Enumeration of selected bacterial populations in a high mountain watershed

1974 ◽  
Vol 20 (11) ◽  
pp. 1487-1492 ◽  
Author(s):  
Q. D. Skinner ◽  
J. C. Adams ◽  
P. A. Rechard ◽  
A. A. Beetle

Nitrate-reducing bacteria, sulfate-reducing bacteria, fluorescent bacteria, and the total viable count were enumerated in three stream systems within a high mountain watershed over a period of two winters and two summers from 1970 to 1972. Spread plate and most probable number procedures showed that the number of fluorescent bacteria, sulfate-reducing bacteria, nitrate-reducing bacteria, and the total count were generally constant throughout the year at the lowest sampling site on the stream systems. However, in some cases and for short periods of time, the numbers of these bacteria appeared to be influenced by recreational use of the land and stream flow. For example, denitrifying bacteria increased in number during the winter recreational period and gave the lowest counts in July.

1998 ◽  
Vol 64 (5) ◽  
pp. 1700-1707 ◽  
Author(s):  
Flemming Vester ◽  
Kjeld Ingvorsen

ABSTRACT A greatly improved most-probable-number (MPN) method for selective enumeration of sulfate-reducing bacteria (SRB) is described. The method is based on the use of natural media and radiolabeled sulfate (35SO4 2−). The natural media used consisted of anaerobically prepared sterilized sludge or sediment slurries obtained from sampling sites. The densities of SRB in sediment samples from Kysing Fjord (Denmark) and activated sludge were determined by using a normal MPN (N-MPN) method with synthetic cultivation media and a tracer MPN (T-MPN) method with natural media. The T-MPN method with natural media always yielded significantly higher (100- to 1,000-fold-higher) MPN values than the N-MPN method with synthetic media. The recovery of SRB from environmental samples was investigated by simultaneously measuring sulfate reduction rates (by a35S-radiotracer method) and bacterial counts by using the T-MPN and N-MPN methods, respectively. When bacterial numbers estimated by the T-MPN method with natural media were used, specific sulfate reduction rates (qSO4 2−) of 10−14to 10−13 mol of SO4 2−cell−1 day−1 were calculated, which is within the range of qSO4 2− values previously reported for pure cultures of SRB (10−15 to 10−14 mol of SO4 2− cell−1day−1). qSO4 2− values calculated from N-MPN values obtained with synthetic media were several orders of magnitude higher (2 � 10−10 to 7 � 10−10 mol of SO4 2−cell−1 day−1), showing that viable counts of SRB were seriously underestimated when standard enumeration media were used. Our results demonstrate that the use of natural media results in significant improvements in estimates of the true numbers of SRB in environmental samples.


1999 ◽  
Vol 65 (9) ◽  
pp. 4230-4233 ◽  
Author(s):  
Christian Knoblauch ◽  
Bo Barker Jørgensen ◽  
Jens Harder

ABSTRACT The numbers of sulfate reducers in two Arctic sediments with in situ temperatures of 2.6 and −1.7°C were determined. Most-probable-number counts were higher at 10°C than at 20°C, indicating the predominance of a psychrophilic community. Mean specific sulfate reduction rates of 19 isolated psychrophiles were compared to corresponding rates of 9 marine, mesophilic sulfate-reducing bacteria. The results indicate that, as a physiological adaptation to the permanently cold Arctic environment, psychrophilic sulfate reducers have considerably higher specific metabolic rates than their mesophilic counterparts at similarly low temperatures.


1999 ◽  
Vol 65 (11) ◽  
pp. 5117-5123 ◽  
Author(s):  
Kirsten Küsel ◽  
Holly C. Pinkart ◽  
Harold L. Drake ◽  
Richard Devereux

ABSTRACT Recent declines in sea grass distribution underscore the importance of understanding microbial community structure-function relationships in sea grass rhizospheres that might affect the viability of these plants. Phospholipid fatty acid analyses showed that sulfate-reducing bacteria and clostridia were enriched in sediments colonized by the sea grasses Halodule wrightii andThalassia testudinum compared to an adjacent unvegetated sediment. Most-probable-number analyses found that in contrast to butyrate-producing clostridia, acetogens and acetate-utilizing sulfate reducers were enriched by an order of magnitude in rhizosphere sediments. Although sea grass roots are oxygenated in the daytime, colorimetric root incubation studies demonstrated that acetogenic O-demethylation and sulfidogenic iron precipitation activities were tightly associated with washed, sediment-free H. wrightii roots. This suggests that the associated anaerobes are able to tolerate exposure to oxygen. To localize and quantify the anaerobic microbial colonization, root thin sections were hybridized with newly developed 33P-labeled probes that targeted (i) low-G+C-content gram-positive bacteria, (ii) cluster I species of clostridia, (iii) species of Acetobacterium, and (iv) species of Desulfovibrio. Microautoradiography revealed intercellular colonization of the roots by Acetobacteriumand Desulfovibrio species. Acetogenic bacteria occurred mostly in the rhizoplane and outermost cortex cell layers, and high numbers of sulfate reducers were detected on all epidermal cells and inward, colonizing some 60% of the deepest cortex cells. Approximately 30% of epidermal cells were colonized by bacteria that hybridized with an archaeal probe, strongly suggesting the presence of methanogens. Obligate anaerobes within the roots might contribute to the vitality of sea grasses and other aquatic plants and to the biogeochemistry of the surrounding sediment.


2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Wahyu Wilopo ◽  
Keiko Sasaki ◽  
Tsuyoshi Hirajim

Permeable reactive barrier column tests were performed to investigate whether anaerobic bacteria in sheep manure could help remove As from groundwater. One column served as a control and was packed with zero-valent iron (ZVI), compost leaf, wood chips, glass beads, and gravel, after which it was sterilized. The other (‘inoculated column’) was packed with the same ingredients, with the addition of sheep manure as a source of anaerobic bacteria. Simulated As-contaminated groundwater was prepared based on groundwater samples from Sumbawa Island, Indonesia, but with the arsenic concentration adjusted to 50 mg/L. The inoculated column was found to remove As more effectively from the simulated groundwater than the sterilized one. A gradual decrease in sulfate concentration was observed in the inoculated column at the rate of 0.26 mmol of sulfate/L/day, suggesting that there was sulfate-reducing activity in the microbial population. In addition, the sulfur isotope ratio showed -4.3 (‰) and 0.2 (‰) in influent and effluent, respectively, indicating that sulfate-reducing bacteria (SRB) consumed δ32S preferentially. Using population size estimates from the most probable number (MPN) method, the population of SRB was found to increase with distance traveled in the column. Profiling the community composition of the bacteria in different fractions of the inoculated column using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) on 16S rRNA sequences suggested that a majority of bacteria were various Clostridium species and one species of Proteobacteria, Geobacter metallireducens GS-15. Some of them may contribute to the removal of arsenic.Keywords: Sheep manure, zero valence iron, arsenic, immobilization, sulfate-reducing bacteria


1999 ◽  
Vol 65 (5) ◽  
pp. 2209-2216 ◽  
Author(s):  
Mark E. Hines ◽  
Robert S. Evans ◽  
Barbara R. Sharak Genthner ◽  
Stephanie G. Willis ◽  
Stephanie Friedman ◽  
...  

ABSTRACT The population composition and biogeochemistry of sulfate-reducing bacteria (SRB) in the rhizosphere of the marsh grass Spartina alterniflora was investigated over two growing seasons by molecular probing, enumerations of culturable SRB, and measurements of SO4 2− reduction rates and geochemical parameters. SO4 2− reduction was rapid in marsh sediments with rates up to 3.5 μmol ml−1day−1. Rates increased greatly when plant growth began in April and decreased again when plants flowered in late July. Results with nucleic acid probes revealed that SRB rRNA accounted for up to 43% of the rRNA from members of the domain Bacteria in marsh sediments, with the highest percentages occurring in bacteria physically associated with root surfaces. The relative abundance (RA) of SRB rRNA in whole-sediment samples compared to that ofBacteria rRNA did not vary greatly throughout the year, despite large temporal changes in SO4 2−reduction activity. However, the RA of root-associated SRB did increase from <10 to >30% when plants were actively growing. rRNA from members of the family Desulfobacteriaceae comprised the majority of the SRB rRNA at 3 to 34% of Bacteria rRNA, with Desulfobulbus spp. accounting for 1 to 16%. The RA ofDesulfovibrio rRNA generally comprised from <1 to 3% of the Bacteria rRNA. The highestDesulfobacteriaceae RA in whole sediments was 26% and was found in the deepest sediment samples (6 to 8 cm). Culturable SRB abundance, determined by most-probable-number analyses, was high at >107 ml−1. Ethanol utilizers were most abundant, followed by acetate utilizers. The high numbers of culturable SRB and the high RA of SRB rRNA compared to that ofBacteria rRNA may be due to the release of SRB substrates in plant root exudates, creating a microbial food web that circumvents fermentation.


Author(s):  
Jasmin Frey ◽  
Sophie Kaßner ◽  
Bernhard Schink

AbstractDegradation of acetone and higher ketones has been described in detail for aerobic and nitrate-reducing bacteria. Among sulfate-reducing bacteria, degradation of acetone and other ketones is still an uncommon ability and has not been understood completely yet. In the present work, we show that Desulfotomaculum arcticum and Desulfotomaculum geothermicum are able to degrade acetone and butanone. Total proteomics of cell-free extracts of both organisms indicated an involvement of a thiamine diphosphate-dependent enzyme, a B12-dependent mutase, and a specific dehydrogenase during acetone degradation. Similar enzymes were recently described to be involved in acetone degradation by Desulfococcus biacutus. As there are so far only two described sulfate reducers able to degrade acetone, D. arcticum and D. geothermicum represent two further species with this capacity. All these bacteria appear to degrade acetone via the same set of enzymes and therefore via the same pathway.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jasmin Frey ◽  
Sophie Kaßner ◽  
Dieter Spiteller ◽  
Mario Mergelsberg ◽  
Matthias Boll ◽  
...  

Abstract Background Degradation of acetone by aerobic and nitrate-reducing bacteria can proceed via carboxylation to acetoacetate and subsequent thiolytic cleavage to two acetyl residues. A different strategy was identified in the sulfate-reducing bacterium Desulfococcus biacutus that involves formylation of acetone to 2-hydroxyisobutyryl-CoA. Results Utilization of short-chain ketones (acetone, butanone, 2-pentanone and 3-pentanone) and isopropanol by the sulfate reducer Desulfosarcina cetonica was investigated by differential proteome analyses and enzyme assays. Two-dimensional protein gel electrophoresis indicated that D. cetonica during growth with acetone expresses enzymes homologous to those described for Desulfococcus biacutus: a thiamine diphosphate (TDP)-requiring enzyme, two subunits of a B12-dependent mutase, and a NAD+-dependent dehydrogenase. Total proteomics of cell-free extracts confirmed these results and identified several additional ketone-inducible proteins. Acetone is activated, most likely mediated by the TDP-dependent enzyme, to a branched-chain CoA-ester, 2-hydroxyisobutyryl-CoA. This compound is linearized to 3-hydroxybutyryl-CoA by a coenzyme B12-dependent mutase followed by oxidation to acetoacetyl-CoA by a dehydrogenase. Proteomic analysis of isopropanol- and butanone-grown cells revealed the expression of a set of enzymes identical to that expressed during growth with acetone. Enzyme assays with cell-free extract of isopropanol- and butanone-grown cells support a B12-dependent isomerization. After growth with 2-pentanone or 3-pentanone, similar protein patterns were observed in cell-free extracts as those found after growth with acetone. Conclusions According to these results, butanone and isopropanol, as well as the two pentanone isomers, are degraded by the same enzymes that are used also in acetone degradation. Our results indicate that the degradation of several short-chain ketones appears to be initiated by TDP-dependent formylation in sulfate-reducing bacteria.


2021 ◽  
Vol 26 (1) ◽  
pp. 1-16
Author(s):  
Julian Esteban Másmela-Mendoza ◽  
Luz Marina Lizarazo Forero

The objective of study was to isolate and determine the identity of denitrifying bacteria from limnetic areas of Lake Tota (Colombian Andes) with and without rainbow trout production activities. We examined the relationships between the lake’s physicochemical factors (oxygen, nitrogen, and phosphorus content) and two bacterial communities (denitrifying bacteria and coliforms). Water samples were taken 20m below the surface from July to September at five limnetic zones; two of which were close to rainbow trout farming areas. In each zone, the concentrations of oxygen, nitrogen, and phosphorus were measured. To identify and quantify the abundance of bacteria, the most probable number (MPN) technique was used, employing minimal medium for denitrifying bacteria and medium for nitrate reducing bacteria (NRB). A greater number of denitrifying bacteria were found in the fish farming zones, identifying bacteria of the genera Bacillus, Pseudomonas, Nocardia, and Streptomyces. The number of nitrate-reducing bacteria revealed statistically significant differences throughout the sampling period, increasing from July to September and was related to a decrease in precipitation. The density of NRB and total phosphorus were directly correlated. High bacterial densities of denitrifyingbacteria and coliforms are indicative of changes from oligotrophic to eutrophic states in the studied limnetic areas.


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