BIOTECHNOLOGICAL STRATEGIES TOWARD AN AROMA KETONE

CECCOLI, ROMINA D.; BIANCHI, DARIO A.; RIAL, DANIELA V.

Congreso; Reunión conjunta SAIB-SAMIGE 2021 (on line) LVII SAIB Meeting - XVI SAMIGE Meeting; 2021

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular - Asociación Civil de Microbiología General

Biocatalytic synthesis is an attractive alternative for the production of flavor and fragrance chemicals. In recent years, this strategy has increasingly been investigated since it is environmentally friendly, presents high regio- and enantio-selectivity and takes place at mild reaction conditions. Flavor production by biotransformation involves chemical reactions catalyzed by microorganisms or enzyme systems and is usually carried out with growing cultures, resting cells, immobilized cells or purified enzymes. The ketone 4-phenyl-2-butanone has been associated to flower and sweet aroma and is considered to be the most abundant attractant compound in flowers. The aim of this work was to evaluate alternative approaches for the biotechnological production of 4-phenyl-2-butanone. One strategy consisted in the selective hydrogenation of the carbonyl activated double bond of 4-phenyl-3-buten-2-one in baker?s yeast biotransformations. Baker?s yeast is the most widely used microorganism to mediate the reduction of enones. We established the conditions for this biotransformation using resting cells and assessed the time course of the reaction. Products were obtained and identified by gas chromatography-mass spectrometry using pure compounds as standards. The relative abundance of each product was estimated over the time of biotransformation. As another strategy toward 4-phenyl-2-butanone, we evaluated the oxidation of 4-phenyl-2-butanol by a putative alcohol dehydrogenase. Alcohol dehydrogenases constitute a large family of enzymes responsible for the reversible oxidation of primary alcohols to aldehydes or secondary alcohols to ketones. In our lab, we cloned and recombinantly expressed a new bacterial gene with homology to previously known alcohol dehydrogenases. We tested the activity of this new enzyme in recombinant whole cell systems with 4-phenyl-2-butanol and 4-phenyl-2-butanone at different pH conditions over the time of biotransformation and compared its performance with native Escherichia coli cells. As a result, we propose two alternative biotechnological strategies to gain access to 4-phenyl-2-butanone by efficient and eco-friendly methods.