D-AMINO-ACID OXIDASE FROM TRIGONOPSIS-VARIABILIS - IMMOBILIZATION OF WHOLE CELLS IN NATURAL POLYMERIC GELS FOR GLUTARYL-7-AMINOCEPHALOSPORANIC ACID PRODUCTION

The enzymatic oxidation of cephalosporin C to glutaryl-7-aminocephalos poranic acid (glutaryl-7-ACA) was carried out utilizing permeabilized whole cells of the yeast Trigonopsis variabilis entrapped in Ca-algina te beads. The biomass, cultured in a rich medium containing nr-methion ine and harvested after 72 h of growth, exhibited high levels of D-ami no acid oxidase activity. Prior to use, the whole cells were permeabil ized with four freeze-thawing cycles and immobilized in polysaccharide matrices, such as Ca-alginate and x-carrageenan, and in an insolubili zed gelatin gel. The best results in terms of activity yield and stora ge stability were obtained with cells entrapped in Ca-alginate beads. These cells were utilized for glutaryl-7-ACA production in a continuou s stirred batch reactor (CSTR) and in a packed bed reactor working as a plug flow reactor (PFR), using 50 mM cephalosporin C as substrate. T he performances of the two systems were compared. The overall producti vities (calculated on a void volume basis) were 1.64 g and 255 mg of g lutaryl-7-ACA l(-1) h(-1) in the PFR and in the CSTR, respectively.