Assessment of Mercury Detoxification Potentiality of Isolated Streptococcus sp. MTCC 9724 under Different Environmental Conditions

Subhas Chandra Santra,Punarbasu Chaudhuri,Srabanti Basu,Subarna Bhattacharyya

doi:10.13189/eer.2013.010207

Abstract

The objectives of the present study were to isolate and identify a suitable mercury resistance bacterial strain and to explore their detoxification potentiality of mercury in different environmental conditions. A strain of Streptococcus sp. MTCC 9724 was isolated from the soil of waste dumping site adjacent to East Calcutta wetlands, West Bengal, India. Minimum inhibitory concentration of mercury was estimated. The bacteria were resistant to lead, arsenic, chromium and copper and antibiotics like Tetracycline, Ofloxacin, Amoxicillin, Ampicillin, Chloramphenicol and Cefadroxil. The bacteria were exposed containing 2, 5 and 10 mg/l of mercury containing media with variable pH, phenol and chloride ions as co-pollutants. It was observed that acidic pH was not suitable for bacterial growth and also for mercury detoxification. The presence of phenol in wastewater actually supported bacterial population growth and also mercury removal within 16 hours time periods, which indicated that utilization of phenol as a sole carbon source for bacterial metabolism, where as chloride ions up to 21 g/l did not inhibit the bacterial growth but significantly decreased the detoxification potentiality of Streptococcus sp. MTCC 9724.

Highlights

Compounds of mercury such as mercuric chloride and organomercurials are toxic to both eukaryotic and prokaryotic cells
The most serious ecological disaster resulting from the frequent use of this heavy metal and its compounds is the indiscriminate discharge of mercury-contaminated effluents into water bodies and adjoining soils, resulting in an unprecedented rise in pollution levels
The present study revealed that Streptococcus sp -MTCC 9724 could successfully remove mercury within 16 hours incubation period (Fig 1)

Summary

Introduction

Compounds of mercury such as mercuric chloride and organomercurials are toxic to both eukaryotic and prokaryotic cells. The most serious ecological disaster resulting from the frequent use of this heavy metal and its compounds is the indiscriminate discharge of mercury-contaminated effluents into water bodies and adjoining soils, resulting in an unprecedented rise in pollution levels. Mercury droplets from thermometer and other medical laboratory equipments are source of pollution in home, pathological laboratories and hospitals [3, 4]. Mercury contamination has been found in marine sediments of Southern Brazil for the periods of 1998 to 2008 [6]. Some fishes collected from the same areas contaminated with mercury ranging from 12.4 ng/g to 216 ng/g [7]. India consumes 50% of global production of Hg[14]

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Methods

Conclusion