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Biological Contamination Control and Planetary Protection Measures as Applied to Sample Acquisition
Published in Yoseph Bar-Cohen, Kris Zacny, Advances in Extraterrestrial Drilling, 2020
James N. Benardini, Moogega Stricker, Kasthuri J. Venkateswaran
Oligotrophs are organisms capable of surviving and proliferating in extremely nutrient-deprived conditions (total organic carbon level <2 mg/L). Species inhabiting extremely oligotrophic environments on Earth have been shown to display an array of distinctive metabolic activities for community growth, including atmospheric nitrogen and organic carbon fixation, methane, hydrogen and iron oxidation, the breakdown of complex organic molecules, and the mobilization of inorganic phosphorous (Barton and Northup, 2007; Barton et al., 2004; Chelius and Moore, 2004). As with all environments, an understanding of the potential energy sources (both electron donors/acceptors) and nutrients that support microbial growth and propagation is critical to understanding microbial adaptation, physiology, colonization, and propagation within oligotrophic environments.
Aerobic Prokaryotes
Published in Volodymyr Ivanov, Environmental Microbiology for Engineers, 2020
These organisms are adapted to live in environments with a low concentration of nutrients including carbon and energy sources. Their adaptation is so stable that many oligotrophs are obligate ones and cannot grow in a medium with a high concentration of carbon and energy sources. Oligotrophic microorganisms are important for the treatment of groundwater, seawater, and freshwater with a low concentration of carbon sources. For example, Hyphomicrobium spp. are budding oligotrophic bacteria capable of oxidizing single-carbon compounds by oxygen or nitrate. They are used in environmental engineering for the removal of nitrate from water using methanol as an electron donor. Stalked oligotrophs from the genus Caulobacter spp. are able to survive during long-term starvation. It is thought that they may perform gene transfers between different bacteria participating in water and wastewater treatment because they are often adhered to the cells of other bacteria.
Enhanced Biodegradation for On-Site Remediation of Contaminated Soils and Groundwater
Published in David J. Wilson, Ann N. Clarke, Hazardous Waste Site Soil Remediation, 2017
Ronald E. Hoeppel, Robert E. Hinchee
It is important to distinguish between viable and nonviable cells and to separate those that are metabolically active from those that are quiescent. Metabolically active microorganisms can be categorized by whether or not they prefer high concentrations of easily degradable food supplies. Zymogenous soil microorganisms are those that respond readily to nutrient supplies. When supplies are plentiful, they readily grow and proliferate. Rapidly growing microorganisms are most numerous in the uppermost soil profile, whereas microbes that grow very slowly and prefer low nutrient concentrations become more important in the deeper soil profiles. The slow-growing microorganisms, termed oligotro-phs, typically are found in environments deficient in food sources. They are not a distinct taxonomic group, but rather a metabolically diverse group that has adapted to surviving nutrient-starved conditions almost indefinitely. Many quiescent microorganisms are oligotrophic, although most microorganisms can remain viable for many years in a state of suspended animation (Lewis and Gattie, 1991). Oligotrophs have been observed to metabolize very low concentrations of specific contaminants and to persist at very low organic fluxes of less than 1 mg/L·day carbon. Because oligotrophs are the dominant group in deeply buried soils, they are very important in promoting in situ bioremediations and in removing very low contaminant concentrations from groundwater. Many oligotrophs revert to normal metabolism when subjected to high nutrient concentrations (Poindexter, 1981).
Forward osmosis membrane bioreactor using Bacillus and membrane distillation hybrid system for treating dairy wastewater
Published in Environmental Technology, 2021
At the genus level, Pirellula and Hyphomicrobium dominated the Bacillus sludge (sludge B) at the beginning of the test, as shown in Figure 5. Pirellula, in the phylum Planctomycetes, are facultative aerobic chemoheterotrophic bacteria that can use ammonia and perform heterotrophic nitrification [29]. Planctomycetes are important for the carbon and nitrogen cycles in oceans. A feature that sets Pirellula apart from other microbes is many sulfatases encoded in the genome. These sulfatases can degrade sulfated glycopolymers that are abundant in marine snow. Hyphomicrobium, in the order Rhizobiales and class Alphaproteobacteria, are aerobic chemoorganotrophic bacteria that perform aerobic denitrification [30]. Gp1, in the phylum Acidobacteria, was dominant in the sludge B1 at the end of the test. Acidobacteria have recently been isolated and defined as oligotrophic bacteria [31]. Membrane fouling at the end of the test caused a low FO water flux, which decreased the influent organic loading, and thus led to the environment becoming oligotrophic. Oligotrophic bacteria are tolerant and play important roles in the nitrogen cycle. For example, oligotrophic bacteria accounted for 74% of the total denitrifying bacteria isolated by Hashimoto [32]. Acidobacteria can also acclimatize to the saline environment [33]. Importantly, Bacillus increased the Gp1 abundance [34].