The composition of the skin microbiota varies widely among individuals when sampled at the same body site. A key question is which molecular factors determine strain-level variability within sub-ecosystems of the skin microbiota. Here, we used a genomics-guided approach to identify an antibacterial biosynthetic gene cluster in Cutibacterium acnes (formerly Propionibacterium acnes), a human skin commensal bacterium that is widely distributed across individuals and skin sites. Experimental characterization of this biosynthetic gene cluster resulted in identification of a new thiopeptide antibiotic, cutimycin. Analysis of individual human skin hair follicles revealed that cutimycin contributed to the ecology of the skin hair follicle microbiota and helped to reduce colonization of skin hair follicles by Staphylococcus species.

Time-restricted eating (TRE) is a dietary intervention that limits food consumption to a specific time window each day. The effect of TRE on body weight and physiological functions has been extensively studied in rodent models, which have shown considerable therapeutic effects of TRE and important interactions among time of eating, circadian biology and metabolic homeostasis. In contrast, it is difficult to make firm conclusions regarding the effect of TRE in people because of the heterogeneity in results, TRE regimens, and study populations. In this review, we: i) provide a background of the history of meal consumption in people and the normal physiology of eating and fasting; ii) discuss the interaction between circadian molecular metabolism and TRE; iii) integrate the results of preclinical and clinical studies that evaluated the effects of TRE on body weight and physiological functions; iv) summarize other time-related dietary interventions that have been studied in people; and v) identify current gaps in knowledge and provide a framework for future research directions.

Summary Environmental pH can be an important cue for symbiotic bacteria as they colonize their eukaryotic hosts. Using the model mutualism between the marine bacterium Vibrio fischeri and the Hawaiian bobtail squid, we characterized the bacterial transcriptional response to acidic pH experienced during the shift from planktonic to host‐associated lifestyles. We found several genes involved in outer membrane structure were differentially expressed based on pH, indicating alterations in membrane physiology as V. fischeri initiates its symbiotic program. Exposure to host‐like pH increased the resistance of V. fischeri to the cationic antimicrobial peptide polymixin B, which resembles antibacterial molecules that are produced by the squid to select V. fischeri from the ocean microbiota. Using a forward genetic screen, we identified a homolog of eptA, a predicted phosphoethanolamine transferase, as critical for antimicrobial defense. We used MALDI‐MS to verify eptA as an ethanolamine transferase for the lipid‐A portion of V. fischeri lipopolysaccharide. We then used a DNA pulldown approach to discover that eptA transcription is activated by the global regulator H‐NS. Finally, we revealed that eptA promotes successful squid colonization by V. fischeri, supporting its potential role in initiation of this highly specific symbiosis.