Bioconversion of corn straw by coupling ensiling and solid-state fermentation.

A two-stage process that combined solid-state fermentation (SSF) and ensiling was used for bioconversion of corn straw, in order to increase nutritional value and palatability for animal feed. SSF of corn straw increased the level of protein from 6.7% to 14.7% and decreased the cellulose by 38.0% and hemicellulose by 21.2%. Cellulase and xylanase were produced during SSF. After SSF, the fermented substrate was directly ensiled by inoculating with lactic acid bacteria (LAB). In situ produced enzymes and bacterial inoculation resulted in a rapid drop in pH, a high level of lactic acid production, partial degradation of cell wall components and generation of reducing sugars (RSs). Efficiency of ensiling at 25 degrees C, 30 degrees C, 35 degrees C, 40 degrees C was evaluated. Temperature influenced the effect of ensiling; the higher the temperature, the shorter the ensiling period. The combined fermentation upgraded the nutritional value, enhanced the efficiency of ensiling and reduced bioprocessing costs.