Antimicrobial activity of monoacylglycerols (MAG) with odd number of carbons prepared from undecanoic (MAG C11:0) and undecenoic (MAG C11:1) was investigated. Data showed that both studied substances successfully inhibited Gram-positive cocci (Staphylococcus aureus) and spore-forming rods (Bacillus cereus). Gram-negative bacteria were highly resistant against MAG C11:0 and showed considerable tolerance against MAG C11:1. Minimum inhibitory concentration (MIC) of MAG C11:1 was possible to determine for Escherichia coli only. Complete inhibition of three fungi genera (Alternaria, Cladosporium, Trichothecium) was achieved using MAG C11:1 with a concentration higher than 750 µg/mL. The growth of Aspergillus niger, Mucor racemosus, Phoma, Scopulariopsis, Trichoderma was significantly reduced. Generally, MAG C11:1 was more efficient than MAG C11:0 against all tested microorganisms. Due to a rich production of degradation enzymes, some fungi species surprisingly adapted their metabolism during growth and were even able to utilise tested MAG as a source of carbon.
Practical applications: MAG composed of fatty acids with odd number of carbons in molecule are a promising group of substances applicable in food industry and cosmetics. They represent materials with broad spectrum of antimicrobial activity, especially against Gram-positive bacteria. More efficient MAG C11:1 with a double bond in molecule can be recommended for reduction of S. aureus that cause food enterotoxicosis.