In vitro Growth Inhibition of Food-borne Pathogens and Food Spoilage Microorganism by Vitamin K5

Abstract

The study investigates the effectiveness of a synthetic vitamin analog (vitamin K5) for the growth inhibition of a total of 14 bacterial pathogens, spoilage-inducing bacteria and three spoilage-inducing molds that were tested during this study. Bacterial growth inhibition by vitamin K5 and vitamin K5 combined with sodium chloride (NaCl) were tested by determining the Minimum Inhibitory Concentrations (MICs) using a broth microdilution method. Antifungal effects of vitamin K5 were determined by measuring the growth of three different spoilage molds on Malt agar plates containing different concentrations of vitamin K5. All bacterial strains assayed were inhibited by vitamin K5 in a range of 64-1,024 μg/ml. When vitamin K5 was combined with 3% NaCl, five out of the 14 bacterial strains assayed showed lower MICs than for vitamin K5 alone. When vitamin K5 was combined with 5% NaCl, nine of the 14 bacterial strains assayed displayed lower MICs than for vitamin K5 alone. With respect to inhibition of molds, 10 μg/ml vitamin K5 induced inhibitory effects against Aspergillus parasiticus NRRL 2999 and Penicillium expansum NRRL 6069, but not Aspergillus flavus NRRL 6540. In contrast, 30 or 50 μg/ml vitamin K5 showed inhibitory effects against the growth of all molds assayed; however, inhibitory effects against aflatoxin production by A. flavus NRRL 6540 were achieved only with 50 μg/ml. These data show that vitamin K5 is a useful antimicrobial agent that at low concentrations causes growth inhibition of a broad spectrum of bacterial pathogens and spoilage bacteria as well as certain molds.