Screening and identification of extractive fermentation solvents using a database

The ethanol fermentation has been studied as a model system for end product inhibition and extractive fermentation. Examination has been done on the basis of theoretical considerations, as well as experimental evaluation. For the latter case, a database has been developed in order to screen more than 1,500 solvents for their suitability as extractants in the system solvent-ethanol-water. Based on this screening, 62 solvents have been tested with yeast cultures to determine experimentally such important parameters as biocompatibility, distribution coefficients and phase stability. Fifteen of these solvents have proven to be completely biocompatible, while 26 were completely toxic, the remaining solvents showing different degrees of inhibition. In this paper, the theoretical and experimental procedures involved in the systematic screening of extractive fermentation solvents will be outlined. Also, some heuristic criteria will be presented that allow for an evaluation of solvent biocompatibility a priori. On a etudie la fermentation de l'ethanol comme systeme modele pour l'inhibition par un produit final et pour la fermentation extractive. Cette etude des basee sur des considerations theoriques ainsi que sur une evaluation experimentale. Dans ce dernier cas, on a etabli une base de donnees pour l'examen de plus de 1500 solvants relativement a leur utilite comme agents d'extraction dans le systeme solvant-ethanol-eau. A partir des resultats de cette etude, on a fait l'essai de 62 solvants en presence de cultures de levures, afin de determiner experimentalement differents parametres importants, tels que la biocompatibilite, les coefficients de distribution et la stabilite des phases; 15 de ces solvants se sont reve1es compleement biocompatibles, 26 se sont averes completement toxiques et les autres ont montre differents degres d'inhibition. On expose, dans le present travail, les procedures theoriques et experimentales employees pour la comparaison systematique des solvants pour la fermentation extractive. On presente aussi quelques criteres heuristiques qui permettent d'evaluer α priori la biocompatibilite des solvants.