一株赤潮藻溶藻菌的筛选鉴定及溶藻特性分析

为缓解赤潮微藻对海洋生态环境的危害性问题,从潮间带泥样中筛选溶藻菌进行生物学特征分析,通过稀释涂布平板法及平板划线分离法从浙江舟山桃花岛潮间带泥样分离筛选菌株,以中肋骨条藻(Skeletonema costatum)及东海原甲藻(Prorocentrum donghaiense)为受试对象,通过丙酮法提取、测定叶绿素含量变化从中筛选高效抑制赤潮微藻生长的菌株。经形态学观察、生理生化特征检测及16S rDNA序列分析比对初步确定菌株的分类地位。通过不同pH、发酵时间、添加比例等单因素实验,对菌株溶藻特性和溶藻活性物质特性进行研究。从潮间带泥样中共获得43株菌,以菌株2-1-2抑制效果最佳,经鉴定属于芽孢杆菌属,初步命名为Bacillus sp. 2-1-2。溶藻菌Bacillus sp. 2-1-2以胞外分泌溶藻物质的方式进行间接溶藻,最适生长pH为7.0±1.0,菌液最佳发酵时间2—4d、最佳添加比例20%;溶藻活性物质耐热性好,对酸碱耐受性佳,但不耐强酸,在pH=10、80℃处理后溶藻率分别可达(90.57±0.43)%和(89.52±0.96)%。对赤潮藻细胞ROS水平与MDA含量...

SCREENING AND IDENTIFICATION OF A HIGHLY EFFICIENT ALGACIDAL BACTERIUM AND ANALYSIS OF BIOLOGICAL CHARACTERISTICS

Nowadays, the marine environment is deteriorating and red tides occur frequently. Algacidal bacteria is one of the efficient ways to inhibit red tides, however, there is still limited research on the algacidal bacteria. In order to alleviate the harmful effects of red tide microalgae on the marine ecological environment, we screened algacidal bacteria from mud samples of intertidal zone, and carried out biological characterization. Skeletonema costatum and Prorocentrum donghaiense were chosen to evaluate the algacidal efficiency. extracted by the acetone method and the chlorophyll content was measured. A total of 43 strains were obtained from primary screening, and the strain which showed best algacidal effect was identified as Bacillus by morphological observation, physiological and biochemical characteristics and 16S rDNA sequence analysis, and was named as Bacillus sp. 2-1-2. The supernatant of bacteria solution showed strong algacidal effect while the resuspension of bacteria showed no or less algacidal effect, indicating an indirect algacidal mechanism. After coculture of the supernatant of bacteria solution with algae for 30min, both ROS and MDA levels of the algae changed very significantly (P<0.01). It is speculated that the mechanism of algae lysis may be the secretion of algae lysis active substances indirectly contacting the algal cells, affecting the normal physiological state of the algal cells, stressing the imbalance of the dynamic oxidation balance of the algal cells, the lipid peroxidation of the algal cells destroying the structural integrity and causing the contents to leak out and gradually break down, inhibiting the growth of algal cells. Different conditions, including pH, fermentation time and adding ratio, were studied to ensure their influence on the algacidal effect of the bacteria solution. The results showed that this strain was not tolerated to acidic nor basic condition. The optimum fermentation time was 2—4d and the optimum addition rate of bacteria solution was 20%. The properties of algacidal substance were preliminary investigated using the supernatant of the bacteria solution. It is notable that the algacidal substance was resistant to heat, basic condition and weak acidic condition. This work provides theoretical basis for the deeper research at the molecular level and further utilization of algicidal bacteria.