Lactic Acid Production By Bacillus Coagulans From Kurthia Huakuii-Detoxified Corn Stover

Lignocellulose is a rich biological resource in the world,but the fermentation efficiency of microorganisms using lignocellulose is severely affected by inhibitors in the hydrolysate.Phenolic compounds and weak acids are the by-products generated from alkali-pretreated lignocellulose which have a severe inhibitory effect on cellulase and microbial fermentation.In order to improve the efficiency of lactic acid fermentation by alkali-pretreated lignocellulose,detoxification of alkali-pretreated lignocellulose is required.Water washing of pretreated lignocellulose can effectively remove inhibitors,but it causes a lot of wastewater.This paper studied the bio-detoxification of phenolic compounds and weak acids by Kurthia huakuii LAM0618 T,and developed a process of lactic acid production from bio-detoxified lignocellulose by Bacillus coagulans LA204.The main results are as follows:(1)K.huakuiiLAM0618~T grew well in YPD medium with 0.5 g/L phenolic compounds and 2.0 g/L formic acid or acetic acid,and degraded 0.5 g/L of phenolic compounds within 36 h.When the concentration of phenolic compounds was higher than 1.0 g/L,the growth of K.huakuiiLAM0618~T was inhibited by hydroxybenzaldehyde,while K.huakuiiLAM0618~T showed the strongly tolerance of high concentrations(8.0 g/L)of formic acid and acetic acid.(2)K.huakuiiLAM0618~T could convert 0.2 g/L of syringaldehyde,vanillin and hydroxybenzaldehyde into less toxic phenolic acids,demonstrating the ability to degrade phenolic compounds.(3)The efficiency of lactic acid production from 80 g/L K.huakuiiLAM0618~T liquid detoxified and non-detoxified NH3-H2O2 pretreated corn stover was compared.The titer of lactic acid produced by detoxified corn stover reached 33.47 g/L.It was significantly higher than that of the non-detoxified group(17.91 g/L)(P<0.01).(4)80 g/L K.huakuiiLAM0618~T detoxified corn stover was used as the initial substrate,and adding the K.huakuiiLAM0618~T detoxified corn stover to 150 g/L,the final titer of lactic acid reached 84.49 g/L,the yield reached 0.56 g/g corn stover,and generally achieving zero discharge of wastewater.This paper provided an effective detoxification method for alkali-pretreated corn stover using K.huakuiiLAM0618~T.In the fed-batch simultaneous saccharification and fermentation,high titer of lactic acid was obtained by bio-detoxified corn stover.And the bio-detoxification method can replace water washing to remove phenolic inhibitors,and can be used for bioethanol and biochemical production by alkali-pretreated lignocellulosic.