Simona Campolongo

Different protein expression profiles in cheese and clinical isolates of Enterococcus faecalis revealed by proteomic analysis

The use of Enterococcus faecalis in the food industry has come under dispute because of the pathogenic potential of some strains of this species. In this study, we have compared the secretome and whole‐cell proteome of one food isolate (E. faecalis DISAV 1022) and one clinical isolate (E. faecalis H1) by 2‐DE and iTRAQ analyses, respectively. Extracellular protein patterns differed significantly, with only seven proteins common to both strains. Notably, only the clinical isolate expressed various well‐characterized virulence factors such as the gelatinase coccolysin (GelE) and the extracellular serine proteinase V8 (SprE). Moreover, various other putative virulence factors, e.g. superoxide dismutase, choline‐ and chitin‐binding proteins and potential moonlighting proteins, have been detected exclusively in the secretome of the clinical isolate, but not in the food isolate. The iTRAQ analysis of whole‐cell proteins of the two strains highlighted a stronger expression of pathogenic traits such as an endocarditis‐specific antigen and an adhesion lipoprotein in the pathogenic strain E. faecalis H1. Subsequently, six food isolates (including E. faecalis DISAV 1022) and six clinical isolates (including E. faecalis H1) were tested for the presence of gelatinase and protease activity in the culture supernatants. Both enzymatic activities were found in the clinical as well as the food isolates which clearly indicates that protease expression is strain specific and not representative for pathogenic isolates. Genetic analyses revealed that not only the gelatinase and serine protease genes but also the regulatory fsr genes must be present to allow protease expression.

Prevalence and Biodiversity of Brettanomyces bruxellensis in Wine from Northwestern Italy

Brettanomyces bruxellensis is a catalyst in the transformation of hydroxycinnamic acids, compounds that naturally occur in grapes, producing volatile phenols that reduce the sensory quality of wine. Depending on their concentrations, volatile phenols can confer off-odors described as phenolic, animal, mousy, wet wool, medicinal, smoky, and spicy. We used a multidisciplinary approach for the detection and quantification of the presence of B. bruxellensis in 87 Italian wines, applying culture-independent and dependent methods (quantitative PCR and traditional microbiological analysis, respectively). Headspace solid-phase microextraction was used to quantify ethylphenols and vinylphenols. Results showed that there was no correlation between culture-dependent and culture-independent methods. Strain biodiversity was investigated by SAU-PCR and showed a differentiation of the isolates based on geographical origin.