Enterotoxigenic Escherichia coli (ETEC) and Shiga toxin-producing E. coli (STEC) strains are the causative agents of severe foodborne diseases in both humans and animals. In this study, porcine pathogenic E. coli strains (n = 277) as well as porcine commensal strains (n = 188) were tested for their susceptibilities to 34 bacteriocin monoproducers to identify the most suitable bacteriocin types inhibiting porcine pathogens. Under in vitro conditions, the set of pathogenic E. coli strains was found to be significantly more susceptible to the majority of tested bacteriocins than commensal E. coli. Based on the production of bacteriocins with specific activity against pathogens, three potentially probiotic commensal E. coli strains of human origin were selected. These strains were found to be able to outcompete ETEC strains expressing F4 or F18 fimbriae in liquid culture and also decreased the severity and duration of diarrhea in piglets during experimental ETEC infection as well as pathogen numbers on the last day of in vivo experimentation. While the extents of the probiotic effect were different for each strain, the cocktail of all three strains showed the most pronounced beneficial effects, suggesting synergy between the tested E. coli strains. IMPORTANCE Increasing levels of antibiotic resistance among bacteria also increase the need for alternatives to conventional antibiotic treatment. Pathogenic Escherichia coli represents a major diarrheic infectious agent of piglets in their postweaning period; however, available measures to control these infections are limited. This study describes three novel E. coli strains producing antimicrobial compounds (bacteriocins) that actively inhibit a majority of toxigenic E. coli strains. The beneficial effect of three potentially probiotic E. coli strains was demonstrated under both in vitro and in vivo conditions. The novel probiotic candidates may be used as prophylaxis during piglets' postweaning period to overcome common infections caused by E. coli.

• Keywords
• E. coli, ETEC, Escherichia, STEC, bacteriocin, pig, probiotic,
• MeSH
• Bacterial Toxins * metabolism   MeSH
• Bacteriocins metabolism   therapeutic use   MeSH
• Escherichia coli * drug effects   genetics   metabolism   MeSH
• Virulence Factors genetics   MeSH
• Feces microbiology   MeSH
• Escherichia coli Infections microbiology   prevention & control   veterinary   MeSH
• Swine Diseases microbiology   prevention & control   MeSH
• Swine MeSH
• Probiotics therapeutic use   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Randomized Controlled Trial, Veterinary MeSH
• Names of Substances
• Bacterial Toxins * MeSH
• Bacteriocins MeSH
• Virulence Factors MeSH

Colicin U is a protein produced by the bacterium Shigella boydii (serovars 1 and 8). It exerts antibacterial activity against strains of the enterobacterial genera Shigella and Escherichia Here, we report that colicin U forms voltage-dependent pores in planar lipid membranes; its single-pore conductance was found to be about 22 pS in 1 M KCl at pH 6 under 80 mV in asolectin bilayers. In agreement with the high degree of homology between their C-terminal domains, colicin U shares some pore characteristics with the related colicins A and B. Colicin U pores are strongly pH dependent, and as we deduced from the activity of colicin U in planar membranes at different protein concentrations, they have a monomeric pore structure. However, in contrast to related colicins, we observed a very low cationic selectivity of colicin U pores (1.5/1 of K+/Cl- at pH 6) along with their atypical voltage gating. Finally, using nonelectrolytes, we determined the inner diameter of the pores to be in the range of 0.7 to 1 nm, which is similar to colicin Ia, but with a considerably different inner profile.IMPORTANCE Currently, a dramatic increase in antibiotic resistance is driving researchers to find new antimicrobial agents. The large group of toxins called bacteriocins appears to be very promising from this point of view, especially because their narrow killing spectrum allows specific targeting against selected bacterial strains. Colicins are a subgroup of bacteriocins that act on Gram-negative bacteria. To date, some colicins are commercially used for the treatment of animals (1) and tested as a component of engineered species-specific antimicrobial peptides, which are studied for the potential treatment of humans (2). Here, we present a thorough single-molecule study of colicin U which leads to a better understanding of its mode of action. It extends the range of characterized colicins available for possible future medical applications.

• Keywords
• Shigella boydii, black lipid membrane, colicin U, ion-selectivity, membrane pores,
• MeSH
• Cell Membrane metabolism   MeSH
• Potassium Chloride pharmacology   MeSH
• Ion Channel Gating MeSH
• Colicins metabolism   MeSH
• Hydrogen-Ion Concentration MeSH
• Lipid Bilayers metabolism   MeSH
• Permeability MeSH
• Shigella boydii metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Potassium Chloride MeSH
• Colicins MeSH
• Lipid Bilayers MeSH

Colicin production in Escherichia coli (E. coli) strains represents an important trait with regard to microbial survival and competition in the complex intestinal environment. A novel colicin type, colicin Z (26.3 kDa), was described as a product of an original producer, extraintestinal E. coli B1356 strain, isolated from the anorectal abscess of a 17 years-old man. The 4,007 bp plasmid (pColZ) was completely sequenced and colicin Z activity (cza) and colicin Z immunity (czi) genes were identified. The cza and czi genes are transcribed in opposite directions and encode for 237 and 151 amino acid-long proteins, respectively. Colicin Z shows a narrow inhibitory spectrum, being active only against enteroinvasive E. coli (EIEC) and Shigella strains via CjrC receptor recognition and CjrB- and ExbB-, ExbD-mediated colicin translocation. All tested EIEC and Shigella strains isolated between the years 1958-2010 were sensitive to colicin Z. The lethal effect of colicin Z was found to be directed against cell wall peptidoglycan (PG) resulting in PG degradation, as revealed by experiments with Remazol Brilliant Blue-stained purified peptidoglycans and with MALDI-TOF MS analyses of treated PG. Colicin Z represents a new class of colicins that is structurally and functionally distinct from previously studied colicin types.

• MeSH
• Escherichia coli genetics   MeSH
• Colicins genetics   MeSH
• Humans MeSH
• Microbial Sensitivity Tests MeSH
• Adolescent MeSH
• Plasmids genetics   MeSH
• Base Sequence MeSH
• Shigella genetics   MeSH
• Check Tag
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Colicins MeSH

Yersiniosis belongs to the common foodborne diseases around the world, and frequently manifests as diarrhea that can be treated with probiotics. Colicin FY is an antibacterial agent produced by bacteria and it is capable of specific growth inhibition of Yersinia enterocolitica, the causative agent of gastrointestinal yersiniosis. In this study, recombinant E. coli producing colicin FY were constructed, using both known probiotic strains EcH22 and EcColinfant, and the newly isolated murine strains Ec1127 and Ec1145. All E. coli strains producing colicin FY inhibited growth of pathogenic Y. enterocolitica during co-cultivation in vitro. In dysbiotic mice treated with streptomycin, E. coli strains producing colicin FY inhibited progression of Y. enterocolitica infections. This growth inhibition was not observed in mice with normal gut microflora, likely due to insufficient colonization capacity of E. coli strains and/or due to spatial differences in intestinal niches. Isogenic Y. enterocolitica producing colicin FY was constructed and shown to inhibit pathogenic Y. enterocolitica in mice with normal microflora. Evidence of in vivo antimicrobial activity of colicin FY may have utility in the treatment of Y. enterocolitica infections.

• MeSH
• Escherichia coli genetics   metabolism   physiology   MeSH
• Colicins metabolism   MeSH
• Mice MeSH
• DNA, Recombinant genetics   MeSH
• Intestines microbiology   MeSH
• Yersinia enterocolitica physiology   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Colicins MeSH
• DNA, Recombinant MeSH

BACKGROUND: Bacteriocin production is an important characteristic of E. coli strains of human origin. To date, 26 colicin and 9 microcin types have been analyzed on a molecular level allowing molecular detection of the corresponding genes. The production incidence of 29 bacteriocin types and E. coli phylogroups were tested in a set of 361 E. coli strains isolated from human urinary tract infections (UTI) and in 411 control strains isolated from feces of patients without bacterial gut infection. RESULTS: Production of 17 and 20 individual bacteriocin types was found in the UTI and control strains, respectively. Microcin H47 encoding determinants were found more often among UTI strains compared to controls (37.9% and 27.0% respectively, p = 0.02) and strains producing microcin H47 belonged predominantly to phylogroup B2 when compared to other bacteriocin producers (67.4% and 36.7%, respectively; p < 0.0001). Producers of 3 or more identified bacteriocin types were more common in the UTI group (20.0% compared to 12.4% in controls, p = 0.03). In the UTI strains, there was a markedly higher number of those producing colicin E1 compared to controls (22.1% to 10.2%, respectively, p = 0.0008). Moreover, colicin E1 production was more common in the UTI bacteriocinogenic strains with multi-producer capabilities. As shown by Southern blotting, pColE1 DNA was not recognized by the ColIa probe and vice versa suggesting that pColE1 was independently associated with pColIa in UTI strains. CONCLUSION: E. coli strains isolated from human urinary tract infections showed increased incidence of microcin H47 and colicin E1 production, respectively. Moreover, colicin E1 itself appears to be a potentially important virulence factor of certain uropathogenic E. coli strains.

• MeSH
• Bacteriocins biosynthesis   genetics   MeSH
• Escherichia coli genetics   isolation & purification   metabolism   MeSH
• Virulence Factors genetics   metabolism   MeSH
• Feces microbiology   MeSH
• Urinary Tract Infections microbiology   MeSH
• Escherichia coli Infections microbiology   MeSH
• Colicins genetics   metabolism   MeSH
• Humans MeSH
• Uropathogenic Escherichia coli genetics   isolation & purification   metabolism   MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Bacteriocins MeSH
• Virulence Factors MeSH
• Colicins MeSH

Striking differences in the production of specific inhibitory agents affecting other strains of the same (or of related) species were found between genera of the family Enterobacteriaceae. We tested 50-163 strains each of the potentially pathogenic genera: Escherichia, Citrobacter, Enterobacter, Kluyvera, and Leclercia for their ability to produce bacteriophages, high-molecular-weight (HMW) and low-molecular-weight (LMW) bacteriocins and siderophores against the same sets of strains, using the cross-test method. The genus Escherichia differs substantially from all other Enterobacteriaceae, harboring a notable proportion of lysogenic (36.6%) and colicinogenic (13.9%) strains. Only 18.2% of the Citrobacter strains are lysogenic and only rarely are they colicinogenic, although in 7.3%, they produce phage tail-like bacteriocins. On the other hand, Kluyvera strains were only in 1.8% lysogenic, no colicinogenic strains were found, but in 7.3%, they produced siderophores causing zones of growth inhibition in agar cultures of strains of the same genus. In Leclercia, 10.0% of the strains were lysogenic, 2.0% produced HMW bacteriocins, no colicinogenic strains were found and 2.0% produced siderophores. Enterobacter has shown 23.1% of strains producing siderophores, whereas merely 7.7% were lysogenic, 1.9% colicinogenic and 3.8% formed phage tail-like bacteriocins. HMW bacteriocins of Enterobacter strains disposed of an unusually wide spectrum of activity. The siderophore activity spectrum was rather wide in any genus, but the siderophores were usually not produced by strains producing phages or colicins.

• MeSH
• Anti-Bacterial Agents biosynthesis   MeSH
• Bacteriocins biosynthesis   MeSH
• Bacteriophages physiology   MeSH
• Enterobacteriaceae classification   metabolism   virology   MeSH
• Incidence MeSH
• Colicins metabolism   MeSH
• Culture Media MeSH
• Humans MeSH
• Lysogeny MeSH
• Molecular Weight MeSH
• Siderophores metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Bacteriocins MeSH
• Colicins MeSH
• Culture Media MeSH
• Siderophores MeSH

Colicins are toxic exoproteins produced by bacteria of colicinogenic strains of Escherichia coli and some related species of Enterobacteriaceae, during the growth of their cultures. They inhibit sensitive bacteria of the same family. About 35% E. coli strains appearing in human intestinal tract are colicinogenic. Synthesis of colicins is coded by genes located on Col plasmids. Until now more than 34 types of colicins have been described, 21 of them in greater detail, viz. colicins A, B, D, E1-E9, Ia, Ib, JS, K, M, N, U, 5, 10. In general, their interaction with sensitive bacteria includes three steps: (1) binding of the colicin molecule to a specific receptor in the bacterial outer membrane; (2) its translocation through the cell envelope; and (3) its lethal interaction with the specific molecular target in the cell. The classification of colicins is based on differences in the molecular events of these three steps.

• MeSH
• Escherichia coli chemistry   metabolism   MeSH
• Escherichia coli Infections microbiology   MeSH
• Colicins classification   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Colicins MeSH