Biodetoxification of Phenolic Inhibitors from Lignocellulose Pretreatment using Kurthia huakuii LAM0618T and Subsequent Lactic Acid Fermentation

Abstract

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. Kurthia huakuii LAM0618T, 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 K. huakuii LAM0618T 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 Bacillus coagulans LA204 at 50 °C through simultaneous saccharification and fermentation (SSF) from 8% (w/w) of NH3/H2O2-pretreated corn stover with or without K. huakuii LAM0618T-biodetoxification, indicating biodetoxification significantly increased lactic acid titer and yield. Importantly, using 15% (w/w) of the NH3/H2O2-pretreated K. huakuii LAM0618T-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 Bacillus coagulans 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.

Anaerobic Digestion of Wheat Straw Pretreated with Soaking in Water and Alkali Medium

“…Zhu et al [2010] showed that lignin degradation during the alkaline pretreatment of corn stover was in the range 9.1% to 46.2% (w/w) depending on NaOH loading that was changed from 1.0% to 7.5% w/w for solidstate. Many studies confirm that phenols may hinder the bacterial growth in the subsequent biological processes of biofuel production from the pretreated biomass [Kim, 2018;Xie et al, 2018]. The phenols concentration in the feedstock examined in this experiment was not very high (Table 2.)…”

Enhanced lactic acid production by Bacillus coagulans through simultaneous saccharification, biodetoxification, and fermentation

“…Glucose, xylose, LA, acetic acid, and formic acid were analyzed using an Agilent 1200 HPLC system (Agilent Technologies Co. Ltd, Palo Alto, CA, USA), equipped with an RID‐10A detector or an SPD‐20A detector, and a Bio‐Rad Aminex HPX‐87H (Hercules, CA, USA), column at the column temperature of 40 °C, as we reported previously . The concentrations of vanillin, syringaldehyde, and p ‐hydroxybenzaldehyde were measured using the HPLC method as we reported previously . The total content of phenolic compounds in the samples was determined by the Folin–Ciocalteu method, with gallic acid as the calibration standard.…”

Bacterial diversity in theclarkiecotype of the photosynthetic sacoglossan,Elysia crispata

“…These bacteria may play a role in nitrification, as hypothesized by Kellogg et al (2016) in corals. One strain of the genus Kurthia has been shown to transform phenolic compounds into acids that are less toxic (Xie et al, 2018).…”