Augmentation in fragrant agarwood oil quality by fermentation with a microbial consortium of bacterium (Microbacterium oxydans) and fungus (Penicillium aethiopicum)

Abstract

Agarwood oil is considered to be one of the costliest essential oils, produced by hydro-distillation of agarwood chips from resin impregnated wood from Aquilaria spp. Prior to distillation, the traditional production process involves a prolonged (up to 90 days) soaking of the wood in water filled basins. This natural fermentation step exposes the wood to interactions with different types of microorganisms like in mixed culture fermentation. Reports have suggested a definite role of fermentation on the qualitative and quantitative properties of the distilled oil. However, these studies relied on single organism led fermentation. The present study explores the consortia approach as a method to enhance the aroma of the oil, simulating natural fermentation. Enzyme activity based screening and co-culture interaction studies were employed to develop three (3) fungal and seven (7) microbial (bacteria-fungi) two-member consortia from microorganisms isolated from traditional agarwood fermentation basins located in Assam, India. The effect of consortia on agarwood oil was validated by fermentation with agarwood chips. Among the fungal consortia, 20PW (Pupureocillium lilacinum) with PG120 (Penicillium aethiopicum) and among bacteria- fungi consortia NH7 (Microbacterium oxydans) with PG120 (Penicillium aethiopicum), showed promising results. GC–MS analysis revealed qualitative enhancement of oil by all consortia compared to the control for key aroma compounds such as Agarospirol, Guaiol, 10S, 11SHimachala-3(12), 4-diene and Aristol-1(10)-en-9-ol. This is the first report where microbial consortia were used for the fermentation of agarwood chips, which enhance the quality of agarwood essential oil.