Amino Acids

, Volume 45, Issue 3, pp 501–512

l-Glutamine regulates amino acid utilization by intestinal bacteria

Original Article

DOI: 10.1007/s00726-012-1264-4

Cite this article as:
Dai, ZL., Li, XL., Xi, PB. et al. Amino Acids (2013) 45: 501. doi:10.1007/s00726-012-1264-4

Abstract

Catabolism of amino acids (AA) by intestinal bacteria greatly affects their bioavailability in the systemic circulation and the health of animals and humans. This study tests the novel hypothesis that l-glutamine regulates AA utilization by luminal bacteria of the small intestine. Pure bacterial strains (Streptococcus sp., Escherichia coli and Klebsiella sp.) and mixed bacterial cultures derived from the jejunum or ileum of pigs were cultured in the presence of 0–5 mM l-glutamine under anaerobic conditions. After 3 h of incubation, samples were taken for the determination of AA utilization. Results showed concentration-dependent increases in the utilization of glutamine in parallel with the increased conversion of glutamine into glutamate in all the bacteria. Complete utilization of asparagine, aspartate and serine was observed in pure bacterial strains after the 3-h incubation. The addition of glutamine reduced the net utilization of asparagine by both jejunal and ileal mixed bacteria. Net utilization of lysine, leucine, valine, ornithine and serine by jejunal or ileal mixed bacteria decreased with the addition of glutamine in a concentration-dependent manner. Collectively, glutamine dynamically modulates the bacterial metabolism of the arginine family of AA as well as the serine and aspartate families of AA and reduced the catabolism of most AA (including nutritionally essential and nonessential AA) in jejunal or ileal mixed bacteria. The beneficial effects of glutamine on gut nutrition and health may involve initiation of the signaling pathways related to AA metabolism in the luminal bacteria of the small intestine.

Keywords

Amino acids Gut bacteria Small intestine Nutrition Swine 

Abbreviations

AA

Amino acids

CFU

Colony forming unit

EAA

Nutritionally essential amino acid

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Laboratory of Gastrointestinal MicrobiologyNanjing Agricultural UniversityNanjingChina
  2. 2.Department of Animal ScienceTexas A&M UniversityCollege StationUSA

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