Biopreservation potential of Enterococcus faecalis isolated from Italian traditional raw milk cheeses

Enterococcus faecalis is frequently associated with raw milk cheeses of Mediterranean area. The genetic diversity of 38 E. faecalis obtained from raw milk products in Italy was assessed through Randomly Amplified Polymorphic DNA PCR (RAPD-PCR) and repetitive extragenic palindromic PCR (rep-PCR). The strains were screened for their antimicrobial activity against 5 food-borne spoilage and pathogenic bacteria and 13 lactic acid bacteria (LAB), commonly used as starter cultures. Investigation was made to identify the bacteriocinogenic potential by searching for bacteriocin-encoding genes. Inhibitory effects against undesirable bacteria, including Bacillus cereus (44.7% of strains), Escherichia coli (18.4%), Listeria monocytogenes (15.8%), Staphylococcus aureus (2.6%), and Clostridium sporogenes (21.1%), were detected. Moderate antagonism towards LAB was found. One strain producing enterocin AS-48 was identified, suggesting that the antimicrobial activity of the phenotypically positive isolates should be neces..

Lactic acid bacteria with cholesterol-lowering properties for dairy applications: In vitro and in situ activity.

Cholesterol-lowering activity is one of the most promising properties of lactic acid bacteria with probiotic characteristics. In the present study, 58 potentially probiotic lactic acid bacteria were tested for their ability to survive in vitro digestion and reduce cholesterol in a medium containing cholesterol and bile acids. The best-performing strains (Lactobacillus casei VC199, Lactobacillus paracasei ssp. paracasei SE160 and VC213, Lactobacillus plantarum VS166 and VS513, Enterococcus faecium VC223, and Enterococcus lactis BT161) resulted in a 42 to 55% reduction of the cholesterol level in broth and were further tested in cheese manufacture. The cholesterol content in all the cheeses decreased with ripening. All the strains were present in the cheese at levels higher than 107 cfu/g until 60 d of ripening, the highest reductions (up to 23%) being obtained when Lb. paracasei ssp. paracasei VC213 and E. lactis BT161 were added during the cheese-making. The adjunct cultures had no negative effect on the sensory characteristics of the cheese. Thus, these strains with proven in vitro properties are good candidates for novel probiotic-containing formulations and could be used to functionalize foods such as dairy fermented products

Villa Ceriani e il suo parco, nuove idee per il riuso conservativo

Nel corso della primavera 2021 Villa Ceriani e il parco sono stati oggetto delle analisi e dei progetti di conservazione e riuso del corso e laboratori di restauro del Politecnico di Milano, Polo territoriale di Lecco. L’efficace e fattiva collaborazione con il Comune e soprattutto con la direttrice del Museo archeologico di Erba ha permesso di mettere a fuoco le necessità e le aspettative delle amministrazioni pubbliche e dei cittadini riguardo una delle più prestigiose e ben conservate ville del territorio comunale. I laboratori di restauro hanno permesso agli studenti di approfondire la conoscenza del sito e dei manufatti grazie al metodo rigoroso della conservazione. I risultati sono stati molti e riguardano diversi aspetti. Innanzitutto, gli studenti hanno affrontato la complessità che l’intervento sul costruito storico implica negli aspetti applicativi. Inoltre, la richiesta di continuo adattamento alle modalità di lavoro, (in classe, a distanza, per piccoli gruppi, raramente sul posto, individualmente con momenti di discussione telematici, ecc.) ha necessariamente sviluppato la capacità di concentrazione sull’obiettivo e di saper sfruttare, in modo flessibile, tutte le risorse che venivano messe a disposizione o che occorreva ricercare. Infine, le modalità di comunicazione preferibilmente on line hanno richiesto di svilupparne l’efficacia favorendo forme espressive integrative (grafiche, fotografiche, di simulazione via software) che hanno potenziato le capacità trasversali alle discipline curriculari del corso di Ingegneria edile - architettura

Molecular typing and differences in biofilm formation and antibiotic susceptibilities among Prototheca strains isolated in Italy and Brazil.

Bovine mastitis caused by Prototheca is a serious and complex problem that accounts for high economic losses in the dairy industry. The main objective of this study was to identify and characterize at genetic level different Prototheca strains and provide the most complete data about protothecal antibiotic resistance. The study involves 46 isolates from Italian (13 strains) and Brazilian (33 strains) mastitic milk. These strains were identified by multiplex PCR and single strand conformation polymorphism analysis and characterized by randomly amplified polymorphic DNA (RAPD)-PCR. Moreover, biofilm production and antibiotic susceptibility were evaluated. Forty-two strains resulted as Prototheca zopfii genotype 2, whereas 4 isolates could belong to a potential new Prototheca species. The RAPD-PCR, performed with 3 primers (M13, OPA-4, and OPA-18), showed a notable heterogeneity among isolates and grouped the strains according to the species and geographical origin. Biofilm production was species-dependent and P. zopfii genotype 2 strains were classified as strong biofilm producers. In vitro antibiotic susceptibility tests indicated that Prototheca strains were susceptible to antibacterial drugs belonging to aminoglycosides group; the highest activity against Prototheca strains was observed in the case of colistin sulfate, gentamicin, and netilmicin (100% of susceptible strains). It is interesting to note that all the Italian P. zopfii genotype 2 strains showed lower minimum inhibitory concentration values than the Brazilian ones. Nisin showed more efficacy than lysozyme and potassium sorbate, inhibiting 31% of the strains. Results obtained in this study confirmed that RAPD-PCR is a rapid, inexpensive, and highly discriminating tool for Prototheca strains characterization and could give a good scientific contribution for better understanding the protothecal mastitis in dairy herd

Different Analytical Approaches in Assessing Antibacterial Activity and the Purity of Commercial Lysozyme Preparations for Dairy Application

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Synergistic Action of Reactive Plasma Particles and UV Radiation to Inactivate Staphylococcus Aureus

The direct application of low-pressure plasma for the decontamination of microorganisms was examined herein. The inactivation efficiency was studied on a Gram-positive bacterium (Staphylococcus aureus) using a plasma process by means of synergistic action of reactive plasma particles and UV radiation. N2 was added to an argon/oxygen plasma mixture in order to improve the effectiveness of S. aureus inactivation. It was found that the decontamination mechanism is based on both the chemical sputtering effect due to the plasma particles and the UV emission originating from the NOγ system from NO radicals in the wavelength range 200–300 nm. The best plasma bactericidal activity was found for an N2 percentage of roughly 10–12%. A count reduction of more than 5 log cycles in a few minutes of S. aureus proves the potentiality of an industrial-grade plasma reactor as a decontamination agent