Removal of chromium by Staphylococcus saprophyticus subsp. bovis strain 1

Abstract

The present study was taken up to carry out the removal of chromium by bacteria. Chromium is a heavy metal which is of concern as it causes chromium toxicity in both plants and animals. The tanneries are a major source of chromium release into the water bodies, and hence this study is aimed at identifying the potential chromium-tolerant bacterium and at studying the bacterium for its maximum tolerance and chromium removal capacity. A total of 20 samples each of soil and industrial effluents were collected from the Peenya industrial area, Bangalore, India. The bacterial isolates were screened for chromium resistance by supplementing the nutrient media with 300 µg/ml of chromium. The  growth of the  bacteria was measured in terms of O.D. at 670 nm. The isolates were further screened by increasing the concentration of chromium from 300 to 3000 µg/ml. The isolate S105c which showed better resistance to chromium compared to other isolates was identified as Staphylococcus saprophyticus subsp. bovis strain 1 based on 16S rRNA sequencing. Optimization of temperature, pH, carbon sources, and nitrogen sources was carried out for the removal of chromium by S. saprophyticus subsp. bovis strain 1.  Atomic absorption spectrophotometric analysis was carried out for the removal of chromium by S. saprophyticus subsp. bovis strain 1 in the mineral salts medium supplemented with 300 µg/ml of chromium. Out of 40 soil and industrial effluent samples collected, a total of 51 isolates were obtained. Out of 51 isolates, 7 isolates gave the highest O.D. values in the presence of 300 µg/ml of chromium. The isolate S10-5c showed maximum tolerance up to 3000 µg/ml of chromium. S.  saprophyticus subsp. bovis strain 1 was able to remove 2% of chromium in the medium at the end of 24 hours under optimized conditions. It can be concluded that the organism Staphylococcus saprophyticus subsp. bovis strain 1 can be used for the removal of chromium from industrial effluents.