Draft Genome Sequence of a New Homofermentative, Lactic Acid-Producing Enterococcus faecalis Isolate, CBRD01

Bio-detoxification Bacteria Isolated from Dye-Polluted Soils Promote Lactic Acid Production from Ammonia Pretreated Corn Stover

Agro-stovers are the most abundant substrates for producing lactic acid, which has great potential application in the production of biodegradable and biocompatible polylactic acid polymers. However, chemical pretreatments on agro-stovers generate inhibitors that repress the subsequent lactic acid fermentation. In this study, three bacterial strains (Enterococcus faecalis B101, Acinetobacter calcoaceticus C1, and Pseudomonas aeruginosa CS) isolated from dye-polluted soils could utilize phenolic inhibitor mimics (vanillin, 4- hydroxybenzaldehyde, or syringaldehyde) from alkaline pretreated corn stovers as a sole carbon source. Lactic acid titer increased from 27.42 g/L (Bacillus coagulans LA204 alone) to 44.76 g/L (CS and LA204) using 50 g/L glucose with 1 g/L 4-hydroxybenzaldehyde added. Lactic acid production from 50 g/L ammonia pretreated corn stover was increased nearly twofold by inoculating phenolic degradation bacteria and lactic acid bacteria (C1& Lactobacillus pentosus FL0421). In the control (FL0421 alone), only 16.98 g/L of lactic acid was produced. The isolated and identified strains degraded the phenolic compounds and increased the lactic acid production from glucose and ammonia pretreated corn stover. These characteristics of the strains support industrial application with efficient in situ detoxification of phenolic compounds during lactic acid production from agro-stovers using simultaneous saccharification and fermentation (SSF).

Production of optically pure L(+)-lactic acid from waste plywood chips using an isolated thermotolerant Enterococcus faecalis SI at a pilot scale

Utilization of renewable and low-cost lignocellulosic wastes has received major focus in industrial lactic acid production. The use of high solid loadings in biomass pretreatment potentially offers advantages over low solid loadings including higher lactic acid concentration with decreased production and capital costs. In this study, an isolated Enterococcus faecalis SI with optimal temperature 42 °C was used to produce optically pure L-lactic acid (> 99%) from enzyme-saccharified hydrolysates of acid-impregnated steam explosion (AISE)-treated plywood chips. The L-lactic acid production increased by 10% at 5 L scale compared to the similar fermentation scheme reported by Wee et al. The fermentation with a high solid loading of 20% and 35% (w/v) AISE-pretreated plywood chips had been successfully scaled up to process development unit scale (100 L) and pilot scale (9 m³), respectively. This is the first report of pilot-scale lignocellulosic lactic acid fermentation by E. faecalis with high lactic acid titer (nearly 92 g L^-1) and yield (0.97 kg kg^-1). Therefore, large-scale L-lactic acid production by E. faecalis SI shows the potential application for industries.