Soil microbial community response to pyrene at the presence of Scirpus triqueter

Phytoremediation of pyrene pollution by Scirpus triqueter in a stimulated wetland system has been studied. The results showed that pyrene removal was higher in the rhizospheric soils (49.8–60.8%) than that in the unplanted (17.5–41.6%) and non-rhizospheric soils (33.0–56.4%). The variation in microbial community compositions was investigated by analyzing phospholipid fatty acids (PLFAs) profiles in microbes under pyrene exposure. The microbial biomass , as revealed by PLFAs, decreased significantly with increasing pyrene concentration in all the three parts of soils. Specifically, the pyrene exposure inhibited the growth of fungi and some microorganisms (indicated by 14:0, 17:0, 16:1ω7c and 7Me17:0) to some degree. Principal component analysis (PCA) also revealed that all the fatty acid negatively correlated with the pyrene at higher concentration. However, the presence of S. triqueter enhanced the proportions of fungi, Gram-negative bacteria and aerobic bacteria, which possibly contributed to the degradation of pyrene. Total PLFAs in rhizospheric soils were profoundly higher than those in non-rhizospheric soils. The results indicated that S. triqueter might induce the colonization of bacteria in the stimulated wetland system, and led to a discrimination of microbial community, which might be one of the mechanisms on pyrene dissipation in phytoremediation system.