Escherichia coli, an Intestinal Microorganism, as a Biosensor for Quantification of Amino Acid Bioavailability

Sensors

Vesela I. Chalova¹  Sujata A. Sirsat¹  Corliss A. O𠆛ryan¹  Philip G. Crandall¹ 

[1] Center for Food Safety-IFSE, and Departments of Food and Poultry Sciences, University of Arkansas, Fayetteville, AR 72704, USA;

关键词: Escherichia coli;    amino acid bioavailability;    microbial biosensors;    amino acid/peptide assimilation;   

DOI  :  10.3390/s90907038

来源: mdpi

【 摘 要 】

In animal diets optimal amino acid quantities and balance among amino acids is of great nutritional importance. Essential amino acid deficiencies have negative impacts on animal physiology, most often expressed in sub-optimal body weight gains. Over supplementation of diets with amino acids is costly and can increase the nitrogen emissions from animals. Although in vivo animal assays for quantification of amino acid bioavailability are well established, Escherichia coli-based bioassays are viable potential alternatives in terms of accuracy, cost, and time input. E. coli inhabits the gastrointestinal tract and although more abundant in colon, a relatively high titer of E. coli can also be isolated from the small intestine, where primary absorption of amino acids and peptides occur. After feed proteins are digested, liberated amino acids and small peptides are assimilated by both the small intestine and E. coli. The similar pattern of uptake is a necessary prerequisite to establish E. coli cells as accurate amino acid biosensors. In fact, amino acid transporters in both intestinal and E. coli cells are stereospecific, delivering only the respective biological l-forms. The presence of free amino- and carboxyl groups is critical for amino acid and dipeptide transport in both biological subjects. Di-, tri- and tetrapeptides can enter enterocytes; likewise only di-, tri- and tetrapeptides support E. coli growth. These similarities in addition to the well known bacterial genetics make E. coli an optimal bioassay microorganism for the assessment of nutritionally available amino acids in feeds.

【 授权许可】

CC BY   
© 2009 by the authors; licensee MDPI, Basel, Switzerland