Ampliação de escala e purificação parcial de ácido propiônico obtido por fermentação usando Propionibacterium freudenreichii subsp ATCC6207

Abstract

Propionic acid (PA) is currently obtained by chemical synthesis from petroleum-derived feedstock. Seeking sustainable approaches, research has focused on the use of microorganisms and renewable biomass in the production process of PA. The demand for PA has grown in recent years because it is considered a safe additive by the Food and Drug Administration (FDA), being widely applied by the chemical and food industries due to its antimicrobial activity. The present work aimed to evaluate the production of PA in bioreactor using fermentation medium with whey permeate (PSL) as carbon source and corn step liquor (AMM) as nitrogen source and to investigate its purification using ion exchange cryogels. The first treatment was carried out with discontinuous fermentation for 120 h, in triplicate, with control and pH variation in a bioreactor with medium composed of PSL, containing 40 g L-1 lactose and 65 g L-1 AMM and inoculum prepared with Propionibacterium freudenreichii subsp ATCC 6207. Every 24 hours, samples were taken to determine lactose concentrations, pH, organic acids (acetic, propionic, and lactic acid), and propionic bacteria counts. The second treatment was conducted with discontinuous fed fermentation, with control of lactose concentration and pH. The fermented medium was composed of PSL and AMM and the same inoculum. The lactose concentration throughout the fed-batch fermentation in the bioreactor was maintained between 5 and 15 g L-1. Samples were also taken for analysis of organic acids (acetic, propionic and lactic) and for counting propionic bacteria. Comparing the two treatments, it was found that the batch process was more efficient in PA production, with yield of 7.41 g.L-1 and productivity of e 0.103 g.L-1.h-1 with 72 h of fermentation. In purification tests, the adsorption of PA was studied at different pH (4, 5, 6 and 7) using taurine functionalized cryogels (Criogel-Tau). The matrix that presented the highest adsorption capacity for PA (256.13 mg g-1) and the lowest adsorption capacity for acetic acid (29.34 mg g-1) was at pH 4. The present study presents an alternative for obtaining and purifying propionic acid, using by-products from the food industry.