BIO-BUTANOL FERMENTATION USING CLOSTRIDIUM ACETOBUTYLICUM AND CLOSTRIDIUM TETANOMORPHUM IN MODIFIED BIOREACTOR FLASKS

摘要

An alternative new generation biofuel to bio-ethanol has attracted researchers to investigate variousrnapproaches for optimization of traditional ABE fermentation to enable bio-butanol to be produced cheaper at anrnindustrial scale. For instance, the use of different or modified Clostridium strains to enhance bio-butanol yields hasrnbeen extensively studied. In this study, single-culture fermentation was investigated usingdifferentinoculumrnconcentrations of Clostridium acetobutylicum andClostridiumtetanomorphum(3, 5, 10 % v/v) to ferment sweetrnsorghum juicewith a Brix index of 14°.Furthermore, co-culture fermentation were conducted using varying ratios ofrnthe two clostridium speciesin modified reactor flasks at pH 6-6.5, and incubated at 37℃ while shaking (150rpm) forrn96 hrs. Cell growth profileswere monitored using UV spectrophotometry at 600nm during both single and co-culturernfermentation. Meanwhile, bio-butanol, residual sugars and by-products were analysed by high-performance liquidrnchromatography (HPLC).The results demonstrated that butanol and organic acids can be produced from sweetrnsorghum juice using a single culture, whereas co-culture only produced acids with no organic solvents. The highestrnbutanol concentrationof6.49 g/L was obtained after96hrs using 10 % v/v C. acetobutylicumas a single culture. Thernhighest organic acid concentration (Lactic acid) of 2.7 g/L was produced when an inoculum ratio of 6.5: 6.5 %v/v C.rnacetobutylicum to C. tetanomorphum were used and fermented for 96 hrs. Sweet sorghum juicehas potential as arncheaper substrate in producing high bio-butanol yield as a product in the presence of C.acetobutylicum. Coculturescanrnalso be used in fermentation of interest to produce high yields of organic acids.