Françoise Fayolle

Biodegradation of ethyl t-butyl ether (ETBE), methyl t-butyl ether (MTBE) and t-amyl methyl ether (TAME) by Gordonia terrae

Abstract. Gordonia terrae strain IFP 2001 was selected from activated sludge for its capacity to grow on ethyl t-butyl ether (ETBE) as sole carbon and energy source. ETBE was stoichiometrically degraded to t-butyl alcohol (TBA) and the activity was inducible. A constitutive strain, G. terrae IFP 2007, derived from strain IFP 2001, was also selected. Methyl t-butyl ether (MTBE) and t-amyl methyl ether (TAME) were not used as carbon and energy sources by the two strains, but cometabolic degradation of MTBE and TAME was demonstrated, to TBA and t-amyl alcohol (TAA) respectively, in the presence of a carbon source such as ethanol. No two-carbon compound was detected during growth on ETBE, but formate was produced during cometabolic degradation of MTBE or TAME. A monooxygenase was involved in the degradation of ethers, because no degradation of ETBE was observed under anaerobic conditions and the presence of a cytochrome P-450 was demonstrated in G. terrae IFP 2001 after induction by cultivation on ETBE.

Large-scale enzymatic hydrolysis of agricultural lignocellulosic biomass. Part 2: Conversion into acetone-butanol

Abstract Large-scale development of a process for conversion of lignocellulosic biomass into acetone-butanol involving steam-explosion pretreatment of the raw material cellulase production, enzymatic hydrolysis of pretreated material and acetone-butanol fermentation of hydrolysates has been carried out in the facilities for biomass conversion located at Soustons, France. Procedures and scale-up of the two steps of enzymatic hydrolysis and fermentation using corncobs the raw material, cellulase production, enzymatic Clostridium acetobutylicum strain capable of a good utilization of xylose and presenting a limited sensitivity to the fermentation inhibitors orginating from the steam-explosion pretreatment is described. Optimization of acetone-butanol fermentation involved, in particular, the definition of a suitable inoculum transfer chain for fermenting untreated hydrolysates. Batch enzymatic hydrolysis of pretreated corncobs at the scale of the 25 m 3 reactor is reported. A detailed description of acetone-butanol production from corncob hydrolysates in 50 m 3 fermenters is presented. Based on the mass balances and performances of the individual steps, economic aspects of the conversion of lignocellulosic biomass by hydrolysis and fermentation are discussed.

Effect of controlled substrate feeding on butyric acid production byClostridium tyrobutyricum

SummaryProduction of butyric acid from wheat flour hydrolysate was studied withClostridium tyrobutyricum. The mode of substrate supply was found a key parameter for fermentation performance as large improvements were obtained by feeding with a non-limiting supply of substrate. With this procedure, increases in product concentration and productivity but also in selectivity and yield for butyrate were obtained. Substrate feeding controlled by the rate of gas production was found preferable to constant rate feeding for reason of convenience and flexibility. In these conditions, a butyrate concentration of 62.8 gl−1 was obtained with a productivity of 1.25 gl−1 h−1, a selectivity of 91.5% and a yield of 0.45 g per g of glucose.

An example of production of natural esters: Synthesis of butyl butyrate from wheat flour

A biological method of butyl butyrate production from a natural source has been investigated. Butanol and butyric acid were produced by optimized batch and fed-batch fermentations on a wheat flour hydrolysate with selected strains of Clostridium. Butanol was recovered from the fermentation broth by distillation and butyric acid by extraction with solvent. Esterification was performed with a lipase in the solvent of extraction.