Coupled biodegradation of p-nitrophenol and p-aminophenol in bioelectrochemical system:Mechanism and microbial functional diversity

Biodegradation mechanisms and microbial functional diversity during coupled pnitrophenol(PNP) and p-aminophenol(PAP) degradation were studied in a bioelectrochemical system. PNP in the biocathode and PAP in the bioanode were almost completely removed within 28 hr and 68 hr respectively. The degradation followed the steps including hydrating hydroxyalkylation, dehydrogenating carbonylation, and hydrolating ring cleavage,etc. Metagemomic analysis based on the KEGG and egg NOG database annotations revealed the microbial composition and functional genes/enzymes related to phenol degradation in the system. The predominant bacteria genera were Lautropia, Pandoraea, Thiobacillus, Ignavibacterium, Truepera and Hyphomicrobium. The recognized biodegradation genes/enzymes related to pollutant degradation were as follows: pmo, hbd, & ppo for phenol degradation,nzba, amie, & badh for aromatic degradation, and CYP & p450 for xenobiotics degradation,etc. The co-occurrence of ARGs(antibiotic resistant genes), such as ade F, Mex J, Erm F, PDC-93 and Escherichiaolidf A, etc., were annotated in CARD database during the biodegradation process. The Proteobacteria & Actinobacteria phylum was the primary host of both the biodegradation genes & ARGs in this system. The microbial functional diversity ensured the effective biodegradation of the phenol pollutants in the bioelectrochemical system.