Molecular Analysis of mlrA Gene Containing Bacteria Isolated from Microcystin Infested Water Bodies

Abstract

Microcystins (MCs) are toxic cyclic heptapeptides produced by few toxic cyanobacteria newlinewhich generally form blooms in eutrophic surface fresh water bodies. They cause acute to newlinechronic poisoning and other health related problems mainly by irreversible inhibition of newlineprotein phosphatases (PP1 and PP2A) and increased formation of reactive oxygen species newline(ROS). Due to limitation of non-biological methods of water treatments the exploration of newlineMCs degrading bacteria is emerging at a quite pace to address, through bioremediation, the newlineproblems posed by MCs in water and water-bodies. Report and study of MCs biodegrading newlinebacteria from India were lacking. However it was evident, from our previous study, that newlinemicrocystin degradation can be achieved by indigenous microcystin degrading bacterial newlinepopulation in its natural place where microcystin producing blooms occur. This study has newlinepresented isolation and characterization of indigenous microcystin degrading bacteria from newlineholy ponds in Utter Pradesh of India. Overall 20 bacterial isolates were isolated from newlineMicrocystis infested different ponds. Out of these 13 isolates were mlrA positive by PCR newlineand were found to be distinct isolates by amplified ribosomal DNA restriction analysis newline(ARDRA). However, ARDRA analysis revealed overall four bacterial groups. On the basis newlineof 16S-rRNA gene sequence the Gram-positive-rod isolate PM1 was identified, with 99% newlineidentity, as Bacillus licheniformis which was shown earlier to cluster with microcystin newlinedegrading bacterium B. subtilis. Vitek analysis using BCL card (Gram-positive spore- newlineforming bacilli) also identified isolate PM1 as B. licheniformis with acceptable newlineidentification confidence level of analysis. LK3 was identified, with 99.84% identity, as newlineExiguobacterium profundum (T) but has not yet been reported as MCs degrader. Antibiotic newlinesusceptibility test of these isolates revealed them to be controlled by many antibiotics, if newlinethey cause disease.