MOLECULAR CHARACTERISATION OF POTENTIAL ARSENIC AND NICKEL RESISTANT BACTERIAL ISOLATES
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Date
2018
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Indira Gandhi Krishi Vishwavidyalaye, Raipur
Abstract
Heavy metal pollution is nowadays increasing day by day which needs to be dealt with immediate effect in order to check its further expansion in our environment. Since last decade, heavy metal contamination has risen significantly in Chhattisgarh state with reports coming from several districts. In order to deal with this problem, a molecular approach was undertaken in which 8 arsenic resistance (RSN1, RSN2, RSN3, RSN4, RSN6, RSN7, RSN8 and RSN10) and 4 nickel resistance (MNi3, INi4, INi5 and HNi3) bacterial isolates were used, which were originally isolated from previous study. Antibiotic susceptibility test was carried out for all the arsenic resistant bacterial isolates in which it was found that these bacterial isolates had shown significant resistance towards these antibiotics suggesting the presence of co-resistance for both metals and antibiotics. The genomic DNA of all 12 isolates was amplified with 16S rRNA gene yielding a 996bp DNA amplicons which were further sequenced using Sanger sequencing method. BLAST (NCBI) result showed that these sequences were similar with Bacillus firmus (RSN1), Brevibacteriumsenegalense (RSN2), Enterobacter cloacae subsp. dissolvens (RSN3), Stenotrophomonaspavanii (RSN6), Achromobactermucicolens (RSN7), Ochrobactrumintermedium (RSN8 and RSN10), Fictibacillushalophilus (MNi3), Bacillus xiamenensis (INi4 and HNi3) and Bacillus pumilus (INi5) respectively. All these sequences were deposited in NCBI gene bank with awarding of accessions numbers. PCR amplification of two arsenic resistant genes (arsC and arsB) and one nickel resistant gene (nre) was done through suitable primers for respective metal resistant bacterial isolates. Out of these genes, arsB gene in RSN3 bacterial isolate was successfully amplified yielding a 750bp DNA amplicon. The promising isolate RSN3 was further used for bioremediation assay. The sample was analysed through Atomic absorption spectroscopy which revealed a 32.22% reduction in arsenate. Furthermore, SEM (Scanning electron microscope) micrographs were observed for morphological alteration which indicated an increase in cell size at 1mM sodium arsenate concentration due to metal accumulation. However at 10mM arsenate concentration, there was a decrease in cell size which was probably due to efflux of arsenite by arsB gene.
Description
MOLECULAR CHARACTERISATION OF POTENTIAL ARSENIC AND NICKEL RESISTANT BACTERIAL ISOLATES
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