Australian Journal of Basic and Applied Sciences, 5(8): 1035-1045, 2011 ISSN 1991-8178 Corresponding Author: Professor Dr Mohd Arif Syed, Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. E-mail:: marifsyed@gmail.com 1035 Isolation, Identification and Characterization of Elevated Phenol Degrading Acinetobacter sp. Strain AQ5NOL 1 1 Siti Aqlima Ahmad, 1 Mohd Arif Syed † , 1 Noorliza Mat Arif, 1 Mohd Yunus Abdul Shukor and 2 Nor Aripin Shamaan. 1 Department of Biochemistry, Faculty of Biotechnology and Molecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia; 2 Faculty of Medicine and Health Sciences, Universiti Sains Islam Malaysia, 13 th Floor, Menara B, Persiaran MPAJ, Jalan Pandan Utama, Pandan Indah, 55100 Kuala Lumpur, Malaysia. Abstract: The increasing phenol and phenolic wastes necessitates the screening of bacteria that are able to degrade phenol. 115 bacterial isolates from several industrial sites and farms in Malaysia were screened for phenol degrading activity in minimal salt media (MSM) containing 0.5 gL -1 phenol. Thirty seven bacterial isolates exhibited phenol degrading activity and of this total, 6 isolates showed high phenol activity after 8 days of incubation. The isolate with the highest phenol degrading activity was subsequently identified as Acinetobacter sp. Strain AQ5NOL 1 based on Biolog TM GN plates and partial 16S rDNA molecular phylogeny. The optimum conditions for achieving high phenol degradation were 0.04% (w/v) (NH 4 ) 2 SO 4 , 0.01% (w/v) NaCl, pH 7, and temperature of 30 o C. Acinetobacter sp. Strain AQ5NOL 1 was found to degrade phenol of up to 1500 mgL -1 concentrations under the optimized conditions. The isolation of Acinetobacter sp Strain AQ5NOL 1 provides an alternative for the bioremediation of phenol and phenolic wastes. Key words: Isolation; Characterization; Elevated phenol degrading activity; Acinetobacter sp. INTRODUCTION Phenol and phenolic wastes from industrial effluents is becoming a growing concern in Malaysia as it heads toward industrialization (Idris and Saed, 2002; Chan and Lim, 2006). In tandem with the increase in phenolic wastes generated from industries, the Department of Environment, Malaysia (2006) reported that the benchmark for phenol of 0.002 mgL -1 in raw drinking water has been exceeded in the municipal water supply, agricultural areas, landfills, golf courses, ex-mining and industrial areas. The unsafe levels of phenol may pose a threat to community health (Hooived et al., 1998). Phenol is resistant to most biological processes because it is toxic to bacteria even at low concentration (Yang and Lee, 2007; Lin et al., 2007). Numerous methods have been developed to treat phenols in wastewater including biodegradation (Adav et al., 2007; Wang et al., 2007), membrane separation (Kujawski et al., 2004), adsorption (Rengaraj et al., 2002; Roostaei and Tezel, 2004), oxidation (Idris and Saed, 2002) and extraction by liquid membrane (Lin et al., 2007). The physico- chemical methods have their own limitations viz. reaction inefficiency, high energy consumption, production of sludge containing iron, and insufficient capacity (Chen et al., 2007). However, biodegradation as a technology for decontaminating phenols is gaining attention due to its eco-friendly characteristics and cost-effectiveness. For biodegradation of phenol to be feasible, screening for microorganisms capable of degrading phenols needs to be done first. Although there are numerous reports on bacteria with low phenol degrading activity, those describing high phenol degrading activity are generally lacking (Al-Sayed et al., 2003). The first report of a bacteria able to degrade 300 mgL -1 phenol was described by Tibbles and Baecker (1989). This was followed by Adav et al., (2007) who reported that strain ATCC 11171 (DQ 831531) is able to degrade phenol at concentrations of up to 1000 mgL -1 while Wang et al., (2007) reported that Acinetobacter sp. strain RD12 (AY 673994) is able to degrade phenol at 1100 mgL -1 .