title: Effects of inhibitors and NaCl on the oxidation of reduced inorganic sulfur compounds by a marine acidophilic, sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH.
abstract: The effect of NaCl and the pathways of the oxidation of reduced inorganic sulfur compounds were studied using resting cells and cell-free extracts of Acidithiobacillus thiooxidans strain SH. This isolate specifically requires NaCl for growth. The oxidation of sulfur and sulfite by resting cells was strongly inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide. Carbonylcyanide m-chlorophenyl-hydrazone and monensin were also relatively strong inhibitors. Thiosulfate-oxidizing activity was not inhibited by these uncouplers. Valinomycin did not inhibit the oxidation of sulfur compounds. NaCl stimulated the sulfur- and sulfite-oxidizing activities in resting cells but not in cell-free extracts. The tetrathionate-oxidizing activity in resting cells was slightly stimulated by NaCl, whereas it did not influence the thiosulfate-oxidizing activity. Sulfide oxidation was biphasic, suggesting the formation of intermediate sulfur. The initial phase of sulfide oxidation was not affected by NaCl, whereas the subsequent oxidation of sulfur in the second phase was Na+-dependent. A model is proposed for the role of NaCl in the metabolism of reduced sulfur compounds in A. thiooxidans strain SH.
authors.affiliation: Department of Biological Function, Faculty of Agriculture, Okayama University, 1-1-1 Tsushima-Naka, Okayama 700-8530, Japan. kamimura@cc.okayama-u.ac.jp
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kamimura
authors.forename: Emi
authors.initials: E
authors.lastname: Higashino
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Kanao
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sugio
mesh_terms: D013856:Acidithiobacillus thiooxidans / Q000378:metabolism*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000031:analogs & derivatives / Q000494:pharmacology; D002474:Cell-Free System; D003470:Culture Media / Q000737:chemistry; D003580:Cytochromes / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D006912:Hydroxyquinolines / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008954:Models, Biological; D008985:Monensin / Q000494:pharmacology; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D011725:Pyridines / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry / Q000494:pharmacology*; D013053:Spectrophotometry; D013440:Sulfides / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry*; D013696:Temperature; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D003470:Culture Media; D003580:Cytochromes; D006912:Hydroxyquinolines; D007476:Ionophores; D011725:Pyridines; D013440:Sulfides; C001333:2-(n-heptyl)-4-hydroxyquinoline N-oxide; D014634:Valinomycin; D012965:Sodium Chloride; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D013455:Sulfur; D008985:Monensin; D012964:Sodium; C023666:pyridine; D010100:Oxygen