The Relationship Between Microcystis S-layer Protein And Population Status And The Production Characteristics Of Bloom Odor Substances

The Microcystis bloom influenced more and more water bodies in China since the end of last century.And in order to control it we should firstly understand the biological mechanism of how the water bloom formation.In this paper,14 strains of Microcystis sp.that most of them can maintain the state of colony aggregation were isolated and cultured from the water bloom samples in the Tai Lake basin(Jiangsu section)and the surrounding area of Nanjing,and carried out two aspects of research on them:(1)the relationship between cell wall surface protein(S-layer)and colony aggregation state;(2)the relationship between Microcystis and main taste-odour(T&O)compounds in water.The main results are summarized as follows:To clarify the relationship between the expression of S-layer protein and the aggregation of microcystis cells,we compared the expression level of S-layer protein of unicellular Microcystis(PCC7806,FACHB-315)and 10 strains of Microcystis by Western Blot.Firstly,we used the gene of PCC7806(CAO89090.1)as template,compared and analyzed the gene sequences of other Microcystis in the database,and a well-conserved protein fragment was selected as the antibody detection target to prepare the specific microcystis S-layer protein specific antibody.The results showed that the expression of S-protein in different Microcystis strains were variable,two of the colony aggregation Microcystis,XW01 and T10,have a content that several times higher than that of other Microcystis.However,the other colony aggregation strains did not show a higher expression level.It is speculated that the reasons for the formation of Microcystis are multifactorial,and the role of S-layer in colonial Microcystis formation requires further validation.Aiming at studying the odor problem caused by water bloom,we detected whether the algae strains produce the main T&O compounds in water or not,we tested the effects of temperature,light,nitrogen and phosphorus on the accumulation of T&O compounds,and the effect of algal decay on the production of odorous substances.Through experimental verification and analysis,it has been confirmed that the source of ?-cyclocitral(CYC)and ?-ionone(ION)were mainly microcystis;the accumulation of the two T&O compounds increased when the concentrations of nitrogen and phosphorus increased,while the content of CYC decreased slightly with the increase of phosphorus concentrations.In the UV irradiation treatment,the accumulation of CYC decreased,but the ION increased.Diatoms are one of the producers of the geosmin(GEO),and the content decreased significantly under low temperature,moreover,on the condition that the algae were mixed to culture,the secretion of GEO increased.The source of MIB form algae may be some Anabaena species.There were no significant increase in the four kinds of T&O compounds in the process of algal decay,and the MIB had been decomposed in large quantities in the aerobic conditions.