芽孢杆菌 B1胞外活性物质对球形棕囊藻的溶藻特性研究

从珠海香洲码头赤潮海水中分离获得1株对球形棕囊藻有显著溶藻效果的芽孢杆菌B1,研究了B1对棕囊藻的溶藻作用方式,溶藻过程中藻细胞结构变化,并采用透析、乙醇沉淀、有机溶剂萃取、酸碱及热稳定性分析等方法探讨了溶藻活性物质的性质.结果表明,B1无菌滤液对棕囊藻有较强的溶藻效应,除藻率达94.9%,B1通过分泌活性物质间接对球形棕囊藻的生长产生抑制;藻培养液中加入B1无菌滤液16 h后,藻细胞发生团聚,细胞壁失去完整性,56 h后藻细胞破碎,胞内物质溶出;相对分子质量<3 500的分泌物是溶藻过程中起主要作用的活性物质,具有较强极性和热稳定性,在121℃加热20 min后,仍然有良好的溶藻能力,除藻率达92.6%,活性物质在pH 9.0左右溶藻能力较强,在乙醇中不发生沉淀反应,由此推测该活性物质为含有酸性或碱性基团的非生物活性分子,不属于蛋白质、核酸、多糖等物质.

Characteristics Study of Extracellular Active Substance of Bacillus sp. B1 on Phaeocystis globosa

The algicidal bacterium named B1 which was identified as Bacillus sp. was isolated from red tide water in Xiangzhou shipside of Zhuhai. The algicidal mode of algae-lysis bacterium B1 and the microstructure of algal cells in the algae-lysing process were studied. In order to explore the properties of extracellular algicidal substances, the sterile condensed bacteria-free filtrate was dialysed, sedimentated by ethanol, extracted by organic solvents and exposed in different heat and pH variations. The results showed that the sterile condensed bacteria-free filtrate could effectively dissolve Phaeocystis globosa (P. globosa), the removal rate was 94.9%, B1 excreted algae-lysing substances to inhibit the growth of algae indirectly. Algicidal process under the visual field of microscope demonstrated that the alga cell rounded and the cell wall lost integrity after 16 h, the algae cell lysed and cellular substances released after 56 h. The molecular weight of the extracellular algae-lysing components of B1 are less than 3 500, the algicidal substances have strong polarity and heat-tolerant, which still had a strong algae-lysing effect after being treated at 121 degrees C, and the removal rate was 92.6%. The algae-lysing ability was stronger while the pH value was kept at 9.0, ethanol can separate extracellular algae-lysing components from other components efficiently. The algae-lysing components may be non-bioactive molecules which contain acidic or alkaline groups, and may not be protein, nuclear acid and polysaccharides.