Oral Presentation 5-03

S. Lamare and M. D. Legoy

Laboratoire de Génie Protéique et Cellulaire
Université de La Rochelle, Pôle Sciences et Technologie
Avenue Marillac, F-17042 La Rochelle, Cedex, France

Telephone: +33-5-4645-8277; Fax: +33-5-4645-8247; E-mail: slamare@univ-lr.fr

Solid/gas catalysis presents many advantages as compared with other systems (i.e., liquid, monophasic, or biphasic). Its strength stems from the potential for obtaining very high conversion yields compatible with a high productivity for a minimal plant scale and for minimizing downstream processes (when they exist), as a result of the following factors: mass transfers are more efficient at the solid/gas interface, enzymes and cofactors are more stable in systems with restricted water availability, problems of solubility of substrates and products do not exist, and the use of solvent is avoided. Moreover, because solid/gas catalysis is synonymous with the use of higher temperatures, microbial contamination of the bioreactor can be avoided. Finally, the scale-up operation for such a process would be facilitated by the use of a gaseous circulating phase.

Experiments performed with lipolytic enzymes for transesterifications, hydrolyses, and esterifications showed that modifications of the interactions between the catalyst and its microenvironment lead to changes in surface polarity and surface solvation, resulting in competition between the different molecules and modifications of "local concentrations" on the catalyst. These modifications have resulted in significant improvements in catalytic activity and stability.

Our basic research has led to the development of a new, cleaner continuous process. This biotechnological process can serve as an alternative solution for producing naturally labeled esters, minimizing the constraints encountered in natural extraction and offering more economical costs as compared with those for chemical processes. The application of solid/gas catalysis is discussed, and the concept of a pilot plant for the synthesis of esters, which represent an important class of aromatic compounds, is presented.