Environmental factors affecting indole production in Escherichia coli

Abstract

A variety of both Gram-positive and Gram-negative bacteria produce large quantities of indole as an intracellular signal in microbial communities. Biosynthesis of indole is well-studied, and while carbon sources and amino acids are important environmental cues for indole production in Escherichia coli, other environmental factors affecting indole production for this strain are less clear. This study demonstrates that the environmental cue pH is an important factor for indole production that further controls biofilm formation of E. coli. Moreover, E. coli produced a higher level of extracellular indole in the presence of the antibiotics ampicillin and kanamycin, and the increased indole enhanced cell survival during antibiotic stress. Additionally, we found here that temperature is another important factor for indole production; E. coli produces and accumulates a large amount of indole at 50°C, even at low cell densities. Overall, our results suggest that indole is a stable biological compound, and E. coli may utilize indole to protect itself against other microorganisms.

Role of Indole Production on Virulence of Vibrio cholerae Using Galleria mellonella Larvae Model

“…The protective role of indole towards various stresses has been described in several microorganisms possibly through inducing efflux system or biofilm formation [31][32][33]. High level of extracellular indole was detected in E. coli in the stress condition of antibiotics treatment and supplementation or increase production of indole enhanced cell survival [10,13,14].…”

“…The presence of indole affects drug resistance, plasmid stability and virulence of E. coli and high concentration of indole decreases biofilm formation in some E. coli strains such as E. coli ATCC25404 and JM109 [7,[11][12][13]. Environmental factors that affect extracellular indole production have been demonstrated in E. coli [14]. Low pH inhibits indole production but it increases at high pH at both 30°C as well as 37°C.…”

“…High temperatures up to 50°C stimulate more indole production than at 25 or 37°C. Sodium chloride, ferrous chloride and cadmium chloride that greatly affect bacteria in the environment, have no effect on indole production [14]. The known roles of indole produced by V. cholerae in response to environmental conditions and its association to pathogenesis are still limited.…”

Effects of a novel nutritional formula specially developed for chronic kidney disease patients on protein-restricted diets: a randomized controlled trial

“…Plasma indoxyl sulfate increased in the CTR group, but was not changed in the SUP group. Production of indole, a precursor of indoxyl sulfate, by intestinal bacteria such as Escherichia coli is considered to alter under various conditions [18,19]. Lactulose and raffinose are known to stimulate growth of Bifidobacteria in the gut [20].…”

Proteus mirabilis interkingdom swarming signals attract blow flies

“…Gram-positive and Gram-negative bacteria both use QS communication to regulate their behavior, including symbiosis, virulence, competence, conjugation, antibiotic production, motility, sporulation and biofilm formation (Davies et al, 1998;González Barrios et al, 2006). Acylhomoserine lactones in Gram-negative bacteria as well as indole, and autoinducer 2 in both Gram-negative and Grampositive bacteria (Jayaraman and Wood, 2008;Han et al, 2010) are typical QS signals. QS regulates swarming motility (Daniels et al, 2004).…”