Substantial extracellular metabolic differences found between phylogenetically closely related probiotic and pathogenic strains of Escherichia coli

Since its first isolation a century ago, the gut inhabitant Escherichia coli strain Nissle 1917 has been shown to have probiotic activities; however, it is yet not fully elucidated which differential factors play key roles in its beneficial interactions with the host. To date, no metabolomics studies have been reported investigating the potential role of small molecules in functional strain differentiation of Nissle from its genetically close neighbors. Here, we present results of liquid chromatography coupled to high-resolution mass spectrometry characterization of extracellular metabolomes of E. coli strains as a proxy of their bioactivity potential. We found that phylogroup B2 strains exported a more diverse arsenal of metabolites than strains of other phylogroups. Zooming into the phylogroup B2 metabolome identified consistent substantial differences between metabolic output of E. coli Nissle and other strains, particularly in metabolites associated to the Argimine biosynthesis pathway. Nissle was found to release higher levels of Ornithine and Citrulline whilst depleting greater amounts of Arginine from the medium. Moreover, a novel Nissle-specific metabolite not reported before in bacteria, 5-(Carbamoylamino)-2-hydroxypentanoic acid (Citrulline/Arginic Acid related) was observed. Finally, Nissle, CFT073 and NCTC12241/ATCC25922 shared the excretion of N5-Acetylornithine, whereas other strains released N2-Acetylornithine or no N-Acetylornithine at all. Thus, we found substantial metabolic differences in phylogenetically very similar E. coli strains, an observation which suggests that it is justified to further investigate roles of small molecules as potential modulators of the gut environment by probiotic, commensal, and pathogenic strains, including E. coli Nissle 1917

The application of metabolomics for herbal medicine pharmacovigilance: a case study on ginseng

Herbal medicines are growing in popularity, use and commercial value; however, there remain problems with the quality and consequently safety of these products. Adulterated, contaminated and fraudulent products are often found on the market, a risk compounded by the fact that these products are available to consumers with little or no medical advice. Current regulations and quality control methods are lacking in their ability to combat these serious problems. Metabolomics is a biochemical profiling tool that may help address these issues if applied to quality control of both raw ingredients and final products. Using the example of the popular herbal medicine, ginseng, this essay offers an overview of the potential use of metabolomics for quality control in herbal medicines and also highlights where more research is needed