Potential of butanol production from Thailand marine macroalgae using Clostridium beijerinckii ATCC 10132-based ABE fermentation

The economical bio-butanol-based fermentation process is mainly limited by the high price of first-generation biomass, which is an intensive cost for the pretreatment of second-generation biomass. As third-generation biomass, marine macroalgae could be potentially advantageous for conversion to clean and renewable bio-butanol through acetone-butanol-ethanol (ABE) fermentation. In this study, butanol production from three macroalgae species (Gracilaria tenuistipitata, Ulva intestinalis, and Rhizoclonium sp.) by Clostridium beijerinckii ATCC 10132 was assessed comparatively. The enriched C beijerinckii ATCC 10132 inoculum produced a high butanol concentration of 14.07 g L-1 using 60 g L-1 of glucose. Among the three marine seaweed species, G. tenuistipitata exhibited the highest potential for butanol production (1.38 g L-1 ). Under the 16 conditions designed using the Taguchi method for low-temperature hydrothermal pretreatment (HTP) of G. tenuistipitata, the maximum reducing sugar yield rate of 57.6% and ABE yield of 19.87% were achieved at a solid to liquid (S/L) ratio of 120, temperature of 110°C, and holding time of 10 min (Severity factor, R0 1.29). In addition, pretreated G. tenuistipitata could be converted to 3.1 g L-1 of butanol using low-HTP at an S/L ratio of 50 g L-1 , temperature of 80°C (R0 0.11), and holding time of 5 min.