SOLID-STATE FERMENTATION OF SOYBEAN MEAL: HYDROLYTIC ENZYMES PRODUCTION AND IMPROVEMENT IN BIOACTIVITY

Abstract

Solid-state fermentation (SSF) is a fermentation process where different agro-industrial residues have been used as substrates to maximize their utilizations and to address the waste disposal issues. Bacillus sp. strain has been studied for its ability to produce different enzymes by SSF of agro-industrial residues. Soybean meal (SBM) is a co-product after solvent extraction process in dietary oil production and high quality source of protein. Herein, SBM was assessed for the production of hydrolytic enzymes through SSF with Bacillus sp. strain for 8 days at 30 °C. Highest obtained yields of producing proteases, cellulases, α-amylases and pectinases were 56.4, 0.89, 0.95 and 1.07 U g-1, respectively. The enzymes produced were very different in biochemical characteristics, including activities at specific temperatures and a wide range of pH values. The highest activity proteases, cellulases, α-amylases exhibited at higher temperatures, 50 °C suggesting the high potential of these enzymes for industrial application involving elevated conditions. Fermented soybean meal (FSBM) was examined in terms of total phenol content (TPC), scavenging DPPH and ABTS radical abilities. Scavenging DPPH and ABTS abilities of FSBM were all stronger than that of SBM. The radical scavenging ability increased by fermentation in accordance with the increase in TPC content. TPC increase from 1.12 to 3.12 mgGAE/g soybean meal after three days of fermentation was observed. The high hydrolytic enzyme activity and stability established plus the low cost of the substrate make this solid-state process a promising tool for biotechnological industry.