| Summary: | Wastewater from traditional silver craft industry creates sever aquatic pollution
due to presence of high concentrations of heavy metals, such as, copper (Cu) and
silver (Ag). In this circumstance bioremediation of toxic metals is considered to
be a great challenge. The objectives of research were selection of copper and
silver resistance bacteria, studies on effect of various concentration of copper and
silver on the growth of isolates, studies bacteria metal accumulation, and
molecular identification of bacteria through 16S rRNA analysis. It was observed
that Cu-BBK 1.1 was copper resistant bacterium, able to grow in presence of 60
mg/L copper in growth medium. Moreover it was observed that bacterial strain
Ag-BAK 6 was a silver resistant bacterium, can grow in presence of 3 mg/L silver
containing medium. Although copper was acted as a nutrient source of isolates,
but it also has an inhibitory effect on the growth of Cu-BBK 1.1. (inhibition
constant (KI), 21,46 mg/L Cu). Furthermore, it was observed that silver has a
negative influence on all types of isolates, except Ag-BAK 6. According to the
experimental observations, silver also plays a negative role at the growth of Ag-
BAK 6 (inhibition constant (KI) 3,66 mg/L Ag). Cu-BBK 1.1 accumulated Cu 5,2
mg/g dry biomass after 48 h, while Ag-BAK 6 accumulated Ag 0,046 mg/g dry
biomass after 24 h. Phylogenic tree was developed based on 16S rRNA gene
molecular analysis, and it was found that Cu-BBK 1.1 and Ag-BAK 6 were
closely related with Bacillus megaterium, (99,86% similarity) and Bacillus
subtilis, (99,85% similarity) respectively.
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