The current study aimed to investigate ethanolic extracts from the following medicinal plant species cultivated in western Romania: Melissa officinalis L., Rosmarinus officinalis L. (RO) and Salvia officinalis L. (SO). Antioxidant activity, total phenolics content and a profile of the main hydroxycinnamic acids (HCAs), including caffeic, ferulic, coumaric and rosmarinic acids, was determined for each plant extract. The in vitro antimicrobial activity against four bacterial strains (Escherichia coli, Listeria-, Pseudomonas aeruginosa and Staphylococcus aureus), and the effect on cell viability in two melanoma cell lines (B164A5 murine melanoma and A375 human melanoma) was also assessed. The results indicated that total phenolics content was 73.76–274.73 mg GAE·g−1 and the antioxidant activity was 2.32–2.87 mM Fe2+·100 g−1. There was found a strong positive correlation (R=0.9691) between total phenolics content and the antioxidant activity in the investigated samples. Regarding the HCA profile obtained by high performance liquid chromatography, the results demonstrated that rosmarinic acid represents the main identified compound. The ethanolic extracts of RO and SO exhibited antibacterial activity against Gram positive and Gram negative bacteria. RO was the most effective in terms of decreasing the cell viability of murine and human melanoma cell lines, while the HCAs did not exhibit any effect on cell viability. These findings suggest that plant extracts from the Lamiaceae family may used in the clinic as natural antibacterial agents.
Biofilms are surface-associated bacterial communities that predominate in natural and pathogenic ecosystems. Their formation in drinking water systems creates potential risks for consumers’ health. Herein we tested biofilm formation on materials commonly used for indoor household drinking water systems (copper, PVC and stainless steel) simulating an average family water usage. Water parameters were determined by standardized methods while biofilm formation was assessed by epifluorescent and laser scanning confocal microscopy, for determining the numbers of attached cells, biofilm thickness, colony size and average colony surface. Results showed a very fast colonization on all materials used, of log 6–7 cm−2 cells disposed on a single layer on copper and PVC. On stainless steel, beginning on the 24th experimental day, there were observed multiple layers of cells and a rapid increase of biofilm thickness. The lowest overall number of attached cells was found on copper. Microorganism colonization and biofilm formation is possible and quite fast on an indoor water system connected to a chlorinated water network. From the tested materials, the greatest risk to consumer health comes from biofilm formation on stainless steel parts which are used in the very large majority of residences.
Introduction: The antimicrobial role of probiotic Lactobacillus casei subspecies casei DG (L. casei DG) and of the mix culture of probiotic Lactobacillus acidophilus LA-5 and Bifidobacterium BB-12 was tested on species of Staphylococcus, Streptococcus, Pasteurella, and Neisseria genera from supragingival sites from dogs with dental disease of different breed, age, sex, weight, and diet. The research was conducted on these four genera because of their importance in zoonotic infections after dog bites. Methodology: Species from Staphylococcus, Streptococcus, Pasteurella, and Neisseria genera were isolated and identified. To test the antimicrobial efficacy of L. casei DG and the mixed culture of probiotic L. acidophilus LA-5 and Bifidobacterium bifidum BB-12 on the pathogenic species, the agar overlay method was used. Results: L. casei DG had a bactericidal effect on all analyzed species isolated from Staphylococcus, Streptococcus, Pasteurella, and Neisseria genera after 24 hours of incubation. The mixed probiotic culture made up of L. acidophilus LA-5 and Bifidobacterium BB-12 species had no bactericidal effect on the species of Staphylococcus and Streptococcus genera, which were resistant. However, it had a bacteriostatic effect on several species of Pasteurella and Neisseria genera. Conclusions: This work highlights the antimicrobial potential of probiotics in vitro, demonstrating that the probiotic L. casei DG has a bactericidal effect on all analyzed species isolated from dental plaque and that the mix culture of probiotic L. acidophilus LA-5 and Bifidobacterium BB-12 has only a bacteriostatic effect.
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