytoplasmic proteins suggest a close coupling of photosynthetic extracellular release and bacterial consumption, providing insights into interactions between phytoplankton, bacteria, and DOM.
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Carrillo, P., J. M. Medina-Sánchez, C. Durán, G. Herrera, V. E. Villafañe et E. W. Helbling. « Synergistic effects of UVR and simulated stratification on commensalistic phytoplankton–bacteria relationship in two optically contrasting oligotrophic Mediterranean lakes ». Biogeosciences 12, no 3 (4 février 2015) : 697–712. http://dx.doi.org/10.5194/bg-12-697-2015.
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Abstract. An indirect effect of global warming is a reduction in the depth of the upper mixed layer (UML) causing organisms to be exposed to higher levels of ultraviolet (UVR, 280–400 nm) and photosynthetically active radiation (PAR, 400–700 nm). This can affect primary and bacterial production as well as the commensalistic phytoplankton–bacteria relationship. The combined effects of UVR and reduction in the depth of the UML were assessed on variables related to the metabolism of phytoplankton and bacteria, during in situ experiments performed with natural pico- and nanoplankton communities from two oligotrophic lakes with contrasting UVR transparency (high-UVR versus low-UVR waters) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified under increased stratification, were higher in the low-UVR than in the high-UVR lake, and stronger on the phytoplanktonic than on the heterotrophic bacterial communities. Under UVR and increased stratification, the commensalistic phytoplankton–bacteria relationship was strengthened in the high-UVR lake where excretion of organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD; i.e., BCD : EOC(%) ratio < 100). This did not occur in the low-UVR lake (i.e., BCD : EOC(%) ratio > 100). The greater UVR damage to phytoplankton and bacteria and the weakening of their commensalistic interaction found in the low-UVR lake indicates that these ecosystems would be especially vulnerable to UVR and increased stratification as stressors related to global climate change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.
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Agustí, S., et C. M. Duarte. « Phytoplankton lysis predicts dissolved organic carbon release in marine plankton communities ». Biogeosciences 10, no 3 (1 mars 2013) : 1259–64. http://dx.doi.org/10.5194/bg-10-1259-2013.
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Abstract. The relationship between the percent extracellular carbon release (PER) and the specific lysis rates of phytoplankton was examined across a range of communities spanning from highly oligotrophic ones in the subtropical Atlantic Ocean to productive ones in the N. African upwelling and the Southern Ocean. Communities in oligotrophic waters supported high phytoplankton cell lysis rates and low particulate primary production rates but high dissolved primary production and PER. The percent extracellular carbon released increased with increasing lysis rates to reach an asymptote at about 80% PER with specific lysis rates > 1.5 d−1, observed in the most oligotrophic conditions tested. These results confirm that high phytoplankton mortality in the oligotrophic ocean leads to high PER, accounting for the large fraction of the photosynthetic carbon channelled through bacteria characteristic of oligotrophic marine communities.
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Alothman, Afrah, Daffne López-Sandoval, Carlos M. Duarte et Susana Agustí. « Bacterioplankton dark CO2 fixation in oligotrophic waters ». Biogeosciences 20, no 17 (31 août 2023) : 3613–24. http://dx.doi.org/10.5194/bg-20-3613-2023.
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Abstract. Dark CO2 fixation by bacteria is believed to be particularly important in oligotrophic ecosystems. However, only a few studies have characterized the role of bacterial dissolved inorganic carbon (DIC) fixation in global carbon dynamics. Therefore, this study quantified the primary production (PP), total bacteria dark CO2 fixation (TBDIC fixation), and heterotrophic bacterial production (HBP) in the warm and oligotrophic Red Sea using stable-isotope labeling and cavity ring-down spectroscopy (13C–CRDS). Additionally, we assessed the contribution of bacterial DIC fixation (TBDIC %) relative to the total DIC fixation (totalDIC fixation). Our study demonstrated that TBDIC fixation increased the totalDIC fixation from 2.03 to 60.45 µg C L−1 d−1 within the photic zone, contributing 13.18 % to 71.68 % with an average value of 33.95 ± 0.02 % of the photic layer totalDIC fixation. The highest TBDIC fixation values were measured at the surface and deep (400 m) water with an average value of 5.23 ± 0.45 and 4.95 ± 1.33 µg C L−1 d−1, respectively. These findings suggest that the non-photosynthetic processes such as anaplerotic DIC reactions and chemoautotrophic CO2 fixation extended to the entire oxygenated water column. On the other hand, the percent of TBDIC contribution to totalDIC fixation increased as primary production decreased (R2=0.45, p<0.0001), suggesting the relevance of increased dark DIC fixation when photosynthetic production was low or absent, as observed in other systems. Therefore, when estimating the total carbon dioxide production in the ocean, dark DIC fixation must also be accounted for as a crucial component of the carbon dioxide flux in addition to photosynthesis.
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Lee, Siew Wen, Choon Weng Lee, Chui Wei Bong, Kumaran Narayanan et Edmund Ui-Hang Sim. « The dynamics of attached and free-living bacterial population in tropical coastal waters ». Marine and Freshwater Research 66, no 8 (2015) : 701. http://dx.doi.org/10.1071/mf14123.
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We investigated the dynamics of attached and free-living bacterial abundance over a period of 18 months in tropical coastal waters of Malaysia. We measured the abundance at both oligotrophic coastal water (Port Dickson) and eutrophic estuary (Klang), and hypothesised that attached bacteria are predominant in eutrophic waters. We found that bacterial abundance was higher at Klang than Port Dickson (Student’s t-test: t=4.87, d.f.=19, P<0.001). Attached bacteria also formed a large fraction of the total bacteria at Klang (75% ±13s.d.) relative to Port Dickson (56% ±22), and showed preference for chlorophyll-a-based particles rather than total suspended solids. The bacterial community structure was clearly different between the two stations but was similar between the attached and free-living bacterial population. Our results showed the importance of attached bacteria in eutrophic water where they could play a major role in carbon and nutrient cycling.
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Chiang, K. P., A. Y. Tsai, P. J. Tsai, G. C. Gong et S. F. Tsai. « Coupling of the spatial dynamic of picoplankton and nanoflagellate grazing pressure and carbon flow of the microbial food web in the subtropical pelagic continental shelf ecosystem ». Biogeosciences Discussions 10, no 1 (7 janvier 2013) : 233–63. http://dx.doi.org/10.5194/bgd-10-233-2013.
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Abstract. In order to investigate the mechanism of spatial dynamics of picoplankton community (bacteria and Synechococcus spp.) and estimate the carbon flux of the microbial food web in the oligotrophic Taiwan Warm Current Water of subtropical marine pelagic ecosystem, we conducted size-fractionation experiments in five cruises by the R/V Ocean Research II during the summers of 2010 and 2011 in the southern East China Sea. We carried out culture experiments using surface water which, according to a temperature-salinity (T-S) diagram, is characterized as oligotrophic Taiwan Current Warm Water. We found a negative correlation bettween bacteria growth rate and temperature, indicating that the active growth of heterotrophic bacteria might be induced by nutrients lifted from deep layer by cold upwelling water. This finding suggests that the area we studied was a bottom-up control pelagic ecosystem. We suggest that the microbial food web of an oligotrophic ecosystem may be changed from top-down control to resource supply (bottom-up control) when a physical force brings nutrient into the oligotrophic ecosystem. Upwelling brings nutrient-rich water to euphotic zone and promotes bacteria growth, increasing the picoplankton biomass which increased the consumption rate of nanoflagellate. The net growth rate (growth rate–grazing rate) becomes negative when the densities of bacteria and Synechococcus spp. are lower than the threshold values. The interaction between growth and grazing will limit the abundances of bacteria (105-106 cells mL-1 and Synechococcus spp. (104-105 cells mL-1) within a narrow range, forming a predator-prey eddy. Meanwhile, 62% of bacteria production and 55% of Synechococcus spp. production are transported to higher trophic level (nanoflagellate), though the cascade effect might cause an underestimation of both percentages of transported carbon. Based on the increasing number of sizes we found in the size-fractionation experiments, we estimated that the predation values were underestimated by 28.3% for bacteria and 34.6% for Synechococcus spp. Taking these corrections into consideration, we conclude that picoplankton production is balanced by nonoflagellate grazing and the diet of nanoflagellate is composed of 64% bacteria and 36% Synechococcus spp.
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Blom, Judith F., Yannick S. Zimmermann, Thomas Ammann et Jakob Pernthaler. « Scent of Danger : Floc Formation by a Freshwater Bacterium Is Induced by Supernatants from a Predator-Prey Coculture ». Applied and Environmental Microbiology 76, no 18 (23 juillet 2010) : 6156–63. http://dx.doi.org/10.1128/aem.01455-10.
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ABSTRACT We investigated predator-prey interactions in a model system consisting of the bacterivorous flagellate Poterioochromonas sp. strain DS and the freshwater bacterium Sphingobium sp. strain Z007. This bacterial strain tends to form a subpopulation of grazing-resistant microscopic flocs, presumably by aggregation. Enhanced formation of such flocs could be demonstrated in static batch culture experiments in the presence of the predator. The ratio of aggregates to single cells reached >0.1 after 120 h of incubation in an oligotrophic growth medium. The inoculation of bacteria into supernatants from cocultures of bacteria and flagellates (grown in oligotrophic or in rich media) also resulted in a substantially higher level of floc formation than that in supernatants from bacterial monocultures only. After separation of supernatants on a C18 cartridge, the aggregate-inducing activity could be assigned to the 50% aqueous methanolic fraction, and further separation of this bioactive fraction could be achieved by high-pressure liquid chromatography. These results strongly suggest the involvement of one or several chemical factors in the induction of floc formation by Sphingobium sp. strain Z007 that are possibly released into the surrounding medium by flagellate grazing.
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Lasternas, S., et S. Agustí. « The percentage of living bacterial cells related to organic carbon release from senescent oceanic phytoplankton ». Biogeosciences 11, no 22 (26 novembre 2014) : 6377–87. http://dx.doi.org/10.5194/bg-11-6377-2014.
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Abstract. Bacteria recycle vast amounts of organic carbon, playing key biogeochemical and ecological roles in the ocean. Bacterioplankton dynamics are expected to be dependent on phytoplankton primary production, but there is a high diversity of processes (e.g., sloppy feeding, cell exudation, viral lysis) involved in the transfer of primary production to dissolved organic carbon available to bacteria. Here, we show the percentage of living heterotrophic bacterioplankton in the subtropical NE Atlantic Ocean in relation to phytoplankton extracellular carbon release (PER). PER represents the fraction of primary production released as dissolved organic carbon. PER variability was explained by phytoplankton cell death, with communities experiencing higher phytoplankton cell mortality showing a larger proportion of phytoplankton extracellular carbon release. Both PER and the percentage of dead phytoplankton cells increased from eutrophic to oligotrophic waters, while abundance of heterotrophic bacteria was highest in the intermediate waters. The percentage of living heterotrophic bacterial cells (range: 60–95%) increased with increasing phytoplankton extracellular carbon release from productive to oligotrophic waters in the subtropical NE Atlantic. The lower PERs, observed at the upwelling waters, have resulted in a decrease in the flux of phytoplankton dissolved organic carbon (DOC) per bacterial cell. The results highlight phytoplankton cell death as a process influencing the flow of dissolved photosynthetic carbon in this region of the subtropical NE Atlantic Ocean, and suggest a close coupling between the fraction of primary production released and heterotrophic bacterial cell survival.
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Chikh, G., J. Pourquié, P. Kaiser et A. M. Davila. « Characterization of the bacterial flora isolated from a pilot-scale lagoon processing swine manure ». Canadian Journal of Microbiology 43, no 11 (1 novembre 1997) : 1079–83. http://dx.doi.org/10.1139/m97-154.
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The bacterial flora of an experimental plant that processes liquid swine manure by an aerated compartmented (multistage) lagoon system has been studied. The total flora is characterized by a larger number of oligotrophic bacteria than eutrophic ones. Each compartment displays a specific flora, different from the flora in the manure, and consisting of a complex assembly of Gram-negative and Gram-positive ubiquitous species, such as Aeromonas spp. and Pseudomonas spp., and specialized species, such as Sphingobacterium spp. and Corynebacterium spp. The fecal indicator microorganisms have been shown to disappear in the course of the processing. A significant population of nitrifying bacteria has been observed at levels up to 104 bacteria∙mL−1.Key words: swine manure, processing lagoon, bacterial flora, wastewater.
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ŠANTIĆ, D., S. ŠESTANOVIĆ, M. ŠOLIĆ, N. KRSTULOVIĆ, G. KUŠPILIĆ, M. ORDULJ et Ž. N. GLADAN. « Dynamics of picoplankton community from coastal waters to the open sea in the Central Adriatic ». Mediterranean Marine Science 15, no 1 (6 décembre 2013) : 179. http://dx.doi.org/10.12681/mms.701.
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Flow cytometry was used to describe seasonal cycles of Prochlorococcus (Prochl), Synechococcus (Syn), picoeukaryotes and heterotrophic bacteria in the central Adriatic Sea along the trophic gradient from January to December 2010. All picoplankton parameters decreased from eutrophic to oligotrophic areas, while the biomass ratio of bacterial to autotrophic picoplankton showed an increase along the trophic gradient. Bacterial biomass ranged from 5.28 to 21.20 μg C l-1. Increased values were present during warmer seasons with the domination of low nucleic acid (LNA) group of bacteria. The high nucleic acid (HNA) bacterial group dominated during the winter and the spring. Bacterial production ranged from 0.09 -0.45 × 104 cells ml-1 h-1 .At coastal stations increased production was present during the winter and the spring and was more or less uniform at open sea stations. Biomasses of Syn and Prochl ranged from 0.16 to 11.47 µg C-1 l-1 and from 0.01 to 3.08 µg C l-1, respectively. They were elevated during the summer and the autumn at coastal stations and during the late winter at the open sea. Syn biomass always dominated over Prochl participating with 61.6-97.2% in biomass of cyanobacteria. Biomass of picoeukaryotes ranged from 1.21 to 21.85 µg C l-1 and was the highest during the winter. Their biomass notably prevailed in autotrophic picoplankton (APP) biomass over that of picocyanobacteria during the whole year. Autotrophic components (Prochl, Syn and picoeukaryotes) made greater contribution to the picoplankton biomass in mesotrophic and eutrophic areas, while heterotrophic bacteria became more important under oligotrophic conditions.
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Hanaka, Agnieszka, Ewa Ozimek, Małgorzata Majewska, Anna Rysiak et Jolanta Jaroszuk-Ściseł. « Physiological Diversity of Spitsbergen Soil Microbial Communities Suggests Their Potential as Plant Growth-Promoting Bacteria ». International Journal of Molecular Sciences 20, no 5 (9 mars 2019) : 1207. http://dx.doi.org/10.3390/ijms20051207.
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The objective of the study was to assess the physiological diversity and metabolic activity of the soil bacterial communities inhabiting Spitsbergen soils in search of bacterial abilities facilitating plant growth promotion. In the soil, the total number of culturable microorganisms, the number of their individual physiological groups (including Siderophore Synthesizing; SSB and Phosphate Solubilizing Bacteria; PSB), the dehydrogenase (DH) activity, and the ability to utilize sources of C, N, P (EcoPlate) were analysed. In bacterial isolates, siderophores production, ACC (1-aminocyclopropane-1-carboxylate) deaminase (ACCD) activity, IAA (indole-3-acetic acid) synthesis were examined. The isolates were applied to the seeds of Phaseolus coccineus regarding their germination and root length. The results showed differences between copio- and oligotrophic bacteria. A usually high number of SSB was accompanied by the raised number of PSB. A bigger number of SSB was connected with low values of Fe in the soil. High DH activity was assisted by greater number of copio- and oligotrophic bacteria, raised average well color development value, and N and C contents in the soil. Germination index was more alike relative seed germination than relative root growth. IAA concentration and ACCD activity were conversely related. Synthesis of siderophores was matched with ACCD activity and its high level was combined with elevated germination index. In spite of different localization of soil samples, some isolates proved similar traits of activity. Distinct affiliation of isolates and their various localizations were displayed. Among all isolates tested, some possessed one main trait of activity, but most of them had two or more significant features for potential plant growth stimulation. These isolates could be an important source of useful bacteria.
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YOSHIDA, Nobuyuki. « Oligobody-A Nanostructure Found in a Super Oligotrophic Bacteria ». Oleoscience 18, no 5 (2018) : 233–40. http://dx.doi.org/10.5650/oleoscience.18.233.
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Kaszubiak, Henryk, et Maria Muszyńska. « The occurence of obligatorily oligotrophic bacteria in the soil ». Zentralblatt für Mikrobiologie 147, no 1-2 (février 1992) : 143–49. http://dx.doi.org/10.1016/s0232-4393(11)80376-8.
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Huang, Yu-Shiuan, et Fo-Ting Shen. « Bioprospecting of facultatively oligotrophic bacteria from non-rhizospheric soils ». Applied Soil Ecology 108 (décembre 2016) : 315–24. http://dx.doi.org/10.1016/j.apsoil.2016.09.004.
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Keshtacher-Liebso, E., Y. Hadar et Y. Chen. « Oligotrophic Bacteria Enhance Algal Growth under Iron-Deficient Conditions. » Applied and environmental microbiology 61, no 6 (1995) : 2439–41. http://dx.doi.org/10.1128/aem.61.6.2439-2441.1995.
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Kjelleberg, S. « Oligotrophic and copiotrophic marine bacteria—observations related to attachment ». FEMS Microbiology Letters 31, no 2 (avril 1985) : 89–96. http://dx.doi.org/10.1016/0378-1097(85)90004-7.
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Slabova, O. I., et D. I. Nikitin. « Immobilization of Oligotrophic Bacteria by Absorption on Porous Carriers ». Microbiology 74, no 3 (mai 2005) : 371–73. http://dx.doi.org/10.1007/s11021-005-0076-x.
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Pulido-Villena, E., A. C. Baudoux, I. Obernosterer, M. Landa, J. Caparros, P. Catala, C. Georges, J. Harmand et C. Guieu. « Microbial food web dynamics in response to a Saharan dust event : results from a mesocosm study in the oligotrophic Mediterranean Sea ». Biogeosciences 11, no 19 (14 octobre 2014) : 5607–19. http://dx.doi.org/10.5194/bg-11-5607-2014.
Texte intégralRésumé :
Abstract. The significant impact of dust deposition on heterotrophic bacterial dynamics in the surface oligotrophic ocean has recently been evidenced. Considering the central role of bacteria in the microbial loop, it is likely that dust deposition also affects the structure and the functioning of the whole microbial food web. In the frame of the DUNE project, aiming to estimate the impact of dust deposition on the oligotrophic Mediterranean Sea through mesocosm experiments, the main goal of the present paper was to assess how two successive dust deposition events affect the dynamics of the microbial food web. The first dust seeding delivered new P and N to the amended mesocosms and resulted in a pronounced stimulation of bacterial respiration. It also induced pronounced, but transient, changes in the bacterial community composition. No significant effects were observed on the abundances of viruses and heterotrophic nanoflagellates. The second dust seeding also delivered new P and N to the amended mesocosms, but the effect on the microbial food web was very different. Bacterial respiration remained constant and bacterial abundance decreased. Compositional changes following the second seeding were minor compared to the first one. The decrease in bacterial abundance coincided with an increase in virus abundance, resulting in higher virus:bacteria ratios throughout the second seeding period. Our study shows that dust deposition to the surface oligotrophic ocean may involve important modifications of the trophic links among the components of the microbial food web with presumed consequences on C and nutrient cycling.
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Chen, Liping, Chenglong Wang et Jianyu Su. « Understanding the Effect of Different Glucose Concentrations in the Oligotrophic Bacterium Bacillus subtilis BS-G1 through Transcriptomics Analysis ». Microorganisms 11, no 10 (26 septembre 2023) : 2401. http://dx.doi.org/10.3390/microorganisms11102401.
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Glucose is an important carbon source for microbial growth, and its content in infertile soils is essential for the growth of bacteria. Since the mechanism of oligotrophic bacterium adaptation in barren soils is unclear, this research employed RNA-seq technology to examine the impact of glucose concentration on the oligotrophic bacterium B. subtilis BS-G1 in soil affected by desertification. A global transcriptome analysis (RNA-Seq) revealed that the significantly differentially expressed genes (DEGs) histidine metabolism, glutamate synthesis, the HIF-1 signaling pathway, sporulation, and the TCA cycle pathway of B. subtilis BS-G1 were significantly enriched with a 0.015 g/L glucose concentration (L group), compared to a 10 g/L glucose concentration (H group). The DEGs amino acid system, two-component system, metal ion transport, and nitrogen metabolism system of B. subtilis BS-G1 were significantly enriched in the 5 g/L glucose concentration (M group), compared with the H group. In addition, the present study identified the regulation pattern and key genes under a low-glucose environment (7 mRNAs and 16 sRNAs). This study primarily investigates the variances in the regulatory pathways of the oligotrophic B. subtilis BS-G1, which holds substantial importance in comprehending the mechanism underlying the limited sugar tolerance of oligotrophic bacteria.
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Carrillo, P., J. M. Medina-Sánchez, C. Durán, G. Herrera, V. E. Villafañe et E. W. Helbling. « Synergistic effects of UVR and simulated stratification on commensalistic algal-bacterial relationship in two optically contrasting oligotrophic Mediterranean lakes ». Biogeosciences Discussions 11, no 8 (25 août 2014) : 12591–629. http://dx.doi.org/10.5194/bgd-11-12591-2014.
Texte intégralRésumé :
Abstract. An indirect effect of global warming is the shallowing epilimnion, causing organisms to be exposed to higher levels of ultraviolet (UVR, 280–400 nm) and photosynthetically active radiation (PAR, 400–700 nm), which could affect primary and bacterial production as well as the commensalistic algal-bacterial relationship. The combined effects of UVR and reduction in the depth of the upper mixed layer (UML) were assessed on variables related to the metabolism of algae and bacteria, during in situ experiments performed with natural microplanktonic communities from two oligotrophic lakes with contrasting UVR-transparency (clear vs. opaque) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified by high mean irradiances, were higher in the UVR-opaque than in the UVR-clear lake, and stronger on the algae than on the heterotrophic bacterial communities. Under UVR and high mean irradiance, the algal-bacterial relationship was strengthened in the UVR-clear lake, where excreted organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD). This did not occur in the UVR-opaque lake. The greater UVR damage to algae and bacteria and the weakening of their commensalistic interaction found in the UVR-opaque lake indicates that these ecosystems would be especially vulnerable to stressors related to global change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.
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Mescioglu, Esra, Eyal Rahav, Natalia Belkin, Peng Xian, Jordan Eizenga, Ania Vichik, Barak Herut et Adina Paytan. « Aerosol Microbiome over the Mediterranean Sea Diversity and Abundance ». Atmosphere 10, no 8 (1 août 2019) : 440. http://dx.doi.org/10.3390/atmos10080440.
Texte intégralRésumé :
Prokaryotic microbes can become aerosolized and deposited into new environments located thousands of kilometers away from their place of origin. The Mediterranean Sea is an oligotrophic to ultra-oligotrophic marginal sea, which neighbors northern Africa (a major source of natural aerosols) and Europe (a source of mostly anthropogenic aerosols). Previous studies demonstrated that airborne bacteria deposited during dust events over the Mediterranean Sea may significantly alter the ecology and function of the surface seawater layer, yet little is known about their abundance and diversity during ‘background’ non-storm conditions. Here, we describe the abundance and genetic diversity of airborne bacteria in 16 air samples collected over an East-West transect of the entire Mediterranean Sea during non-storm conditions in April 2011. The results show that airborne bacteria represent diverse groups with the most abundant bacteria from the Firmicutes (Bacilli and Clostridia) and Proteobacteria (Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria) phyla. Most of the bacteria in our samples have previously been observed in the air at other open ocean locations, in the air over the Mediterranean Sea during dust storms, and in the Mediterranean seawater. Airborne bacterial abundance ranged from 0.7 × 104 to 2.5 × 104 cells m−3 air, similar to abundances at other oceanic regimes. Our results demonstrate that airborne bacterial diversity is positively correlated with the mineral dust content in the aerosols and was spatially separated between major basins of the Mediterranean Sea. To our knowledge, this is the first comprehensive biogeographical dataset to assess the diversity and abundance of airborne microbes over the Mediterranean Sea. Our results shed light on the spatiotemporal distribution of airborne microbes and may have implications for dispersal and distribution of microbes (biogeography) in the ocean.