EFFECTS OF SUBMERGED MACROPHYTES CERATOPHYLLUM DEMERSUM L. ON SEDIMENT MICROBIAL COMMUNITY

摘要

Phospholipid fatty acids (PLFAs) were used to evaluate the effects of submerged macrophytes Ceratophyllum demersum L. on sediment microbial community structure in mesocosms. Different microfloras were observed in rhizosphere and non-rhizosphere sediments with C. demersum revegetation and control. More anaerobic bacteria were found in the sediment with C. demersum, especially in the non-rhizosphere sediment (P ＜ 0.05). The monounsatu-rated FAs representing Gram-negative (Gram~-) bacteria were relatively abundant in the presence of C. demersum, while the ratios of normal saturated to monounsaturated PLFAs in the sediments (rhizosphere & non-rhizosphere) were both significantly lower than those of control (P ＜ 0.05). A shift in composition from Gram-positive bacteria (Gram~+) to more Gram~- bacteria dominated bacterial community due to C. demersum revegetation was noted. Based on the ratio of the sum of iso and anteiso fatty acids of 15:0 to 16:0 ((i15:0+a15:0)/16:0) and the Shannon-Wiener diversity index (H_b~1), the colonization of C. demersum was determined to cause low diversity of microbial community in rhizosphere, and high diversity in non-rhizosphere.