Production of natural flavor compounds using Bacillus subtilis-fermented soybean meal extract and their biological potential: a comprehensive in vitro study

Abstract

This study aims to investigate the production of natural flavor compounds through the utilization of <i>Bacillus subtilis</i>-fermented soybean meal extract and evaluate their biological potential. The experiment involved a comprehensive <i>in vitro</i> investigation to assess the capabilities and effects of the produced flavor compounds. The resulting flavor compounds were subjected to various <i>in vitro</i> tests to assess their properties, including cytotoxicity, antioxidant activity, anticancer potential, antiviral activity, and antimicrobial activity. To enhance the fermentation process, soybean meal extract was fortified with a combination of L-Lysine and L-Threonine. Gas chromatography-mass spectrometry (GC/MS) analysis was conducted on the fermented soybean meal using two strains of <i>Bacillus subtilis</i>, namely <i>NRCH123</i> and <i>NRCZ144</i>. This analysis revealed the presence of various volatile compounds in all extracts, including Butylated hydroxytoluene. The fermented soybean extract with <i>bacillus subtilis</i> NRCZ144 (B2) fortified with a combination of 2.5% (w/w) L-Lysine and 2.5% w/w L-threonine (SLT2) exhibited a rich profile of flavor compounds, with Eucalyptol being identified as the predominant compound. The antioxidant activity of the SLT₂ extract was found to be 72.04% at a concentration of 100 μg/mL, indicating significant antioxidant potential. Furthermore, when tested against the human liver cancer cell line HepG2, the extract demonstrated anticancer activity with an IC50 value of 2.26 μg/mL. The extract exhibited potent cytotoxicity, with an IC50 value of 1.02 μg/mL. Importantly, the SLT₂ extract displayed strong antibacterial and antifungal activity, even at very low concentrations. The extract's antimicrobial properties indicate its potential for inhibiting the growth of bacteria and fungi.