The human gut microbiota impacts host metabolism and has been implicated in the pathophysiology of obesity and metabolic syndromes. However, defining the roles of specific microbial activities and metabolites on host phenotypes has proven challenging due to the complexity of the microbiome-host ecosystem. Here, we identify strains from the abundant gut bacterial phylum Bacteroidetes that display selective bile salt hydrolase (BSH) activity. Using isogenic strains of wild-type and BSH-deleted Bacteroides thetaiotaomicron, we selectively modulated the levels of the bile acid tauro-β-muricholic acid in monocolonized gnotobiotic mice. B. thetaiotaomicron BSH mutant-colonized mice displayed altered metabolism, including reduced weight gain and respiratory exchange ratios, as well as transcriptional changes in metabolic, circadian rhythm, and immune pathways in the gut and liver. Our results demonstrate that metabolites generated by a single microbial gene and enzymatic activity can profoundly alter host metabolism and gene expression at local and organism-level scales.

The rapid emergence of antibiotic-resistant pathogenic bacteria has accelerated the search for new antibiotics. Many clinically used antibacterials were discovered through culturing a single microbial species under nutrient-rich conditions, but in the environment, bacteria constantly encounter poor nutrient conditions and interact with neighboring microbial species. In an effort to recapitulate this environment, we generated a nine-strain actinomycete community and used 16S rDNA sequencing to deconvolute the stochastic production of antimicrobial activity that was not observed from any of the axenic cultures. We subsequently simplified the community to just two strains and identified sp. AA4 as the producing strain and M145 as an inducing strain. Bioassay-guided isolation identified amycomicin (AMY), a highly modified fatty acid containing an epoxide isonitrile warhead as a potent and specific inhibitor of Amycomicin targets an essential enzyme (FabH) in fatty acid biosynthesis and reduces infection in a mouse skin-infection model. The discovery of AMY demonstrates the utility of screening complex communities against specific targets to discover small-molecule antibiotics.

Bile salt hydrolase (BSH) enzymes are widely expressed by human gut bacteria and catalyze the gateway reaction leading to secondary bile acid formation. Bile acids regulate key metabolic and immune processes by binding to host receptors. There is an unmet need for a potent tool to inhibit BSHs across all gut bacteria in order to study the effects of bile acids on host physiology. Here, we report the development of a covalent pan-inhibitor of gut bacterial BSH. From a rationally designed candidate library, we identified a lead compound bearing an alpha-fluoromethyl ketone warhead that modifies BSH at the catalytic cysteine residue. Strikingly, this inhibitor abolished BSH activity in conventional mouse feces. Mice gavaged with a single dose of this compound displayed decreased BSH activity and decreased deconjugated bile acid levels in feces. Our studies demonstrate the potential of a covalent BSH inhibitor to modulate bile acid composition in vivo.

Purpose To determine reasons for hesitancy towards COVID-19 vaccination and motivators to increase COVID-19 vaccine uptake among Black Americans. Design Mixed-methods. Setting Individual interviews in March-April 2021 Participants Black adults (20-79 years) who attended a church in Boston, MA and identified as “vaccine hesitant” (n = 18). Methods Individual in-depth Zoom interviews to elicit participant views on vaccines in general, specific reasons for COVID-19 vaccine hesitancy, and trusted sources of information. Participants were also asked about possible motivators that could increase COVID-19 vaccine uptake. Transcripts were de-identified and analyzed for major themes using an inductive approach. Results Analysis included 18 complete interviews. Lack of trust in the government, healthcare, or pharmaceutical companies (n = 18), rushed development (n = 14), fear of side effects (n = 12), history of medical mistreatment (n = 12), and a perception of low risk of disease (n = 9) were the top-cited reasons for COVID-19 vaccine hesitancy. Motivators likely to increase COVID-19 vaccine uptake included more data (n = 17), friends and family getting vaccinated (not celebrities) (n = 11), and increased opportunities that come along with being vaccinated (n = 8). Conclusion There were many reasons for COVID-19 vaccine hesitancy, as reported by participants who were all Black Americans in the Boston area. The public health challenge of increasing vaccine uptake in the Black community is nuanced and intervention efforts may be more successful if delivered by trusted members of the community and tailored to the needs of individuals.