The essential oil of Citronella is commonly extracted via typical steam distillation of citronella plan parts. However, the oil yield is generally low (0.22% - 1.0%), causing burden to many entrepreneurs to meet the strong demand. Therefore, the study was conducted to improve the yield of citronella oil recovery by introducing an optimised enzymatic assisted pre-treatment using crude microbial enzymes isolated from the soil surrounding the citronella roots. Firstly, the lignocellulosic components of dried citronella roots were investigated to evaluate the most abundance component for selection of enzymes useful for pre-treatment. The composition analysis has identified cellulose as the major lignocellulosic component (38.21%±1.65), followed by hemicellulose (30.49%±0.93), lignin (21.12%±1.86) and extractives (4.97%±0.22). 31 out of 52 isolated strains have been identified as positive cellulase producer. Based on the calculated cellulolytic indexes, 4 strains i.e; UniMAPF7, UniMAPF16, UniMAPF24, and UniMAPF27 were selected for application in the laboratory scale pre-treatment process. Results from the growth curve analysis and enzyme activity study suggested that the optimal time for enzyme harvesting occurred at day 5 for UniMAPF7, day 4 for UniMAPF24 and day 3 for UniMAPF16 and UniMAPF27. Laboratory scale oil extraction of pre-treated citronella root with crude enzymes of UniMAPF7 and UniMAPF24 yielded in a significant 2.5-fold and 1.7-fold increased in citronella oil recovery, respectively, when compared to the untreated citronella root as control.
