Microbial Degradation of Various Organic Pollutants Using Bacteria Isolated From Petroleum Sludge

Intensification of agriculture and manufacturing industries has resulted in increased release of a wide range of xenobiotic compounds to the environment. The extensive discharge of hazardous waste in industrial wastewater and the recalcitrant nature of some of these organic pollutants have fueled a strong interest in exploring efficient and environmentally friendly approaches for wastewater remediation. Bioremediation approaches can provide efficient, inexpensive and environmentally safe cleanup tools. In the present study, our main objective was to isolate novel bacterial strains from UAE petroleum sludge and to examine their abilities to degrade various aromatic pollutants, including azo dyes and emerging pollutants. We report here on the isolation and purification of novel bacterial strains from petroleum sludge that were capable of efficiently degrading various classes of aromatic dyes. Of these 12 isolates, extensive biochemical and optimization studies were carried out with the most promising strain, MA1. The optimum culture conditions of MA1 strain were found to be at pH 7, with 100 ppm dye concentration, and under aerobic condition. DNA sequencing of the 16S rRNA gene was carried out for the 12 bacterial strains and the data showed that the isolates belonged to two different bacterial species: Bacillus cereus and Pseudomonas guariconensis. Confirmation of the degradation of the aromatic compounds by the chosen bacterial strains was done using HPLC and LC-MS/MS analyses. This novel strain, MA1, was able to efficiently degrade aromatic dyes (e.g. Toluidine Blue, Ponceau BS, Reactive Black 5 and Congo Red) and more importantly various emerging pollutants of human concern such as sulfamethoxazole, prometryn, and fluometuron