Microbial Biotransformation of Agriwaste into a High Value Natural Insecticide Nootkatone

Present investigation focuses on the production of Nootkatone, a high value sesquiterpenoid (3500 USD/Kg), obtained from agri-horticultural waste residues of fruit peels and essential oil from grapefruit (Citrus) species. The most expensive aromatic nootkatone was obtained in good yield (49%) by using Chlorella vulgaris followed by 44% yield by Mucor sp. from peel essential oil, while valencene as substrate gave excellent yield (89%) by C. vulgaris and by Mucor sp. (87%) by biotransformation from grapefruit. The other species of green algae Chlorella (C. fusuca, C. pyrenoidosa, C. vulgaris) and fungi (Mucor sp. and Aspergillus niger) were also used. The product (Nootkatone) is a natural insecticide that repels and kills ticks, mosquitos and other biting bugs for several hours. This is generally synthesized chemically but the process is tricky and quite inefficient. It takes several steps to synthesize with pure chemistry, and at every step there is some loss of starting material and thus process is not cost effective. The production of Nootkatone through microbial biotransformation is simple one-step process and more economic. The so called ‘aroma chemical’ can be effectively used commercially for pharmaceuticals, flavours, fragrances and as a safe insect repellent.