Isolation Of Algae-lysing Microorganism And The Priliminary Study On Charactistic Of Algae-lysing Effect

In our study, a primary isolation system of some special algae lysing microorganisms was set up. Through the system, abdellovibrio like organism(BLO) Y and actinomycetes 11 were isolated from the East Lake and soil aside respectively in Wuhan, China.Y , which could pass through the membrane filter of 0.22μm, secreted unknown algae-lysing substances by capable of killing the host bacteria. Y could kill a few cyanobacteria species and its algae-lysing ability could be maintained through continuous infection. But no algae-lysing effect was observed in eukaryotic algae culture.As the result of infection of Y on Microcystis aeruginosa DS show that 4, 24,48h later, the mortality ratio of M.aeruginosa DS were 12.1%, 23.0%, 100% respectively. 32h later the concentration of Y reached its peak(about 10⁸ cell-mL^-1), 2 days later, when algae cells were completely lysed, the concentration of Y sharply decreased to about 10² cell-mL^-1 and maintained this concentration as long as 3 to 5 days.The algae-lysing characters of Y under certain environmental factors were studied and the result indicated that presented obvious infection effect at temperature from8-32°C,dark, intense light irradiation, but was sensitive to heat and ethanol. (i.e. It would completely lose the activity after insulated at 45°C for 15 mins or exposured to ethanol at a very low concentration (0.0001%).) Also, the strong ability of algae-lysing ability of Y could be preserved only by continous addition of cyanobacteria into the colture. The continous expanded plaques were observed on plate of canobacteria or bacteria growing. Thus, the strain would be stored at 4°C and the viability of algae-lysing could be sustained for 1-2 month.We constructed a method for effective isolation actinomycetes, which was simple, exact and reliable. Using this method ,we isolated more than 200 actinomycete stains from soil ,among which 30 actinomycete stains could form clear algae-inhibiting-zopm on wild M.aeruginosa plate. Among the 30 actinomycetes,6 strains had strong ability of anti-contamination against other fungi and bacteria ,1 stain(No.2-No.11) started to secrete algae-lysing substance after 72h incubation. And then, the atinomycete sample culture of 72 hours was mixed with culture of wild M.aeruginosa at higher and lower concentration (Chla range from 0.2 to 1μg·mL^-1). The mortality of M.aeruginosa after 24...