Production of Exopolysaccharides by Lactobacillus plantarum ATCC 8014 and Concentration by Nanofiltration

Abstract

Functional food may promote specific physiological benefits besides the properties of nourishing and feeding, thanks to the presence of physiologically healthy ingredients such as probiotics and prebiotics. Amongst the probiotics is Lactobacillus plantarum, which belongs to the group of lactic acid bacteria (LAB). Energy obtainment by these microorganisms occurs through carbohydrate fermentation, producing mainly lactic acid but also exopolysaccharides (EPS), which presents technological application on the food industry mainly by their prebiotic properties. In order to enable the obtainment of EPS, a production process of L. plantarum ATCC 8014 was established in aerobic conditions in an airlift bioreactor, using supplemented tofu whey as substrate. The process was compared to the generally employed MRS medium. EPS concentration was performed by nanofiltration (NF), carried at 35 °C and 6 bars, and samples analyzed via HPLC-IR. The cultivation allowed biomass yields of up to 3.2 g/L and 2.7 g/L, and EPS yields of 350 mg/L and 210 mg/L for the TWS and MRS media, respectively. On the NF process, the final concentrated extract was obtained with VRF (volume reduction factor) of 4.0, with increases of up to 80% on EPS contents. During membrane processing, it was verified that the greatest part of the flux resistance (60%) was caused by a polarized gel layer. This study showed that the use of tofu whey is applicable for EPS production and that nanofiltration is an efficient procedure to concentrate the prebiotic compounds obtained during the cultivation of L. plantarum ATCC 8014.