3-indolylacetonitrile decreases Escherichia coli O157:H7 biofilm formation and Pseudomonas aeruginosa virulence.
Intercellular signal indole and its derivative hydroxyindoles inhibit Escherichia coli biofilm and diminish Pseudomonas aeruginosa virulence. However, indole and bacterial indole derivatives are unstable in the microbial community because they are quickly degraded by diverse bacterial oxygenases. Hence, this work sought to identify novel, non-toxic, stable and potent indole derivatives from plant sources for inhibiting the biofilm formation of E. coli O157:H7 and P. aeruginosa. Here, plant auxin 3-indolylacetonitrile (IAN) was found to inhibit the biofilm formation of both E. coli O157:H7 and P. aeruginosa without affecting its growth. IAN more effectively inhibited biofilms than indole for the two pathogenic bacteria. Additionally, IAN decreased the production of virulence factors including 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), pyocyanin and pyoverdine in P. aeruginosa. DNA microarray analysis indicated that IAN repressed genes involved in curli formation and glycerol metabolism, whereas IAN induced indole-related genes and prophage genes in E. coli O157:H7. It appeared that IAN inhibited the biofilm formation of E. coli by reducing curli formation and inducing indole production. Also, corroborating phenotypic results of P. aeruginosa, whole-transcriptomic data showed that IAN repressed virulence-related genes and motility-related genes, while IAN induced several small molecule transport genes. Furthermore, unlike bacterial indole derivatives, plant-originated IAN was stable in the presence of either E. coli or P. aeruginosa. Additionally, indole-3-carboxyaldehyde was another natural biofilm inhibitor for both E. coli and P. aeruginosa.
Lee
Jin-Hyung
JH
School of Display and Chemical Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 712-749, Korea.
Cho
Moo Hwan
MH
School of Display and Chemical Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 712-749, Korea.
Lee
Jintae
J
School of Display and Chemical Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 712-749, Korea.
D000097:Acetonitriles / Q000494:pharmacology*; D018830:Adhesins, Escherichia coli / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D007211:Indoles / Q000378:metabolism / Q000494:pharmacology*; D008855:Microscopy, Electron, Scanning; D020411:Oligonucleotide Array Sequence Analysis; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D012329:RNA, Bacterial / Q000235:genetics; D014774:Virulence / Q000187:drug effects; D037521:Virulence Factors / Q000096:biosynthesis
C518704:3-indolylacetonitrile; D000097:Acetonitriles; D018830:Adhesins, Escherichia coli; D001426:Bacterial Proteins; D007211:Indoles; D012329:RNA, Bacterial; D037521:Virulence Factors; C077481:Crl protein, Bacteria; C030374:indole