The Primary Research On 3 Algae-lysing Bacteria

Several algae-lysing bacteria were isolated from 4 ponds in Wuhan City, three of which were labeled M6, M8 and M13. Their physiological and biochemical properties indicated that M6, M8 and M13 were characterized to be Staphylococcus, Bacillus and Arthrobacter respectively. Under the same culture condition, their growth curves were determined as follows: the lag phase of M6, M8 and M13 lasted respectively about 8h, 8h and 4h;the stationary phase started separately as about 60h, 32h and 44h. The plasmids of the three bacteria were identified, the results showed M8 hadn't plasmid, the plasmid of M6 and Ml3 were about 20Kb.The 3 bacteria showed algae-lysing effects on blue-green algae (cyanobacteria). They presented a broad algae-lysing range, i.e. they lysed Plectonema boryanum IU594, Nostoc sp.96, Anabaena sp. PCC595, Phormidium foveolarum IU427, Miorocystis aeruginosa, Lyngbya ketzingii IU1547 tested. Likewise, the infecting effects of the bacteria on the blue-green algae were more markedly in liquid medium than in solid medium .The threshold density of M6,M8 and Ml3 for significant cell lysis were about M6-105/mL, M8-106/mL,M13-105/mL respectively. The influence of 3 bacteria on Nostoc and Synechococcus were studied, we got the results as follows: the number of the bacteria would increase while the algae were lysing; if the algae weren't lysed; the number of the bacteria would change little.Phosphorous is one of the key elements that lead to water bloom. The test was designed to study the growth of the 3 bacteria and phosphates [K2HPO4+KH2PO4 (1:1)]. The results indicated that inorganic phosphates affected the growth of the 3 bacteria. They grew better at high phosphorous.It was observed that the filtrates of the bacterial culture showed significant lytic effect on blue-green algae, indicating the anti-algal effect results from the substances released by the bacteria in addition to the competitions of Phosphorous between the 3 bacteria and algae.A protozoon was isolated. It belonged to a kind of ciliate. It could ingest Synechococcus and Anacystis. The grazing characteristics of it by Synechococcus were observed. The results exhibited that the number of Synechococcus decreased quickly in 60h after the ciliate was inoculated. The protozoa couldn't ingest the 3 algae-lysing bacteria, which showed that they could help to the algae elimination together.