Produção de L(+)-ácido lático a partir de subprodutos agroindustriais por Lactobacillus rhamnosus ATCC 9595

Abstract

The lactic acid (LA) is used in the food, chemical, pharmaceutical, textile and packaging. The AL can be produced by chemical synthesis, by fermentation. In fermentation processes, the cost of culture medium is one factor to be reduced. In this sense, the use of agro-industrial by-products such as potatoes (carbon source) and corn steep liquor (nitrogen source) can be economically viable options. This study aimed to apply a screening design for selecting composition variables of the fermentation medium through a PlackettBurman design type (PB) and further optimization of the medium for the production of L (+)-lactic acid by Lactobacillus rhamnosus ATCC 9595 by replacing conventional sources of carbon and nitrogen by agro industrial byproducts, excess potato production and corn steep liquor, and a scale-up was also performed using a bioreactor. In PB12 eight factors were evaluated: glucose concentrations, yeast extract, sodium acetate, K2HPO4, MgSO4.7 H2O, MnSO4. 4H2O, CaCO3 and Tween 80. Only CaCO3 was significant for the production of LA. In the second stage, it was used the Central Composite Rotatable Design (CCRD) with full factorial 23, the glucose was replaced by potato flour previously hydrolyzed, the yeast extract was replaced by corn steep liquor and there were several concentrations of CaCO3. The highest concentration of LA (183.83 g/L) was obtained using 220 g/L of potato flour, 55 g/L of corn steep liquor and 45 g/L of CaCO3 during 72 h at 37°C, there was obtained 2.553 g/L.h productivity and 94.2% yield.180.45 g/L of LA was produced in bioreactor with a medium composed of 210 g/L of potato flour, 65 g/L of corn steep liquor and 55 g/L of CaCO3 presenting productivity of 2,506 g/L.h and yield of 96.7%. The results of this study demonstrated that the use of potato flour and corn steep liquor, with use of acid neutralizing such as CaCO3 for the production of lactic acid by fermentation by Lactobacillus rhamnosus is feasible. The PlackettBurman, central composite design and response surface analysis methodology are effective methods for the improvement and optimization of fermentation processes.