Isolation, Identification And Degradation Effect Of Active Bacteria For Microcrystis Aeruginosa And Microcystins

In recent years, harmful algal blooms (HABs) have frequently caused large-scale red tides and posed lots of threats to life body. It has been accured frequently and the affected regions increased gradually. For many years, scientists paid lots of attention to HABs and HABs is becoming a global water problem. It is increasingly urgent to develop useful strategies for reducing the negative impacts of HABs. In the past few years, we found that biological control methods have been regarded as a novel and safe method. In this paper, the highly effective algicidal bacteria and bacteria with MC-LR degradation activity were isolated from eutrophication waters in Zhejiang Hangzhou. The molecular identification, physiological and biochemical characteristics were also investigated. Microcystis aeruginosa was used as a mode species and MC-LR was extracted from it.Two algicidal bacteria (HJC-1, HJC-2) which exhibited high an tialgal activity against Microcystis aeruginosa were isolated from eu trophication waters. Based on their morphology, physiological and b iochemical characteristics and16S rDNA sequence, the isolated strai ns were identified as Bacillus subtilis and Arthrobacterium sp. The best algicidal effect was obtained after72h, the Chl α removal effi ciency of HJC-1and HJC-2were98.2%>94.3%. After immobilization, algicidal activity were84.07%and79.02%. Transmission electron mic roscope was subsequently used to investigate cells structures after3d with culture of strain HJC-1. The results indicated that the cell membranes and cell walls of Microcystis aeruginosa were broken w hile the gas vesicles and some particulate matters such as the cytop lasm phosphate particles and blue bodies disappeared. In addition th e cellular ultrastructure of the photosynthetic lamellae was also foun d to be disordered and disappeared.Three bacteria capable of degrading microcystins were isolated f rom a hypertrophic lake in Zhejiang university named DM-1、DM-2、 DM-3. On the basis of16S rDNA sequencing, DM-1、DM-2were tentatively identified as Citrobacter sp. and DM-3was identified as Paenibacillus polymyxa. After3days, the degradation percentages of MC-LR were40.2%,75.08%.97.23%. Compared with those re ported bacteria, DM-3exhibited lots of advantages. And they exhibi ted high degradation activities towards MC-LR after immobilization.