Browsing by Author "Icgen, B"

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    Exposure to sulfide causes population shifts in sulfate-reducing consortia
    (Elsevier, 2006) Icgen, B; Harrison, S T L
    The shift in the community structure of a mixed culture of sulfate-reducing bacteria (SRB) at 0.5, 0.75, 1, and 1.5 kg m−3 sulfide loadings was investigated in an anaerobic continuous bioreactor used for treatment of sulfate-containing wastewater by fluorescence in situ hybridization (FISH), using SRB species-specific and group-specific 16S rRNA-targeting probes. Hybridization analysis using these 16S rRNA-targeted oligonucleotide probes revealed that sulfide was toxic for Desulfonema, Desulfobulbus spp. and the Desulfobacteriaceae group, although it was not toxic for Desulfobacter, Desulfotomaculum, Desulfobacterium spp. or the Desulfovibrionaceae group. On the other hand, only a high concentration of sulfide of 1.5 kg m−3 was found to be toxic for the Desulfococcus group in the bioreactor. When the sulfide in the feed was 1.00 kg m−3 the sulfate-reducing capacity of the system decreased, and this decrease was more pronounced when the inlet sulfide was further increased to 1.5 kg m−3
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    Identification of population dynamics in sulfate-reducing consortia on exposure to sulphate
    (Elsevier, 2006) Icgen, B; Harrison, S T L
    The microbial population structure and function of a mixed culture of sulfate-reducing bacteria (SRB) maintained in anaerobic continuous bioreactors were tracked before and after a major perturbation, which involved the addition of sulfate to the influent of a bioreactor when operated at steady state at 35 °C, pH 7.8 and a 2.5 day residence time with feed stream containing 10 and 15 kg m−3 sulfate as terminal electron acceptor and 19.6 and 29.4 kg m−3 ethanol as carbon source and electron donor, respectively. The population structure determined by fluorescence in situ hybridization (FISH), by using 16S rRNA-targeted oligonucleotide probes, was linked to the functional performance of the SRB in the reactor. Hybridization analysis using these 16S rRNA-targeted oligonucleotide probes revealed that a high concentration of sulfate was toxic for Desulfobacterium and Desulfobulbus. On the other hand, the Desulfococcus group was found to be the most dominant group of SRB in the feed stream containing 15 kg m−3 sulfate as terminal electron acceptor and 29.4 kg m−3 ethanol as carbon source and electron donor.
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    A study of the relative dominance of selected anaerobic sulphate-reducing bacteria in a continuous bioreactor revealed by fluorescence in situ hybridisation
    (Springer, 2007) Icgen, B; Moosa, S; Harrison, S T L
    The diversity and the community structure of sulfate-reducing bacteria (SRB) in an anaerobic continuous bioreactor used for treatment of a sulfate-containing wastewater were investigated by fluorescence in situ hybridization. Hybridization to the 16S rRNA probe EUB338 for the domain Bacteria was performed, followed by a nonsense probe NON338 as a control for nonspecific staining. Sulfate-reducing consortia were identified by using five nominally genus-specific probes (SRB129 for Desulfobacter, SRB221 for Desulfobacterium, SRB228 for Desulfotomaculum, SRB660 for Desulfobulbus, and SRB657 for Desulfonema) and four group-specific probes (SRB385 as a general SRB probe, SRB687 for Desulfovibrioaceae, SRB814 for Desulfococcus group, and SRB804 for Desulfobacteriaceae). The total prokaryotic population was determined by 4′,6-diamidino-2-phenylindole staining. Hybridization analysis using these 16S rRNA-targeted oligonucleotide probes showed that, of those microbial groupings investigated, Desulfonema, Desulfobulbus, spp., and Desulfobacteriaceae group were the main sulfate-reducing bacteria in the bioreactor when operated at steady state at 35°C, pH 7.8, and a 2.5-day residence time with feed stream containing 2.5 kg m−3 sulfate as terminal electron acceptor and 2.3 kg m−3 acetate as carbon source and electron donor.