MICROBIAL-PRODUCTION OF 2,3-BUTANEDIOL FROM WATER HYACINTH

A scheme for microbial production of 2,3-butanediol from water hyacinth (WH), a nuisance weed, is presented. It consists in sun-drying WH followed by crushing, alkaline treatment at high temperature, enzymatic hydrolysis, and fermentation. A caustic soda concentration of 1% and steam pressure of 1 kg/cm2 for 1 h were optimal for delignification and yielded 35 g delignified water hyacinth (DLWH)/100 g crude water hyacinth. A slurry concentration of 5%, an enzyme concentration yielding filter-paper cellulase activity (FPCA) of 14 IU/g DLWH, a temperature of 50-degrees-C, a pH of 4.8, and an incubation period of 48 h were optimal for enzymatic hydrolysis yielding 19 g/litre reducing sugars. Prefermentation hydrolysis followed by combined hydrolysis and fermentation (PH-CHF) was most efficient and yielded 15 g 2,3-butanediol per 100 g DLWH. An HRT of 4 h corresponding to a productivity of 1.4 g/litre/h of 2,3-butanediol with anaerobic-fixed-film and upflow-anaerobic-sludge-blanket (UASB) reactor systems was achieved on WH hydrolysate in a continuous mode.