The adhesion of spores of five different Bacillus species to solid surfaces of different hydrophobicity was evaluated. The spore surface hydrophobicity was measured using hydrophobic interaction chromatography (HIC). A large variation in hydrophobicity was found among the spores of the different species tested. The degree of adhesion of spores to the solid surfaces was consistent with the results obtained using the HIC method. The most hydrophobic spores, according to the HIC method, adhered in a much larger extent to the hydrophobic surfaces. Furthermore, spores generally adhered to a greater extent to hydrophobic and hydrophilic surfaces than did the vegetative cells.

No abstract

The biotransfer potential in food processing is defined as the ability of the microorganisms present on equipment surfaces both before and after cleaning procedures to contaminate products during processing. Growth of Bacillus biofilms was detectable on both stainless-steel and Teflon© surfaces after all the cleaning procedures. B. cereus and B. subtilis cells adhered more firmly to unsoiled than to soiled surfaces, whereas B. thuringiensis adhered most firmly to soiled surfaces. The results showed that the removal of biofilms from surfaces was more difficult from stainless steel because the microorganisms were attached more tenaciously to rough surfaces. Biofilms were cleaned most effectively from unsoiled surfaces with a simple rinsing procedure; thus the mechanical forces of the flow are very important in the cleaning. The chemical and heat treatments used for cleaning had the greatest impact on the abundance of living microorganisms. All the procedures tested did not remove biofilm material effectively from the surfaces. Significantly more cells were removed when the alkaline phase in the alkaline-acid treatment of the cleaning-in-place (CIP) procedure was prolonged, and ethylene diaminetetraacetic acid (EDTA) was used.

The adhesion of Bacillus cereus spores (NCTC 2599) to hydrophobic and hydrophilic glass surfaces was studied when environmental conditions were varied. The spores were exposed in media of different polarities as well as different pH and ionic concentrations. With increasing ethanol concentrations, the polarity of the medium was decreased and the predominant force of attraction was found to be hydrophobic. The spore surface was uncharged at a pH around 3, at which value the spore was most adhesive to both hydrophobic and hydrophilic glass. This could be attributable to the absence of electrostatic repulsion. An increased ionic concentration of the bulk increased the degree of adhesion especially to the hydrophilic surfaces. This indicates the suppression of a solvation barrier at high ionic concentrations, when the polymers of the spore surface become dehydrated.

The aim of this study was to characterize human isolates of Lactobacillus species for their capacity to interfere with the growth of different strains of Candida species in vitro in the search for a potential probiotic. Growth inhibition of Candida species was screened using an agar-overlay method. Inhibiting strains were selected to assay the effect of a cell-free Lactobacillus culture filtrate (LCF) on the growth of isolates of Candida albicans and Candida glabrata. A total of 126 human Lactobacillus isolates was investigated. Eighteen isolates significantly inhibited the growth of C. albicans on agar. The LCF of one of these strains showed strong inhibition of both C. albicans and C. glabrata. This strain was genetically identified as Lactobacillus fermentum and designated L. fermentum Ess-1. Further tests to evaluate the probiotic potential of this strain indicated that L. fermentum Ess-1 strain is a promising probiotic for use in clinical trials to treat and prevent vulvo-vaginal candidiasis.