Enzyme-displaying whole-cell yeast is becoming an alternative to immobilized enzyme. Here, a recombinant Pichia pastoris displaying Candida antarctica lipase B (CALB) was used to catalyze the synthesis of geranyl butyrate with geraniol and butanoic acid as substrates in n-heptane. Response surface methodology (RSM) with a four-variable five-level central composite design (CCD) was applied when biocatalyst concentration, geraniol concentration, butanoic acid/ geraniol molar ratio, and water activity were taken as influential factors to improve the production of geranyl butyrate. The results indicated that both substrates molar ratio and water activity affected significantly the geranyl butyrate yield (p < 0.05). Biocatalyst concentration 20.9 g/L, geraniol concentration 0.57 mol/L, butanoic acid/geraniol molar ratio 1.21:1, and water activity 0.53 were the optimum of the ester synthesis. Under the above conditions, the geraniol conversion rate was 98.5 % in 10 mL reaction after 9 h reaction, which was equivalent to 126 g/L geranyl butyrate. When the esterification reaction was scaled up in batch stirred reactors, 97.87 % of geraniol conversion rate in 200 mL as well as 97.56 % in 500 mL could be obtained.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.