Biodegradation of Phenol by Bacteria Strain Acinetobacter Calcoaceticus PA Isolated from Phenolic Wastewater

A phenol-degrading bacterium strain PA was successfully isolated from the effluent of petrochemical wastewater. Based on its morphological, physiological and biochemical characteristics, the strain PA was characterized as a Gram-negative, strictly aerobic, nonmotile and short rod-shaped bacterium that utilizes phenol as a sole carbon and energy source. 16S rDNA sequence analysis revealed that this strain is affiliated to Acinetobacter calcoaceticus in the group of Gammaproteobacteria. The strain was efficient in removing 91.6% of the initial 800 mg∙L −1 phenol within 48 h, and had a tolerance of phenol concentration as high as 1700 mg∙L −1 . These results indicated that A. calcoaceticus possesses a promising potential in treating phenolic wastewater.

1. Introduction

The massive production and application of phenol in industrial activities make it a major environmental pollutant in most wastewater various facilities, such as oil refineries, coking plants, pharmaceuticals and plastic industries [1,2]. Many aquatic organisms, including microorganisms, plants and fishes, pose a risk of mutagenic, teratogenic and carcinogenic effects in the environments that contain phenol pollutants. Thus, phenol has been classified as a highly hazardous chemical [3], and has been included in the list of priority pollutants by the U.S. Environmental Protection Agency [4]. Finding an efficient method to remove phenol effectively has attracted increasing concern for the environmental remediation and the health welfare of human beings.

Physico-chemical methods, such as ultra violet, ozonation, hydrogen peroxide, Fenton’s reagent, or a combination of these methods, have been employed to eliminate phenol in industrial wastewater [5,6]. These methods were effective in removing phenol but were complex and costly. Hence, the development of improved technologies capable of degrading phenol in the environments is necessary. Alternatively, the biodegradation of phenols is an environmentally friendly and cost-effective technology currently preferred to reduce phenol compounds [7].

Based on the theory that a few microorganisms can utilize phenol as the sole source of carbon and energy [8,9], numerous bacterial species have been isolated and characterized as phenol-degrading microorganisms [10,11]. These bacterial species include Pseudomonas putida [12], Rhodococcus erythropolis [13], Bacillus subtilis [14], Bacillus brevis [11], Serratia marcescens [15], Arthrobacter citreus [16], Alcaligenes faecalis [17], Sphingomonas [18], and Acinetobacter [19,20,21]. Native microbial species have been reported to be more adaptive and capable of out-competing non-indigenous microorganisms in the remediation of special polluted environments [22]. Therefore, identifying new phenol-degrading bacteria is necessary for the bioremediation of the phenol-contaminated environments in various regions.

In the current study, a bacterial strain capable of degrading phenol was isolated from the petrochemical wastewater in South China. The strain PA was affiliated to Acinetobacter calcoaceticus in the group of Gammaproteobacteria. The degradation efficiencies of phenol for the strain were then examined. In addition, the growth limitation of the strain in elevated phenol concentrations was evaluated.