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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As a byproduct of activated sludge process, excess sludge has become one of the current problems in the field of environmental protection for its yield huge、high moisture content and easy to pollution. In this study, the joint technology combining ozone with ultrasonic was applied in treatment of excess sludge by strong ozone oxidation and prominent ultrasonic cavitation. The effect on lysis excess sludge cells was explored comprehensively. The lysis mechanism of excess sludge cells degraded by ozone + ultrasonic was revealed by analysis of three-dimensional spectral fluorometer, optical microscope and scanning electron microscopy (SEM). The results showed that the MLSS was 22.92% lower than the untreated sludge, the SCOD and [Formula: see text] -N content in the supernatant of the sludge was 1792 and 105.77 mg/L, which was 96.49% and 17.67% higher than the untreated. The supernatant of treated excess sludge contained macromolecular organic matters composed of proteins, polysaccharides, humic acids, and fulvic acids, etc. The whole process of lysis cells of excess sludge degraded by ozone + ultrasonic could be inferred that the microbial particles of excess sludge were exposed after EPS destructed, and then the cell walls of these exposed microbial particles were broken so that a great number of intracellular materials were released. Furthermore, these intracellular material composed of macromolecular organic matters were degraded into small molecule organic matters, HO, CO, etc. Finally, the excess sludge was treated gradually by ozone + ultrasonic.

Using Streptomyces erythreus isolated from pharmaceutical residues as a biosorbent, the characteristics and mechanism of its absorbing Pb2+ was studied. The results showed that absorptive ability of bacterial mycelia modified by sodium hydroxide was improved greatly. The reaction mechanism of modified bacterial mycelia uptake Pb2+ was analyzed by back scattered electron microscope(BSEM) and infrared spectroscopy (IR). The results of experiments indicated that some chemical groups such as -COO-、C-H and O-H among cell walls of bacterial mycelia might play the key functions adsorbing Pb2+. It was presumed that the process of modified bacterial mycelia lead uptake might be a chemical and physical process collaboratively which occurred on the cell surface of bacterial mycelia chiefly based on exchangeable reaction.