Inhibitors tolerance analysis of Clostridium sp. strain LJ4 and its application for butanol production from corncob hydrolysate through electrochemical detoxification

Lignocellulose is a promising feedstock for butanol production owing to its abundance and renewability, however, most solventogenic clostridia could not directly convert these low-cost resources. Fermentable sugars could only be produced through pretreatment and hydrolysis processes, but furan and phenolic derivatives occurring in the lignocellulosic hydrolysate would inhibit cells’ growth and final butanol production capability. Compared to reported solventogenic Clostridia, the newly isolated Clostridium sp. strain LJ4 possessed high tolerance towards furan derivatives. Genes of sdr4, sdr1, akr, fmn and ad2 in strain LJ4 may play key roles in the bioconversion of furan derivatives based on the transcriptional levels’ analysis. As the phenolic derivatives containing in the undetoxified corncob hydrolysate were higher than the limited tolerance of strain LJ4, an electrochemical detoxification method was accordingly adopted to reduce the toxicity of phenolic derivatives without the loss of reducing sugars and generation of by-products. After 24 h detoxification of acid treated corncob hydrolysate, the phenolic compounds were decreased by nearly 40%, and 4.7 g/L of butanol was finally produced by strain LJ4 with 1.6-fold improvement than that from the un-detoxified corncob hydrolysate. Electrochemical technique could become a promising approach for biofuels or biochemicals production from undetoxified lignocellulosic hydrolysate owing to its high removal efficiency of phenolic derivatives without sugar loss.