PRODUCCIÓN DE ETANOL A PARTIR DE SUERO DE LECHE EN CULTIVO POR LOTE ALIMENTADO CON CICLOS REPETIDOS

Ethanol production from Kluyveromyces marxianus var. marxianus 8554 was evaluated using previously de-proteinated whey as a substrate, by means of fed-batch culture with repeated cycles. All the experiments were made by triplicate using two lactose concentrations, 6.0% and 10.0% w/v, at pH 5,0°C and 30°C, with agitation at 150rpm. A Bioflo 4000 bioreactor was used with working volume of 4,500 liters and automatic temperature and agitation speed controls. The reactor was fed at 0, 3,75l·h^sup -1^ using 4h cycles. The fresh and concentrated whey was characterized in terms of pH, phosphorus, ash, lactose through spectrophotometric phenolsulfuric acid method, nitrogen content by the Kjeldahl method, and protein multiplying the percent nitrogen by 6.38. Biomass in the culture medium was determined by dry weight loss. Ethanol production was determined by gas chromatography. Results showed that ethanol production in the fed-batch culture with repeated cycles gave better results in comparisson to those obtained with loading.