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New contributions for industrial n-butanol fermentation: An optimized Clostridium strain and the use of xylooligosaccharides as a fermentation additive

Grassi, M.C.B., Carazzolle, M.F., Nakagawa, B.T., Ferrari, A., Nagamatsu, S., Santos, C.R., Murakami, M.T., Pirolla, R.A.S., Pereira, G.A.G.
Biomass and bioenergy 2018 v.119 pp. 304-313
Clostridium saccharoperbutylacetonicum, acetone, butanol, culture media, ethanol, fermentation, industry, molasses, raw materials, xylooligosaccharides
n-Butanol is a chemical widely used in industry, with an approximate annual output of 4 million tons and a market valued at USD 8.6 billion. It was first produced by ABE fermentation (acetone - n-butanol - ethanol) at the beginning of the twentieth century using molasses as a substrate, an expensive raw material that made the process economically unfeasible. In this work, we developed a second-generation fermentation process using cellulosic sugar as the substrate. A strain of Clostridium saccharoperbutylacetonicum has been evolved to n-butanol resistance, and we have found that the addition of xylooligosaccharides to the culture medium leads to a significant increase in the n-butanol yield and productivity. As a result, an n-butanol titer of 12.5 g/L and a productivity of 0.43 g/L.h were obtained, a respective gain of 17% and 58% relative to the initial process. These advances indicate that second-generation technologies can make viable the production of renewable n-butanol.