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Reducing Bacteria (reducing + bacteria)
Selected AbstractsDirect analysis of sulfate reducing bacterial communities in gas hydrate-impacted marine sediments by PCR,DGGEJOURNAL OF BASIC MICROBIOLOGY, Issue S1 2009Christopher E. Bagwell Abstract Molecular investigations of the sulfate reducing bacteria that target the dissimilatory sulfite-reductase subunit A gene (dsr A) are plagued by the nonspecific performance of conventional PCR primers. Here we describe the incorporation of the FailSafeÔ PCR System to optimize environmental analysis of dsr A by PCR amplification and denaturing gradient gel electrophoresis. PCR,DGGE analysis of dsr A composition revealed that SRB diversity was greater and more variable throughout the vertical profile of a marine sediment core obtained from a gas hydrate site (GC234) in the Gulf of Mexico than in a sediment core collected from a nearby site devoid of gas hydrates (NBP). Depth profiled dsr B abundance corresponded with sulfate reduction rates at both sites, though measurements were higher at GC234. This study exemplifies the numerical and functional importance of sulfate reducing bacteria in deep-sea sedimentary environments, and incremental methodological advancements, as described herein, will continue to streamline the analysis of sulfate reducer communities in situ. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Comparison of electrochemical techniques during the corrosion of X52 pipeline steel in the presence of sulfate reducing bacteria (SRB)MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 10 2005R. Galvan-Martinez Abstract This work compares three electrochemical techniques, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN), used in the study of corrosion of X52 steel samples in an environment containing a culture of sulfate reducing bacteria (SRB). The study emphasizes the different electrochemical information obtained when using these techniques in microbiologically influenced corrosion (MIC) studies. [source] Low-temperature (9°C) AMD treatment in a sulfidogenic bioreactor dominated by a mesophilic Desulfomicrobium speciesBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2009Hannele Auvinen Abstract The possibilities for the treatment of low-temperature mine waste waters have not been widely studied. The amenability of low-temperature sulfate reduction for mine waste water treatment at 9°C was studied in a bench-scale fluidized-bed bioreactor (FBR). Formate was used as the electron and carbon source. The first influent for the FBR was acidic, synthetic waste water containing iron, nutrients, and sulfate, followed by diluted barren bioleaching solution (DBBS). The average sulfate reduction rates were 8,mmol,L,1,day,1 and 6,mmol,L,1,day,1 with synthetic waste water and DBBS, respectively. The corresponding specific activities were 2.4 and 1.6,mmol SO,g VSS,1 day,1, respectively. The composition of the microbial community and the active species of the FBR was analyzed by extracting the DNA and RNA, followed by PCR-DGGE with the universal bacterial 16S rRNA gene primers and dsrB -primers specific for sulfate-reducing bacteria. The FBR microbial community was simple and stable and the dominant and active species belonged to the genus Desulfomicrobium. In summary, long-term operation of a low-temperature bioreactor resulted in enrichment of formate-utilizing, psychrotolerant mesophilic sulfate reducing bacteria. Biotechnol. Bioeng. 2009; 104: 740,751 © 2009 Wiley Periodicals, Inc. [source] Zero valent iron as an electron-donor for methanogenesis and sulfate reduction in anaerobic sludgeBIOTECHNOLOGY & BIOENGINEERING, Issue 7 2005Srilakshmi Karri Abstract Zero valent iron (ZVI) is a reactive media commonly utilized in permeable reactive barriers (PRBs). Sulfate reducing bacteria are being considered for the immobilization of heavy metals in PRBs. The purpose of this study was to evaluate the potential of ZVI as an electron donor for sulfate reduction in natural mixed anaerobic cultures. The ability of methanogens to utilize ZVI as an electron-donor was also explored since these microorganisms often compete with sulfate reducers for common substrates. Four grades of ZVI of different particle sizes (1.120, 0.149, 0.044, and 0.010 mm diameter) were compared as electron donor in batch bioassays inoculated with anaerobic bioreactor sludge. Methanogenesis was evaluated in mineral media lacking sulfate. Sulfate reduction was evaluated in mineral media containing sulfate and the specific methanogenic inhibitor, 2-bromoethane sulfonate. ZVI contributed to significant increases in methane production and sulfate reductioncompared to endogenous substrate controls. The rates of methane formation or sulfate reduction were positively correlated with the surface area of ZVI. The highest rates of 0.310 mmol CH4 formed/mol Fe0·day and 0.804 mmol SO reduced/ mol Fe0·day were obtained with the finest grade of ZVI (0.01 mm). The results demonstrate that ZVI is readily utilized as a slow-release electron donor for methanogenesis and sulfate reduction in anaerobic sludge; and therefore, has a promising potential in bioremediation applications. © 2005 Wiley Periodicals, Inc. [source] Toxic Effects of Chromium(VI) on Anaerobic and Aerobic Growth of Shewanella oneidensis MR-1BIOTECHNOLOGY PROGRESS, Issue 1 2004Sridhar Viamajala Cr(VI) was added to early- and mid-log-phase Shewanella oneidensis ( S. oneidensis) MR-1 cultures to study the physiological state-dependent toxicity of Cr(VI). Cr(VI) reduction and culture growth were measured during and after Cr(VI) reduction. Inhibition of growth was observed when Cr(VI) was added to cultures of MR-1 growing aerobically or anaerobically with fumarate as the terminal electron acceptor. Under anaerobic conditions, there was immediate cessation of growth upon addition of Cr(VI) in early- and mid-log-phase cultures. However, once Cr(VI) was reduced below detection limits (0.002 mM), the cultures resumed growth with normal cell yield values observed. In contrast to anaerobic MR-1 cultures, addition of Cr(VI) to aerobically growing cultures resulted in a gradual decrease of the growth rate. In addition, under aerobic conditions, lower cell yields were also observed with Cr(VI)-treated cultures when compared to cultures that were not exposed to Cr(VI). Differences in response to Cr(VI) between aerobically and anaerobically growing cultures indicate that Cr(VI) toxicity in MR-1 is dependent on the physiological growth condition of the culture. Cr(VI) reduction has been previously studied in Shewanellaspp., and it has been proposed that Shewanella spp.may be used in Cr(VI) bioremediation systems. Studies of Shewanella spp. provide valuable information on the microbial physiology of dissimilatory metal reducing bacteria; however, our study indicates that S. oneidensis MR-1 is highly susceptible to growth inhibition by Cr(VI) toxicity, even at low concentrations [0.015 mM Cr(VI)]. [source] | ||||||||||