Research Journal of Biotechnology Vol. 13 (4) April (2018) Res. J. Biotech 11 Isolation and characterization of phenol degrading bacteria Stenotrophomonas sp. SKC_BP54 Kasbekar Santosh 1 , Pal Rajesh Ramavadh 3 and Shanthakumar S.P. 2 * 1. Microbiology Department, Dada Ramchand Bakhru Sindhu Mahavidyalaya, Nagpur, INDIA 2. Laboratory for Insect Sciences, Department of Zoology, St. Joseph's college, Langford road, Bengaluru, Karnataka, INDIA 3.Nagarjuna Fertilizers and Chemicals Limited, Hyderabad, Telangana, INDIA *spshanthakumar@gmail.com Abstract Bioremediation of phenol by microbial cultures is a widely accepted approach for mitigation of this pollutant from environment. Herein, four phenol- degrading bacterial species were isolated from the oil- effluent contaminated soil samples of Kalmeshwar area in Nagpur, Maharashtra, India. The cultures were evaluated for the feasibility of practical bioremediation of industrial wastewater laden with aromatics such as phenol. All the four isolates identified as Stenotrophomonas sp. (SKC_BP54), Pandoraea sp. (SKC_BP7), Pseudomonas geniculata (SKC_BI20) and Pseudomonas geniculata (SKC_BI20) showed complete phenol removal from media in 72 h; however, SKC_BP54 proved to be most efficient and thus was used for subsequent biodegradation studies. Shake flask experiments were carried out for several initial phenol concentrations of 500 mg/L, 1000 mg/L, 1500 mg/L and 2000 mg/L. SKC_BP54 showed most efficient phenol degradation kinetics, removing phenol with the rate of 15.15 mg/L/h for initial phenol concentration of 1000 mg/L. Furthermore, optimum pH and temperature for bioremediation activity of SKC_BP54 were found to be pH 7 and 30 0 C respectively. Owing to tolerance towards high phenol concentration, Stenotrophomonas sp. SKC_BP54 could prove to be a great future prospect for phenol bioremediation strategies. Keywords: Phenol bioremediation, Stenotrophomonas, Degradation kinetics. Introduction Phenol, polyhydroxy aromatic hydrocarbon and its derivatives (halogenated, nitro, alkyl etc.) are major harmful chemicals being dumped into the environment from various industries involving coke manufacturing plants, petrochemical plants, coal gasification, oil refining, pharmaceutical plants, steel plants, dye manufacturing industries, textile industries etc. 1 The contamination of soil and water with such toxic chemically synthesized aromatic persistent compounds presented a severe peril to environment owing to their great solubility and toxicity. Therefore, U.S. Environmental Protection Agency (USEPA) has enlisted phenol as prime pollutant with potential to cause aquatic micro-flora and fauna at concentration as low as 0.005 mg/L and is pernicious to fishes at concentration range of 5–25 ppm. The presence of phenol in water adversely affects seed germination in field crops 2 . Additionally, in case of human diagnostic health hazards like liver, heart, nervous system disorder and possible carcinogenesis are reported due to phenol intoxication via ingestion, contact or inhalation. Thus, a threshold limit of 20 mg in an average day has been prescribed for phenol exposure in case of human 3 . Below this limit phenol toxicity will not be predominant. As per the guidelines from World Health Organization (WHO), phenol concentration limit in drinking water has been recommended at 1 μg/L 4 . Hence, it is important to remediate the phenol and its substitutes from industrial sources before discharging into the water bodies for welfare of both human and wildlife. Several physiochemical techniques such as granular or biological activated carbon, ozonation, chlorination, H2O2/UV process, solvent extraction and reverse osmosis, anaerobic processes, the electro Fenton method and stripping are used for phenol removal from the wastewater. However, these methods are not practically feasible owing to high costs involved in the process and collateral generation of toxic secondary intermediates which can be equally hazardous. On the other hand, the microbe-mediated phenol bioremediation technology has been in trend for last three decades 5 . Bioremediation is an environmental friendly technology resulting into need of isolation and identification of new and robust microorganisms with phenol degradation potential. Numerous reports are available for microorganisms including bacteria, yeast and filamentous fungi that have acquired the catabolic potential to remediate phenol at varying concentration ranges. The wide varieties of microorganisms that can aerobically degrade phenol include Alcaligenes eutrophus, Arthrobacter, Bacillus stearothermophilus, Pseudomonas aeruginosa, Pseudomonas cepacia G4, Pseudomonas putida, Pseudomonas resinovorans and Ralstonia eutropha while Desulfobacterium phenolicum sp. can anaerobically degrade phenol 6-15 . Herein, isolation and characterization of efficient bacteria from contaminated soil of Steel plant campus, located at Kalmeshwar, Nagpur are reported. Enrichment of soil sample in nutrient limiting media in presence of chemical grade phenol was employed to