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Chemical Factors
Published in Michael J. Kennish, Ecology of Estuaries Physical and Chemical Aspects, 2019
When dissolved oxygen declines below 10% of saturation, organisms die and the biological oxygen demand (BOD) rises, promoting the development of anoxia. In anoxic environments, anaerobic bacteria proliferate, with nitrogenous oxide reducers absorbing oxygen by reducing nitrate to nitrite and forming ammonia or nitrogen gas. In addition, sulfate-reducing bacteria reduce sulfate to hydrogen sulfide which, when liberated, increases mortality of estuarine organisms and the BOD as it permeates through the water column. To protect the biotic resources of estuaries, Battelle Columbus Laboratories301 maintains that dissolved oxygen levels should exceed 4 mg/ℓ.
Radionuclide Concentrations in Soils lution-Processed Organic Solar Cells
Published in Michael Pöschl, Leo M. L. Nollet, Radionuclide Concentrations in Food and the Environment, 2006
When sulfate-reducing bacteria were added to the assays under conditions allowing sulfate reduction, less 137Cs adsorption was observed in all soils, but the effect was more pronounced in tropical samples than in the arid samples (Figure 5.7). Sulfate reduction resulted in a decrease in adsorption in Tippera soils from 90% to 50%, and by more than half an order of magnitude in Blain soils. The implication of these results for tropical soils contaminated with radionuclides such as 137Cs is that microbial activity can result in the transfer of radionuclides from the soil to other organisms through increased bioavailability [24].
Gut microbiota associations with metabolic syndrome and relevance of its study in pediatric subjects
Published in Gut Microbes, 2021
Ana K. Carrizales-Sánchez, Tomás García-Cayuela, Carmen Hernández-Brenes, Carolina Senés-Guerrero
Sulfate-reducing bacteria also use H2 to produce hydrogen sulfide (H2S). Desulfovibrio spp. is the most highly active species and greatest affinity bacteria for H2. Since both sulfate‐reducing bacteria and methanogens from the gut compete for the same pool of H2, the availability of sulfate for H2S production is the bottleneck for this preference.65,67Desulfovibrio piger has been associated with abundance of Collinsella aerofaciens, an Actinobacterium that conducts sugar fermentation removing H2, lactate, and formate. This is relevant since C. aerofaciens has been linked with BA metabolism, the regulation of blood cholesterol, the production of SCFAs, and gut homeostasis.72,73 However, production of H2S in the gastrointestinal tract seem to also be related in arterial blood pressure homeostasis and provide cardioprotective effects, but mechanisms are still unclear.72 Of note, a higher concentration of H2S seems to be relevant for liver and adipose tissue since it has been shown to promote the regulation of insulin sensitivity, stimulate hepatic gluconeogenesis and glycogenolysis, inhibit glucose and glycogen storage usage, and regulate lipolysis, inflammation, and adipokine production.74
Deprivation of dietary fiber in specific-pathogen-free mice promotes susceptibility to the intestinal mucosal pathogen Citrobacter rodentium
Published in Gut Microbes, 2021
Mareike Neumann, Alex Steimle, Erica T. Grant, Mathis Wolter, Amy Parrish, Stéphanie Willieme, Dirk Brenner, Eric C. Martens, Mahesh S. Desai
Additionally, specific species within the Rikenellaceae (Alistipes),44,45Lachnospiraceae46,47 and Muribaculaceae45 families are thought to possess the capacity to degrade mucus. Thus, in line with our 14SM model,13 our results suggest that the deprivation of dietary fiber may also increase mucus-degrading populations in the SPF mice containing their native gut microbiota. An increase in Desulfovibrionaceae family (Figure 1d) is consistent with the significant increase of Desulfovibrio piger (family: Desulfovibrionaceae), which was previously observed in fiber-deprived 14SM-colonized gnotobiotic mice.13 An increase in these sulfate-reducing bacteria indicates higher availability of sulfate groups that are used as an electron acceptor by this group of bacteria. A possible source of this increased sulfate could be the terminal sulfate groups on the colonic mucin-associated glycans.10
Influence of short-term changes in dietary sulfur on the relative abundances of intestinal sulfate-reducing bacteria
Published in Gut Microbes, 2019
Allison Dostal Webster, Christopher Staley, Matthew J. Hamilton, Merry Huang, Kathryn Fryxell, Raymond Erickson, Amanda J. Kabage, Michael J. Sadowsky, Alexander Khoruts
Diseases associated with chronic gut inflammation, such as Crohn’s disease and ulcerative colitis (UC), have increased in incidence since World War II in Western countries, and are emerging rapidly in countries that are becoming more westernized.1 Dietary changes that include increased content of animal protein and saturated fat are associated with westernization. One possible mechanism that may link increased dietary protein and fat content with gut inflammation is increased production of hydrogen sulfide (H2S), which is an end product of microbial fermentation and a potential toxin.2,3 Sulfate-reducing bacteria (SRB) constitute one of the main producers of H2S in the gut, and it is hypothesized that increased content of dietary sulfur may enhance SRB activity.4