Journal of Environmental Biology

Growth kinetics of a diesel-degrading bacterial strain from

petroleum-contaminated soil

F.A. Dahalan¹, I. Yunus¹, W.L.W. Johari^2,3, M.Y. Shukor¹*, M.I.E. Halmi¹, N.A. Shamaan⁴? and M.A. Syed¹

¹Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, University Putra,

Malaysia-43400 UPM Serdang, Selangor, Malaysia

²Department of Environmental Science, Faculty of Environmental Studies, Universiti Putra,

Malaysia-43400 UPM Serdang, Selangor, Malaysia

³Centre of Excellence for Environmental Forensics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

⁴Faculty of Medicine and Health Sciences, Islamic Science University of Malaysia, Pandan Indah, 55100 Kuala Lumpur, Malaysia

*Corresponding Author E-mail: yunus@biotech.upm.edu.my

Publication Data

Paper received:

04 March 2013

Revised received:

07 May 2013

Accepted:

01 June 2013

Abstract

A diesel-degrading bacterium was isolated from a diesel-contaminated site in Selangor, Malaysia. The isolate was tentatively identified as Acinetobacter sp. strain DRY12 based on partial 16S rDNA molecular phylogeny and Biolog? GN microplate panels and Microlog^? database. Optimum growth occurred from 3 to 5% diesel and the strain was able to tolerate as high as 8% diesel. The optimal pH that supported growth of the bacterium was between pH 7.5 to 8.0. The isolate exhibited optimal growth in between 30 and 35^?C. The best nitrogen source was potassium nitrate (between 0.6 and 0.9% (w/v)) followed by ammonium chloride, sodium nitrite and ammonium sulphate in descending order. An almost complete removal of diesel components was seen from the reduction in hydrocarbon peaks observed using Solid Phase Microextraction Gas Chromatography analysis after 10 days of incubation. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibiting growth with a correlation coefficient value of 0.97. The maximum growth rate- ?max was 0.039 hr^-1 while the saturation constant or half velocity constant Ks and inhibition constant Ki, were 0.387% and 4.46%, respectively. MATH assays showed that 75% of the bacterium was found in the hexadecane phase indicating that the bacterium was hydrophobic. The characteristics of this bacterium make it useful for bioremediation works in the Tropics.

 Key words

Isolation, Characterization, Diesel-degrading, Acinetobacter sp., Haldane

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