Exploring biosynthetic pathways for aromatic ester production

Synthetic biology and metabolic engineering has aided the production of chemicals using renewable resources, thus offering a solution to our dependence on the dwindling petroleum resources. While a major portion of petroleum resources go towards production of fuels, a significant fraction also goes towards production of specialty chemicals. There has been a growing interest in recent years in commercializing bio-based production of such high value compounds. In this thesis the biosynthesis of aromatic esters has been explored, which have typical application as flavor and fragrance additive to food, drinks and cosmetics. Recent progress in pathway engineering has led to the construction of several aromatic alcohol producing pathways, the likes of which can be utilized to engineer aromatic ester biosynthesis by addition of a suitable enzyme from the acyltransferase class. Enzyme selection and screening done in this work has identified chloramphenicol O-acetyltransferase enzyme(CAT) as a potential candidate to complete the biosynthetic pathways for each of 2-phenethyl acetate, benzyl acetate, phenyl acetate and acetyl salicylate. In the end, E. coli strains capable of producing up to 60 mg/L 2-phenethyl acetate directly from glucose were successfully constructed by co-expressing CAT in a previously engineered 2-phenylethanol producing host.