In vitro susceptibility of human gut microbes to potential food preservatives based on immobilized phenolic compounds.

The development of novel food preservatives based on natural antimicrobials such as phenolic compounds is increasing, but their safety should be established before use, including evaluating their impact on the gut microbiota. This work explored the influence of antimicrobial phenolics presented in different forms on selected human gut microbiota members through in vitro susceptibility tests. The bacteria tested exhibited a wide range of susceptibilities to phenolics depending on the molecule structure and mode of administration. Agathobacter rectalis and Clostridium spiroforme, members of the phylum Firmicutes, were the most sensitive strains. Susceptibility was strain- and species-specific, suggesting that it may not be possible to easily extrapolate results across the human microbiome in general. Species of other phyla including Bacteroidetes, Actinobacteria, Proteobacteria and Verrucomicrobia were more resistant than Firmicutes, with growth of some strains even enhanced. Our results provide insights into the biocompatibility of free and immobilized phenolics as potential food additives.