Sains Malaysiana 40(11)(2011): 1231–1235

Detection of Toluene Degradation in Bacteria Isolated

from Oil Contaminated Soils

(Pengesanan Pencuraian Toluena oleh Bakteria yang dipencilkan dari Tanah yang dicemari Minyak)

Ainon Hamzah, Arezoo Tavakoli & Amir Rabu*

Molecular Biology Laboratory, School of Biosciences and Biotechnology

Faculty Science and Technology, Universiti Kebangsaan Malaysia 43600 UKM Bangi, Selangor D.E., Malaysia

Received: 18 June 2010 / Accepted: 15 August 2010

ABSTRACT

Toluene (C7H8) a hydrocarbon in crude oil, is a common contaminant in soil and groundwater. In this study, the ability to degrade toluene was investigated from twelve bacteria isolates which were isolated from soil contaminated with oil. Out of 12 bacterial isolates tested, most of Pseudomonas sp. showed the capability to grow in 1 mM of toluene compared with other isolates on the third day of incubation. Based on enzyme assays towards toluene monooxygenase, Pseudomonas aeruginosa UKMP-14T and Bacillus cereus UKMP-6G were shown to have the highest ability to degrade toluene. The toluene monoxygenase activity was analysed by using two calorimetric methods, Horseradish peroxidase (HRP) and indole-indigo. Both of the methods measured the production of catechol by the enzymatic reaction of toluene monooxygenase. In the HRP assay, the highest enzyme activity was 0.274 U/mL, exhibited by Pseudomonas aeruginosa UKMP-14T. However, for indole-indigo assay, Bacillus cereus UKMP-6G produced the highest enzyme activity of 0.291 U/ml. Results from both experiments showed that Pseudomonas aeruginosa UKMP-14T and Bacillus cereus UKMP-6G were able to degrade toluene.

Keywords: Degradation; horseradish peroxidase indigo (HRP); indole; toluene

ABSTRAK

Toluena (C7H8) hidrokarbon dalam minyak mentah adalah bahan pencemar yang sering terdapat dalam tanah dan air bawah tanah. Dalam kajian ini, kebolehan untuk mencuraikan toluena oleh 12 pencilan bakteria yang dipencilkan daripada tanah tercemar minyak dikaji. Daripada 12 pencilan bakteria yang diuji, kebanyakan Pseudomonas sp. menunjukkan keupayaan untuk hidup di dalam 1 mM toluena berbanding dengan pencilan lain pada hari ketiga pengeraman. Berdasarkan pengasaian enzim toluena monooksigenase, Pseudomonas aeruginosa UKMP-14T dan Bacillus cereus UKMP-6G menunjukkan keupayaan tertinggi untuk mencuraikan toluena. Aktiviti toluena monooksigenase diasai menggunakan dua kaedah kalorimetri, iaitu peroksida horseradish (HRP) dan indole–indigo. Kedua-dua kaedah ini mengukur pembentukan katekol oleh tindak balas enzim toluena monooksigenase. Melalui asai HRP, aktiviti enzim yang tertinggi ialah 0.274 U/ml, yang dihasilkan oleh Pseudomonas aeruginosa UKMP-14T. Manakala untuk asai indole-indigo, Bacillus cereus UKMP-6G menghasilkan aktiviti enzim yang tertinggi iaitu 0.291 U/mL. Hasil kedua-dua eksperimen ini menunjukkan Pseudomonas aeruginosa UKMP-14T dan Bacillus cereus UKMP-6G berupaya untuk mencuraikan toluena.

Kata kunci: Indigo; indol; pencuraian; peroksida Horseradish (HRP); toluene

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*Corresponding author; email: amirrabu@gmail.com