Undernutrition in Bangladeshi children is associated with disruption of postnatal gut microbiota assembly; compared to standard therapy, a microbiota-directed complementary food (MDCF) significantly improved their ponderal and linear growth. Here, we characterize a fatty acid amide hydrolase (FAAH) from a growth-associated intestinal strain of Faecalibacterium prausnitzii cultured from these children. This enzyme, expressed and purified from E. coli, hydrolyzes a variety of N-acylamides, including oleoylethanolamide (OEA), neurotransmitters, and quorumsensing N-acyl homoserine lactones, and synthesizes a range of N-acylamides, notably N-acyl amino acids. Treating germ-free mice with N-oleoylarginine and N-oleolyhistidine, major products of FAAH OEA metabolism, markedly affected expression of intestinal immune function pathways. Administering MDCF to Bangladeshi children significantly reduced fecal OEA, a satiety factor whose levels were negatively correlated with the abundance and expression of their F. prausnitzii FAAH. This enzyme, structurally and catalytically distinct from mammalian FAAH, is positioned to regulate levels of a variety of bioactive molecules.

Untargeted metabolomic analyses were performed using an Agilent 1290 LC system coupled to an Agilent Model 6545 Qtof mass spectrometer (Santa Clara, CA). Reversed phase separation was achieved on a BEH C18 column (2.1 x 150 mm, 1.7 μm, Waters Corp., Milford, MA) that was heated to 35 °C. For analyses carried out in the positive ESI mode, the mobile phase consisted of 0.1% formic in water (A) and 0.1% formic acid in acetonitrile (B). For analyses in the negative mode, the mobile phase consisted of 5mM ammonium bicarbonate formic in water (A) and 5mM ammonium bicarbonate in acetonitrile/water (95:5 v/v) (B). A flow rate of 0.3 mL/minute was applied (gradient program: from 0 to 14 minutes, mobile phase B eluted from 5% to 100%, followed by 3 minutes at 100% of B). An equilibration time of 3 minutes was used. Normal phase separation was conducted on a Cortex HILIC column (2.1 x 150 mm, 1.6 μm, Waters Corp., Milford, MA) that was heated to 45 °C. 10 mm ammonium acetate in 5/95 acetonitrile/water (A) and 10 mm ammonium acetate in 95/5 acetonitrile/water (B) were the mobile phases. Metabolites were eluted from the columns at 0.4 ml/min using a 1–60% phase A gradient over 17 min followed by 4-minute-long equilibration. Data were collected in the range from m/z 50 to 1000, and m/z 50 to 650 for MS full-scan analysis and MS/MS analysis, respectively. The key parameters of Qtof were set as follows: nozzle voltage, 1000 V for positive and 1500V for negative; capillary voltage, 3000 V for positive and 3500v for negative; drying gas, N₂; drying gas flow rate, 10 L/min; collision gas, high purity N2; drying gas (N₂) temperature, 325 °C; vaporizer/sheath gas temperature, 350 °C; sheath gas flow rate, 12 L/min.