title: Isolation and characterization of alkaliphilic, chemolithoautotrophic, sulphur-oxidizing bacteria.
abstract: Alkaliphilic sulphur-oxidizing bacteria were isolated from samples from alkaline environments including soda soil and soda lakes. Two isolates, currently known as strains AL 2 and AL 3, were characterized. They grew over a pH range 8.0-10.4 with an optimum at 9.5-9.8. Both strains could oxidize thiosulphate, sulphide, polysulphide, elemental sulphur and tetrathionate. Strain AL 3 more actively oxidized thiosulphate and sulphide, while isolate AL 2 had higher activity with elemental sulphur and tetrathionate. Isolate AL 2 was also able to oxidize trithionate. The pH optimum for thiosulphate and sulphide oxidation was between 9-10. Some activity remained at pH 11, but was negligible at pH 7. Metabolism of tetrathionate by isolate AL 2 involved initial anaerobic hydrolysis to form sulphur, thiosulphate and sulphate in a sequence similar to that in other colourless sulphur-oxidizing bacteria. Sulphate was produced by both strains. During batch growth on thiosulphate, elemental sulphur and sulphite transiently accumulated in cultures of isolates AL 2 and AL 3, respectively. At lower pH values, both strains accumulated sulphur during sulphide and thiosulphate oxidation. Both strains contained ribulose bisphosphate carboxylase. Thiosulphate oxidation in isolate AL 3 appeared to be sodium ion-dependent. Isolate AL 2 differed from AL 3 by its high GC mol % value (65.5 and 49.5, respectively), sulphur deposition in its periplasm, the absence of carboxysomes, lower sulphur-oxidizing capacity, growth kinetics (lower growth rate and higher growth yield) and cytochrome composition.
authors.affiliation: Institute of Microbiology, Russian Academy of Sciences, Prospect 60-let Octyabrya, 7/2, 117811 Moscow, Russia.
authors.forename: D Y
authors.initials: DY
authors.lastname: Sorokin
authors.forename: L A
authors.initials: LA
authors.lastname: Robertson
authors.forename: J G
authors.initials: JG
authors.lastname: Kuenen
mesh_terms: D000693:Anaerobiosis; D001419:Bacteria / Q000166:cytology / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism* / Q000648:ultrastructure; D001482:Base Composition; D002245:Carbon Dioxide / Q000032:analysis; D003580:Cytochromes / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D004783:Environmental Microbiology; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D010084:Oxidation-Reduction; D019897:Periplasm / Q000737:chemistry / Q000648:ultrastructure; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D013440:Sulfides / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D013456:Sulfur Acids / Q000378:metabolism; D013776:Tetrathionic Acid / Q000378:metabolism; D013885:Thiosulfates / Q000032:analysis / Q000378:metabolism
chemical_list: D003580:Cytochromes; D004269:DNA, Bacterial; D013431:Sulfates; D013440:Sulfides; D013456:Sulfur Acids; D013885:Thiosulfates; D002245:Carbon Dioxide; C009597:trithionic acid; D013455:Sulfur; D013776:Tetrathionic Acid; C032915:polysulfide; D012964:Sodium; D012273:Ribulose-Bisphosphate Carboxylase