Whole sugar 2,3-butanediol fermentation for oil palm empty fruit bunches biorefinery by a newly isolated Klebsiella pneumoniae PM2

Effective utilization of cellulose and hemicelluloses is essential to sustainable bioconversion of lignocellulose. A newly isolated xylose-utilizing strain, Klebsiella pneumoniae PM2, was introduced to convert the biomass whole sugars into high value 2,3-butanediol (2,3-BDO) in a biorefinery process. The fermentation conditions were optimized (30 degrees C, pH 7, and 150 rpm agitation) using glucose for maximum 2,3-BDO production in batch systems. A sulfite pretreated oil palm empty fruit bunches (EFB) whole slurry (substrate hydrolysate 119.5 g/L total glucose mixed with pretreatment spent liquor 80 g/L xylose) was fed to strain PM2 for fermentation. The optimized biorefinery process resulted in 75.03 +/- 3.17 g/L of 2,3-BDO with 0.78 +/- 0.33 g/L/h productivity and 0.43 g/g yield (87% of theoretical value) via a modified staged separate hydrolysis and fermentation process. This result is equivalent to approximately 135 kg 2,3-BDO and 14.5 kg acetoin precursors from 1 ton of EFB biomass without any wastage of both C6 and C5 sugars.

Automated summary

Efficient conversion of cellulose and hemicelluloses into high value 2,3-butanediol is crucial for sustainable bioconversion of lignocellulose. By optimizing fermentation conditions and using pretreated waste as substrate, it is possible to achieve high productivity of 2,3-BDO from biomass without wasting any sugars.