scholarly journals Interactions of bactivorous grazers and heterotrophic bacteria with dissolved organic matter

1985 ◽  
Vol 23 ◽  
pp. 129-141 ◽  
Author(s):  
GT Taylor ◽  
R Iturriaga ◽  
CW Sullivan
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Heterotrophic Bacteria

scholarly journals Diel dynamics of dissolved organic matter and heterotrophic prokaryotes reveal enhanced growth at the ocean’s mesopelagic fish layer during daytime

2019 ◽  
Author(s):  
Xosé Anxelu G. Morán ◽  
Francisca C. García ◽  
Anders Røstad ◽  
Luis Silva ◽  
Najwa Al-Otaibi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Heterotrophic Bacteria ◽  
Mesopelagic Fish ◽  
Diel Cycles ◽  
Organic Carbon Concentration ◽  
Mesopelagic Zone ◽  
Heterotrophic Prokaryotes ◽  
Specific Growth Rates

ABSTRACTContrary to epipelagic waters, where biogeochemical processes closely follow the light and dark periods, little is known about diel cycles in the ocean’s mesopelagic realm. Here, we monitored the dynamics of dissolved organic matter (DOM) and planktonic heterotrophic prokaryotes every 2 h for one day at 0 and 550 m (a depth occupied by vertically migrating fish during light hours) in oligotrophic waters of the central Red Sea. We additionally performed predator-free seawater incubations of samples collected from the same site both at midnight and at noon. Comparable in situ variability in microbial biomass and dissolved organic carbon concentration suggests a diel supply of fresh DOM in both layers. The presence of fish in the mesopelagic zone during daytime promoted a sustained, longer growth of larger prokaryotic cells. The specific growth rates were consistently higher in the noon experiments from both depths (surface: 0.34 vs. 0.18 d−1, mesopelagic: 0.16 vs. 0.09 d−1). Heterotrophic bacteria and archaea in the mesopelagic fish layer were also more efficient at converting DOM into new biomass. These results suggest that the ocean’s twilight zone receives a consistent diurnal supply of labile DOM from diel vertical migrating fishes, enabling an unexpectedly active community of heterotrophic prokaryotes.

scholarly journals Natural Assemblages of Marine Proteobacteria and Members of the Cytophaga-Flavobacter Cluster Consuming Low- and High-Molecular-Weight Dissolved Organic Matter

2000 ◽  
Vol 66 (4) ◽  
pp. 1692-1697 ◽  
Author(s):  
Matthew T. Cottrell ◽  
David L. Kirchman
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Bacterial Community ◽  
Dissolved Organic Matter ◽  
Relative Abundance ◽  
Heterotrophic Bacteria ◽  
Phylogenetic Groups ◽  
Whole Cells ◽  
Biogeochemical Models

ABSTRACT We used a method that combines microautoradiography with hybridization of fluorescent rRNA-targeted oligonucleotide probes to whole cells (MICRO-FISH) to test the hypothesis that the relative contributions of various phylogenetic groups to the utilization of dissolved organic matter (DOM) depend solely on their relative abundance in the bacterial community. We found that utilization of even simple low-molecular-weight DOM components by bacteria differed across the major phylogenetic groups and often did not correlate with the relative abundance of these bacterial groups in estuarine and coastal environments. The Cytophaga-Flavobacter cluster was overrepresented in the portion of the assemblage consuming chitin,N-acetylglucosamine, and protein but was generally underrepresented in the assemblage consuming amino acids. The amino acid-consuming assemblage was usually dominated by the α subclass of the class Proteobacteria, although the representation of α-proteobacteria in the protein-consuming assemblages was about that expected from their relative abundance in the entire bacterial community. In our experiments, no phylogenetic group dominated the consumption of all DOM, suggesting that the participation of a diverse assemblage of bacteria is essential for the complete degradation of complex DOM in the oceans. These results also suggest that the role of aerobic heterotrophic bacteria in carbon cycling would be more accurately described by using three groups instead of the single bacterial compartment currently used in biogeochemical models.

scholarly journals Photodegradation and biodegradation of dissolved organic matter on the surface of the Greenland Ice Sheet

2020 ◽  
Author(s):  
Miranda J. Nicholes ◽  
Christopher Williamson ◽  
Martyn Tranter ◽  
Alexandra Holland ◽  
Marian Yallop ◽  
...  
Keyword(s):  
Organic Matter ◽  
Solar Radiation ◽  
Dissolved Organic Matter ◽  
Bacterial Communities ◽  
Heterotrophic Bacteria ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Algal Pigment ◽  
Surface Ice ◽  
Dom Composition

Abstract. The surface (supraglacial) environment of the Greenland Ice Sheet (GrIS) is an active site for the storage, transformation and transport of carbon, which is driven by extremely high levels of solar radiation throughout the ablation season. Within the south west of the GrIS, blooms of Streptophyte micro-algae (hereafter glacier algae) at abundances of ~ 105 cell mL−1 dominate primary production in the surface ice and provide dissolved organic matter (DOM) to the heterotrophic bacterial community. Glacier algae contain photoprotective secondary phenolic pigment that comprises a large proportion of the cell (~ 4 % of the dry weight) and could represent a substantial, additional carbon source for the heterotrophic community. The transformation and degradation of DOM by solar radiation (photodegradation) and heterotrophic communities (biodegradation) represent two crucial controls on DOM composition and quantity; however, the influence of these processes within the surface ice is yet to be constrained. This study therefore assessed responses in the composition and quantity of two carbon sources (glacier algae secondary pigment and surface ice DOM) following exposure to UV, PAR, UV+PAR (photodegradation) and subsequent incubation with bacterial communities isolated from the ambient environment (biodegradation). Our results indicate that exposure to predominantly UV radiation altered the composition of glacier algal pigment and surface ice DOM; however, the quantity of DOM remained constant. Biodegradation caused the greatest changes to both DOM composition and quantity, particularly in surface ice DOM. Secondary pigment extracted from glacier algae was not a highly bioavailable source of carbon and did not support significant growth of surface ice heterotrophic bacterial communities. Conversely, low molecular weight compounds in surface ice DOM were rapidly utilised by heterotrophic bacteria supporting between a 3 and 9-fold increase in bacterial abundance over a 30-day incubation. We found that photodegradation of glacier algal pigment and surface ice DOM did not influence heterotrophic consumption. Photodegradation and biodegradation of DOM in the surface ice habitat are likely intimately linked and act as fundamental controls on the composition and quantity of DOM exported to downstream environments.

scholarly journals Aerobic release and biodegradation of dissolved organic matter from frozen peat: Effects of temperature and heterotrophic bacteria

2020 ◽  
Vol 536 ◽  
pp. 119448 ◽  
Author(s):  
Dahédrey Payandi-Rolland ◽  
Liudmila S. Shirokova ◽  
Paty Nakhle ◽  
Marawit Tesfa ◽  
Ahmed Abdou ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Heterotrophic Bacteria ◽  
Effects Of Temperature
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