Isolation and Characterization of Microcystin Degrading Bacteria from Holy Ponds in India

Anil Kumar,Vikram Pal Gandhi

doi:10.3126/ijasbt.v4i4.16249

Abstract

Microcystins (MCs) are toxic cyclic heptapeptides produced by few toxic cyanobacteria and generally form blooms in eutrophic surface fresh water bodies. They cause acute to chronic poisoning and other health related problems mainly by irreversible inhibition of protein phosphatases (PP1 and PP2A) and increased formation of reactive oxygen species (ROS). Due to limitation of non-biological methods of water treatments the exploration of MCs degrading bacteria is emerging at a quite pace to address, through bioremediation, the problems posed by MCs in water and water-bodies. Report and study of MCs biodegrading bacteria from India were lacking. However it was evident, from our previous study, that microcystin degradation can be achieved by indigenous microcystin degrading bacterial population in its natural place where microcystin producing blooms occur. This study has presented isolation and characterization of indigenous microcystin degrading bacteria from holy ponds in Utter Pradesh of India. Overall 20 bacterial isolates were isolated from Microcystis infested different ponds. Out of these 13 isolates were mlrA positive by PCR and were found to be distinct isolates by amplified ribosomal DNA restriction analysis (ARDRA). However, ARDRA analysis revealed overall four bacterial groups. On the basis of 16S-rRNA gene sequence the Gram-positive-rod isolate PM1 was identified, with 99% identity, as Bacillus licheniformis which was shown earlier to cluster with microcystin degrading bacterium B. subtilis. Thus the present study revealed, for the first time, probable microcystin degrading bacteria in water-bodies from India. The potential and the metabolic pathway of PM1 and other mlrA positive isolates need to be further studied and validated to confirm their application in microcystin bioremediation. Int J Appl Sci Biotechnol, Vol 4(4): 436-447

Highlights

MCs are non-ribosomal peptides and are synthesized by a large multifunctional enzyme complex consisting of non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) domains encoded on microcystin synthetase gene cluster of variable composition and organization (Carmichael, 1992; Christiansen et al, 2003; Imanishi and Harada, 2004; Moffitt and Neilan, 2004; Pearson et al, 2010; Rouhiainen et al, 2004; Tillett et al, 2000)
Sample Collection, Isolation and Biochemical Characterization of Bacteria In order to obtain native bacteria with high MC-degradation efficiency, samples were collected from four ponds which were reported earlier/infested with cyanobacterial blooms
Bacteria were grown on Luria Bertani (LB) agar and were isolated to pure cultures employing standard pure culture techniques

Summary

Introduction

Microcystin is a well characterized cyclic heptapeptide hepatotoxin and it has been reported from various places of the world. (Carmichael, 1992; Carmichael et al, 2001; Chaturvedi et al, 2015; Harke et al 2016; Herry et al, 2008; Izaguirre et al, 2007; Kumar and Verma, 2012; Kumar et al, 2011; Lalita et al 2009; Lopez-Archilla et al, 2004; Lehman, 2007; Prakash et al 2009 and 2016; Tyagi et al, 2006; Xiao et al, 2009). Microcystins (MCs) are produced by few cyanobacterial species belonging to genera Anabaena, Microcystis, Nostoc, Planktothrix and Nodularia (Chaturvedi et al, 2015; Christiansen et al, 2003; Codd et al, 1997; Keil et al, 2002; Moffitt and Neilan, 2004; Rouhiainen et al, 2004; Satyaprakash et al, 2009 and 2016; Singh et al, 2001; Tillett et al, 2000; Tyagi et al, 2006). Other structural isoforms of microcystin vary in amino acid composition at two position 2, 4 and various modification at various position of the structure (McElhiney and Lawton, 2005; Welker and von Dohren, 2006)

Methods

Results

Conclusion