Investigation On Yeast Competitiveinhibition Of Algae Bloom

In recent years, eutrophication has become a major environmental problem of China as well as the world, but physical, chemical and other control method which is now commonly used is not quite effective. Microbiological method is characterized by cheapness, safety and undestroying with ecological environment of water, and therefore microbiological method, as a future direction of eutrophication prevention and controlling, is becoming the focus of researchers.In this study, selective media was used to enrich yeast from the Effective Micro-organisms (EM). By way of adding yeast, glucose, yeast + glucose and the zymolytic glucose solution into the mixed algae during the period of logarithmic growth phase, the inhibitory effect on the algae bloom were investigated. And basic categories of the active substances inhibiting algal were determined through high press liquid chromatography-size exclusion chromatography (HPLC-SEC) and Excitation-Emission Matrix (EEM) analysis. The main conclusions are as follows:After YPD medium separation and enrichment, EM showed good algicidal activity in the presence of nutrients. In the mixed algae inoculated with mixed yeast and added with liquid glucose, the algae chlorophyll concentration significantly decreased and continued to maintain at a low level. Inhibition rate reached 94% by the concentration of chlorophyll in the 20-day experimental period. In the absence of growth substrate, the mixed liquid yeast did not produce inhibition of algal bloom; whereas the algae added by high temperature sterilized extracellular matters of yeast showed a good inhibition activity. It indicated that the algal inhibition activity of yeast is generated by extracellular matters which have high thermal stability. Through microscope observation of inhibited algal cells, it is found that the inhibited algal cells have clear external contours, integrate structures, pale color and decreasing chlorophyll concentrations. It suggested that through destruction of algal chlorophyll, the inhibiting algae active substance of the mixed yeast achieves the effect. By the analysis of HPLC-SEC and EEM of the water samples, it is initially found that the inhibiting algae substance is a kind of acidic substance which contains aromatic rings.