The Research On The Inhibiting Effects Of Two Alage-lysing Bacteria On Microcystis Aeruginosa

Microcystis aeruginosa is the main component of algae bloom.The algae-lysing bacteria were isolated from water and sediment collected from the Fenhe River in Taiyuan,and these bacteria strains were identified by physiological and biochemical methods.The study includes the algae-lytic effect of two bacteria and characteristics of extracellular algae-lysing components from these bacteria strains.The results were showed as follows:1.Isolation and identification of algicidal bacteriaAmong 91 bacterial strains isolated from water and sediment sample collected from the Fenhe River in Taiyuan,two of them showed strong lytic activities.According to the morphological and physiological characteristics,they belong to Raoultella planticola and Aeromonas sp..2.Selection of culture media for bacteriaThe culture of algae bacteria could affect the growth of M.aeruginosa.When inoculated in the beef-protein medium and LB medium,about 100%of M.aeruginosa was removed,while starch culture medium could improve the growth of M.aeruginosa.Thus,starch culture medium was selected to be the medium used in this study.3.The lytic effect of different inoculation ratios of bacteria strainsFor the two algicidal bacteria,when the inoculation ratio was 2%,they had no lytic effect on the M.aeruginosa.When the ratio increased to 8%,there was no M.aeruginosa could be survived.So the high inoculation ratio of bacteria strains was beneficial to the lytic effect.4.The lytic effect of different cell ages bacteria strainsM.aeruginosa could be completely removed by these two strains bacteria at different cell ages.However,the time of algical completely decreased with the cell age increased.The algical effect had not obvious change when the strains were up to exponential growth phases.5.The lytic effect of different growth phases of the algaeThe antialgal efficiencies of these two strains bacteria were different to the various growth phages of M.aeruginosa.The removal rate was higher when M.aeruginosa in lag phase and logarithmic phase.Only 50%of the algae could be removed when the M.aeruginosa was at stationary phase.The earlier bacteria strains be inoculated the sooner all algae can be removed.6.The algicidal mechanisms of two algae-lysing bacterias.Both of the two algae-lysing bacteria achieved lytic effects by indirect attack(secreting a kind of extracellular products),which may be a protein.The algicidal substance showed a little bit effect on growth of M.aeruginosa with special conditions,such as high temperature,strong acid and alkaline.After addition these two strains bacteria,cellular morphology changes with time,and their photosynthetic systems were destroyed.So the algicidal mechanisms of strain 39#and 91#are the strains could break the cell of M.aeruginosa.As above,Raoultella planticola.and Aeromonas sp.are two ideal algae-lysing bacteria.The lytic effect was related to different inoculation ratios of bacteria strains,bacteria strains cell age,and the growth phases of algae.The substances produced by the two strains could inhibit the growth of M.aeruginosa.This study provided excellent germplasm resources and technical support for the prevention and control of water-bloom,which had important practical application value.