Lactic acid production by Carnobacterium sp. isolated from a maritime Antarctic lake using eucalyptus enzymatic hydrolysate

Biotechnol Rep (Amst). 2021 Jun 7:31:e00643. doi: 10.1016/j.btre.2021.e00643. eCollection 2021 Sep.

Abstract

Carnobacterium sp., a lactic acid bacterium isolated from a maritime Antarctic lake, was evaluated for lactic acid production from a lignocellulosic hydrolysate. Eucalyptus sawdust, a residue from pulp and paper industries, was subjected to alkaline pretreatment to enhance its enzymatic hydrolysis. Fermentations were performed without and with pH control using eucalyptus enzymatic hydrolysate containing a mixture of glucose and xylose sugars. The sugars were successfully converted into lactic acid in 24 h, resulting in 7.6 g/L of lactic acid and a product yield of 0.50 g/g for pH controlled at 6.5. Fed-batch fermentation performed at a controlled pH of 6.5 improved both the lactic acid production (30 g/L) and the biomass growth (4.2 g/L). l-lactic acid optical purity higher than 95 % was obtained. These results demonstrated the potential usage of Carnobacterium sp in l-lactic acid production from eucalyptus.

Keywords: Carnobacterium; Eucalyptus; Fermentation; Lactic acid; Lignocellulose.