Abstract
In the present study a yeast strain isolated from industrial wastewater, identified as Candida tropicalis, showed chromium (Cr) tolerance level up to 5 mM. Yeast grown in minimal salt medium containing Cr (VI) ions for 48 h and crude enzyme extracts were tested for chromate reductase activity. Optimum temperature and pH of chromate reductase were 30 °C and pH of 7. The enzyme activity was greatly enhanced in the presence of divalent metal cations. Total protein profile revealed some protein bands were present in hexavalent chromium [Cr (VI)] treated samples but were absent in non-treated samples, especially low molecular-weight protein bands in the mass range of < 25 kDa with greater intensity in Cr (VI) treated samples. Yeast cells were able to uptake Cr (VI) between 21 and 80 mg g− 1 within 2–12-d of time, indicating yeast strain promising potential for Cr (VI) removal from the wastewater. The present study results suggest that C. tropicalis is a suitable candidate for bioremediating chromium ions from the contaminated-environment.
Highlights
One of the most abundant elements on earth is chromium (Cr) existing in various oxidation states ranging from 0 to + 6 [1]
C. tropicalis [25] exhibiting the highest ability to tolerate chromium effectively up to 5 mM was selected for further study
In the present study, C. tropicalis showed significant resistance against Cr (VI) and growth was slowed in Cr-treated cultures as compared to the control
Summary
One of the most abundant elements on earth is chromium (Cr) existing in various oxidation states ranging from 0 to + 6 [1]. Cr is used in leather tanning, textile dyeing, chrome electroplating and finishing, metal processing industries, wood treatment, mining equipment, corrosion inhibition in power plants, manufacturing of refractory materials, and pigments. This extensive anthropogenic use has increased its concentration in environment higher than the recommended into the environment [2, 3]. The United State Environmental Protection Agency has declared it as a priority pollutant [4]. Industrial effluents contain multiple metals including chromium and chromium salts which have adverse effects on the microbial biota [8]
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