Simultaneous saccharification and fermentation of steam-exploded XXXX stover at high glucan loading and high temperature.

@entity4336 @entity375 @entity1068 @entity9266
BACKGROUND: Simultaneous saccharification and fermentation (SSF) is a promising process for bioconversion of lignocellulosic biomass. High glucan loading for hydrolysis and fermentation is an efficient approach to reduce the capital costs for bio-based products production. The SSF of steam-exploded @entity4336 stover (SECS) for @entity1068 production at high glucan loading and high temperature was investigated in this study. RESULTS: Glucan conversion of @entity4336 stover biomass pretreated by steam explosion was maintained at approximately 71 to 79% at an enzyme loading of 30 filter paper units (FPU)/g glucan, and 74 to 82% at an enzyme loading of 60 FPU/g glucan, with glucan loading varying from 3 to 12%. Glucan conversion decreased obviously with glucan loading beyond 15%. The results indicated that the mixture was most efficient in enzymatic hydrolysis of SECS at 3 to 12% glucan loading. The optimal SSF conditions of SECS using a novel @entity375 were inoculation optical density (OD)600   =   4.0, initial pH  4.8, 50% nutrients added, 36  hours pre-hydrolysis time, 39  C, and 12% glucan loading (20% solid loading). With the addition of 2% @entity9266 , glucan conversion, @entity1068 yield, final @entity1068 concentration reached 78.6%, 77.2%, and 59.8  g/L, respectively, under the optimal conditions. The results suggested that the solid and degradation products' inhibitory effect on the hydrolysis and fermentation of SECS were also not obvious at high glucan loading. Additionally, glucan conversion and final @entity1068 concentration in SSF of SECS increased by 13.6% and 18.7%, respectively, compared with separate hydrolysis and fermentation (SHF). CONCLUSIONS: Our research suggested that high glucan loading (6 to 12% glucan loading) and high temperature (39  C) significantly improved the SSF performance of SECS using a thermal- and @entity1068 -tolerant strain of @entity375 due to the removal of degradation products, sugar feedback, and solid's inhibitory effects. Furthermore, the surfactant addition obviously increased @entity1068 yield in SSF process of SECS.
