Abstract: A strain of bacteria XXG was isolated from rice fields irrigated from Taihu Lake. The bacterial genus was determined by analyzing its morphological characteristics, physiology biochemistry experiment and 16SrDNA sequence. Single factor test was conducted on the addition ratio of medium, the volume ratio of bacteria to algae, the density of bacteria and density of algae to study the effect of each factor on the effect of lysing algae. Box-Behnken Design (BBD) was used to design three major factors, namely, temperature (X1), pH (X2) and shaker speed (X3), to optimize the environmental factors that affect the lysing rate of algae. The method of lysing algae was initially examined by comparing the effect of bacterial weight suspension and sterile fermentation liquid on algal liquid. The experimental results showed that the similarity degree between XXG and Paenibacillus sp. KU573975 was 99.27%, and was initially identified as Paenibacillus. When the optimum volume ratio of bacterial to algal was 5.6%, the lysing rate of XXG bacteria to Microcystis aeruginosa solution at the early logarithmic growth stage reached at 77.1% after 6 d. Three important environmental factors that affected the efficiency of XXG algal lysing had a cross effect. The quadratic regression model of lysing rate of algae with the temperature, pH and shaker speed was established with P<0.0001 and R2 was 0.9727. Under the optimal algae-lysing characteristics, the lysing rate of algae was the highest when the temperature was 30℃, the pH was 7.5, and the shaking speed was 150 r/min, and the lysing rate of algae was up to 92.02%. Aseptic fermentation liquid without algal bacterial still had algae-lysing effect. It was speculated that the main algae-lysing processing of XXG bacteria was indirect effect. The reduction in algae-lysing effect produced by aseptic fermentation liquid compared with bacterial fermentation liquid may be achieved by the bacteria in bacterial fermentation liquid continuing to secrete some algae-lysing active substances.

Key words: algae-lysing bacterium, Microcystis aeruginosa, dissolved algae condition, algicidal characteristics, Paenibacillus

摘要： 从太湖水系灌溉的水稻田中分离出一株细菌XXG作为受试菌株，通过分析其形态特征表现、生理生化实验及16SrDNA序列确定菌属；对培养基投加比、菌藻体积比、菌密度、藻密度进行单因素试验，研究各因素对溶藻效果的影响；选择温度(X1)、pH(X2)、摇床转速(X3)3个主要因素采用Box-Behnken Design (BBD)设计，优化影响溶藻率的环境因素；通过对比菌体重悬液和无菌发酵液对藻液的影响，初步探究其溶藻方式。实验结果表明，XXG菌与Paenibacillus sp. KU573975相似高达99.27%，初步判定该菌株为类芽孢杆菌(Paenibacillus)；最佳菌藻体积比为5.6%，XXG菌对处于对数生长期前期的铜绿微囊藻液的6 d溶藻率达77.1%；影响XXG溶藻率的3个重要环境因素具有交叉作用，得出溶藻率与温度、pH、摇床转速的二次回归模型，该模型P<0.0001，R2=0.9727，在最佳溶藻特性下，当温度为30℃、pH=7.5、摇床转速为150 r/min时溶藻率最高，溶藻率可达92.02%；无菌发酵液仍有溶藻效应，推测XXG菌的主要溶藻方式为间接溶藻，无菌发酵液相较于细菌发酵液产生溶藻效应的减弱可能由细菌发酵液中的菌体继续分泌某种溶藻活性物质来实现。

关键词: 溶藻细菌, 铜绿微囊藻, 溶藻条件, 溶藻特性, 类芽孢杆菌