Response surface methodology to optimize the conditions for Enterococcus faecium YA002 producing H2 from xylose

A bacterium was newly isolated from cow dung, and identified as Enterococcus faecium YA002 by 16S rRNA gene sequence analyzing. It showed high H-2 production performance in dark fermentation with xylose as substrate, the fermentative conditions including xylose concentration, ratio of nitrogen source to carbon source in mass (N/C ratio), temperature, and initial pH were optimized by response surface methodology (RSM) with a Box-Behnken design (BBD). After regression analyzing, it could be found that H-2 production was well fitted by a quadratic polynomial equation, and significantly affected by the four studied factors. The optimal conditions were xylose concentration of 22.69 g/L, N/C ratio of 0.127, temperature of 37.2 degrees C, and initial pH of 8.0, and the experimental H-2 production under the conditions was 2918.91 +/- 125.49 mL/L, which was 97.91% of the predicted H-2 production. The results indicated that Enterococcus faecium YA002 was an ideal inoculum for dark fermentative H-2 production from xylose, and the conditions for the H-2 production were successfully optimized by response surface methodology. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A newly isolated bacterium Enterococcus faecium YA002 from cow dung showed high H-2 production performance in dark fermentation with xylose as substrate. The fermentative conditions were optimized by response surface methodology, with the optimal conditions resulting in an experimental H-2 production of 2918.91 ± 125.49 mL/L, which was 97.91% of the predicted H-2 production.