Isolation and Characterization of a Diesel-degrading Bacterium From Waters Near the Langkawi UNESCO Kilim Karst Geoforest Park

Abstract

This study explored the biodegradation potential of bacterial isolates from various locations in Malaysia, focusing on their ability to utilize diesel as a carbon source. Among the ten isolates tested, isolate 4, identified as Pseudomonas sp. strain UPM-Langkawi 3 based on morphological, cultural, and biochemical properties, exhibited significant growth on 2.5% diesel, indicating rapid activation of diesel assimilation mechanisms. Using the ABIS online software analysis, the strain was provisionally identified as Pseudomonas sp. UPM-Langkawi 3. Experimental results demonstrated that the optimal conditions for the growth of strain UPM-Langkawi 3 were between 6 and 8 % (v/v) diesel concentration, a temperature of between 28 and 35 °C, and a pH range of between 7.5 to 8.5. The strain showed inhibited growth at higher diesel concentrations and temperatures above 40 °C, as well as at a lower pH of 5.7. Among several inorganic nitrogen sources tested, 0.9% w/v ammonium sulphate was found to be the most effective, corroborating previous research. The study underscores the efficacy of Pseudomonas sp. strain UPM-Langkawi 3 in degrading diesel, suggesting its potential use in bioremediation of diesel-contaminated environments. Further research should employ molecular identification techniques, such as 16srRNA gene sequencing, to confirm the species identity and optimize biodegradation conditions. This work establishes a foundation for utilizing indigenous bacterial strains in environmental management strategies, particularly for areas impacted by hydrocarbon pollutants.