Algicidal Bacteria Against Anabaena Flos-aquae And Their Algae-lysing Characteristics

Harmful algal blooms (HABs) have become a serious problemthroughout the world in recent years. Little is known about the effect ofalgicidal bacteria on Anabaena flos-aquae which is a fresh-watercyanobacteria usually cause water bloom in lake and river. We adopt agreat deal of Microbiology, Molecular Biology, Bioinformatics,biotechnology in Ecotoxicology and Animal toxicology on A. flos-aquaeand algicidal bacteria. Our experiments involve: isolation, identification,phylogenetic analysis of three strains of algicidal bacteria; the effect ofalgicidal bacteria on the growth rate and photosynthetic pigments of A.flos-aquae; the study on algicidal mode of the algicidal bacteria; theinfluence of algicidal bacteria on antioxidant system and so on. Theresults as follows:The algicidal isolates were closely related to the following genera:SSAL-1and SSAL-6related to Bacillus; SSAL-8related toAcinetobacter. The Bacillus SSAL-1, Bacillus SSAL-6andAcinetobacter SSAL-8were preserved in China General MicrobiologicalCulture Collection Center with CGMCC No.6194, CGMCC No.6195andCGMCC No.6196respectively. Genbank accession no. of threealgicidal bacteria were JX627584, JX660686, JX660687, respectively.The effect of every strain of algicidal bacterium on growth andphotosynthetic pigments of A. flos-aquae followed a similar mannernamed concentration-dependence, i.e., the effects of inhibition on cell number and photosynthetic pigments increased gradually when theconcentration of algicidal bacteria increased from5%to35%. A.flos-squae exposed to three algicidal bacteria was more sensitive to strainBacillus SSAL-1and Bacillus SSAL-6than those exposed to strainAcinetobacter SSAL-8.Bacillus SSAL-1and Bacillus SSAL-6depended on indirect modeto attack the A. flos-aquae while Acinetobacter SSAL-8depended onboth direct and indirect mode.The results showed that the responses of the antioxidant enzymesystem in A. flos-aquae were influenced by algicidal bacteria. All threeantioxidant enzymes (SOD, CAT and POD) exhibited a rise-drop pattern,whereas MDA content were increased significantly.The Kunming mice showed no obvious death in the dose of5g/kg(the maximum dose of toxicity test) and8.75g/kg (the correspondingdose of the best algicidal effect). The body weight of individual micewas slightly reduced, but the weight were gradually restored over time.There was no significant difference in organ coefficient of the liver,kidney and brain in each treatment group compared with the controlgroup.