Fed-batch strategies for biodetoxification in production of optically pure lactic acid from softwood hydrolysate using Pediococcus acidilactici

Abstract

Optically pure lactic acid (LA) is important for the development of specialized applications for poly-lactic acid (PLA). To pursue sustainable production, feedstocks such as lignocellulosic biomass need to be investigated. The present study focused on the production of L-LA from softwood hydrolysate with Pediococcus acidilactici TY112. One of the challenges when using this substrate is the presence of inhibitors, such as furfural and 5-hydroxymethylfurfural (HMF), formed during pretreatment. To investigate adaptation, fed-batch experiments on softwood hydrolysate and model media were conducted. Although LA production was still affected by the presence of other inhibitors in the hydrolysate, P. acidilactici TY112 was capable of converting HMF and furfural and partly detoxify both hydrolysate and synthetic media. The strain adapted to the inhibitors present, if fed at a low rate (30 mL·h−1 for model medium with inhibitors and 15 mL·h−1 for softwood hydrolysate, both with 30 g·L−1 glucose and 45 g·L−1 mannose). Regarding carbon source consumption, a feeding rate of 30 mL·h−1 limited the uptake of glucose, leading to improved mannose uptake, with LA yields higher than 0.86 g·g−1. This study shows the potential of P. acidilactici TY112 for the production of L-LA from softwood hydrolysate which is regarded as inhibitory.