Seeds of Abies nebrodensis were subjected to laboratory tests aimed to detect fungal contaminants and to obtain xenobiotic-free seedlings, by the use of different surface sterilising agents. ...Moreover, hot water at 60 °C was used to suppress any fungal microorganisms colonizing the inner tissues. Alternaria alternata, Aspergillus flavus and Stemphylium vesicarium were the most frequent fungal contaminants. Non-contaminated seeds showed germination values ranging from 0 to 36.4% depending on the applied sterilization protocol. Further analyses will be carried out to establish the influence of these fungi on the seed germination process and their relationship with seedlings of A. nebrodensis.
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ABSTRACTLeccinum scabrum (Bull.) Gray (Boletaceae) is an edible mycorrhizal species with potential application interest due to its food and medicinal properties. A field investigation carried out ...during summer in the Białowieża Primeval Forest, located along the border between Belarus and Poland allowed to collect samples for chemical composition analysis and antibacterial activity evaluation. Mushroom extracts were prepared with microwave-assisted as well as ultrasound-assisted extraction techniques (UAE and MAE). The analysis of a dry sample of L. scabrum showed a significant content of vitamins and minerals and also a remarkable content of carbohydrates, protein, dietary fibre, total sugars, total free amino acids, and polyunsaturated fatty acids. The antibacterial activity of L. scabrum aqueous extracts showed inhibitory activity against all tested bacteria. In general, MAE extract exhibits a higher inhibition activity against Listeria monocytogenes ATCC 19114. As regards the Minimum Inhibitory Concentration (MIC) values, the high antibacterial activity of MAE extract was detected for L. monocytogenes ATCC 19114 and Escherichia coli ATCC 25922. Regarding UAE, high antibacterial activity was detected for Salmonella enterica ATCC 13076 and L. monocytogenes ATCC 19114. Based on data hereby reported, L. scabrum is a culinary-medicinal mushroom with a promising potential use as a high-quality food and nutraceutical mycological resource.
Background: Tuber aestivum Vittad., known as black summer truffle, represents high-value food especially used as garnishment in nouvelle cuisine. The aim of this study was to investigate on the ...viable microbial populations associated with T. aestivum ascomata collected in different sites of Sicily and one locality of Umbria (Italy).
Methods: The ripe ascomata of black summer truffles were collected from Central Italy. Cell densities of spoilage bacteria, fecal indicators, potential pathogens, yeasts, and molds were analyzed. Statistical analysis was conducted with XLSTAT software.
Results: The microbiological counts of truffles ranged between 6.00 and 9.63 log Colony Forming Unit (CFU)/g for total mesophilic count and between 6.18 and 8.55 log CFU/g for total psychrotrophic count; pseudomonads were in the range 6.98-9.28 log CFU/g. Listeria spp. and coagulase-positive streptococci detected in no samples. Coagulase-negative streptococci were found in some samples with 2.11-4.76 log CFU/g levels. Yeasts and filamentous fungi were detected at consistent levels of 3.60-7.81 log CFU/g. Significant differences (p<0.01) were found between samples and also for all microbial groups.
Conclusion: This study evidenced that the common brushing procedure applied for preparation of truffles is not sufficient to eliminate microbial risks for consumers. The application of an efficient decontamination treatment is strongly suggested before consumption of fresh truffles.
Background: Consumption of raw cheese may be associated with different diseases. This study aimed to evaluate behavior of four pathogenic bacteria during manufacture and ripening of Protected ...Designation of Origin (PDO) Pecorino Siciliano cheese.
Methods: The experimental cheese groups were inoculated with pathogenic bacteria, including Escherichia coli O157, Listeria monocytogenes, Salmonella Enteritidis, and Staphylococcus aureus. The cheese making processes were monitored from milk curdling until 3 months ripened cheeses and the levels of Lactic Acid Bacteria (LAB) and the four dairy pathogens were evaluated by plate counts. Randomly Amplified Polymorphic DNA (RAPD)-Polymerase Chain Reaction (PCR) analysis was applied to confirm that the colonies isolated during the several steps of production were the same strains added in milk. Statistical analysis was done using XLStat software.
Results: The levels of mesophilic and thermophilic coccus and rod LAB in curd were comparable in both trials and reached values between 8-9 log10 Colony Forming Unit (CFU)/g in cheeses at 90 days of ripening. The four pathogenic bacteria were found in experimental curd at levels higher than those inoculated in milk and completely disappeared after 60 days of ripening. The RAPD analysis clearly demonstrated the presence of the added strain during production and confirmed the results of plate counts.
Conclusion: This work showed that the production conditions of PDO Pecorino Siciliano cheese decreased growth of E. coli O157, L. monocytogenes, S. Enteritidis, and S. aureus
Background: Lactic Acid Bacteria (LAB) are an important group of microorganisms responsible for the fermentation dairy products. This study was done to identify the dominant lactic acid bacteria in ...naturally fermented milks from Messinese goat’s breed. Methods: Eighteen individual raw milk samples collected from Messinese goat’s breed were acidified at pH 5.20 and left to spontaneously ferment at 37 °C for 4 days. All samples were analyzed for rod- and coccus-shaped LAB. Also, all presumptive LAB were isolated and differentiated according to their phenotypic properties and genetic polymorphisms and then identified by sequencing the 16S rRNA gene. Data were statistically analyzed using SAS 9.2 software. Results: Levels of coccus- and rod-shaped LAB were in the range of 1.78-7.10 log and 1.00-7.09 log colony forming unit/ml, respectively. The microbiological counts on the two different growth media were significantly (p<0.05) different among the samples. Among 12 identified strains, the most numerous one was Enterococcus hirae (n=4), followed by E. faecium (n=3), while the other species (E. durans, E. faecalis, E. lactis, Lactococcus lactis, and Leuconostoc lactis) included one strain each. Conclusion: The major group identified in this study was mainly represented by members of Enterococcus genus. Although Enterococcus spp. are related to the typicality of some traditional fermented dairy products, this study highlights the need for risk assessment of pathogenic enterococci species for the consumers.
Transition metal oxides in the d0 perovskite class, defined broadly to include WO3, have shown promise as light absorbers for photocatalytic applications. These compounds are highly tunable in their ...composition and atomic structure, and consequently, in their electronic structure and properties. Through the lens of atomic orbital interactions and density functional theory calculations, the present work explores how and why certain structural distortions tune the band gaps and band edges of WO3 and d0 perovskite oxides. It is determined that, because an individual distortive mode (e.g., polar distortion along or octahedral rotation around a cubic perovskite axis) changes the character of only some band-edge orbitals, combinations of distortive modes may tune band gaps much more significantly than the sum of individual modes. The implications of this tunability are discussed for WO3 as a photocatalyst, and for d0 perovskite oxides more generally.
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