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Biodegradation of Microcystin-LR by Indigenous Microorganism and Their Community Structure in Sediment of Chaohu Lake

Author: HuFan
Tutor: ChenXiaoGuo
School: Wuhan University of Technology
Course: Environmental Engineering
Keywords: Microcystin Sediment Vertical distribution Degradation Microbial community structure
CLC: X172
Type: Master's thesis
Year: 2011
Downloads: 55
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Abstract


Microcystin (Microcystin MC) is a class of secondary metabolites by cyanobacteria, due to its strong liver toxicity in animals and humans causing serious harm, water bodies MC migration and transformation of research is very important practical significance. Microbial degradation in natural waters MC removed one of the main ways from different environments were isolated and identified a variety of MC-degrading bacteria and pure strain MC degradation pathway have some knowledge, but for the actual environment different media MC degradation, degrading bacteria distribution and degradation of the MC is still shallow understanding of the effects of microbial community structure. Indoor simulation were studied under aerobic and anaerobic conditions, sediment indigenous microbial degradation of MCLR, in order to deepen the understanding of MC degradation and degrading bacteria distribution of the actual environment; different depths sediment changes in the structure of the microbial community structure and microbial communities before and after the degradation of the MC in order to obtain the information of the of MC degradation process for the microbial community structure. The contents and results of this study are as follows: 1) the different depths of sediments indigenous microbial degradation of MCLR under aerobic and anaerobic conditions, different depths of sediments MCLR can occur rapidly degraded, MCLR after 4-5 days of lag phase, degradation in the 3d to the detection limit. Chaohu surface water MCLR degradation of 15d yet. MCLR degradation rate of sediments under aerobic conditions, is gradually decreased with increasing sediment depth. The uppermost sediment and the lowermost sediments under anaerobic conditions, the degradation rate of MCLR fastest slower degradation rate of the intermediate layer. Repeat to add MCLR sediment microbial degradation capacity is increased, in 1d 5mg/LMCLR degraded to below the detection limit, and the degradation process does not lag phase. Anaerobic degradation process detects a degradation products generated, the product of degradation of the MCLR MCLR degradation After completion will be degraded to below the detection limit, to infer that the product was Adda. 2) the vertical distribution of the sediment microbial community structure analyzed by DGGE profiles found in the upper sediments near the water column, microbial community structure is more complex, biodiversity, and with sediment depth increases, DGGE gradually reduce the number of bands. This shows that the microbial diversity in sediments decreased with increasing depth. 3) MCLR degradation sediment microbial community structure of aerobic degradation before and after the number of bands in the DGGE profile has increased, there has been some new bands, and dominant species of bacteria in the sediment has undergone some changes. This indicates the MCLR to join its degradation is the process of sediment microbial community structure impact.

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CLC: > Environmental science, safety science > The basic theory for the Environment and Science > Environmental Biology > Environmental Microbiology
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