Anti-Listeria activity of lactic acid bacteria in two traditional Sicilian cheeses

<em>Listeria monocytogenes</em> is a pathogen frequently found in dairy products, and its growth is difficult to control. Bacteriocinlike inhibitory substances (BLIS), produced by lactic acid bacteria (LAB), having proven <em>in vitro</em> anti-<em>Listeria</em> activity, could provide an innovative approach to control <em>L. monocytogenes</em>; however, this application needs to be evaluated <em>in vivo</em>. In this study, twenty LAB strains isolated from different Sicilian dairy environments were tested for control of growth of <em>L. monocytogenes</em> in three different experimental trials. First, raw and UHT milk …

Characterisation of the microflora contaminating the wooden vats used for traditional Sicilian cheese production

Traditional Sicilian cheese productions are carried out employing traditional wooden vats, called <em>tina.</em> Many studies have highlighted the beneficial role of wooden dairy equipment by contributing to enriching the milk microflora and improving the acidification processes. The present work was undertaken to evaluate the safety of the wooden vats used to coagulate milk. To this purpose, the different microbial populations hosted onto the internal surfaces of the vats used to produce two different stretched cheeses, namely <em>Caciocavallo Palermitano</em> and <em>Vastedda della valle del Belìce DOP</em>, were investigated for the presence of spoilag…

Analisi filogenetica condotta su ceppi di Bovine Diarrhea Virus (BVDV) isolati in Sicilia

La Diarrea Virale del Bovino-Malattia delle Mucose, è una malattia infettiva che colpisce i bovini, ampiamente diffusa a livello mondiale. L’agente infettivo responsabile è un virus provvisto di envelope e con un genoma ad RNA a singolo filamento e a polarità positiva, appartenente al genere Pestivirus, famiglia Flaviviridae. A causa dell’elevata capacità di andare in contro a mutazioni genetiche, esistono numerose varianti di BVDV con diverso assetto antigenico e differente patogenicità. Ad oggi sono noti due genotipi: il BVDV-I e il BVDV-II. Il BVDV-I comprende almeno 13 sottotipi, mentre ne sono stati descritti solo 2 per il BVDV-II. Quest’ultimo, poco diffuso nel nostro territorio, è re…

Investigation and control of a Norovirus outbreak of probable waterborne transmission through a municipal groundwater system

During March 2011 an outbreak of gastroenteritis occurred in Santo Stefano di Quisquina, Agrigento, Sicily, Italy. Within two weeks 156 cases were identified among the 4,965 people living in the municipality. An epidemiological investigation was conducted to characterize the outbreak and target the control measures. A case was defined as a person developing diarrhea or vomiting during February 27–March 13, 2011. Stool specimens were collected from 12 cases. Norovirus (NoV) genotype GII.4 variant New Orleans 2009 was identified in stool samples from 11 of 12 cases tested (91.7%). Epidemiological investigations suggested a possible association with municipal drinking water consumption. Water …

Surveillance of a municipal drinking-water supply after a Norovirus outbreak in Italy

Phenotypic and genotypic study on antibiotic resistance and pathogenic factors of Staphylococcus aureus isolates from small ruminant mastitis milk in South of Italy (Sicily)

Staphyloccoccus aureus is the major cause of mastitis in small ruminants in the Mediterranean farms causing severe losses to dairy industry. Antibiotic treatment has been the most common approach to control these infections. Aim of this study was to investigate antimicrobial resistance (AMR), virulence factors and biofilm-related genes of 84 Sicilian strains of S. aureus isolated from sheep and goats milk during two different periods δT1 (2006-2009) and δT2 (2013-2015). Kirby Bauer method and Polymerase Chain Reaction (PCR) were utilized to monitor AMR and related genes (mecA, tetK, tetM, ermA, ermC). Moreover, toxin genes (tsst-1, sea-see, seg-sej, and sep) and biofilm genes (bap, ica, sas…

Retrospective study on the hygienic quality of fresh ricotta cheeses produced in Sicily, Italy

The present work was carried out to investigate the microbiological profile of Sicilian ewes’ ricotta cheeses during fifteen years of investigations (2002-2016). The samples were collected between those conferred to the Istituto Zooprofilattico Sperimentale della Sicilia (IZSSi) Adelmo Mirri, Palermo (Italy), by the competent authority during official control, by food business operator in HACCP systems and in research projects. Enterobacteriaceae, Escherichia coli and coagulase-positive staphylococci (CPS) were found only in some samples. Bacillus cereus was detected in c.a. 16% of samples but the level of contaminations did not reach the threshold that leads to significant toxin production…

Valutazione in vitro di bacteriocin-like inhibitory substances prodotte da batteri lattici isolati da formaggi tradizionali siciliani

I batteri lattici (LAB) sono in grado di produrre differenti sostanze antimicrobiche tra cui le batteriocine, sostanze di natura proteica che stanno riscuotendo un crescente interesse per il loro possibile impiego come bio-conservanti per controllare e contenere i microrganismi indesiderati responsabili di contaminazioni e/o deterioramento delle matrici alimentari. Gli autori descrivono i risultati di uno screening volto all’identificazione di bacteriocin-like inhibitory substances (BLIS) prodotte da LAB isolati da processi produttivi di formaggi tradizionali siciliani utilizzando due metodi di screening e valutando la natura proteica delle sostanze antimicrobiche eventualmente prodotte, me…

Transfer, composition and technological characterization of the lactic acid bacterial populations of the wooden vats used to produce traditional stretched cheeses

The biofilms of 12 wooden vats used for the production of the traditional stretched cheeses Caciocavallo Palermitano and PDO Vastedda della valle del Belìce were investigated. Salmonella spp. and Listeria monocytogenes were never detected. Total coliforms were at low numbers with Escherichia coli found only in three vats. Coagulase-positive staphylococci (CPS) were below the enumeration limit, whereas lactic acid bacteria (LAB) dominated the surfaces of all vats. In general, the dominance was showed by coccus LAB. Enterococci were estimated at high numbers, but usually between 1 and 2 Log cycles lower than other LAB. LAB populations were investigated at species and strain level and for thei…

In vitro evaluation of bacteriocinlike inhibitory substances produced by lactic acid bacteria isolated during traditional sicilian cheese making

Bacteriocins are antimicrobial proteins produced by bacteria that inhibit with a bactericidal or bacteriostatic mode of action, the growth of other bacteria. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognized as safe (GRAS) and useful to control the frequent development of pathogens and spoilage microorganisms; for this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances (BLIS), by …

The Sicilian rock partridge: latest data on genetic integrity from four different relict areas

Sicily (Italy) hosts a “relict”, endemic population of the birds Alectoris graeca whitakeri commonly known as Sicilian Rock Partridge. In the last decades, due to the risk of restocking with other European and Asiatic species for hunting purpose, a study was carried out to investigate the potential risk of hybridisation. The mtDNA control-region and nuclear microsatellites were genotyped. Due to the importance of the species, samples were mainly characterized by feather and stool samples, and rarely by carcasses found in the environment, from year 2011 to 2012. A panel of 7 microsatellite loci was validated. Three multiplexes that allowed the simultaneous amplification of 3 microsatellites,…

Analysis of antigen-specific immune response in Brucella infection

Microbial diversity of traditional Sicilian cheeses

In the last years, the microbial characterisation of traditional Sicilian cheeses, such as Caciocavallo Palermitano, Protected Designation of Origin (PDO) Pecorino Siciliano and PDO Vastedda della valle del Belìce have been the object of different studies conducted by our research group. To this purpose, the aim of the present study was to describe the microbial population of traditional Sicilian cheeses.