In vitro evaluation of antimicrobial activity of Short and Medium Chain Fatty Acids

The aim of this study (ASAS 2017) was to investigate the MIC₅₀ (value which inhibits 50% of the tested isolates) of organic acid salts against Salmonella enterica spp. enterica (7 strains), E. coli (9 strains) and C. perfringens (6 strains). The products tested were sodium butyrate (BUT), sodium heptanoate (HEP), sodium salt of coconut fatty acid distillate (DICOSAN/DIC) and their combinations BUT+DIC (1:1 ratio) and HEP+DIC (1:1 ratio). MIC₅₀ was determined in triplicate at pH 4.8 and 6. The results at pH 4.8 of MIC₅₀ against E. coli showed that HEP was the most effective (32 ppm) followed by HEP+DIC (128 ppm), BUT (512 ppm) and BUT+DIC (1024 ppm). Regarding to Salmonella, HEP was also the most effective (32 ppm) followed by HEP+DIC and BUT (256 ppm), and DIC and BUT+DIC (512 ppm). At pH 6 for E. coli, HEP was the most effective (3125 ppm) followed by HEP+DIC (3500 ppm), and BUT (62500 ppm). Regarding to Salmonella, HEP was also the most effective (1562 ppm) followed by BUT (125000 ppm). Finally, the results against C. perfringens showed that DIC was the most effective (15.4 ppm) followed by HEP+DIC (21.5 ppm), BUT+DIC (27.6 ppm), HEP (1562 ppm) and BUT (31250 ppm). In summary, HEP was the most effective against Gram-, while DIC was the most effective against Gram+. HEP+DIC showed an increased effect of DIC against Salmonella and also an increased effect of HEP against C. perfringens. The combination of BUT with DIC potentiated the effect of BUT against C. perfringens.