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.

Characterization of the Haemophilus influenzae tehB gene and its role in virulence

“…Further evidence for this proposal is the observed presence of small black deposits following growth of H. influenzae in the presence of sublethal levels of tellurite (data not shown). These deposits have been reported with other organisms challenged with tellurite and are presumed to be insoluble tellurium (elemental) (Chasteen & Bentley, 2003;Amoozegar et al, 2008). The deposits were observed in cultures of both the wild-type and the tehB deletion mutant strains and indicate that the reduction of tellurite to the insoluble metalloid proceeds in the absence of tehB.…”

Halophile isolation to produce halophilic protease, protease production and testing crude protease as a detergent ingredient

“…Bacillus Mk22 secreted protease with maximum activity after 7 days; clear zones (24 mm) indicated high proteolytic activity, which was similar to previously reported data (Amoozegar et al, 2008). Protease production was tested at different parameters, in which the maximum production was attained at 45°C (Figure 3), pH 8 (Figure 4), and 12% NaCl ( Figure 5).…”

Progress in decontamination by halophilic microorganisms in saline wastewater and soil

“…Amoozegar et al (2008) found a moderately halophilic Gram-positive coccus designated as Salinicoccus sp. strain QW6 showing high capacity in the removal of toxic oxyanions of tellurium under a wide range of factors.…”