title: Production of l(+)-lactic acid from acid pretreated sugarcane bagasse usingBacillus coagulansDSM2314 in a simultaneous saccharification and fermentation strategy.
abstract: BACKGROUND
  Sugars derived from lignocellulose-rich sugarcane bagasse can be used as feedstock for production of l(+)-lactic acid, a precursor for renewable bioplastics. In our research, acid-pretreated bagasse was hydrolysed with the enzyme cocktail GC220 and fermented by the moderate thermophilic bacteriumBacillus coagulansDSM2314. Saccharification and fermentation were performed simultaneously (SSF), adding acid-pretreated bagasse either in one batch or in two stages. SSF was performed at low enzyme dosages of 10.5-15.8 FPU/g DW bagasse.
  
  
  RESULTS
  The first batch SSF resulted in an average productivity of 0.78 g/l/h, which is not sufficient to compete with lactic acid production processes using high-grade sugars. Addition of 1 g/l furfural to precultures can increaseB. coagulansresistance towards by-products present in pretreated lignocellulose. Using furfural-containing precultures, productivity increased to 0.92 g/l/h, with a total lactic acid production of 91.7 g in a 1-l reactor containing 20% W/W DW bagasse. To increase sugar concentrations, bagasse was solubilized with a liquid fraction, obtained directly after acid pretreatment. Solubilizing the bagasse fibres with water increased the average productivity to 1.14 g/l/h, with a total lactic acid production of 84.2 g in a 1-l reactor. Addition of bagasse in two stages reduced viscosity during SSF, resulting in an average productivity in the first 23 h of 2.54 g/l/h, similar to productivities obtained in fermentations using high-grade sugars. Due to fast accumulation of lactic acid, enzyme activity was repressed during two-stage SSF, resulting in a decrease in productivity and a slightly lower total lactic acid production of 75.6 g.
  
  
  CONCLUSIONS
  In this study, it is shown that an adequate production of lactic acid from lignocellulose was successfully accomplished by a two-stage SSF process, which combines acid-pretreated bagasse,B. coagulansprecultivated in the presence of furfural as microorganism, and GC220 as enzyme cocktail. The process may be further improved by enhancing enzyme hydrolysis activities at high lactic acid concentrations.
authors.affiliation: Bioprocess Engineering, Wageningen University and Research, PO Box 16, 6700 AA Wageningen, The Netherlands ; Food and Biobased Research, Wageningen University and Research, PO Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Edwin C
authors.initials: EC
authors.lastname: van der Pol
authors.affiliation: Bioprocess Engineering, Wageningen University and Research, PO Box 16, 6700 AA Wageningen, The Netherlands ; Food and Biobased Research, Wageningen University and Research, PO Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Eggink
authors.affiliation: Bioprocess Engineering, Wageningen University and Research, PO Box 16, 6700 AA Wageningen, The Netherlands.
authors.forename: Ruud A
authors.initials: RA
authors.lastname: Weusthuis
keywords: Bagasse; Enzymatic hydrolysis; Fermentation; Lactic acid; Lignocellulose; Simultaneous saccharification and fermentation (SSF)