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In the present study, six Lactococcus lactis and seven Lactiplantibacillus plantarum strains isolated from artisanal Sardinian dairy products were evaluated for their efficacy in controlling the growth of Listeria monocytogenes during the storage of miniature fresh cheese manufactured on a laboratory scale to exploit their possible use as biopreservatives. The strains were tested for antimicrobial activity and some technological characteristics before using them in miniature fresh cheese to evaluate their in situ antilisterial effect. Our results showed that five strains (L. lactis 16FS16-9/20234-11FS16 and Lpb. plantarum 1/14537-4A/20045) could be considered suitable candidates for use as protective cultures in fresh cheese manufacture since they significantly lowered the pathogen counts by 3–4 log units compared to the control; however, all strains tested were capable of decreasing L. monocytogenes numbers. Our results suggest that the single and combined action of the acidifying power and the production of bacteriocin of these strains was capable of controlling and/or reducing the growth of L. monocytogenes. Considering their technological characteristics, they might be used as starter/adjunct cultures to increase the safety of the products, perhaps in association with other antimicrobial hurdles. [ABSTRACT FROM AUTHOR]

With the aim of selecting LAB strains with antilisterial activity to be used as protective cultures to enhance the safety of dairy products, the antimicrobial properties of 117 Lactococcus lactis subsp. lactis isolated from artisanal Sardinian dairy products were evaluated, and six strains were found to produce bacteriocin-like substances. The capacity of these strains to antagonize Listeria monocytogenes during cocultivation in skimmed milk was evaluated, showing a reduction of L. monocytogenes counts of approximately 4 log units compared to the positive control after 24 h of incubation. In order for a strain to be used as bioprotective culture, it should be carefully evaluated for the presence of virulence factors, to determine what potential risks might be involved in its use. None of the strains tested was found to produce biogenic amines or to possess haemolytic activity. In addition, all strains were sensitive to clinically important antibiotics such as ampicillin, tetracycline, and vancomycin. Our results suggest that these bac+ strains could be potentially applied in cheese manufacturing to control the growth of L. monocytogenes. [ABSTRACT FROM AUTHOR]

The mechanism of the candidacidal activity of histatins 3 and 5 (Hst) is still a matter of debate. Previous studies have indicated that Hst induce cell permeabilization, generation of reactive oxygen species (ROS) by mitochondria, inhibition of the respiratory chain, and energy-dependent cytotoxic release of ATP. On the other hand, the multiplicity of effects and the apparent contrast between experimental data continue to render the mechanism of Hst-induced killing of C. albicans unclear. In this investigation, using fluorescent probes (the potential-sensitive mitochondrial probe tetramethylrhodamine methyl ester perchlorate, TMRM; the ROS-sensitive probe dihydrofluorescein diacetate, DHF; the membrane-impermeant probe, calcein) and autofluorescence data we observed that Hst induce ROS generation by mitochondria undergoing a high energy swelling condition, accompanied by oxidation of cytosolic NAD(P)H and mitochondrial flavoproteins. ROS generation and swelling, attributable to an inhibition of the respiratory chain and to impairment of the K/H-exchanger, were followed by mitochondrial depolarization. Mitochondrial changes were accompanied by massive calcein influx, indicative of cell permeabilization, and prominent alterations of the cell size, shape, and optical density. The loss of proliferative activity was correlated, on a single cell basis, to the acquisition of a lipofuscin-like autofluorescence. Microsc. Res. Tech. 66:219-228, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is one of the main public health concerns of this century. This resistance is also associated with oxidative stress, which could contribute to the selection of resistant bacterial strains. Bearing this in mind, and considering that flavonoid compounds are well known for displaying both activities, we investigated a series of hydroxy-3-arylcoumarins with structural features of flavonoids for their antibacterial activity against different bacterial strains. Active compounds showed selectivity against the studied Gram-positive bacteria compared to Gram-negative bacteria. 5,7-Dihydroxy-3-phenylcoumarin (compound 8) displayed the best antibacterial activity against Staphylococcus aureus and Bacillus cereus with minimum inhibitory concentrations (MICs) of 11 μg/mL, followed by Staphylococcus aureus (MRSA strain) and Listeria monocytogenes with MICs of 22 and 44 μg/mL, respectively. Moreover, molecular docking studies performed on the most active compounds against Staphylococcus aureus tyrosyl-tRNA synthetase and topoisomerase II DNA gyrase revealed the potential binding mode of the ligands to the site of the appropriate targets. Preliminary structure–activity relationship studies showed that the antibacterial activity can be modulated by the presence of the 3-phenyl ring and by the position of the hydroxyl groups at the coumarin scaffold. [ABSTRACT FROM AUTHOR]

Twenty-three Lactobacillus strains of dairy origin were evaluated for some functional properties relevant to their use as probiotics. A preliminary subtractive screening based on the abilities to inhibit the growth of microbial pathogens and hydrolyze conjugated bile salts was applied, and six strains were selected for further characterization including survival under gastrointestinal environmental conditions, adhesion to gut epithelial tissue, enzymatic activity, and some safety properties. All selected strains maintained elevated cell numbers under conditions simulating passage through the human gastrointestinal tract, well comparable to the values obtained for the probiotic strain Lactobacillus rhamnosus GG, and were able to adhere to Caco-2 cells to various extents (from 3 to 20%). All strains exhibited high aminopeptidase, and absent or very low proteolytic and strong β-galactosidase activities; none was found to be haemolytic or to produce biogenic amines and all were susceptible to tetracycline, chloramphenicol, erythromycin, ampicillin, and amoxicillin/clavulanic acid. Our results indicate that the Lactobacillus strains analyzed could be considered appropriate probiotic candidates, due to resistance to GIT simulated conditions, antimicrobial activity, adhesion to Caco-2 cell-line, and absence of undesirable properties. They could be used as adjunct cultures for contributing to the quality and health related functional properties of dairy products. [ABSTRACT FROM AUTHOR]

Background and Aim: On January 9, 2020, the World Health Organization (WHO) declared that Chinese health authorities had identified a new coronavirus strain never before isolated in humans, the 2019-nCoV later redefined SARS-CoV-2, that still today represent a public health problem. The present survey started on 10 February 2020 with the aim of a) assessing the risk perception in healthcare workers and young students, following the evolution of attitudes, perception and knowledge over time, b) provide useful information to the general population during survey., Results: A study sample consisting of 4116 Italian individuals of both sexes was enrolled. High levels of risk perception, low perception of self-efficacy and low levels of knowledge scores (24.55 ± 5.76 SD) were obtained indicating the need for continuous population monitoring as well as further communication strategies carried out at institution levels., Conclusion: The results of the present study could help public health authorities in carrying out informative campaigns for general population and could be an important tool in evaluating public knowledge and misperceptions during the management of the COVID-19. (www.actabiomedica.it).