Biodegradation of Microcystin-RR Extracted from Cyanobacterial Blooms by Sphingopyxis sp.USTB-05

The occurrence of cyanobacterial water blooms is a world wide concern in environmental health. Microcystin-RR (MC-RR) could be produced by cyanobacterial cells collected from Dianchi Lake and its content was about 0.12 mg/g in cyanobateria samples. A promising bacterial strain of Sphingopyxis sp. USTB-05 we previously isolated was found to have a strong ability in the biodegradation of MC-RR extracted from cyanobaterial cells. The effects of O₂, temperature and pH on the growth of Sphingopyxis sp. USTB-05 and biodegradation of MC-RR were further investigated, which indicated that initial MC-RR of 42.3 mg/L could be completely removed within 36 h at 30°C, initial pH of 7.0 and in the presence of O₂. Furthermore, an obvious intermediate product was observed during the biodegradation process of MC-RR, which had a high similarity of UV absorption spectra of MC-RR. This study provides a significant basis on the efficient removal of MC-RR from water polluted by harmful cyanobacterial blooms.