Properties of an Antimicrobial Molecule Produced by an Escherichia coli Champion

Abstract

Over recent decades, the number and frequency of severe pathogen infections have been increasing. Pathogen mitigation strategies in human medicine or in livestock operations are vital to combat emerging arsenals of bacterial virulence and defense mechanisms. Since the emergence of antimicrobial resistance, the competitive nature of bacteria has been considered for the potential treatment or mitigation of pathogens. Previously, we identified a strong E. coli competitor with probiotic properties producing a diffusible antimicrobial molecule(s) that inhibited the growth of Shiga toxin-producing E. coli (STEC). Our current objective was to isolate and examine the properties of this antimicrobial molecule(s). Molecules were isolated by filter sterilization after 12 h incubation, and bacterial inhibition was compared to relevant controls. Isolated antimicrobial molecule(s) and controls were subjected to temperature, pH, or protease digestion treatments. Changes in inhibition properties were evaluated by comparing the incremental cell growth in the presence of treated and untreated antimicrobial molecule(s). No treatment affected the antimicrobial molecule(s) properties of STEC inhibition, suggesting that at least one molecule produced is an efficacious microcin. The molecule persistence to physiochemical and enzymatic treatments could open a wide window to technical industry-scale applications.

Escherichia coli: Physiological Clues Which Turn On the Synthesis of Antimicrobial Molecules

“…Culture conditions for the Molecule extraction assay [ 20 ]: O/N cultures of O157A and O103F were diluted to an OD of 0.1 measured at a wavelength of 600 nm in either fresh EC, LB, TSB, TSB/EC or TSB+ ( Table 1 ) and grown for 3 h. The 3 h culture was then used as inoculum for molecule isolation assays.…”

“…Molecule extraction assays were performed as previously described [ 20 ]. In short, both O103F and O157A were grown separately for 12 h in liquid media and subsequently filter-sterilized to remove all the bacterial cells and complex biomolecules by size exclusion.…”

“…Previously, by creating an agarose-based physical barrier between competitive E. coli strains, our so-called omelette method, we identified a champion strain (O103F) that produced one and/or a complex of strong diffusible molecule(s) (subsequently referred to as molecule) with antimicrobial properties that maintained a strong zone of no growth monitored for up to 7 days and had the strongest zone of no growth even when the agar barrier thickness and distance between competitors increased incrementally [ 19 ]. Subsequent experiments using a molecule extraction assay revealed that the molecule has microcin characteristics, including the persistence to physiochemical conditions (pH 3 and 11, autoclave temperature ≥121 ℃ and pressure ≥ 12.4 N/cm 2 ) as well as enzymatic digestion treatments [ 20 ]. Based on our current understanding, no viable biological molecule can persist autoclave conditions with the exception of misfolded prions, endospores and microcins, suggesting that after micro filtration and subsequent treatment, the remaining molecule is likely a microcin.…”

Bioprocessing and integration of a high flux screening systematic platform based on isothermal amplification for the detection on 8 common pathogens

“…Pathogens mediated infectious diseases in human beings and animals remain a major concern in public health [1]. During a large variety of common pathogens, E. coli, P. aeruginosa, S. aureus (especially methicillin-resistant Staphylococcus aureus, MRSA), coagulase-negative staphylococci (MRCNS), V. parahaemolyticus, L. monocytogenes and Salmonella are the leading pathogens responsible for large number of human infections and diseases [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, bacterial identification of such pathogens requires up to several days [16].…”

Antibacterial Peptides

“…Apart from providing a tool to investigate the mode of action of antibacterials on Gram-positive bacteria, this approach might be particularly useful to screen novel AMPs. Other key studies by Flórez-Castillo [3], Della Pelle [4], Paquette [5], and their collaborators have reported on the structural properties, molecular docking simulation experiments, and/or antibacterial potential of specific antimicrobials, i.e., Ib-M6, Antarctic fish (transcriptome-derived) Trematocine, and E. coli antimicrobial molecule, respectively. The data presented are of great interest in the field and may help the design of potent candidate AMPs.…”