Amino Acid-Derived Bacterial Metabolites in the Colorectal Luminal Fluid: Effects on Microbial Communication, Metabolism, Physiology, and Growth

Abstract

Undigested dietary and endogenous proteins, as well as unabsorbed amino acids, can move from the terminal part of the ileum into the large intestine, where they meet a dense microbial population. Exfoliated cells and mucus released from the large intestine epithelium also supply nitrogenous material to this microbial population. The bacteria in the large intestine luminal fluid release amino acids from the available proteins, and amino acids are then used for bacterial protein synthesis, energy production, and in other various catabolic pathways. The resulting metabolic intermediaries and end products can then accumulate in the colorectal fluid, and their concentrations appear to depend on different parameters, including microbiota composition and metabolic activity, substrate availability, and the capacity of absorptive colonocytes to absorb these metabolites. The aim of the present review is to present how amino acid-derived bacterial metabolites can affect microbial communication between both commensal and pathogenic microorganisms, as well as their metabolism, physiology, and growth.

Bacterial Exofactors Modulate Biofilm Growth and Resistivity to Antimicrobial Drugs

“…However, P. aeruginosa degrades the indole and promotes E. coli biofilm formation [31]. Similarly, bacterial metabolites modulate bacterial growth and antimicrobial resistivity depending upon the nature and properties of the bacteria [17] [32]…”

“…Since exofactors from different bacteria have different concentrations of certain common factors (e.g., catalase, oxidase, kinases, proteases) and some additional factors (e.g., hyaluronidases, pyruvic acid & mupirocin) that influence the growth and modify the bacterial susceptibility to antibacterial drugs by the affect on different components of the bacteria [12] [16]. Some metabolites, for example, amino acid-derived, have a positive influence on the bacterial growth activities [17], while some have negative impacts on bacterial growth [18]. We cultured the selected bacteria with the presence of cell-free su-…”

Proteomics and metabolomics analyses of Streptococcus agalactiae isolates from human and animal sources

“…On the other hand, 4-hydroxybenzoic acid, galactonic acid, indole-3-propionic acid, indoleacetic acid, phenylacetic acid, and phenylglyoxal were uniquely identified in animal strains. They are implicated mainly in growth and survival, energy production, antibiotic resistance, signaling, biofilm formation, and oxidative stress 63 – 65 .…”