Broad-spectrum antimicrobial activity of cinnamoyl esterase-producing lactobacilli and their application in fermented rice bran
J Sci Food Agric. 2021 Nov 17. doi: 10.1002/jsfa.11654. Online ahead of print.
BACKGROUND: Cinnamoyl esterase (CE) can release antioxidant phenolic acids from its non-digestible ester-linked form. Fermentation using CE-producing lactic acid bacteria (LAB) can be useful in the food industry because of its ability to produce bioactive compounds and antibacterial metabolites. The purpose of this study was to confirm the food applicability of LAB with CE-producing ability and broad-spectrum antibacterial activity.
RESULTS: Among the 219 bacterial strains identified in infant feces, 5 Lactobacillus gasseri and 6 Limosilactobacillus fermentum with a high CE activity were isolated. The survival rate of all selected LABs was >95% at pH 2.5 for 3 h and >70% when treated with 0.3% bile salt for 4 h. Moreover, cell-free supernatants of all strains strongly inhibited 5 food-borne bacterial pathogens (Listeria monocytogenes, Salmonella enterica, Escherichia coli O157:H7, Bacillus cereus, and Staphylococcus aureus) and 3 toxin-producing fungal pathogens (Aspergillus niger, Penicillium sp., and Fusarium oxysporum). To improve phenolic acid content and rice bran preservation, L. fermentum J2 with the strongest CE activity and L. gasseri N2 with the strongest antibacterial activity were used in rice bran fermentation, respectively. FRB-J2 (fermented rice bran with L. fermentum J2) and FRB-N2 (fermented rice bran with L. gasseri N2) significantly increased caffeic acid and ferulic acid (p<0.01). FRB-J2 and FRB-N2 artificially inoculated with F. oxysporum showed no visible fungal growth during the test period (21 days).
CONCLUSION: Fermentation by L. fermentum J2 and L. gasseri N2 can help extend the shelf life of rice bran-based products and produce bioactive compounds. This article is protected by copyright. All rights reserved.