THE REACTION OF THE PRODUCTION OF SOLVENTS, ETHANOL (ALCOHOLIC FERMENTATION) OR ACETONE AND BUTANOL (ACETONOBUTYLIC FERMENTATION), CAN BE REPRESENTED IN GENERAL TERMS BY THE FOLLOWING:
SUBSTRATE (S) + MICROORGANISMS ----- MICROROGANISMS + SOLVANT (S) + CO-METABOLITES.

IF IT IS ACCEPTED THAT A MICROORGANISM STORED AT HIGH CELLULAR DENSITY HAS A POTENTIAL SPECIFIC PRODUCTIVITY FOR YEAST OF 2G/L OF ETHANOL PER G OF BIOMASS PER HOUR, PRODUCTIVITIES OF ABOUT 300G/LH CAN BE EXPECTED TO BE OBTAINED IF THE CELLULAR CONCENTRATION IS RAISED TO THE MAXIMUM VALUE IN THE REACTOR.

THE RESEARCH WILL THEREFORE FOCUS ON THE YEASTS THAT INHIBIT THE GROWTH AND PRODUCTION KINETICS AND CELLULAR ACTIVITY AND THE DEVELOPMENT OF PROCESSES TO PROVIDE HIGH CELLULAR DENSITY CROPS.

FOCUS OF RESEARCH.
ONCE THE IMPROTANCE OF THE EFFECT OF SUBSTRATES AND CONCENTRATIONS IN FINAL PRODUCTS HAS BEEN DEFINED BY MEANS OF KINETIC ANALYSIS OF THESE PROCESSES, THE PROJECT MUST MOVE IN SEVERAL DIRECTIONS:
- IDENTIFICATION AND ROLE OF THE CO-METABOLITES OF FERMENTATION, IN PARTICULAR FOR THE INHIBITION PHENOMENA, DEFINITION OF THEIR EFFECTS IN THE OVERALL FERMENTATION PROCESS FOR AN EXHAUSTIVE EVALUATION OF THE POTENTIAL OF ALCOHOLIC AND ACETO-BUTYLIC FERMENTATION.

- DETAILED KNOWLEDGE OF THE CO-METABOLITE INHIBITION PHENOMENA WHICH WILL MAKE IT POSSIBLE TO CONSIDER EITHER PHYSIOLOGICAL DISACTIVATION BY MEANS OF RESEARCH INTO DESENSITIZED LAYERS OR TECHNOLOGICAL DISACTIVATION BY MEANS OF RESEARCH INTO PHYSICAL MEANS OF ELIMINATION (ADSORPTION, EXTRACTION, DENATURATION).

- FEASIBILITY STUDY INTO PROCESSES COMBINING FERMENTATION AND THE CO-METABOLITE ELIMINATION TECHNIQUES DEFINED ABOVE.

- RESEARCH INTO CONTINUOUS FERMENTATION TECHNIQUES LEADING TO THE DEVELOPMENT OF DENSE CROPS WHILE MAINTAINING CELLULAR VIABILITY IN BIOREACTORS:

- RECYCLING OF CELLS BY MEANS OF MEMBRANE OR FLOCCULATION PROCESSES

- CELL RETENTION BY MEANS OF IMMOBILIZATION.

THE INTEGRATION OF PHYSIOLOGICAL DATA INTO THE DESIGN OF BIOREACTORS SHOULD MAKE IT POSSIBLE TO IMPROVE SIGNIFICANTLY THE PRODUCTIVITY OF FERMENTATION TO PRODUCE SOLVENTS WHILE MAINTAINING THE YIELDS AND IN PARTICULAR THE FINAL TITERS IN PRODUCTS OBTAINED FROM DISCONTINUOUS CROPS..

AN INCREASE IN PRODUCTIVITY BY VOLUME WILL MAKE IT POSSIBLE TO REDUCE THE SIZE OF THE INSTALLATIONS, THUS MAKING INDUSTRIAL CONTINUOUS FERMENTATION PROCESSES FOR THE PRODUCTION OF SOLVENTS ECONOMICALLY VIABLE.