Bioconversion of Hg and Molecular Characterization of merA and merB Gene in a Clone Constructed by Culture Independent Technique

Abstract

The anthropogenic use of mercury (Hg) has led to the wide outlook to the problem and health concerns caused by it. Metagenomic approach has opened the galore to the ease of access to the gene pool. The permissible limit of Hg is 0.001ppm but there are some sites in India having very high concentration of Hg (Ulhas estuary, Mumbai, having 107 ppm Hg). Library of clones containing mer operon, was constructed using culture independent technique. Out of 150 clones studied, UC07 has shown growth at 70ppm Hg. It has also shown antibiotic resistance towards vancomycin (30 mcg), Kanamycin (30 mcg) and Norfllaxin (10 mcg). Clone has the capability to volatilize 97.94% of 5ppm Hg which gradually decreased to 47% with the increase in Hg to 70ppm. Validation study using actual site (Ulhas soil) showed the effective conversion of Hg up to 99.9% by UC07. The clone contains both merA and merB genes, so it can be effectively utilized for organic and inorganic contaminated site. This is the first study of validation of clone using Hg contaminated site. The results are quite promising which shows that UC07 can be utilized effectively for bioconversion of both organic as well as inorganic form of Hg contamination.

Keywords

• mercury
• metagenomic
• mercury resistance
• mer operon
• antibiotic resistance
• mercury volatilization.