Indole Metabolism By Phenol-stimulated Activated Sludges: Performance, Microbial Communities,and Network Analysis

Indole,as one of the typical nitrogen heterocyclic compounds,not only cause environmental pollution but also affect human health.Indole and phenol often coexist in the coking wastewater,while the co-metabolism of phenol and indole and effects of phenol on microbial communities of indole metabolism were less explored.In addition,it was found that the resources of indole-degrading strains were still limited.In this thesis,indole(group A)or indole and phenol(group B)were systematically investigated in sequencing batch reactors(SBRs).High-throughput sequencing technology and traditional pure culture technology were combined to reveal the metabolic process of indole in wastewater from both microbial community and pure strain characteristics.The main research results are as follows:The performance of SBR in treating phenol-indole-containing wastewater was examined.The experiments showed that both groups maintained high efficiency for the removal of indole or phenol and chemical oxygen demand(CODCr)during the operation.Results suggested that phenol promoted the removal of indole.In the experimental group,the fluorescence center changed,and the intensity of soluble microbial by-product-like and tyrosine-like regions increased.The microbial community diversity,composition,structure,potential functions,and microbial interactions within activated sludge microbial communities were analyzed using Illumina high-throughput sequencing technology.The results showed that α-diversity was reduced in both groups.According to the relative abundance analysis,the indole-degrading genus Comamonas was the core genus in both groups,and the abundance of group B was higher.In addition,the proportion of unique OTUs corresponding to Burkholderia increased after phenol stimulation.PICRUSt analysis showed that phenol-stimulated activated sludge may produce more key enzymes involved in indole metabolism.Based on the phylogenetic molecular ecological networks(p MENs),the positive interactions between the key functional genus Burkholderia and other bacteria were increased.Indole-degrading bacteria were screened from reactor sludge by traditional pure culture technique and their indole metabolic characteristics were investigated.After species identification,it was found that pure culture could obtain strains corresponding to the dominant genera in the microbial community to a certain extent.Studies have shown that Burkholderia sp.YJIP-F1 had the best ability for indole degradation and indigo production among the 8 strains.Response surface methodology(RSM)was used to optimize the biosynthesis rate of indigo synthesis by the strains.In conclusion,this study reveals the interspecific interaction of microbial communities in complex systems by integrated culture-dependent and independent techniques.And provides a new strain resource for the biosynthesis of indigo pigments.