Effects Of Microcystins On Several Strains Of Aquatic Bacteria

China is one of the countries where cyanobacterial bloom happens most frequently and has the most extensive distribution. In recent decades, China’s economy and development has been restricted due to the damage of lake ecosystem, along with the harm to its function and declining water quality. The main harm that cyanobacterial bloom brings comes from algal toxins. Some research shows that algal toxins can be produced by 25%～75% of cyanobacterial bloom in the world. Microbe, including bacteria, fungi and actinomycetes, plays an important role in our environment because it not only promotes the biogeochemical cycle, but also acts as the main consumer and decomposer. In water, microbe is the most sensitive biological group, which is most particularly influenced by environmental changes. Microbe in water not only has a close relation to the water environment it lives in, but also an important effect on substance cycle and energy flow. Microbe has strong ability and effect on pollutant’s degradation and transformation, so it also plays an important role in the polluted water.The water sample taken from mid-Songhua River in the east, Harbin, Heilongjiang Province, along with microcystin (MC-LR) is selected as research subjects. Bacteria selective medium was applied to the isolation and culture of the bacteria strains and 7 strains were isolated, including 4 of Bacillus sp.,2 of Neisseria sp. and 1 of Escherichia sp..Then the strains were isolated with the toxin in different concentration including 1mg/L,5mg/L and 10mg/L. When the toxin concentration was 1mg/L, the content of soluble sugar in the strains decreased by 1.98%～18.21%, with that of soluble protein decreasing by 6.97%～52.56%, the strains’ activities of POD decreasing by 1.01%～ 18.92%, the strains’ activities of SOD decreasing by 4.84%～11.76%, the strains’ activities of CAT decreasing by 6.5%～9.57%; when the toxin concentration was 5mg/L, the content of soluble sugar in the strains decreased by 7.41%～26.14%, with that of soluble protein decreasing by 9.3%～75.64%, the strains’activities of POD increasing by 3.08%～17.85%, the strains’activities of SOD increasing by 30.42%～ 53.54%, the strains’activities of CAT increasing by 10.13%～19.37%; when the toxin concentration was 10mg/L, the content of soluble sugar in the strains decreased by 12.87%～36.47%, with that of soluble protein decreasing by 17.44%～83.33%,the strains’activities of POD increasing by 0.69%～36.92%, the strains’activities of SOD decreasing by 1.4%～14.75%, the strains’ activities of CAT increasing by 18.94%～ 49.7%.Observing and testing the indexes can lay the foundation for deep research in the effect of algal toxins on aquatic bacteria, as well as the theoretical foundation of the early-warning and treatment of cyanobacterial bloom pollution, along with the restoration of ecosystem.