Characterization of 4-nonylphenol-degrading bacterial consortium obtained from a textile wastewater pretreatment plant

4-nonylphenol (4-NP) isomers are toxic and recalcitrant compounds often resulting, together with short chain NPnEO, from ethoxylated nonylphenol (NPnEO) biodegradation in conventional activated sludge plants. In this work, a microbial consortium, defined as Consortium A, capable of removing 100 mg/L of 4-NP with no accumulation of metabolites with aromatic moiety was isolated from textile wastewaters after enrichment with 4-NP. The consortium showed remarkable degradation activities towards several short chain NPnEO congeners. Culture dependent techniques were used to isolate from the consortium twenty-six strains assigned to seven different ARDRA groups. Two- and three-member co-cultures were prepared with the strains showing highest 4-NP degrading capabilities, but neither the single strains nor the co-cultures were as efficient in 4-NP degradation as Consortium A. FISH was used to characterize the microbial composition of Consortium A: it evidenced a strong occurrence of Proteobacteria and, in particular, of Gammaproteobacteria along with a relevant stability of the culture. Therefore, the isolated consortium has the potential of being used in the development of a biotechnological process for the tertiary treatment of effluents of activated sludge plants fed with NPnEO contaminated wastewaters.