Research On Biodegradation, Kinetic Models And Environmental Metabolomics Of Phenolic Wastewater By Key Strain Of Microbial Consortia

Real phenolic wastewater, containing various phenolic compounds such asphenol, m-cresol and4-chlorophenol, was so complex that the biodegradationprocesses are very complicated with kinds of substrates interactions. Microbialconsortia with the members metabolism function integrated benefits theco-metabolism of the complex phenols in wastewaters. Thus, objects of this paperwere the screening of microbial consortia to degrade phenols effectively, theinteractions of phenols in the biodegradation progresses and the mechanisms of theinteractions revealed by environmental metabolomics.Firstly, six strains degrading phenols effectively were obtained from activesludge of coking plant, and characterized by physiological and16S rRNA genesequence analysis. The results showed that the strains were Pseudomonas sp. cbp1-1,Pseudomonas sp. cbp1-3, Sphingobacterium sp. cbp2, Stenotrophomonas sp. cbp3,Ochrobactrum sp. cbp4and Pseudomonas sp. df1. Pseudomonas sp. cbp1-3was theonly one that could degrade200mg/L phenol,100mg/L m-cresol and100mg/L4-chlorophenol within22h, whereas microbial consortia compositing ofPseudomonas sp. cbp1-3, Ochrobactrum sp. cbp4and Pseudomonas sp. df1coulddegrade the three phenols mixture more effectively than anyone of the individualstrains within16h.Secondly, the interactions of phenol, m-cresol and4-chlorophenol inbiodegradation progresses by Pseudomonas sp. cbp1-3were investigated. The resultsshowed that phenol and m-cresol had a reciprocal inhibition to each other, and they(only below300mg/L) both promoted the4-CP biotransformation. But4-CP of even60mg/L strongly inhibited the other phenols biodegradation in their mixtures withcomplete degradation times prolonged at least25%. Moreover, new kinetic modelswere proposed for cell growth on ternary substrates and fitted the experimental datavery well. Further, sensitivity analysis found (i=12,13and23) were the mostsensitive parameters and indicated that the interactions between the phenols play moresignificant role in the cell growth than their self-inhibitions.Finally, the mechanisms of the interactions between phenol and4-chlorphenolwere revealed by environmental metabolomics. Compared with succinate, phenol, 4-chlorophenol and phenols mixtures caused obvious variation in the metabolism ofcbp1-3. Amino acid metabolism was inhibited and protein degradation was increasedby phenolic compounds, tricarboxylic acid cycle and glycolysis were also restricted inthe phenols degradation, thus cell growth was slowed down with the low level ofenergy metabolism. The perturbation on cell membrane was indicated by theaccumulation of fatty acid induced by the phenols. Some amine compounds andsulphur-amino acid increased to resist the oxidative stress induced by the phenols. Itshould be noted that4-chlorophenol widely inhibited the transformation ofmetabolites containing benzene ring structure. Especially, compared with themetabolism of cell in the phenol biodgradation, accumulation level of catecholincreased to250%in the4-chlorophenol biodegradation, while when the phenol wasadded, it decreased to150%, which indicated that4-chlorphenol could inhibit thedegradation of catechol, the key metabolite in phenol metabolism, and phenol couldrelieve such inhibition and promote the4-chlorophenol transformation by the pathwayof hydroquinone and benzenetriol.