Effect of probiotic bacteria on porcine rotavirus OSU infection of porcine intestinal epithelial IPEC-J2 cells.

Rotavirus infections in nursing or post-weaning piglets are known to cause diarrhea, which can lead to commercial losses. Probiotic supplementation is used as a prophylactic or therapeutic approach to dealing with microbial infections in humans and animals. To evaluate the effect of probiotic bacteria on porcine rotavirus infections, non-transformed porcine intestinal epithelial IPEC-J2 cells were used as an in vitro model, and three different procedures were tested. When cells were exposed to seven probiotics at concentrations of 105, 106, or 107 CFU/mL for 16 h and removed before rotavirus challenge, infection reduction rates determined by flow cytometry were as follows: 15% (106) and 18% (105) for Bifidobacterium longum R0175, 15% (107) and 16% (106) for B. animalis lactis A026, and 15% (105) for Lactobacillus plantarum 299V. When cells were exposed to three selected probiotic strains for 1 h at higher concentrations, that is, 108 and 5 × 108 CFU/mL, before infection with rotavirus, no significant reduction was observed. When the probiotic bacteria were incubated with the virus before cell infection, a significant 14% decrease in the infection rate was observed for B. longum R0175. The results obtained using a cell-probiotics-virus platform combined with flow cytometry analysis suggest that probiotic bacteria can have a protective effect on IPEC-J2 cells before infection and can also prevent rotavirus infection of the cells.

Effect of the homogenization technique on the enumeration of psychrotrophic bacteria in food absorbent pads.

Four methods were tested for enumerating bacteria present in the absorbent pads (AP) used in packaging chicken and other meats. Viable counts were ascertained at day 0 and day 7 (d0 and d7, respectively). Sampling bacterial cells from AP were carried out using a countertop blender, Stomacher, sonication, and blender in combination to sonication. The release of bacterial cells by breaking down the AP with the blender resulted in the highest CFU counts. At d0, a bacterial recovery rate of 94% was obtained with the blender, while the recovery rates using Stomacher or sonication alone were 58% and 73%, respectively. At d7, the Stomacher treatment also gave the lowest colony forming unit (CFU) values in the AP incubated at 7 °C. Sonication of the AP prior to homogenization with the blender did not increase CFU counts. Results suggested that breaking down the AP with a blender gives higher CFU levels than the Stomacher, which is the most commonly used technique for this purpose.

Microencapsulation of a Staphylococcus phage for concentration and long-term storage.

In an effort to reduce food safety risks, virulent phages are investigated as antibacterial agents for the control of foodborne pathogens. The aim of this study was to evaluate microencapsulation (ME) as a tool to concentrate and store staphylococcal bacteriophages. As a proof of concept, phage Team1 belonging to the Myoviridae family was microencapsulated in alginate gel particles of 0.5 mm (micro-beads) and 2 mm (macro-beads) of diameter. Gel contraction occurred during the hardening period in the CaCl2 solution, and the diameters of the initial alginate droplets shrunk by 16% (micro-beads) and 44% (micro-beads). As compared to the phage counts in the alginate solution, this contraction resulted in the increase of the phage titers, per g of alginate gel, by factors of 2 (micro-beads) and 6 (micro-beads). The encapsulation yield was highest in the macro-beads. Although phage Team1 was successfully frozen in beads, ME did not improve phage stability to freeze-drying. The addition of glycerol protected the microencapsulated phages during freezing but had no effect on free phage suspensions. Finally, ME improved storage stability at 4 °C but had no impact on freezing or drying over three months of storage.

Evidence for Escherichia coli O157:H7 attachment to water distribution pipe materials by scanning electron microscopy.

Scanning electron microscopy observation was used to investigate the adhesion of Escherichia coli O157:H7 on water distribution pipe surfaces such as copper and polyethylene plastic at different contact times and storage temperatures. Our results indicated that E. coli cells could easily attach to both surface types after exposures as short as 1 or 4 h at ambient (20 degrees C) and refrigeration temperatures (4 degrees C). Also, we found that copper surfaces have a higher number of attached E. coli cells than plastic surfaces. The number of cells attached to each type of material depended on the nature of the water distribution pipe surfaces and the length of contact time. In addition, the surface energy value of each surface estimated by contact angle measurements using water, alpha-bromonaphthalene, and dimethyl sulfoxide as wetting agents showed that both copper (41.2 megajoules [MJ] m(-2)) and plastic (45.8 MJ x m(-2)) have a low energy surface. In no cases could evidence of extracellular material be observed on surfaces with either exposure condition.

Antimicrobial effect of natural preservatives in a cooked and acidified chicken meat model.

The inhibitory effect of Microgard 100, Microgard 300, nisin, Alta 2002, Perlac 1902, sodium lactate and essential oil of mustard on microorganisms experimentally inoculated was screened in an acidified chicken meat model (pH = 5.0) and stored for 2 weeks at a none restrictive growth temperature of 22 degrees C. All antimicrobials tested were used at the highest concentration recommended by their manufacturer. Sausage batter made with mechanically deboned chicken was inoculated with a mixed culture of Escherichia coli ATCC 25922, Brochothrix thermosphacta CRDAV452, and a protective culture Lactobacillus alimentarius BJ33 (FloraCan L-2). A final cell concentration of 3-4 log CFU g (-1) was targeted after cooking at a core temperature of 55 degrees C for each microorganism in order to assess cell count variation effectively. Composition, water activity (a(w)), pH and redox potential of the sausage model was also evaluated. The E. coli population decreased steadily during storage and was close or below detection level (< 1 log CFU g (-1)) for all treatments, including the control, after 14 days. Sodium lactate was most effective against B. thermosphacta; population was 4 log lower than the control after 14 days of storage. When essential oil of mustard was used, aerobic mesophilic bacteria and lactic acid bacteria were significantly lower than the control after 2 days of storage (P < or = 0.05). The other antimicrobial agents tested had no significant effect on the aerobic mesophilic bacteria, E. coli, B. thermosphacta and lactic acid bacteria counts, when compared to the control.

Attachment of Arcobacter butzleri, a new waterborne pathogen, to water distribution pipe surfaces.

The capability of Arcobacter butzleri to attach to various water distribution pipe surfaces, such as stainless steel, copper, and plastic, was evaluated using scanning electron microscopy. Our results indicated that Arcobacter cells could easily attach to all surface types and the number of attached cells depended on the length of exposure and temperatures (4 and 20 degrees C). Extracellular fibrils were also observed on the stainless steel surface, especially after 72 h of contact times at both refrigeration and ambient temperatures. In addition, the surface energy value of each material was estimated by contact angle measurements using water, alpha-bromonaphthalene, and dimethylsulfoxide. The surface energy of A. butzleri was 58.6 mJ x m(-2) and the surface energy values of the three surfaces studied showed that plastic had a low energy surface (26.1 mJ x m(-2)) as did copper (45.8 mJ x m(-2)) and stainless steel (65.7 mJ x m(-2)).