Biodegradation of phenol by a native mixed bacterial culture isolated from crude oil contaminated site

Abstract

An efficient phenol degrading mixed bacterial culture was isolated from sludge sample collected from one of the refinery located in Assam, India. The mixed culture was found to consist of three bacterial strains. These were identified as Stenotrophomonas acidaminiphila, Brevibacterium sp. and Brucella sp. Batch phenol biodegradation experiments were carried out for a wide range of initial phenol concentrations after pH and temperature optimization. It was found that the mixed culture was able to degrade a maximum phenol concentration up to 1000 mg L−1 within 96 h while the maximum specific growth rate (μmax) was observed at 100 mg L−1. The pH and temperature required for optimal phenol degradation was 6.5 and 37 °C respectively. The mixed culture degrades phenol via ortho-cleavage pathway by formation of an intermediate (cis, cis-muconate) which was detected spectrophotometrically at 260 nm. The experimental data were validated by fitting the growth and substrate utilization curves with their corresponding simulated dynamic profiles obtained by solving Haldane's equation via MATLAB R2015a with μmax = 0.155 h−1 and KI = 400 mg L−1.