The carrageenan fermentation process for (L)-lactic acid production using Lactobacillus plantarum: effect of fermentation time

Abstract

The increase in plastic production has raised concerns about the depletion of fossil fuels. In addition, the environmental problems related to improper plastic waste have become progressively concerning. Polylactic acid (PLA) is one of the most intriguing biopolymers for the fabrication of biodegradable plastic. More importantly, PLA has sharply increased interest in producing its monomer, lactic acid (LA). Considering the expensive cost of LA production, exploring the potential of refined kappa-carrageenan (RKC) as a low-cost substrate is crucial. This work aimed to study RKC hydrolysate’s effect (20g L−1) on lactic acid production. A set of parameters were evaluated, including lactic acid content by high-performance liquid chromatography (HPLC) analysis, optimum bacterial growth, and reducing sugar content. The results showed that by utilizing RKC as the substrate, the growth of Lactobacillus plantarum reached its maximum within 24 hours of fermentation. The reduced sugar content decreased from 18.8 to 0.8 g L−1 after 72 hours of fermentation. More importantly, about 18.5 g L−1 of LA was produced. In conclusion, the present findings suggest that RKC can be potentially used as an alternative substrate for lowering LA production costs.