Open AccessBreast milk urea as a nitrogen source for urease positiveBifidobacterium infantis
Author(s) -
Patrick Schimmel,
Lennart Kleinjans,
Roger S. Bongers,
Jan Knol,
Clara Belzer
Publication year - 2021
Publication title -
fems microbiology ecology/fems microbiology, ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1093/femsec/fiab019
Subject(s) - urease , biology , bifidobacterium longum , urea , microbiome , breast milk , metagenomics , nitrogen , microbiology and biotechnology , food science , enzyme , feces , bifidobacterium , biochemistry , gene , fermentation , chemistry , lactobacillus , bioinformatics , organic chemistry
Human milk stimulates a health-promoting gut microbiome in infants. However, it is unclear how the microbiota salvages and processes its required nitrogen from breast milk. Human milk nitrogen sources such as urea could contribute to the composition of this early life microbiome. Urea is abundant in human milk, representing a large part of the non-protein nitrogen (NPN). We found that B. longum subsp. infantis (ATCC17930) can use urea as a main source of nitrogen for growth in synthetic medium and enzyme activity was induced by the presence of urea in the medium. We furthermore confirmed the expression of both urease protein subunits and accessory proteins of B. longum subsp. infantis through proteomics. To the same end, metagenome data were mined for urease-related genes. It was found that the breastfed infant's microbiome possessed more urease-related genes than formula fed infants (51.4:22.1; 2.3-fold increase). Bifidobacteria provided a total of 106 of urease subunit alpha alignments, found only in breastfed infants. These experiments show how an important gut commensal that colonizes the infant intestine can metabolize urea. The results presented herein further indicate how dietary nitrogen can determine bacterial metabolism in the neonate gut and shape the overall microbiome.