Produção de ácido lático a partir da biomassa da alga vermelha Solieria filiformis via fermentação com Lactobacillus rhamnosus

Abstract

Lactic acid is a product with great industrial importance, because of its multiple applications in various industries. Lactic acid production via fermentation process represents more than 50% of the total world production, being one of the most studied processes, mainly for increases in productivity and lower production costs purposes. The main goal of this work was to produce lactic acid via fermentation process, using the biomass hydrolysate of red seaweed Solieria filiformis as a source of fermentable sugars and the lactic acid bacteria Lactobacillus rhamnosus. First, the biomass was hydrolyzed using 10% (w/v) of dry biomass and 1M H2SO4 solution, in reactor at 100°C for 15 minutes. Then, a first fermentation was conducted using three Lactobacillus rhamnosus strains in hydrolysate without pH control. The lactic acid production was analyzed by HPLC through final and consumed total reducing sugar and lactic acid production (g.L-1), productivity (g.L-1.h-1) and yield (%). The results showed no significant differences between the strains, obtaining ±11,5 g.L-1 of lactic acid, ±0,23 g.L-1.h-1 of productivity and ±78% of yield at the end of the 48 hours process. A second fermentation was then conducted with one of the strains, in hydrolysate with pH control, to prevent bacteria inhibition by lowering pH and to increase lactic acid production. The same parameters were analyzed for with and without pH control fermentation processes comparison. The results showed superiors values for lactic acid production (18,74 g.L-1), productivity (0,33 g.L-1.h-1) and yield (100%). Therefore, it was concluded that the trains were capable of sugar consumption from S. filiformis hydrolysate and lactic acid production, more expressively in the pH control process, evidencing that it is a limiting factor for lactic acid fermentation process.