Biotechnological production of l(+)-lactic acid from wood hydrolyzate by batch fermentation of Enterococcus faecalis

Abstract

The inhibition of lactic acid fermentation by wood hydrolyzate was decreased (approx. 20%) by adaptation of Enterococcus faecalis RKY1 to wood hydrolyzate-based medium whereby lactic acid productivity and cell growth were enhanced by 0.5 g l⁻¹ h⁻¹ and 2.1 g l⁻¹, respectively. When the diluted or concentrated wood hydrolyzate (equivalent to 25–100 g glucose l⁻¹) was supplemented with 15 g yeast extract l⁻¹, 24–93 g lactic acid l⁻¹ was produced at a rate between 1.7 g l⁻¹ h⁻¹ and 3.2 g l⁻¹ h⁻¹.