ISOLATION AND STUDY OF LUBRICATING-OIL DEGRADING MICROORGANISMS FROM OIL-CONTAMINATE SOIL SITES

Abstract

The contamination of soil with used engine lubricants adversely affects both living organisms and the environment. One of the widely adopted approaches for treating such contaminated sites is bioremediation using microorganisms. This study aimed to isolate microorganisms capable of degrading lubricating oil from soil collected from three different automobile repair shops. The isolation process, using the spread plate method on Nutrient Agar, resulted in a total of eight microbial isolates. Based on nucleotide sequence analysis of the 16S rRNA and 18S rRNA genes, the isolates were classified into six genera: Achromobacter (1 isolate), Brucella (1 isolate), Candida (1 isolate), Kalmanozyma (1 isolate), Microbacterium (3 isolates), and Tsukamurella (1 isolate). Lipase enzyme production was assessed using Tween-80 agar, revealing that five out of the eight isolates (62.5%) exhibited lipase activity. Among them, Kalmanozyma sp. KS5-2 demonstrated the highest enzyme production, rated at +++. The oil degradation efficiency of the isolates was further evaluated using the weight loss method. Kalmanozyma sp. KS5-2 exhibited the highest degradation efficiency, achieving a 64% reduction of used engine lubricant within three days at an oil concentration of 1%. These findings highlight the potential application of Kalmanozyma sp. KS5-2 in bioremediation and provide a foundation for future research.