Microcystin-LR biodegradation by Sphingopyxis sp. USTB-05 |
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Authors: | Chengbin Xiao Hai Yan Junfeng Wang Wei Wei Jun Ning and Gang Pan |
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Institution: | (1) Department of Earth and Environment, Florida International University, 11200 SW 8th Street, Miami, FL 33199-001, USA;(2) Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; |
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Abstract: | A promising bacterial strain for biodegrading microcystin-LR (MC-LR) as the sole carbon and nitrogen source was successfully
isolated from Lake Dianchi, China. The strain was identified as Sphingopyxis sp. USTB-05, which was the first isolated MCs-biodegrading Sphingopyxis sp. in China. The average biodegradation rate of MC-LR by Sphingopyxis sp. USTB-05 was 28.8 mg·L−1 per day, which was apparently higher than those of other bacteria reported so far. The optimal temperature and pH for both
strain USTB-05 growth and MC-LR biodegradation were 30°C and 7.0, respectively. The release of MC-LR from the cyanobacterial
cells collected from Lake Guishui and the biodegradation of MC-LR by both strain and cell-free extract (CE) were investigated.
The results indicated that MC-LR with the initial concentration of 4.0 mg·L−1 in water was biodegraded by Sphingopyxis sp. USTB-05 within 4 d, while MC-LR with the initial concentration of 28.8 mg·L−1 could be completely removed in 3 h by CE of Sphingopyxis sp. USTB-05 containing 350 mg·L−1 protein. During enzymatic biodegradation of MC-LR, two intermediate metabolites and a dead-end product were observed on an
HPLC chromatogram. Moreover, the similar scanning profiles of MC-LR and its metabolic products indicate that the Adda side-chain
of MC-LR was kept intact in all products. |
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