Bio degradation of phenol by halophilic Pseudomonas sp. Strain SL-1 and evaluation of its resistance of heavy metals

Abstract

Phenol is one typical pollutant in many kinds of industrial wastewater, and some of them frequently existed in saline condition and coexistence with heavy metals. These factors lead to more difficulties of phenol biodegradation. In this study, an efficient phenol-degrading halophilics train SL-1 was isolated from petroleum-contaminated soil and identified as Pseudomonas sp. Strain SL-1 was able to completely degrade up to 800 mg/L phenol less than 40 h but biodegradation was inhibited at higher phenol concentrations. The considerable pH condition for strain SL-1 was slightly acidic condition in a range between 5.0 and 7.0, and the optimal pH value was 7.0. Meanwhile, strain SL-1 was able to biodegrade phenol efficiently in high NaCl concentration up to 20%. Furthermore, strain SL-1 showed a good tolerance of heavy metals. It maintained high phenol removal efficiency in the presence of 10 mM of Zn(II), Cu(II), Mn(II) and Pb (II). In additional, functional genes encoding phenol hydroxylase and catechol 2,3-dioxygenase were present in strain SL-1 as determined. This indicated that phenol biodegraded by strain SL-1 via meta-cleavage pathway. The excellent biodegradation performance showed that strain SL-1 possesses a broad application prospect in phenol bioremediation under complex environmental conditions.