After several rounds of milling process for sugars extraction from sugarcane, certain amounts of water-soluble carbohydrates (WSC) still remain in sugarcane bagasse. It is a bottleneck to utilize WSC in sugarcane bagasse biorefinery, since these sugars are easily degraded into inhibitors during pretreatment. Herein, a simple pre-fermentation step before pretreatment was conducted, and 98 % of WSC in bagasse was fermented into d-lactic acid. The obtained d-lactic acid was stably preserved in bagasse and 5-hydroxymethylfurfural (HMF) generation was sharply reduced from 46.0 mg/g to 6.2 mg/g of dry bagasse, after dilute acid pretreatment. Consequently, a higher d-lactic acid titer (57.0 g/L vs 33.2 g/L) was achieved from the whole slurry of the undetoxified and pretreated sugarcane bagasse by one-pot simultaneous saccharification and co-fermentation (SSCF), with the overall yield of 0.58 g/g dry bagasse. This study gave an efficient strategy for enhancing lactic acid production using the lignocellulosic waste from sugar industry.
Keywords: 5-Hydroxymethylfurfural; One-pot fermentation; Sugarcane bagasse; Water-soluble carbohydrates; d-lactic acid.
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