The effect of surface properties on bacterial retention: a study utilising stainless steel and TiN/25.65at.%Ag substrata

The requirement for antimicrobial surfaces to control microorganisms for use in the food industries is increasing. A TiN/25.65at.%Ag coating and a stainless steel (304 2R) surface were characterised for roughness parameters, chemistry and physicochemistry (PC). Microbiological analysis was performed to determine the antimicrobial efficacy and retention of Staphylococcus aureus and Escherichia coli on the surfaces. Zone of inhibition assays were successful against only E. coli on the TiN/25.65at.%Ag coating. A bacterial respiratory assay demonstrated that the TiN/25.65at.%Ag coating was antimicrobial against both bacteria. Retention assays demonstrated that the physicochemistry of the bacteria and surfaces influenced bacterial retention. Multifractal analysis of the retained bacteria demonstrated that the surface properties affected the spread and clustering, but not the density of the bacteria. This work suggests that surface properties influenced specific species: surface interactions and therefore surfaces need to be tailored to specific requirements depending on the environment and microorganisms to be targeted. This work may aid in the production of coatings or surfaces that may provide more hygienic conditions

Genomic, Proteomic and Physiological Characterization of a T5-like Bacteriophage for Control of Shiga Toxin-Producing Escherichia coli O157:H7

Despite multiple control measures, Escherichia coli O157:H7 (STEC O157:H7) continues to be responsible for many food borne outbreaks in North America and elsewhere. Bacteriophage therapy may prove useful for controlling this pathogen in the host, their environment and food. Bacteriophage vB_EcoS_AKFV33 (AKFV33), a T5-like phage of Siphoviridae lysed common phage types of STEC O157:H7 and not non-O157 E. coli. Moreover, STEC O157:H7 isolated from the same feedlot pen from which the phage was obtained, were highly susceptible to AKFV33. Adsorption rate constant and burst size were estimated to be 9.31×10−9 ml/min and 350 PFU/infected cell, respectively. The genome of AKVF33 was 108,853 bp (38.95% G+C), containing 160 open reading frames (ORFs), 22 tRNA genes and 32 strong promoters recognized by host RNA polymerase. Of 12 ORFs without homologues to T5-like phages, 7 predicted novel proteins while others exhibited low identity (<60%) to proteins in the National Centre for Biotechnology Information database. AKVF33 also lacked the L-shaped tail fiber protein typical of T5, but was predicted to have tail fibers comprised of 2 novel proteins with low identity (37–41%) to tail fibers of E. coli phage phiEco32 of Podoviridae, a putative side tail fiber protein of a prophage from E. coli IAI39 and a conserved domain protein of E. coli MS196-1. The receptor-binding tail protein (pb5) shared an overall identify of 29–72% to that of other T5-like phages, with no region coding for more than 6 amino acids in common. Proteomic analysis identified 4 structural proteins corresponding to the capsid, major tail, tail fiber and pore-forming tail tip (pb2). The genome of AKFV33 lacked regions coding for known virulence factors, integration-related proteins or antibiotic resistance determinants. Phage AKFV33 is a unique, highly lytic STEC O157:H7-specific T5-like phage that may have considerable potential as a pre- and post-harvest biocontrol agent