Poster Presentation 2-23
Fermentation of Lignocellulosic
Biomass to L-(+) Lactic acid by a Novel Second Generation Biocatalyst
Milind Patel, Mark Ou, L.O. Ingram and K.T. Shanmugam*
Phone: 352-846-0965
Fax:
352-392-5922
Simultaneous saccharification
and fermentation (SSF) of biomass-derived sugars is a cost-effective process
for production of fuel ethanol and commodity chemicals. The fungal cellulases
required for SSF contributes significantly to the overall cost. The biocatalysts currently in use have growth
and fermentation optima far removed from the catalytic optima for fungal cellulases. To
minimize the amount of cellulases required for SSF,
we have isolated a Bacillus sp., strain 36D1,
with growth optimum (50oC, pH 5.0) similar to that of the fungal cellulase optimal activity (50oC, pH 5.0). This isolate fermented glucose and xylose, major sugars in biomass, and produced L-(+) lactate
as the fermentation product. In a crystalline
cellulose (Solka-Floc) SSF, all the available glucose
present in the cellulosic substrate was completely
fermented to L-(+) lactate at an optical purity of 95%. The highest rate of SSF to lactate was
observed at 55oC and pH 5.0 at a cellulase
concentration of 15FPU (Spezyme CE)/g glycan. Bacillus sp. strain 36D1
also co-fermented cellulose and the sugars (xylose,
glucose and arabinose) present in sugarcane bagasse acid-treated hemicellulose
hydrolysate to L-(+) lactic acid. The potential use of this biocatalyst for
simultaneous saccharification and co-fermentation
(SSCF) will be presented.