Sulfate-reducing Bacteria In Soil Research Articles

Synergistic passivation performance of cadmium pollution by biochar combined with sulfate reducing bacteria

The use of sulfate-reducing bacteria (SRB) for the remediation of Cd-contaminated soil is an attractive option. However, there are various factors that limit the activity of free SRB in soil, which hinders the rapid reduction of sulfate. The immobilized SRB technology has been proposed as a possible solution to overcome this barrier. This study aimed to isolate an Enterobacter sp. strain (SRB15-3-2) with high resistance to Cd2+ from a tailing. Wheat, maize, and rice straws were selected to prepare biochar for inoculating the screened bacteria. The results showed that wheat straw biochar pyrolyzed at 700 °C (WS700) had the highest performance in carrying SRB for Cd2+ immobilization. Furthermore, the WS700 was found to promote SRB15-3-2 for offering S2− and functional groups (C-S, C=O, C=C, C-C=O, and C-O-C, etc.) during the immobilization process. The immobilized SRB with WS700 (ISRBWS700) agglomerated and reacted with Cd2+ to form metal precipitations, predominantly CdS and CdCO3. Which lead to a significant decrease of exchangeable-Cd in contaminated soil (with initial Cd concentrations of 1, 5, and 20 mg/kg) by 18.5%–31.6% after applying the ISRBWS700, indicating that the indigenous soil microbes were been protected from Cd toxicity. Additionally, ISRBWS700 exhibited a synergistic effect in enhancing SRB15-3-2 propagation and the activities of saccharase, urease, and acid phosphatase, compared to the separate treatment of SRB15-3-2 and WS700. Overall, ISRBWS700 prepared in this study represented an accessible way to resolve Cd-contaminated soil, which provided new theoretical insights into eco-friendly technologies for Cd-polluted soil remediation both in development and sustainable aspects.

Nano zero-valent iron enhances the absorption and transport of chromium in rice (Oryza sativa L.): Implication for Cr risks management in paddy fields

Chromium (Cr) accumulating in soil caused serious pollution to cultivated land. At present, nano zero-valent iron (nZVI) is considered to be a promising remediation material for Cr-contaminated soil. However, the nZVI impact on the behavior of Cr in the soil-rice system under high natural geological background value remains unknown. We studied the effects of nZVI on the migration and transformation of Cr in paddy soil-rice by pot experiment. Three different doses of nZVI (0, 0.001 % and 0.1 % (w/w)) treatments and one dose of 0.1 % (w/w) nZVI treatment without plant rice were set up. Under continuous flooding conditions, nZVI significantly increased rice biomass compared with the control. At the same time, nZVI significantly promoted the reduction of Fe in the soil, increased the concentration of oxalate Fe and bioavailable Cr, then facilitated the absorption of Cr in rice roots and the transportation to the aboveground part. In addition, the enrichment of Fe(III)-reducing bacteria and sulfate-reducing bacteria in soil provided electron donors for Cr oxidation, which helps to form bioavailable Cr that is easily absorbed by plants. The results of this study can provide scientific basis and technical support for the remediation of Cr -polluted paddy soil with high geological background.

Effects of Microbial Activities on Mercury Methylation in Farmland near Mercury Mining Area

In order to study the main effect of microbial activities on mercury(Hg) methylation in farmland, mercury contaminated upland soils and paddy soils near Hg mining area were sampled as experimental soils. Four treatments were designed including only sterilization as the control, accelerating the activities of sulfate reducing bacteria(SRB), inhibiting the SRB's activities, and accelerating the activities of iron-reducing bacteria(FeRB), to know the effects of microbial and non-microbial factors on mercury methylation in soils. The results were as follows:the highest concentration of methylmercury(MeHg) was observed in soils with SRB accelerated treatment, and the increments of MeHg concentrations in upland soils and paddy soils ranged from 0.15 μg·kg-1 to 0.38 μg·kg-1 and 1 μg·kg-1 to 2 μg·kg-1, respectively. Comparatively, little increments of MeHg concentration were seen in soils with SRB inhibited treatment and FeRB accelerated treatment, which were lower than 0.025 μg·kg-1. Compared with upland soils, more MeHg was formed in Paddy soils and the concentrations of MeHg in paddy soils were 4-9 times of that in upland soils. Variation in the number of SRB in soils was similar to that in the concentration of MeHg in soils, and the number of SRB was positively correlated with the concentration of MeHg concentrations in soils(R2=0.57,P<0.01). The above results indicated that activities of reducing bacteria, especially SRB, played key role in the methylation in soils. In addition, more attention should be paid to paddy soils due to the high potential of methylation when conducting any assessment and taking any measure to manage the health risk caused by the exposure to mercury.

The number of ecological and trophic groups of microorganisms in Yazivske sulfur deposit

The quantity of major ecological-trophic groups of microorganisms on the territory of Yazivske sulfur deposit was studied. It was established that the quantity of all ecological-trophic groups of aerobic microorganisms in the soil at a depth of 50 cm was decreases compared to the quantity of microorganisms in the soil at a depth of 30 cm. The smallest quantity of bacteria of all ecological-trophic groups was in the water. It was established that acidophilic colorless sulfur bacteria dominated in all the samples of soil and water of Yazivske sulfur deposit. Their quantity in the sediment and soil was (12.9±0.3)·1011 — (6±0.3)·1011 CFU/g ADS (CFU/g ADS — colony forming units per gram of absolutely dry soil), respectively. Quantity of neutrophilic colourless sulfur bacteria was (9.6±0.5)·104 — (1.2±0.01)·105 CFU/g ADS. The quantity of anaerobic microorganisms, such as denitrifying, sulfate- and sulfur-reducing bacteria, was the lowest. The quantity of sulfur-reducing bacteria in the soil was (1.15±0.2)·104 — (8.1±0.3)·104 CFU/g ADS, in sediment — (3.5±0.22)·103 CFU/g ADS, in the water they were in a small quantity — 14 CFU/ml. The quantity of sulfate-reducing bacteria in soil and sludge was (1.9±0.05)·103 — (3.3±0.2)·103 CFU/g ADS. The quantity of microscopical fungi in soil and sludge did not exceed the quantity of fungi in the control variant. The total quantity of saprophytes, nitrifiers, oligonitrophylls and aerobic cellulose degrading bacteria in studied samples was higher than in control. pH of all soil, sediment and water samples of Yazivske sulfur deposit was poorly alkaline (7.51 to 8.3)

Effects of Spartina alterniflora Invasion on the Abundance, Diversity, and Community Structure of Sulfate Reducing Bacteria along a Successional Gradient of Coastal Salt Marshes in China

Little is known about consequences of Spartina alterniflora invasion on soil sulfate-reducing bacteria (SRB). This study compared the abundance, diversity, and community structure of SRB in S. alterniflora and in native plant communities along a successional gradient (bare mudflat, young/mature S. alterniflora, Suaeda salsa, and Phragmites australis) in coastal salt marshes of Eastern China. Quantitative polymerase chain reaction of dissimilatory sulfite reductase (dsrB) gene was applied to assess SRB abundance, and the diversity and composition of SRB was analyzed by 454 pyrosequencing of partial dsrB gene. We found that S. alterniflora had a significantly higher abundance and diversity of SRB than native plant species. For all plant covers, Desulfobacteraceae was the largest soil SRB group, with a relative abundance of 33.6%, followed by Desulfobulbaceae (29.2%). S. alterniflora showed a higher relative abundance of Desulfobacteraceae (42.5%) than native species (29.5%) did. Notably, S. alterniflora invasion decreased the relative abundance of a SRB branch clustering with the thermophilic Thermodesulfovibrio yellowstonii. In conclusion, S. alterniflora invasion of the eastern coast of China has greatly increased the abundance and diversity of SRB communities and altered their structure. This might further influence carbon mineralization and inhibit the production of methane in China’s coastal marshes.

Underground Bacteria Generates H2S and Trips Control Panels

Summary Instrument equipment shelters (IESs) are important control buildings within operating plants, housing the critical instrumentation and control system (ICS) panels that are essential for plant operations. At one such IES building in one of the plants operated by Abu Dhabi Gas Industries Limited (GASCO), frequent tripping of ICS panels was encountered, without pre-alarm indication, leading to plant upsets and posing risk to the safe operations of the plant. Occasionally, the odor of hydrogen sulfide (H2S) was observed. This paper addresses the measures undertaken to identify the source of generation and diffusion of corrosive agents into the IES and remedial measures to eliminate this chronic problem. A detailed study was carried out that included soil- and water-sample collection and specialized laboratory testing, collection and testing of electronic cards, discussion with control-system vendors, and desktop evaluation of data. Analysis of electronic cards identified corrosion of electronic components within the panels as the primary reason for the tripping of panels. Corrosion of electronic components was concluded to be caused mainly by diffusion of H2S into the building, also as confirmed by control-system vendors. Ingress of corrosive agents through air inlets/doors was eliminated as a cause because of the absence of any signs of corrosion in heating, ventilation, and air-conditioning (HVAC) air intakes and because of maintenance of positive air pressure within the building. Extensive investigation and testing of soil indicated the presence of a high concentration of sulfate-reducing bacteria (SRB) in the vicinity of the building. A high groundwater table containing sulfates provided nutrition to the SRB. The bacteria reduced the sulfates present in the groundwater to H2S. The H2S, thus generated, diffused into the building through cable entry sleeves, reaching the area beneath the false flooring on which panels were mounted, and subsequently entering the panels. The presence of conducive temperature and humidity facilitated the reaction of H2S with electronic cards, thereby causing corrosion and tripping of panels. The key remedial measures that were recommended—namely, dewatering the surrounding area and lowering groundwater levels to starve the bacteria, thus rendering it dormant and preventing H2S generation, and sealing of cable entry sleeves to prevent any external gas ingress into the building—were implemented, resulting in resolution of the issue and maintaining the safety and integrity of plant operations. Tripping of ICS panels because of H2S generation by bacteria present in soil is a rare phenomenon, not commonly encountered in oil and gas plants. In areas where the groundwater table is high, the construction of buildings needs to be planned carefully. Geotechnical investigation shall include testing for the presence of organic content, sulfates, and SRB in soil and groundwater, in addition to conventional tests.

Analysis of Corrosion Defects on Oil Pipeline Surface Using Scanning Electron Microscopy and Soil Thionic and Sulfate-reducing Bacteria Quantification

We completed an analysis of corrosion defects on oil pipeline surface by instrumentality of scanning electron microscopy and identified soil thionic and sulfate-reducing bacteria quantity. A surface of samples was studied by using of raster electron microscopy as a preparation for qualitative and quantitative analysis of elemental composition. Was identified a quantity of sulfate-reducing and thionic bacteria in a samples of soil contiguous to the surface of underground oil pipelines in the of Khanty- Mansiysk autonomous region territory (Ugra). A result of this research shows a significant oxidative activity, which accompanied an expressed corrosion process. Microbiological analysis of soil shows an existence of thionic bacteria and an absence of sulfate- reducing bacteria. Microorganisms existed in soil induces the corrosion of pipeline steel. Using of scanning electron microscopy in a combination with finding of quantitative specification of thionic and sulfate-reducing bacteria in soils allows to study the nature of corrosive surface of the oil pipelines and to evaluate an extension degree of biocorrosion in complex.

Effect of Bacteria in Soil towards the Corrosion of Water-Pipeline: A Review

Corrosion is a process of deterioration of metal surfaces where the metals were degraded into another compound. Soil is one of the medium known to have constituted to corrosion of metals. The soil creates an environment for the movement of electrons. The level of corrosion in soil can vary from major material loss or to minor effects. The buried pipelines are exposed to the soil that may experience corrosion attack. The study of the soil as a corrosive environment is important to mitigate the problem which may be serious to the environment and economy. There are few factors that contribute to the corrosion processes. This review focuses only to sulfate and sulfate reducing bacteria in soil. Hence, this review investigates the relationship of sulfate and sulfate-reducing bacteria in soil.

2-bromoethanesulfonate (BES) Enhances Sulfate-reducing Bacterial Population and Dichlorodiphenyltrichloroethane (DDT) Dechlorination in an Anaerobic Paddy Soil

2-bromoethanesulfonate (BES) is a structural analogue of 2-mercaptoethanesulfonic acid (coenzyme M) and often used to specifically inhibit methanogenesis. The role of BES and sulfate on the reductive dechlorination of dichlorodiphenyltrichloroethane (DDT) was compared in an anaerobic soil slurry reactor of sulfate-reducing system in this study. The population of soil sulfate-reducing bacteria (SRB) was markedly decreased under DDT condition compared to DDT-free reactor, while greatly increased by sulfate and slightly increased by BES. However, the dechlorination rate of DDT was the highest in the DDT+BES treatment, followed in order by DDT+Sulfate and the control condition. In the DDT+BES treatment, more than 60% of DDT-Cl was cleaved within 16 weeks, which was about 124% and 369% greater than that in the DDT+Sulfate treatment and under the control condition, respectively. The results suggested that the inhibition of methanogenesis by BES was another pathway to improve sulfate-reducing activity and the related dechlorination rate of DDT in waterlogged soils.

Effects of Pesticide-Contamination on Population and Activity of Bacteria in Purple Paddy Soil

The effect of pesticides on microbial in soil is susally used as an important guide line for estimating the ecological safty of soil. Effects of pesticide-contamination on population and activity of bacteria were investigated in purple paddy soil by in door culture method. The results showed that the population and activity of methanogens was stimulated slightly by adding carbofuran or butachlor in paddy soil, but significantly inhibited by adding of butachlor (10mg kg-1), carbofuran (0.5mg kg-1) and carbendazim (10mg kg-1) in paddy soil. At 7th day the inhibition reached the maximum and then gradually reduced down to the level in control. 1mg kg-1 carbufuran and butachlor markedly stimulate the populations and activity of soil methane-producing bacteria, soil anti-nitrifying bacteria, soil nitrogen-fixing bacteria, and soil sulfate-reducing bacteria in purple paddy rice soils. Higher concentration carbufuran and butachlor significantly inhibite the populations and activity of above bacteria. Then the inhibition effects of the contaminants were gradually attenuating. The population and activity of above bacteria were inhibited by different level carbendazim.

Guiding Mercury's Meandering

Geochemistry![Figure][1] CREDIT: ISTOCK.COM Mercury's toxicity impels wide-ranging study of the binding and redox behavior of the element under varying environmental conditions. Sulfate-reducing bacteria in soils and sediments are known to enhance mercury accumulation in higher species such

Methylmercury production in High Arctic wetlands.

Mercury is present at elevated levels in the top predators living in High Arctic ecosystems. Because only methylmercury (MeHg) bioaccumulates in food chains, the sources need to be identified. In temperate environments, wetlands are considered to be the principal sources of MeHg, with sulfate-reducing bacteria (SRB) thought to be responsible. The present study investigated whether High Arctic wetlands produced MeHg and whether SRB were involved in MeHg formation. Frozen soil was collected from 18 High Arctic wetlands before ground thaw, and when analyzed for MeHg, values were low, averaging 0.065 ng/g. When soils were incubated for 30 and 60 d at typical summer Arctic soil temperatures (4 degrees C and 8 degrees C), MeHg increased up to 100-fold. These laboratory observations were consistent with field measurements of wetland surface water, where MeHg concentrations increased from near detection limits (0.02 ng/L) at the inflow to an average of 1.21 ng/L at the outflow. Both laboratory and field data showed MeHg production in High Arctic wetlands. The prevalence of SRB in soil was low, however, and DNA analysis of the dissimilatory sulfate-reductase gene specific to SRB was positive at only one site. The present study showed that wetlands in the High Arctic can produce MeHg but that SRB may not the dominant mercury methylators.

Reductive Dechlorination of Tetrachloroethylene by Soil Sulfate-Reducing Microbes under Various Electron Donor Conditions

Biotransformation of tetrachloroethylene (PCE) by soil sulfate-reducing bacteria was investigated using acetate, lactate and methanol as electron donors. Results show that the effectiveness of biotransformation of PCE by soil sulfate-reducing bacterial is dependent upon the type of electron donor used.

Characterization of the diversity of sulfate-reducing bacteria in soil and mining waste water environments by nucleic acid hybridization techniques.

Nucleic acid hybridization techniques were used to characterize the sulfate-reducing bacterial communities at seven waste water and two soil sites in Canada. Genomic DNA was obtained from liquid enrichment cultures of samples taken from these nine sites. The liquid enrichment protocol favored growth of the sulfate-reducing bacterial component of the communities at these sites. The genomic DNA preparations were analyzed with (i) a specific gene probe aimed at a single genus (Desulfovibrio), (ii) a general 16S rRNA gene probe aimed at all genera of sulfate-reducing bacteria and other bacteria, and (iii) whole genome probes aimed at specific bacteria. This three-pronged approach provided information on the sulfate-reducing bacterial community structures for the nine sites. These were compared with each other and with the sulfate-reducing bacterial communities of western Canadian oil field production waters, studied previously. It was found that there is considerable diversity in the sulfate-reducing bacterial community at each site. Most sulfate-reducing bacteria isolated from distinct sites are genomically different and differ also from sulfate-reducing bacteria found in oil field production waters.

A new agar plate method for the quantitative study of sulfate-reducing bacteria in soil

Abstract Sulfate-reducing bacteria, widely distributed in natural environments, have a specific ability to reduce sulfate and to form hydrogen sulfide, which reacts with iron or/and manganese present in the environments and forms a black precipitate of iron or/and manganese sulfide. This specific reaction is useful for the simple and selective detection of sulfate-reducing bacteria in mixed bacterial populations as in soil.