The Study On The Effect Of Bacteria On Organic Phosphorus Cycling In Sediment Of Xihu Lake

Understanding phosphorus cycling at the sediment-water interface in lakes is important because of the key role of P in causing lake eutrophication. Recent studies have suggested that the uptake, storage and release of P by microorganisms in lake sediments can be of major importance in P-cycling in lakes. Either before or after dredging of the West Lake, the higher concentration of organic phosphorus(OP) in the sediment which occupied 50%~80% of total phosphorus, showed that it is meaningful to study in the organic phosphorus cycling in West Lake.The Bowman-Cole and Ivanoff method were employed fractionation of organic phosphorus in the sediment of organic Phosphorus in the sediment of West Lake respectively. The results showed that the Ivanoff method might be more suitable. The influence of microorganism on OP-cycling at the sediment-water interface was studied in an experimental system.The distribution of microbial biomass,which was determined by the chloroform fumigation-extration method, and the actibity of alkaline phosphatase were both measured in order to predict the state of microbial growth. Results showed that after 6 days, the content of OP began to increase clueing to the uptake and storage of phosphorus by microorganism. Between 14 days and 24 days, the content of OP decreased because of the mineralization process caused by microorganism, which was displayed by the activity Alkaline phosphatase. Therefore,the results showed that the decomposition of OP by microorganism were changed to the mineralization process just after 1~2 weeks,especially for the moderately labile OP.Six strains of bacteria,which have the ability to decompose organic phosphors,were isolated and purified from the sediments of West Lake. In this study, the amount of which reached to 9.9* 10~4 phosphobacteria/ml, being the most abundant, in the center of the Lake. According to the characteristics of colony morphology, six OP bacteria were selected and their forms and biochemical characteristics were tested. Laboratory...