title: Isolation and initial characterization of the tellurite reducing moderately halophilic bacterium, Salinicoccus sp. strain QW6.
abstract: Among the 49 strains of moderately halophilic bacteria isolated from the salty environments of Iran, a Gram-positive coccus designated as strain QW6 showed high capacity in the removal of toxic oxyanions of tellurium in a wide range of culture medium factors including pH (5.5-10.5), temperature (25-45 degrees C), various salts including NaCl, KCl, and Na(2)SO(4) (0.5-4 M), selenooxyanions (2-10 mM), and at different concentrations of potassium tellurite (0.5-1 mM) under aerobic condition. Phenotypic characterization and phylogenetic analyses based on 16S rDNA sequence comparisons indicated that this strain was a member of the genus Salinicoccus. The maximum tellurite removal was exhibited in 1.5M NaCl at 35 degrees C, while the activity reduced by 53% and 47% at 25 and 45 degrees C, respectively. The optimum pH for removal activity was shown to be 7.5, with 90% and 83% reduced removal capacities at the two extreme values of 5.5 and 10, respectively. The impact of different concentrations of selenooxyanions (2-10 mM) on tellurite removal by strain QW6 was evaluated. The ability of strain QW6 in the removal of tellurite in the presence of 6mM selenite increased by 25%. The concentration of toxic potassium tellurite in the supernatant of the bacterial culture medium decreased by 99% (from 0.5 to 0.005 mM) after 6 days and the color of the medium changed to black due to the formation of less toxic elemental tellurium.
authors.affiliation: Department of Microbiology, School of Biology, University College of Science, University of Tehran, Tehran, Iran. amozegar@khayam.ut.ac.ir <amozegar@khayam.ut.ac.ir>
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Amoozegar
authors.forename: Morahem
authors.initials: M
authors.lastname: Ashengroph
authors.forename: Feridon
authors.initials: F
authors.lastname: Malekzadeh
authors.forename: Mohamad
authors.initials: M
authors.lastname: Reza Razavi
authors.forename: Saied
authors.initials: S
authors.lastname: Naddaf
authors.forename: Mahboubeh
authors.initials: M
authors.lastname: Kabiri
mesh_terms: D000332:Aerobiosis; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020459:Genes, rRNA; D006863:Hydrogen-Ion Concentration; D007492:Iran; D008969:Molecular Sequence Data; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012965:Sodium Chloride / Q000378:metabolism; D018038:Sodium Selenite / Q000378:metabolism; D012988:Soil Microbiology; D040141:Staphylococcaceae / Q000145:classification* / Q000302:isolation & purification* / Q000378:metabolism; D013691:Tellurium / Q000378:metabolism*; D013696:Temperature
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012965:Sodium Chloride; D018038:Sodium Selenite; C026660:tellurous acid; D013691:Tellurium