Microbial biodiversity screening for metal accumulators from mineral ore rich site in Andhra Pradesh, India

Abstract

Problem Statement: Since the site selected for screening was a source of magnetite, the objective of this study was to isolate some groups of magnetotactic bacteria and microbes with potential of metal accumulation. Approach: The culture based approach was used for the study. Pure isolates obtained were characterized on the basis of morphology, biochemical tests, physiology as well as at the 16S rDNA based molecular level. They were screened for their metal accumulating ability. Results: Five pure bacterial isolates were obtained by culture dependent method, isolation being done on a modified Magnetospirillum magnetotacticum specific medium (DSMZ-380). These isolates not only exhibited morphological variation as found from Environmnetal Scanning Electron Microscopy (ESEM), but their cell surface also varied greatly in composition which was confirmed from various staining. Similarly another observed fact was that inspite of the same source of isolation, these strains exhibited a varied temperature and pH tolerance which indicates the diversity in the population. 16S rDNA based analysis shows the molecular identification and real time PCR based pathogenecity analysis proved that they lacked S. aureus or P. aeruginosa like pathogenic gene(s). The isolates were screened for metal accumulating property and all were found to tolerate a wide range of heavy metals and among them certain strains bear high potential of accumulation of metals like copper and chromium. Conclusion: This study reports the isolation and characterization of 5 novel bacterial isolates from the mining area of Andhra Pradesh, India revealing its rich biodiversity. It also points towards the ability of media DSMZ-380 to support growth of metal accumulating non-magnetotactic isolates.