盐碱水中地衣芽孢杆菌抑制铜绿微囊藻生长研究

Growth Inhibition of Microcystis aeruginosa by Bacillus licheniformis in Saline-Alkaline Water

基于菌藻平衡原理控制蓝藻,可降低盐碱地养殖池塘铜绿微囊藻(Microcystis aeruginosa)对养殖生物的危害。在实验室条件下,研究了盐碱水中地衣芽孢杆菌(Bacillus licheniformis)对铜绿微囊藻生长的抑制效果并探索其抑藻途径。结果显示,在碳酸盐碱度6.4 mmol/L、盐度3.5、pH 8.9的盐碱水中,地衣芽孢杆菌对初始密度为1.0×10^(6)、6.0×10^(6)、20×10^(6)个/mL的铜绿微囊藻均有明显抑制作用,抑制率分别达到51.8%、71.1%、65.7%;地衣芽孢杆菌无菌滤液对铜绿微囊藻生长也表现出显著的抑制效果,其中无菌滤液加入量为实验水体2%时的抑制效果最好,培养6 d后藻密度仅为4.5×10^(6)个/mL,处理组叶绿素a含量较对照组降低了58.8%,与铜绿微囊藻光合作用相关的PSBA1和PSBD1基因表达下降,光合作用途径受到抑制;盐碱水中地衣芽孢杆菌对铜绿微囊藻具有较好的抑制效果。

Cyanobacteria such as Microcystis aeruginosa are the primary source of algal blooms in saline-alkaline ponds and endanger aquaculture organisms.Microbe-based algae control has attracted attention because of potential effectiveness,species specificity,and eco-friendliness.Previous research has shown that Bacillus licheniformis can inhibit M.Aeruginosa growth in fresh water.In this study,the growth inhibition of M.aeruginosa by B.licheniformis and its inhibition mechanism were investigated under laboratory conditions.We aimed to provide basic data for the control of cyanobacteria blooms in saline-alkaline aquaculture and propose a feasible method for regulating the quality of saline-alkaline water.In this study,there were two groups of experiments.One group was set as follows:three treatments with initial M.aeruginosa concentrations of 1×10^(6),6×10^(6),and 20×10^(6) cells/mL,and an initial concentra-tion of B.licheniformis of 7.1×10^(6) CFU/mL.The second group of experiments was set as follows:three treatments with an initial M.aeruginosa concentration of 1×10^(6) cells/mL,and cell-free filtrates of B.licheniformis solution at concentrations of 0.5%,1%and 2%.Each treatment was run in triplicate with a control,and the experiment lasted seven days.Cell density and absorbance of M.aeruginosa in each treatment was determined every three days.Growth of M.aeruginosa was significantly inhibited by B.licheniformis in saline-alkaline water under experimental conditions:carbonate alkalinity,6.4 mmol/L;pH,8.9 and salinity,3.5.The inhibition rates of M.aeruginosa at initial M.aeruginosa concentrations of 1×10^(6) cells/mL,6×10^(6) cells/mL and 20×10^(6) cells/mL were,respectively,51.8%,71.1%and 65.7%,with normal M.aeruginosa growth in the control.The cell-free filtrate of B.licheniformis also showed a strong inhibitory effect on the growth of M.aeruginosa,and was most pronounced at the highest concen-tration(2%),with the M.aeruginosa concentration of 4.5×10^(6) cells/mL after culture for 6 d.At a filtrate concentration of 2%,the chlorophyll-a content in the experimental group was 58.8%lower than that in the control group,a significant reduction.B.licheniformis affected the expression of key M.aeruginosa genes involved in photosynthesis,such as PSBA1 and PSBD1,with significant downward regulation.In conclusion,B.licheniformis was found to inhibit M.aeruginosa photosynthesis in saline-alkaline water,consequently inhibiting growth.