Bioremediation of inorganic mercury through volatilization and biosorption by transgenic Bacillus cereus BW-03(pPW-05)

A transgenic bacterium Bacillus cereus BW-03(pPW-05) was constructed by transforming a plasmid harbouring mer operon of a marine bacterium Bacillus thuringiensis PW-05 into another mercury resistant marine bacterium B. cereus BW-03 with mercury biosorption capability. The transformant was able to remove >99% of mercury supplement in-vitro by simultaneous volatilization (>53%) and biosorption (similar to 40%). Encapsulation of the transformant increased its mercury removal potential to almost 100%. Additionally, B. cereus BW-03((PW)-P-p-05) could resist wide variations of salinity (5-30 ppt), pH (Brierley et al., 1989; Chung et al., 1989; Chen and Wilson, 1997; Chakraborty and Das, 2014) and mercury (5 -50 ppm) and survived in mercury contaminated simulated environment up to 7 days. -SH and -COOH groups were possibly involved for mercury biosorption under laboratory conditions. The potential for application of this transgenic bacterium for in-situ bioremediation was demonstrated in a microcosm experiment, where it removed 96.4% inorganic mercury synergistically with the normal microbiota. (C) 2015 Elsevier Ltd. All rights reserved.