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222 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGYpolysaccharides, vitamins, etc. Lactic acid bacteria produce energy via lactic acid fermentation under anaerobic conditions [10]. Lactobacillus strains also have secondary metabolic processes with phenolic compounds such as (i) glycosyl hydrolases, which convert flavonoid glycosides to corresponding aglycones; (ii) esterases, which degrade methyl gallate, tannins, or phenolic acid esters; (iii) decarboxylases and reductases; and (iv) benzyl alcohol dehydrogenase, which catalyzes the reversible oxidation of some aromatic alcohols to aldehydes with the concomitant reduction of NAD+. These enzyme activities were primarily investigated in L. plantarum strains [5].Some factors that may influence the antibacterial activity of the fermentation production may be due to lactic acid and other organic acids produced, which could lower the pH of the environment and discourage the growth of harmful microorganisms [10]. Reduced or decarboxylated phenolic acids may have lower antibacterial activity compared to their precursors. Lactic acid-fermenting bacteria were known to have the capacity to tolerate phenolic compounds compared to other genera (e.g., Enterobacteria, Clostridium spp., and Bacteroides spp.) [5]. In our study, MRSA strains were more susceptible to the MFP than to S. aureus and E. coli strains. In particular, the fermented MFP increased antibacterial activity against S. aureus and E. coli. In this study, the growth of L. plantarum, L. acidophilus, and L. caseistrains was not affected by the concentration of MFP. The primary influencing elements were identified as pH and the content of organic acids and sugars. The research results of Thuong et al. (2021) showed that sugar was an important carbon source that bacteria use for growth and fermentation. The amount of organic acid in myrtle fruit is 1.2 %u00b1 0.2 g/L, creating a mildly acidic pH environment (pH 6.1-6.5) suitable for lactic fermentation. The sugar content analyzed in myrtle fruit puree is 9.2 %u00b1 0.5 g/L.