SOYA MOLASSES FERMENTING MICROORGANISMS SCREENING FOR LACTIC ACID PRODUCION

The use of agroindustrial byproducts for the production of value-added chemicals is a worldwide trend for a sustainable and competitive economy - Bioeconomy. Soybean molasses is a byproduct used mainly in animal feed formulations. Being a nutrient rich material, the present work aims to select lactic acid bacteria that adapt the best to this medium for lactic acid production, an important product for the food and chemical industry. Eleven LAB strains belonging to the genera Lactobacillus and Lactococcus were preselected from the strains collection of the Food Biotechnology Laboratory of Feira de Santana State University (UEFS). Screening was performed by plating the pre-selected strains in MRSA culture medium and diluted molasses. MRSA was formulated according to the HIMEDIA Manual. Soybean molasses, supplied by CJ SELECTA, was diluted with water 1: 3 m / m. In both media, 3% agar and 5 mL / L solution of bromocresol purple and bromocresol green 10g / L indicators were added and the pH adjusted to 6.9. The inoculum was prepared by adding 1.5 ml of the frozen culture (12% glycerol at -18°C) in 100 ml of MRS and incubating at 33°C or 37°C for 24h at 100 rpm. For inoculation of the plates, 15 µL of the fresh culture was added to the center of the plate and incubated at 33°C / 37°C for 24h. Yellow halos were observed, indicating pH reduction due to lactic acid production, ranging from 1mm to 20mm in diameter around the inoculated microbial biomass, contrasting with the greenish blue color of MRSA and brown color from molasses. The most suitable microorganism was Lactobacillus sp. RE 07 which was selected for subsequent studies.