In Vitro Antimicrobial Activities of Organic Acids and Their Derivatives on Several Species of Gram-Negative and Gram-Positive Bacteria

Abstract

The objective of this study was to determine the in vitro antimicrobial activity of several organic acids and their derivatives against Gram-positive (G+) and Gram-negative (G−) bacteria. Butyric acid, valeric acid, monopropionin, monobutyrin, monovalerin, monolaurin, sodium formate, and ProPhorce—a mixture of sodium formate and formic acid (40:60 w/v)—were tested at 8 to 16 concentrations from 10 to 50,000 mg/L. The tested bacteria included G− bacteria (Escherichia coli, Salmonella enterica Typhimurium, and Campylobacter jejuni) and G+ bacteria (Enterococcus faecalis, Clostridium perfringens, Streptococcus pneumoniae, and Streptococcus suis). Antimicrobial activity was expressed as minimum inhibitory concentration (MIC) of tested compounds that prevented growth of tested bacteria in treated culture broth. The MICs of butyric acid, valeric acid, and ProPhorce varied among bacterial strains with the lowest MIC of 500–1000 mg/L on two strains of Campylobacter. Sodium formate at highest tested concentrations (20,000 mg/L) did not inhibit the growth of Escherichia coli, Salmonella Typhimurium, and Enterococcus faecalis, but sodium formate inhibited the growth of other tested bacteria with MIC values from 2000 to 18,800 mg/L. The MIC values of monovalerin, monolaurin, and monobutyrin ranged from 2500 to 15,000 mg/L in the majority of bacterial strains. Monopropionin did not inhibit the growth of all tested bacteria, with the exception that the MIC of monopropionin was 11,300 mg/L on Clostridia perfringens. Monolaurin strongly inhibited G+ bacteria, with the MIC value of 10 mg/L against Streptococcus pneumoniae. The MIC tests indicated that organic acids and their derivatives exhibit promising antimicrobial effects in vitro against G− and G+ bacteria that are resistant to antimicrobial drugs. The acid forms had stronger in vitro antimicrobial activities than ester forms, except that the medium chain fatty acid ester monolaurin exhibited strong inhibitory effects on G+ bacteria.

Antimicrobial Potential of Biosynthesized Silver Nanoparticles by Aaronsohnia factorovskyi Extract

“…Several studies showed similar observations: the study of the silver nanoparticles loaded by extracts from Allophylus serratus leaf [18] or by Tectona grandis seeds extract [19]. [11]. The second-highest relative intensity was that the 1,3-benzodioxol-4-ol, a phenolic benzothiazole derivative, which approved various b ological importance because of its anticancer, antimicrobial, and antioxidant activiti [12].…”

From Acidifiers to Intestinal Health Enhancers: How Organic Acids Can Improve Growth Efficiency of Pigs

“…are mainly susceptible to MCFA, while Gram-negative bacteria (i.e., Escherichia coli, Campylobacter jejuni, Salmonella spp.) are more sensitive to SCFA [27,28]. This can be explained by the lipophilic nature of MCFA that allows them to have a stronger antibacterial activity mainly against Gram-positive species, whereas the presence of lipopolysaccharide (LPS) in the Gram-negative cell wall confers resistance to these species [29].…”

Formic Acid as an Antimicrobial for Poultry Production: A Review

“…While the majority of the research on formic acid as an antimicrobial in food animal production has focused on foodborne Salmonella spp., there have been some studies with other pathogens inhabiting the GIT. As indicated by the in vitro work of Kovanda et al (68), formic acid may be effective against other GIT foodborne pathogens as well, including E. coli and Campylobacter jejuni. Early research indicated that organic acids, such as lactic acid and commercial blends that contained formic acids as one of several components, could lower Campylobacter levels in poultry (135,138).…”

“…The chemical form of formate the bacteria are exposed to appears to matter as well. Kovanda et al ( 68 ) screened several Gram-negative and Gram-positive microorganisms and compared Minimum Inhibitory Concentration (MIC) responses on sodium formate (500–25, 000 mg/L) and a blend of sodium formate and free formate (40/60 w/v; 10–10,000 mg/L). Based on the MIC estimates, they found that sodium formate was only inhibitory to strains of Campylobacter jejuni, Clostridium perfringens, Streptococcus suis , and Streptococcus pneumoniae , but not E. coli, Salmonella Typhimurium, or Enterococcus faecalis .…”