Environmental biology

Isolation and algae-lysing characteristics of the algicidal bacterium B5

MU Rui-min , FAN Zheng-qiu , PEI Hai-yan , YUAN Xue-liang , Liu Si-xiu , WANG Xiang-rong


Received January 30, 2007,Revised June 25, 2007, Accepted , Available online

Volume 19,2007,Pages 1336-1340

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Water blooms have become a worldwide environmental problem. Recently, algicidal bacteria have attracted wide attention as possible agents for inhibiting algal water blooms. In this study, one strain of algicidal bacterium B5 was isolated from activated sludge. On the basis of analysis of its physiological characteristics and 16S rDNA gene sequence, it was identified as Bacillus fusiformis. Its algaelysing characteristics on Microcystis aeruginosa, Chlorella and Scenedesmus were tested. The results showed that: (1) the algicidal bacterium B5 is a Gram-negative bacterium. The 16S rDNA nucleotide sequence homology of strain B5 with 2 strains of B. fusiformis reached 99.86%, so B5 was identified as B. fusiformis; (2) the algal-lysing e ects of the algicidal bacterium B5 on M. aeruginosa, Chlorella and Scenedesmus were pronounced. The initial bacterial and algal cell densities strongly influence the removal rates of chlorophyll-a. The greater the initial bacterial cell density, the faster the degradation of chlorophyll-a. The greater the initial algal cell density, the slower the degradation of chlorophyll-a. When the bacterial cell density was 3.6 107 cells/ml, nearly 90% of chlorophyll-a was removed. When the chlorophyll-a concentration was less than 550 mg/L, about 70% was removed; (3) the strain B5 lysed algae by secreting metabolites and these metabolites could bear heat treatment.

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