Saccharina latissima, candy-factory waste, and digestate from full-scale biogas plant as alternative carbohydrate and nutrient sources for lactic acid production

TL;DR

This study demonstrates that low-cost industrial residues like seaweed hydrolysate, candy-factory waste, and digestate can be effectively used as substrates for microbial lactic acid production, offering a sustainable alternative to petroleum-based materials.

Contribution

It introduces a novel use of industrial residues as substrates for lactic acid fermentation, including a scaled-up co-fermentation process achieving high lactic acid yields.

Findings

Lactic acid bacteria successfully utilized sugars from seaweed hydrolysate and candy waste.

Seaweed hydrolysate and digestate supported microbial fermentation as nutrient sources.

Scaled-up co-fermentation produced 65.65 g/L lactic acid with high productivity.

Abstract

To substitute petroleum-based materials with bio-based alternatives, microbial fermentation combined with inexpensive biomass is suggested. In this study Saccharina latissima hydrolysate, candy-factory waste, and digestate from full-scale biogas plant were explored as substrates for lactic acid production. The lactic acid bacteria Enterococcus faecium, Lactobacillus plantarum, and Pediococcus pentosaceus were tested as starter cultures. Sugars released from seaweed hydrolysate and candy-waste were successfully utilized by the studied bacterial strains. Additionally, seaweed hydrolysate and digestate served as nutrient supplements supporting microbial fermentation. According to the highest achieved relative lactic acid production, a scaled-up co-fermentation of candy-waste and digestate was performed. Lactic acid reached a concentration of 65.65 g/L, with 61.69% relative lactic acid production, and 1.37 g/L/hour productivity. The findings indicate that lactic acid can be successfully produced from low-cost industrial residues.