Hexavalent Chromium Bioremoval through Adaptation and Consortia Development from Sukinda Chromite Mine Isolates

Abstract

Indigenous isolates from the waters of chromite mining sites at Sukinda Valley, Orissa, India, showed a considerable enhancement in Cr (VI) bioreduction rate through adaptation and consortia development. On the basis of 16S-rRNA sequencing, these isolates were identified as Bacillus subtilis VITSUKMW1, Acinetobacter junii VITSUKMW2, and Escherichia coli VITSUKMW3. The native isolates showed a high tolerance at 500–1000 mg L –1 of Cr (VI). An increase in the reduction rate from 0.199–0.477 mg L –1 h –1 to 0.5–1.16 mg L –1 h –1 at 5–20 mg L –1 of initial Cr (VI) concentration was achieved by the adapted isolates. An increase in the growth rate and Cr (VI) reduction rate [0.86–2.6813 mg L –1 h –1 at 5–100 mg L –1 of initial Cr (VI) concentration] was observed in the ternary consortium of adapted isolates. The FT-IR spectra revealed the active participation of the bacterial surface groups in the reduction. The development of sequential processes (native → adapted → consortia) employing Cr (VI) tolerant isolates, proves to be a potential bioremediation strategy for specific chromite mine sites.