Molecular characterization of Sulfobacillus and related organisms

[摘要] ENGLISH ABSTRACT:Thirteen Sulfobacillus strains from different geographical locations and twoAlicyclobacillus strains were included in this study. These organisms proved to bemoderately thermophillic (two different sets of optimal temperatures of 45°C and 55°Cwere found), Gram-positive, endospore forming bacteria. The pH optima of the strainstested was pH 2.5 and the pH range lay between pH 1.5 and pH 5.0. It was establishedthat some strains of Sulfobacillus had the capacity for anaerobic growth when using ferriciron as an electron donor. It was determined that S. thermosuljidooxidans was the speciesfound within South African biooxidation plants. Plasm ids were identified within strain611 (S. thermosuljidooxidans) isolated from a Billiton commercial plant.The sample of Sulfobacillus strains used in this study could clearly be divided into twogroups based on the analysis of their 16S rRNA gene sequences as well as the number ofribosomal (rm) operons present as determined by Southern hybridization.A system for the convenient identification of Sulfobacillus species was developed usingseveral of the techniques employed in this study. Preliminary identifications can beobtained by restriction enzyme digestion of the PCR amplified 16S rRNA gene.Confirmation of this placement can be done by comparison of the 16S - 23S rRNAspacer region amplification band sizes. Once the preliminary identification has beencompleted it is possible to place the isolate in the correct species by making use of thedifferences in sugar utilization that the species exhibit. The more laborious method of16S rRNA sequence comparisons can be undertaken if there is still any uncertainty as towhich species an isolate belongs to. Phylogenetic results obtained from the 16S rRNA gene sequence indicates that the genusSulfobacillus should probably be divided into two individual genera. Further informationgathered from the phylogenetic comparisons indicates that strain Riv-14 previouslyassigned to S. ambivalens is more closely related to S. montseratensis. Data obtainedfrom 16S - 23S rRNA spacer region analysis confirms this result.Future work includes the use of DNA-DNA hybridization studies and mol% G+C ratio'sin order verify the presence of two distinct genera as well as placing Riv-14 within thecorrect species.

[发布机构] Stellenbosch University