| Recently, aquatic environment and aquatic ecological safety have been greatly endangered by microcystin due to the severe eutrophication problem. The use of bacteria to remove microcystin attracted many concern because of its economical, safe and efficient. In this paper,2strains of bacteria were isolated from cultured active sludge and proved to have high MC-LR degradation ability. Bacteria W2and W4were selected as research objective to study the characteristics of MC-LR degradation. The MC-LR degradation mechanisms were discussed intially and the16S rDNA sequence analytical method was used to identify two strains of algae-lysing bacteria. The main contents and achievements of this study are as follows.The initial bacterial cell density and MC-LR concentration strongly influence the removal of MC-LR, the greater the initial bacterial cell density, the faster the degradation of MC-LR; the higher the initial MC-LR concentration, the slower the degradation of MC-LR. Both of the2bacteria have their highest MC-LR removal rate when pH is8.1. The removal rate of MC-LR is increased with the increase of temperature and achieve highest removal rate between30～35℃. Additional carbon resource will suppress the removal of MC-LR by bacteria.The study of the mechanisms of2strains of MC-LR degradation bacteria shows that the strain W2、W4all remove MC-LR by neither secreting metabolites to degrade nor only absorbing it into their body, but direct utilizing MC-LR as its carbon resource and transferring MC-LR to other substances. Also both W2and W4can inhibite the growth of Microcystis aeruginosa, thus to inhibit the generation of intracellular MC-LR.The2strains were identified by the sequence analysis of16S rDNA. The DNA sequence similarity analysis showed that the strain W2shared99.8%sequence homology with one strain of A.caviae ATCC15467T, the strain W4shared99.8%sequence homology with one strain of A.sanarellii A2-67T. Strain W2and W4both belonged to Aeromonas sp. |
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