Reduction of Cr (VI) by immobilised cells of Desulfovibrio vulgaris NCIMB 8303 and Microbacterium sp NCIMB 13776

Humphries, A., Nott, K.P., Hall, L.D. and Macaskie, L.E. (2005) Reduction of Cr (VI) by immobilised cells of Desulfovibrio vulgaris NCIMB 8303 and Microbacterium sp NCIMB 13776. Biotechnology and Engineering, 90 (5). pp. 589-596.

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Abstract

Hexavalent chromium, a carcinogen and mutagen, can be reduced to Cr(III) by Desulfovibrio vulgaris NCIMB 8303 and Microbacterium sp. NCIMB 13776. This study examined Cr(VI) reduction by immobilized cells of the two strains in a common solution matrix using various entrapment matrices. Chitosan and PVA‐borate beads did not retain integrity and supported low or no reduction of Cr(VI) by the cells. A commercial preparation (Lentikats) was stable but also did not support Cr(VI) reduction. K‐carrageenan beads were stable in batch suspensions but gel integrity was lost after only 5 h in a flow‐through system in the presence of 100 μM Cr(VI). The best immobilization matrices were agar and agarose, where the initial rates of reduction of Cr(VI) (from 500 μM solution) for D. vulgaris NCIMB 8303 and Microbacterium sp. NCIMB 13776 were 127 (agar) and 130 (agarose), and 15 (agar) and 12 (agarose) nmol h−1 mg dry cell wt−1, respectively. The higher removal of Cr(VI) by D. vulgaris was also seen in 14‐mL packed‐bed flow‐through columns, where, at a flow rate of 2.4 mL h−1, the percentage removal of Cr(VI) was ∼95% and 60% for D. vulgaris and Microbacterium sp., respectively (agar‐immobilized cells). The Cr(VI) reducing activities of D. vulgaris and Microbacterium sp. were lost after 159 and 140 h, respectively. Examination of the beads for structural integrity within the columns in situ using magnetic resonance imaging after 24 and 100 h of continuous operation against Cr(VI) (with negligible Cr retained within the columns) showed that agar beads were more stable with time. The most appropriate system for development of a continuous bioprocess is thus the use of D. vulgaris NCIMB 8303 immobilized in an agar gel matrix

Item Type: Article
Divisions: Crop and Environment Sciences
Depositing User: Mr Darren Roberts
Date Deposited: 07 Nov 2018 09:21
Last Modified: 29 Nov 2018 14:15
URI: http://hau.repository.guildhe.ac.uk/id/eprint/16373

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