Effect of the Sugarcane Bagasse Deacetylation in the Pentoses Fermentation Process

Biomass alkaline deacetylation prior to acid pretreatment can be a promising alternative to reduce the toxicity of hemicellulosic hydrolysates and improve second-generation bioethanol production. In this paper, the effect of alkaline deacetylation of sugarcane bagasse on bioethanol production by Spathaspora passalidarum was evaluated. Sugarcane bagasse deacetylated hemicellulosic hydrolysate (DHH) was processed using the following sequence: (1) deacetylation (0.4%, w/v NaOH, 70 degrees C, 3 h) and (2) acid pretreatment (0.5% (v/v) of H2SO4, 140 degrees C, 15 min). Non-deacetylated, hemicellulosic hydrolysate (HH), was obtained applying only acid pretreatment (0.5% (v/v) of H2SO4, 140 degrees C, 15 min). Biomass deacetylation reduced the content of acetic acid and some phenolic compounds in the hydrolysate (DHH) compared to acid pretreatment (HH), which resulted in its low toxicity. Thus, the bioethanol production with DHH was of 16.92 g L-1, whereas only 1.3 g L-1 of bioethanol was obtained with HH fermentation. Deacetylation process provided a 13-fold increase in bioethanol production by S. passalidarum, showing that alkaline deacetylation followed by sulfuric acid pretreatment is a promising strategy to increase bioethanol production. This procedure provided a simple and practical alternative to the classic methods of detoxification of hemicellulosic hydrolysate from sugarcane bagasse.

Automated summary

Alkaline deacetylation of biomass before acid pretreatment can reduce toxicity of hemicellulosic hydrolysates and enhance bioethanol production. In this study, deacetylation of sugarcane bagasse prior to acid pretreatment significantly increased bioethanol production, demonstrating a promising strategy for improving bioethanol yield. This approach offers a simple and practical alternative for detoxification of hemicellulosic hydrolysates from sugarcane bagasse.