Identification of genes encoding heavy metal transporting proteins in selected bacteria of an effluent

Abstract

Characterizing microbial genes that encode proteins involved in heavy metal tolerance is useful for bioremediation. The genes czcD and zntA (948 bp and 2448bp) encode proteins reported to be involved in transporting heavy metals from cytoplasm to periplasm in bacteria. In this study, extracted genomic DNA of strains of Staphylococcus epidermidis (O5, O6, O7, O8, O9, O10, D7), Staphylococcus warneri (G, Ow) and Aeromonas jandaei (O3), isolated from an industrial effluent in Sri Lanka, were used to amplify partial czcD and zntA genes by polymerase chain reactions (PCR). Three different primer sets were designed for the amplification of czcD gene of S. epidermidis and S. warneri and zntA gene of A. jandaei. Genomic DNA was isolated using a modified guanidium thiocyante method. In PCR, a fragment of 672 bp was obtained for all strains of S. epidermidis except strain D7, at an annealing temperature of 54 oC and a fragment of 794 bp was obtained for Ow strain of S. warneri at an annealing temperature of 53 oC. In analysis through Bioedit software, amino acid sequences of amplified fragments were 100% similar to amino acid sequence encoded by partial czcD genes of S. epidermidis (Accession Number: NC_004461) and S. warneri (Accession Number: NC_020164) respectively. A fragment of 647 bp was obtained for PCR that carried out for O3 strain of A. jandaei at an annealing temperature of 57 0C. Amino acid sequence of the amplified fragment showed 98% identity to Zn, Cd, Hg and Pb transporting ATPase protein in A. jandaei in BLAST search compared to the ZntA. Presence of czcD gene in Staphylococcus sp. and Zn, Cd, Hg, Pb transporting ATPase gene in Aeromonas sp. were confirmed.