Biodetoxification of Phenolic Inhibitors from Lignocellulose Pretreatment using LAM0618 and Subsequent Lactic Acid Fermentation.

Phenolic inhibitors generated during alkaline pretreatment of lignocellulosic biomasses significantly hinder bacterial growth and subsequent biofuel and biochemical production. Water rinsing is an efficient method for removing these compounds. Nevertheless, this method often generates a great amount of wastewater, and leads to the loss of solid fiber particles and fermentable sugars. LAM0618, a recently identified microorganism, was herein shown to be able to efficiently transform phenolic compounds (syringaldehyde, hydroxybenzaldehyde, and vanillin) into less toxic acids. Taking advantage of these properties, a biodetoxification method was established by inoculating LAM0618 into the NH₃/H₂O₂-pretreated unwashed corn stover to degrade phenolic inhibitors and weak acids generated during the pretreatment. Subsequently, 33.47 and 17.91 g/L lactic acid was produced by LA204 at 50 °C through simultaneous saccharification and fermentation (SSF) from 8% (/) of NH₃/H₂O₂-pretreated corn stover with or without LAM0618-biodetoxification, indicating biodetoxification significantly increased lactic acid titer and yield. Importantly, using 15% (/) of the NH₃/H₂O₂-pretreated LAM0618-biodetoxified corn stover as a substrate through fed-batch simultaneous saccharification and fermentation, high titer and high yield of lactic acid (84.49 g/L and 0.56 g/g corn stover, respectively, with a productivity of 0.88 g/L/h) were produced by LA204. Therefore, this study reported the first study on biodetoxification of alkaline-pretreated lignocellulosic material, and this biodetoxification method could replace water rinsing for removal of phenolic inhibitors and applied in biofuel and biochemical production using the alkaline-pretreated lignocellulosic bioresources.