Antibacterial Activity of the Purified Monolaurin from Enzymatic Glycerolysis of Palm Kernel Olein-Stearin against Bacillus subtilis

Background and Objective: Monolaurin can be produced by enzymatic glycerolysis of a palm kernel olein-stearin mixture. Monolaurin can act as an antibacterial agent against Gram-positive and Gram-negative bacteria. Few studies have investigated activity of monolaurin against Bacillus subtilis cells and spores. Therefore, the aim of this study was to investigate effects of a purified monolaurin from enzymatic glycerolysis of palm kernel olein-stearin mixture on growth, spore germination, cell surface hydrophobicity and cell structure of Bacillus subtilis FNCC 0060. Material and Methods: Monolaurin was produced using palm kernel-olein mixture under the best enzymatic glycerolysis condition and purified using solvent (hydroalcoholic) method. Effects of a purified monolaurin on Bacillus subtilis growth and spore germination were studied using nutrient broth. Analysis of cell surface hydrophobicity was carried out using microbial adhesion to hydrocarbons assay and cell structure was studied using transmission electron microscope. Completely randomized experimental design was used and each treatment was carried out in triplicate. Analysis of variance and Duncan multiple range tests were used to analyze data. Results and Conclusion: Results showed that purified monolaurin inhibited growth of Bacillus subtilis FNCC 0060. Moreover, development of Bacillus subtilis in nutrient broth with monolaurin of 100-5,000 ppm was slower than that without monolaurin. Higher concentration in the media decreased the microbial specific growth rate and increased doubling time. Spores of Bacillus subtilis FNCC 0060 in nutrient broth with monolaurin of 100-1,000 ppm delayed germination for up to seven days of incubation. Presence of monolaurin significantly decreased bacterial cell adherence. Furthermore, cytoplasm of Bacillus subtilis FNCC 0060 seemed shrunk significantly, causing cytoplasmic damages and disorganization of the components. Conflict of interest: The authors declare no conflict of interest © This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 4.0 License (CC BY-NC 4.0). To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.