Essential oil, also known as fragrant oil, is a fragrant oily substance extracted from flowers, roots, leaves or stems of perfume plants through the techniques such as distillation, extraction, and compression. The main components of some essential oil are propenyl benzenes. These compounds are usually used as starting mataials to synthesize fragrants in flavor and fragrance industry. Natural fragrants with high values could be obtained by biotransformation of these propenyl benzenes using microbes or enzymes. For example, eugenol and isoeugenol which are the main components of clove essential oil with typical propenyl benzenes structures are used as starting materials to produce vanillin in flavor and fragrance industry. Therefore, in this project, we selected these two compounds as model substances of propenyl benzenes. Strains that can metabolize above substances were isolated, so as to obtain valuable fragrant compounds. Meanwhile, the factors that affected biotransformation, metabolic pathways of, metabolic characters and isolation of vanillin from fermentation broth were studied.A bacterium, designated as HS8, was isolated from soil based on its ability to degrade isoeugenol. HS8 could convert isoeugenol to vanillin. Strain HS8 appeared as a strictly aerobic, Gram-positive rod with spore This strain exhibited positive reactions for catalase, nitrate reduction, starch hydrolysis, citrate utilization, and Voges-Proskauer test. Acid was produced from D-glucose, L-arabinose, D-xylose and D-mannitol. The strain has more than 99% homogeneity with Bacillus subtilis according to 16S rDNA gene sequencing. Based on these data, HS8 was identified as a Bacillus subtilisA preliminary investigation had been carried out to study the characteristics by which strain HS8 metabolize isoeugenol. Isoeugenol is toxic to cells, but the growth of HS8 was barely affected with the presence of 0.5% isoeugenol. The growth of HS8 was suppressed when isoeugenol surpasses 1.0%. The growth of HS8 was totally