Mercury bioremediation by mercury accumulating Enterobacter sp. cells and its alginate immobilized application

Abstract

The effective microbial remediation of the mercury necessitates the mercury to be trapped within the cells without being recycled back to the environment. The study describes a mercury bioaccumulating strain of Enterobacter sp., which remediated mercury from the medium simultaneous to its growth. The transmission electron micrographs and electron dispersive X-ray analysis revealed the accumulation of remediated mercury as nano-size particles in the cytoplasm as well as on the cell wall. The Enterobacter sp. in the present work was able to accumulate mercury, without being engineered in its native form. The possibility of recovering the accumulated mercury from the cells is also indicated. The applicability of the alginate immobilized cells in removing mercury from synthetic and complex industrial effluent in a batch mode was amply demonstrated. The initial load of 7.3 mg l(-1) mercury in the industrial effluent was completely removed in 72 h. The cells immobilized in calcium alginate were similarly effective in the complete removal of 5 mg l(-1) HgCl(2) of mercury from the synthetic effluent in less than 72 h. The immobilized cells could be reused for multiple cycles.

Detoxification of mercury pollutant leached from spent fluorescent lamps using bacterial strains

“…Therefore the reported biouptake capacity of our bacterial strains (C. muytjensii, E. helveticus, and C. amalonaticus) is mainly explained by their abilities to biouptake mercury by storing and absorbing it in their cytoplasm hence less mercury levels were reported after the removal of bacterial cells from the filtrate used for measurement. Our suggestion coincides with the study of Sinha and Khare (2012) as they reported similar mechanism of bio-uptake for Enterobacter sp.…”

“…The major advantage of bioremediation either by volatilization or biosorption is to uptaking and detoxifying Hg(II) and organic Hg species to elemental Hg, thereby preventing food chain accumulation (Sinha and Khare, 2012;Wagner-Dobler, 2013). To prevent accumulation and facilitate volatilization, after bacterial uptake, incineration might be the best solution (Xu et al, 2015).…”

Employing Response Surface Methodology for Optimization of Mercury Bioremediation by Vibrio parahaemolyticus PG02 in Coastal Sediments of Bushehr, Iran

“…Free cells of Enterobacter decreased almost 66% of initial mercury concentration in aqueous solution during 48 h of incubation when exposed to initially 5 mg L −1 mercury. However, its alginate immobilized form was more efficient with about 95% removal under the same conditions . The maximum mercury removal by calcium alginate immobilized B. cereus biomass was 98.9%, which was achieved after 120 h of incubation under 10 mg L −1 initial mercury concentration.…”

Screening of mercury‐resistant and indole‐3‐acetic acid producing bacterial‐consortium for growth promotion of Cicer arietinum L.

“…The immobilized cells can be reused for up to four consecutive cycles of Hg‐detoxification experiments as reported by Amin and Latif, . The immobilization of E. cloacae and its potential to remediate mercury has also been evaluated as a complete removal of Hg +2 from mercury enriched media . So in conclusion, the immobilization of culture is better technique as compared to the usage of free cells for bioremediation of mercury after 8 days at large scale.…”