Abstract Description

The bacteria of the gut microbiome are a crucial element of human health, however in-depth mechanistic studies and analysis of microbe-microbe interactions within the community requires bacterial isolates. Culturing of the gut microbiota has been hindered by the requirement of more complex and diverse growth conditions than those of traditional culture methods and thus many important species remain uncultured. Expansion of available cultured isolates from the gut microbiome is the crucial step towards their investigation as potential future biotherapeutics. Metagenomic studies have identified associations between specific bioactive compounds (e.g. polyphenols, omega-3 fatty acids) present in ingested food and an increased abundance of bacteria belonging to the Order Eubacteriales (class Clostridia). The members of this diverse taxon include both non-spore forming and spore-forming species, many with important and beneficial functions that extend beyond just the human gut. In this study, a faecal sample was treated with ethanol to enrich for the spore-forming bacteria followed by faecal culturing in Brain Heart Infusion broth, supplemented with either coffee (polyphenol-rich), clove essential oil (containing the phytonutrient eugenol) or flax oil (rich in omega-3 fatty acids) to promote the growth of the target taxa. This led to the isolation of less commonly cultured strict anaerobes including a strain of the species Blautia wexlerae, which was isolated from the eugenol-supplemented culture. This species is of great interest for its potential for modulating host metabolic health. Two strains of the spore-forming species Flavonifractor plautii, an understudied species of the gut microbiome, were isolated from the flax oil-supplemented cultures. These results demonstrate that less conventional but targeted culturing conditions can aid in the isolation of fastidious microbes with yet untapped benefits to human health. Future work will apply 16S rRNA microbiome sequencing to investigate whether the addition of the supplements to the ethanol-treated stool cultures specifically enriched for the Eubacteriales. The probiotic potential of the isolates will be evaluated through whole genome sequence analysis.