枯草芽孢杆菌对铜绿微囊藻抑制效果的研究

为探讨枯草芽孢杆菌(Bacillus subtilis)对铜绿微囊藻(Microcystis aeruginosa)的抑制效果,在实验室条件下,研究了枯草芽孢杆菌不同生长时期(延迟期、对数期、稳定期和衰亡期)无菌滤液对铜绿微囊藻生长的影响、枯草芽孢杆菌抑制铜绿微囊藻生长的作用方式以及无菌滤液影响下铜绿微囊藻丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性和光合色素含量的变化.结果显示:枯草芽孢杆菌对数期、稳定期和衰亡期滤液抑藻效果明显好于延迟期,作用第8d,对铜绿微囊藻的去除率分别达到81.19%、91.41%、91.82%;4个处理组铜绿微囊藻的叶绿素a含量均显著低于对照组.添加稳定期滤液后,铜绿微囊藻MDA含量显著升高,SOD活性先升高后降低;在对光合色素的影响中,类胡萝卜素受到的影响不如叶绿素a显著.结果表明,枯草芽孢杆菌对铜绿微囊藻的抑制效果是通过分泌胞外物质实现的,且分泌物具有很强的热稳定性.推测该胞外分泌物能够破坏光合色素,影响光合作用,抑制藻细胞的生长;同时抑制SOD活性,使细胞膜脂过氧化程度不断加深,进而破坏藻细胞的完整性,表现出对藻很强的抑制效果.

Inhibition of Microcystis aeruginosa by Bacillus subtilis

To investigate the inhibition of Bacillus subtilis against Microcystis aeruginosa, the bacterium-free filtrate of B. subtilis culture from different growth periods (delayed, log, stable and decline phase) were used to study its inhibition and mode of action against M. aeruginosa. The MDA, SOD activity and the photosynthetic pigments content in M. aeruginosa were measured. The results showed that the inhibition of M. aeruginosa by the B. subtilis filtrate was greater in log phase, stable phase and decline phase than that in delayed phase with removing efficiency of 81.19%, 91.41% and 91.82%, respectively on day 8. The chlorophyll a contents of M. aeruginosa in treated groups were significantly lower than that in the control group. The MDA contents increased obviously in treated group and the SOD activity increased first and then decreased when M. aeruginosa was cultured in the filtrate-containing medium. Carotenoids were not affected as much as chlorophyll a. Results showed that B. subtilis inhibited the growth of the algae by secreting extracellular substances. And these substances were highly thermal-stable. It was speculate that the substances can hinder the photosynthesis by destroying the photosynthetic pigments and increase the membrane lipid peroxidation by inhibiting the SOD activity at the same time, resulting in inhibition of M. aeruginosa.