African Journal of Biotechnology Vol. 6 (23), pp. 2675-2681, 3 December 2007   

ISSN 1684–5315 © 2007 Academic Journals        

Full Length Research Paper

Isolation, biochemical and molecular characterization of 2-chlorophenol-degrading Bacillus isolates

Roda F. Al-Thani¹, Desouky A.M. Abd-El-Haleem^1,2* and Mona Al-Shammri¹

¹Biological Sciences Department, College of Arts and Sciences, Qatar University, Doha, Post Code 2713, Qatar.

²Environmental Biotechnology Department, Genetic Engineering and Biotechnology Institute, Mubarak City for Scientific Research and Technology Applications, New-Burgelarab City, Alexandria, Egypt.

*Corresponding author. E-mail: abdelhaleemm@yahoo.de. Tel: 009744852702.

Accepted 30 October, 2007

Pure cultures of 2-chlorophenol degrading bacteria were isolated from a natural enrichment that may be adapted to chlorophenols in the industrial zone at Umm-Saied city (Qatar). The bacteria were identified by 16S rDNA analysis, using PCR with universal primers. Comparative analysis of the 16S rDNA sequence (~ 550 bp) in the GenBank database revealed that these bacteria are related to the genus Bacillus. Molecular heterogeneity among 2-chlorophenol-degrading bacteria was investigated using REP-PCR chromosomal fingerprinting and correlated with antibiotic profile analysis. REP-PCR results strongly confirmed that the bacterial isolates from different Qatari soils produced different fingerprinting patterns. The distribution of phenol hydroxylase catabolic gene among examined isolates revealed that three isolates out of six yielded positive PCR products. Degradation of 2-chlorophenol was studied using theses cultures in liquid medium under aerobic conditions, at initial concentrations of 0.25 – 2.5 mM 2-chlorophenol. Undegraded 2-chlorophenol was quantified by high-performance liquid chromatography (HPLC). Degradation rates by isolates could be determined at concentrations up to 1.5 mM. However, higher concentrations of 2-chlorophenol (2.5 mM) were inhibitory to cell growth.

Key words: Bacillus, biodegradation, chlorophenol, Qatar.