The Interaction Of Microcystins And Aquatic Bacteria

Microcystins (MCs) are a class of cyclic heptapeptide bioactive compounds, it is the most widely distributed, the largest output and the most affected algal toxins in the algal blooms pollution. The biodegradation of microcystin is one of the main degradation pathway in water. This paper has summarized the existing researches at home and abroad, and studied the interaction between MCs and aquatic bacterias.This article mainly consists of two parts:first of all, microcystins (MCs) were degraded by the bacteria isolated from Wuhan, degradation results showed that the degradation bacterias is common in water, but the degradation rate is not high. The degradation efficiency of single strain is only 18.88% in 20h, the degradation rate of mixed bacterias is only 24.2% in 5 days, suggesting that in the case of sufficient carbon and nitrogen sources, MCs are no priority by bacterias, but also because only add a dozen micrograms per liter of MCs, also affected the degradation of MCs.Second, this article focused on MCs's influences on the growth and antioxidant enzymes of three bacterial strains, the results showed that bacterias have a stronger tolerance on MCs, it is no significant difference between the experimental group and the control group about ZD-32; for ZS-5, when the concentration of MCs is 100ug/L, it isn't differ with the control group, but with the increased of MCs concentration, the experimental group is obviously inhibited compared with the control group, especially 5mg/L of MC concentration. Terms of HGN2, it is significantly different between 5mg/L experimental group and control group at 6h (P<0.05), it is significantly different between lmg/L experimental group and control group at 18h. In general, in the conditions of liquid shaking culture, MCs on the growth of three strains of bacteria were not significantly inhibitory effect. by measuring superoxide dismutase (SOD) and catalase (CAT) showed that these two enzymes of the three bacterias had responded to MCs, indicating that antioxidant enzymes could resist the toxic effect of MCs, and make MCs resist the bacteria. In addition, three strains's SODand CAT activities had largely differ between each other, indicating that different strains are different for the response to different concentrations of MCs, suggesting that it may be related to the different anti-MCs of different strains. In addition, We also study on the biodegradation of MCs by three bacterias, the results showed it was not change much, which means that MCs could not degraded by the three bacterias.