Production of flavour ketones in aqueous-organic two-phase systems by using free and microencapsulated fungal spores as biocatalysts

The formation of 2-alkanones by free and microencapsulated P. roquefortii s pores in an aqueous-organic two-phase system was investigated by using subs trates supplied as a solution in decane. It was shown that the spores remai ned catalytically active after entrapment within permeable polyamide microc apsules and readily catalyzed the formation of 2-pentanone, 2-heptanone, an d 2-undecanone from short-chain alkyl esters of hexanoic, octanoic, and lau ric acid, respectively, with the rate of reaction being markedly dependent on the type and concentration of the ester substrate used. in general, the optimal concentration of the esters in decane was found to be much higher t han that of the respective fatty acid substrates and, in the case of alkyl dodecanoates, the biotransformation could be carried out efficiently even i n the absence of added solvent Further analysis revealed a significant diff erence in the reaction rates observed with free and microencapsulated spore s at 0.5 but not at 3.0 M methyl dodecanoate, suggesting that at high subst rate concentrations the biotransformation was no longer limited by mass tra nsfer. (C) 2000 Elsevier Science Inc. All rights reserved.