title: Thiobacillus sp. W5, the dominant autotroph oxidizing sulfide to sulfur in a reactor for aerobic treatment of sulfidic wastes.
abstract: The floating filter technique was successfully adapted for the isolation of the dominant, chemolithoautotrophic, sulfide-oxidizing bacterium from a sulfur-producing reactor after conventional isolation techniques had failed. The inoculated polycarbonate filters, floating on mineral medium, were incubated under gaseous hydrogen sulfide at non-toxic levels. This technique gave 200-fold higher recoveries than conventional isolation techniques. Viable counts on the filters, making up 15% of the total count, appeared to be all of the same species. Chemostat cultures of the new isolate had a very high sulfur-forming capacity, converting almost all hydrogen sulfide in the medium to elemental sulfur under high sulfide loads (27.5 mmol l-1 h-1) and fully aerobic conditions. This behaviour closely resembled that of the microbial community in the sulfur-producing reactor. Moreover, similar protein patterns were obtained by electrophoresis of cell-free extracts from the isolate and the mixed culture. It has therefore been concluded that this isolate represents the dominant sulfide-oxidizing population in the reactor. The isolate has been shown to be a new Thiobacillus species, related to Thiobacillus neapolitanus. In view of the general confusion currently surrounding the taxonomy of the thiobacilli, a new species has not been formally created. Instead, the isolate has been given the working name Thiobacillus sp. W5.
authors.affiliation: Department of Microbiology, Delft University of Technology, The Netherlands.
authors.forename: J M
authors.initials: JM
authors.lastname: Visser
authors.forename: G C
authors.initials: GC
authors.lastname: Stefess
authors.forename: L A
authors.initials: LA
authors.lastname: Robertson
authors.forename: J G
authors.initials: JG
authors.lastname: Kuenen
mesh_terms: D000332:Aerobiosis; D001426:Bacterial Proteins / Q000032:analysis; D001431:Bacteriological Techniques; D019149:Bioreactors / Q000382:microbiology*; D015169:Colony Count, Microbial; D017077:Culture Media, Conditioned / Q000032:analysis; D004269:DNA, Bacterial / Q000032:analysis; D006862:Hydrogen Sulfide / Q000378:metabolism; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010100:Oxygen / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013440:Sulfides / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*; D013855:Thiobacillus / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism*; D014866:Waste Products
chemical_list: D001426:Bacterial Proteins; D017077:Culture Media, Conditioned; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D013440:Sulfides; D014866:Waste Products; D013455:Sulfur; D010100:Oxygen; D006862:Hydrogen Sulfide