In vitro Susceptibility and Evaluation of Techniques for Understanding the Mode of Action of a Promising Non-antibiotic Citrus Fruit Extract Against Several Pathogens

Conclusion This study confirms the in vitro antibacterial activity of BIOCITRO® against Gram-negative and Gram-positive bacteria. For most of the strains, the product reached the bactericidal effect at the same concentration of the bacteriostatic effect and maximum difference between MIC and MBC was two dilution steps. The less susceptible species of the study were S. enterica ssp. enterica and E. coli with MBC90 values of 256 and 128 μg/mL, respectively, while the most susceptible was C. perfringens with MBC90 of 16 μg/mL. After short exposition time to the product, the significant effect over the viability of the stationary phase cells ranged from 8 to 256 μg/mL. With regard to the mode of action of the product, by means of FC, FTIR spectroscopy and SEM we demonstrated that it causes changes in the permeability, structure, composition and morphology of the bacterial envelope in a similar way to other citrus fruit extracts. Changes affected practically all components of the cell envelope but mainly to carbohydrates and polysaccharides of the cell wall. Furthermore, the alteration of the membrane permeability increased with the concentration of the product, although it did not always affect the viability of the cell, as was observed for the strains of E. coli and two of the strains of S. enterica ssp. enterica, which displayed using FC higher number of cells with altered membranes than non-viable cells at the same concentration. In addition to oth...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research