| With the increasing eutrophication, water-bloom is becoming more and more frequent, seriously impact on water ecosystem security and health of people living around.so, it is urgent to find an effective way to eliminate water-bloom. Alage-lying bacteria overcome the physical and chemical methods inadequate, become a hotspot of biological control of water-bloom, has a very broad application prospects.For the sake of further research on algae-lytic effect of YZ which was isolated from a lake in Qingdao, the algae-lytic influences of different content of YZ bacteria-free filtrate on the growth of M.aeruginosa FACHB469, the content of chlorophyll and malondialdeh-yde (MDA), superoxide dismutase (SOD) activity, the actual photochemical efficiency of PSⅡin the light (φPSⅡ=yield), the maximal relative electron transport rate (Pm), light use efficiency (a) in M.aeruginosa FACHB469 were studied.Besides, this paper further discussed on the algicidal characteristics of YZ substance,which including its polarity,the pH stability and the activated carbon absorption. The results were showed as follows:1. Studies by single factor test on the optimum fermenting conditions of alage-lysing bacteria YZ, the results were as follows:when incubation temperature was 36-38℃, pH condition was 6.0-8.0, the rotational speed was 180 r/min, the incubation time was 96 h, YZ has the best algicidal effect on M. aeruginosa FACHB469, after co-culture for 12 days, the alage nearly turned white.2. When the inoculation ratio was 10%, not only exclude the interference of bacterial culture, but also maintaining the maximum lytic effect.3. YZ had a strong dissolution on M.aeruginosa FACHB469, different concentration of bacteria-free filtrate had different influence on the alagicidal effect, as results show:the more bacteria-free filtrate was added into alage,the better removal effect on the M.aeruginosa FACHB469. But considering the medium interference, so the volume ratio of 10% YZ sterile filtrate to the algae was the best ratio.4. The photosynthesis of M.aeruginosa FACHB469 was greatly disturbed by YZ.12 days after co-culture, the actual photochemical efficiency of PSⅡin the light (φPSⅡ=yield), the maximal relative electron transport rate (Pm), light use efficiency (a) fell 97%,99% and 98% separately. There was more significant decline in a and Pm than Yield.5. Bacterium YZ caused oxidation stress and lipid peroxidation on M.aeruginosa FACHB469. The activities of SOD was increased significantly then decreased but the MDA contents in alage cells was increased continually.6. The algicidal substance of YZ had pH stability, The results showed that after pH 2.0 and pH 9.0 treatment, the algicidal substance still removing the M.aeruginosa during 12 days. Four kinds of solvents which has different polarity extracted the algicidal substance, the result shows that it is not highly hydrophilic polar substances, but one or more lipophilic substances. Compared with the control group, its dissolution on M.aeruginosa FACHB469 had been weaken after the activated carbon absorption.In summary,YZ can significantly damage the photosynthetic system of Microcystis aeruginosa, inhibited the growth of alage.It could be recovered easily, which is an ideal method to eliminate water-bloom. Although currently only in laboratory conditions to study the lytic character, but for production of lytic agent has great theoretical significance. |
