Microcin MccPDI reduces the prevalence of susceptible Escherichia coli in neonatal calves

Abstract

Aims: Microcin MccPDI-producing Escherichia coli have a fitness advantage in dairy calves. For this project, we determined whether MccPDI is responsible for the in vivo fitness advantage, which is a necessary condition before MccPDI strains can be considered viable candidates for inhibiting pathogenic serovars of E. coli. Methods and Results: Neonatal calves were coinoculated with either MccPDIproducing E. coli or MccPDI-knockout mutants in conjunction with a susceptible strain. After 6 days, the MccPDI-producing E. coli-25 strain clearly dominated the E. coli-186 susceptible strain in the inoculated calves (P = 0Á003). MccPDI-producing E. coli composed a higher log percentage of the total population of lactose-fermenting bacteria in the faeces (5Á51 log CFU per 8Á03 log CFU) compared with the knockout strain (2Á6 log CFU per 8Á23 log CFU) (P = 0Á01), and it was more consistently recovered from the lower gastrointestinal tract at the time of necropsy (P = 0Á01). Conclusion: Our findings support the hypothesis that MccPDI is functional in vivo and it is most likely responsible for a fitness advantage in vivo. Significance and Impact of the Study: MccPDI-producing E. coli strongly inhibit pathogenic E. coli strains in vitro. We show herein that MccPDI functions in vivo, and thus, these strains may be candidate probiotics against pathogenic strains of E. coli.

Genome-Wide Screening Identifies Six Genes That Are Associated with Susceptibility to Escherichia coli Microcin PDI

“…All resulting complemented strains were competed against the E. coli 25⌬traM strain in M9 medium with IPTG and chloramphenicol as described above. For competition experiments with the K⌬ompF(ompF) strain, the concentration of IPTG was reduced to 20 M. The E. coli 25⌬traM strain was used for these experiments because it produces the PDI phenotype against susceptible strains but is nonconjugative due to the insertion of a chloramphenicol gene in traM (3).…”

“…In trans expression of ompF in the ⌬dsbA and ⌬dsbB strains did not restore a susceptible phenotype, indicating that these proteins are probably involved with the formation of disulfide bonds for OmpF or microcin PDI. E scherichia coli strain 25 (E. coli 25; cattle origin) has an in vitro and in vivo competitive advantage against other E. coli strains that is linked to the production of the microcin PDI (MccPDI) (1)(2)(3). The inhibitory phenotype was first observed in vitro (4) and later called "proximity-dependent inhibition" (PDI), because inhibition occurred only when competing cells were in close proximity to sensitive cells (1).…”

Autoinducer-2 Quorum Sensing Contributes to Regulation of Microcin PDI in Escherichia coli

“…MccPDI was first described from a cattle E. coli isolate 25 ( E. coli 25) and it inhibits a diversity of E. coli strains including enterohemorrhagic E. coli (EHEC) serotypes O157:H7 and O26 (Eberhart et al, 2012 , 2014 ; Zhao et al, 2015 ). The inhibitory phenotype was characterized as “proximity-dependent inhibition” (PDI) due to the apparent need for the producing strain to be in close proximity to inhibit susceptible cells (Sawant et al, 2011 ; Eberhart et al, 2012 ).…”

Antimicrobial Effect of Probiotics against Common Pathogens

“…The antimicrobial activity of probiotic microorganisms has a very wide area application including adjuvant therapy to antibiotic consumption or for correcting dysbiosis of the gastrointestinal tract microbiome due to diarrhoea [37,38,106], antagonistic activity in humans against urinary tract infections [26,66,75], eradicating H. pylori infections [87], nosocomial infections [15,96], dental biofilm formation [72], lowering serum cholesterol [10,55], treating fevers [31], as well as in the agro-food industry for manufacturing fermented products [44,62,107], preventing food spoilage [16,23,41], as food additives for functional foods [50,56,57,59,67,97], as prophylactic agents, adjuvants or alternatives to antibiotic therapies to antibiotic therapy in poultry [34,47,68], cattle [105,108], pigs [45], fish [74,78] and other livestock industry [104], just to name a few.…”