Attachment of Listeria innocua to Polystyrene: Effects of Ionic Strength and Conditioning Films from Culture Media and Milk Proteins

2014 ◽  
Vol 77 (3) ◽  
pp. 427-434 ◽  
Author(s):  
GILLES ROBITAILLE ◽  
SÉBASTIEN CHOINIÈRE ◽  
TIMOTHY ELLS ◽  
LOUISE DESCHÈNES ◽  
AKIER ASSANTA MAFU

It is recognized that bacterial adhesion usually occurs on conditioning films made of organic macromolecules absorbed to abiotic surfaces. The objectives of this study were to determine the extent to which milk protein–coated polystyrene (PS) pegs interfere with biofilm formation and the synergistic effect of this conditioning and hypertonic growth media on the bacterial adhesion and biofilm formation of Listeria innocua, used as a nonpathogenic surrogate for Listeria monocytogenes. PS pegs were uncoated (bare PS) or individually coated with whey proteins isolate (WPI), β-lactoglobulin, bovine serum albumin, or tryptic soy broth (TSB) and were incubated in bacterial suspensions in modified Welshimer's broth. After 4 h, the number of adherent cells was dependent on the coating, as follows: TSB (107 CFU/ml) > bare PS > β-lactoglobulin > bovine serum albumin ≈ WPI (104 CFU/ml). The sessile cell counts increased up to 24 h, reaching >107 CFU per peg for all surfaces (P > 0.1), except for WPI-coated PS; this indicates that the inhibitory effects of milk protein conditioning films are transient, slowing down the adhesion process. The 4-h bacterial adhesion on milk protein–coated PS in modified Welshimer's broth supplemented with salt (0 to 10% [wt/vol]) did not vary (P > 0.1), indicating that conditioning with milk proteins was the major determinant for inhibition of bacterial adhesion and that the synergetic effect of salt and milk proteins on adhesion was minimal. Moreover, the presence of 5 to 10% salt significantly inhibited 24-h biofilm formation on the TSB-coated and bare PS, with a decrease of >3 log at 10% (wt/vol) NaCl and almost completely depleted viable sessile bacteria on the milk protein–coated PS.

2014 ◽  
Vol 82 (1) ◽  
pp. 78-85 ◽  
Author(s):  
Joanna Fotschki ◽  
Anna Szyc ◽  
Barbara Wróblewska

The similarity of mare's milk to breast milk makes it an interesting substrate for the creation of dairy beverages. The aim of this study was to determine the immunoreactivity of the digested mare's milk products carried out by lactic acid fermentation with Lactobacillus casei LCY, Streptococcus thermophilus MK10 and Bifidobacterium animalis Bi30. Simulation of digestion with saliva, pepsin and pancreatin/bile salts was carried out. The immunoreactivity of the milk proteins was assessed by competitive ELISA. The separation of proteins was studied using a tricine SDS-PAGE method. It has been demonstrated that lactic acid fermentation significantly decreases the immunoreactivity of β-lactoglobulin, β-casein, κ-casein and bovine serum albumin. The level of reduction was connected to the type of bacterial strain. The simulated digestion processes caused the decline of immunoreactivity, and the decreases obtained in the experiment were as follows: lactoferrin: 95%, β-lactoglobulin: 94%, β-casein: 93%, α-lactalbumin: 82%, α-casein: 82%, bovine serum albumin: 76% and κ-casein: 37%. The results of the study indicated that microbial fermentation with tested strains is a valuable method for reducing the immunoreactivity of mare's milk proteins. However, further studies with other bacterial strains are needed to gain a higher level of elimination or total reduction of mare's milk immunoreactivity to possibly introduce fermented mare's milk into the diet of patients with immune-mediated digestive problems.


1966 ◽  
Vol 21 (4) ◽  
pp. 305-313 ◽  
Author(s):  
G. Reske ◽  
F. Nimmerfall ◽  
J. Stauff

Interactions of eosin with three different substrates, β-lactoglobuline, bovine serum albumin and cysteine, in aqueous solutions of pH 7 under illumination with light of wavelengths 5200—5400 Å are investigated by changes in absorption spectrum characteristics, SH-group activities and phosphorescence intensities.Only with bovine serum albumin the major part of protein conversion, as shown by spectral changes and diminution of SH-groups due to eosin-sensitized photo-oxidation. In β-lactoglobuline an oxidizing photoreaction occurs, by which eosin is vanishing to the same degree as the protein shows loss of SH-groups and spectral alterations indicating attack on aromatic amino acid residues. There is no red shift of the eosin absorption band at 5170 Å as is observed in solutions of bovine serum albumin, where the intensity of phosphorscence is about 100 fold compared with the intensity obtained by solutions of β-lactoglobulin.The aerobic eosin photoreaction in solutions of β-lactoglobulin is faster than aerobic photobleaching of the dye. Still faster is its bleaching photoreaction with cysteine, which is nearly independent of oxygen.


1991 ◽  
Vol 40 (1) ◽  
pp. 55-69 ◽  
Author(s):  
Naotoshi Matsudomi ◽  
Douglas Rector ◽  
J.E. Kinsella

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