Viability and surface properties of spores subjected to a cleaning-in-place procedure: Consequences on their ability to contaminate surfaces of equipment

Hydrophobicity and specific biofilm features of Bacillus cereus spores subjected to pH stresses

“…However, to the best of the authors' knowledge, this property has not been investigated when cells were submitted to more severe pH-stresses, like those encountered during cleaning procedures. Faille et al (2010) have already shown exosporium glycoproteins to be seriously damaged by spore treatments using severe alkaline stress (2% NaOH at 80°C for 20 min) and this should result in a decrease in spore hydrophobicity as shown in the current study. On another hand, hydrophilic spores displayed more limited hydrophobicity changes as compared to highly hydrophobic spores, so that the highest percentage of hydrophobicity change (40.5%) was recorded for the most hydrophobic strain, BC ATCC 11778.…”

“…The biofilms formed by pH-treated spores, in all culture media were not well developed structures, in terms of tridimensional architecture, or net-like patterns. This should be ascribed to the loss of the viability of most of the pH-treated spores or the loss of their ability to adhere due to damaged structures, as previously demonstrated (Faille et al, 2010;Shaheen et al, 2010). As an illustration, the 48 h old biofilm formed in nutrient broth was little elaborated structure which consists of a twodimensional net-like attachment pattern, previously described for biofilms formed in poorly nutritional conditions (Marsh et al, 2003).…”

“…Spore suspensions were pH-treated using the protocol of Faille et al (2010), with minor modification. One volume of the stock suspensions was added to 1 volume of aqueous 2% w/v NaOH or 1% HNO3 w/v to absorbance values between 0.8-1.…”

“…Tubes containing NaOH or HNO3 spore mixtures were respectively incubated at 80 and 70°C for 10 min. After each treatment, spores were rapidly cooled, harvested as previously described (Faille et al, 2010) and re-suspended in saline to absorbance values between 0.8-1. Hydrophobicity of the pH-treated spores was assessed as described above.…”

“…Spores of B. cereus have mainly been investigated for survival, adhesion and biofilm formation after CIP-like stresses (Faille et al, 2010;Salutiano et al, 2010;Shaheen et al, 2010). However, it remains unknown how the conditions encountered by spores during cleaning procedures affected spore surface hydrophobicity.…”