The study of tellurite tolerance and its bioremoval by a halophilic actinobacterial strain, QS-2006

A Gram-positive moderately halophilic tellurite reducing actinobacterial strain was isolated from saline soil, and designated as strain QS-2006 .This strain showed high level tolerance to potassium tellurite up to 500 mM of tellurite. The liquid cultures of the strain QS-2006 reduce tellurite to its elemental and less toxic form. Tellurite removal was assayed by colorimetric method using diethyldithiocarbamate (DDTC). The results showed that at least 50% tellurite was removed in the presence of glucose or sucrose as a carbon source during 4 days. Effects of various factors including: temperature, mixing, various concentrations of salts and tellurite concentrations ware investigated. Mixing has an increasing effect on the removal rate. At concentration of 2mM by increasing the mixing from 0 to 220 rpm the removal rate reached up to 94%. At 34ºC and Te concentration of 0.4 mM and 2mM the removal is 69% and 92% respectively. Intracellular Te (0) deposits were showed by energy dispersive X -ray (EDX) analysis and transmission electron microscopic.