The soil yeast Tetrapisispora phaffii secretes a killer toxin, named Kpkt, that shows β-glucanase activity and is lethal to wine spoilage yeasts belonging to Kloeckera/Hanseniaspora, Saccharomycodes and Zygosaccharomyces. When expressed in Komagataella phaffii, recombinant Kpkt displays a wider spectrum of action as compared to its native counterpart, being active on a vast array of wine yeasts and food-related bacteria. Here, to gather information on recombinant Kpkt cytotoxicity, lyophilized preparations of this toxin (LrKpkt) were obtained and tested on immortalized human keratinocyte HaCaT cells, a model for the stratified squamous epithelium of the oral cavity and esophagus. LrKpkt proved harmless to HaCaT cells at concentrations up to 36 AU/mL, which are largely above those required to kill food-related yeasts and bacteria in vitro (0.25-2 AU/mL). At higher concentrations, it showed a dose dependent effect that was comparable to that of the negative control and therefore could be ascribed to compounds, other than the toxin, occurring in the lyophilized preparations. Considering the dearth of studies regarding the effects of yeast killer toxins on human cell lines, these results represent a first mandatory step towards the evaluation the possible risks associated to human intake. Moreover, in accordance with that observed on Ceratitis capitata and Musca domestica, they support the lack of toxicity of this toxin on non-target eukaryotic models and corroborate the possible exploitation of killer toxins as natural antimicrobials in the food and beverages industries.

• Klíčová slova
• HaCaT cells, Kpkt, natural antimicrobial, yeast killer toxin,
• Publikační typ
• časopisecké články MeSH

Chitosan, fucoidan, and polyvinyl alcohol are categorized as polymers with biomedical applications. Ampicillin, on the other hand, is considered as an important antibiotic that has shown effectivity in both gram-positive and gram-negative micro-organisms. The aforementioned polymers possess unique properties that are considered desirable for cell regeneration although they exhibit drawbacks that can affect their final application. Therefore, films of these biomaterials were prepared and they were characterized using FTIR, SEM, XRD, degree of swelling and solubility, and MTT assay. The statistical significance of the experiments was determined using a two-way analysis of variance (ANOVA) with p < 0.05. The characterization techniques demonstrated that the obtained material exhibits properties suitable for cell regeneration, and that a higher concentration of natural polymers promotes cells proliferation to a greater extent. The presence of PVA, on the other hand, is responsible for matrix stability and dictates the degree of swelling and solubility. The SEM images demonstrated that neither aggregations nor clusters were formed, which is favorable for the biological properties without detrimental to the morphological and physical features. Cell viability was comparatively similar in samples with and without antibiotic, and the physical and biological properties were not negatively affected. Indeed, the inherent bactericidal effect of chitosan was reinforced by the presence of ampicillin. The new material is an outstanding candidate for cell regeneration as a consequence of the synergic effect that each component provides to the blend.

• Klíčová slova
• ampicillin, bioartificial polymeric material, cell proliferation, chitosan, fucoidan, polyvinyl alcohol,
• Publikační typ
• časopisecké články MeSH

Bio-artificial polymeric systems are a new class of polymeric constituents based on blends of synthetic and natural polymers, designed with the purpose of producing new materials that exhibit enhanced properties with respect to the individual components. In this frame, a combination of polyvinyl alcohol (PVA) and chitosan, blended with a widely used antibiotic, sodium ampicillin, has been developed showing a moderate behavior in terms of antibacterial properties. Thus, aqueous solutions of PVA at 1 wt.% were mixed with acid solutions of chitosan at 1 wt.%, followed by adding ampicillin ranging from 0.3 to 1.0 wt.% related to the total amount of the polymers. The prepared bio-artificial polymeric system was characterized by FTIR, SEM, DSC, contact angle measurements, antibacterial activity against Staphylococcus aureus and Escherichia coli and antibiotic release studies. The statistical significance of the antibacterial activity was determined using a multifactorial analysis of variance with ρ < 0.05 (ANOVA). The characterization techniques did not show alterations in the ampicillin structure and the interactions with polymers were limited to intermolecular forces. Therefore, the antibiotic was efficiently released from the matrix and its antibacterial activity was preserved. The system disclosed moderate antibacterial activity against bacterial strains without adding a high antibiotic concentration. The findings of this study suggest that the system may be effective against healthcare-associated infections, a promising view in the design of novel antimicrobial biomaterials potentially suitable for tissue engineering applications.

• Klíčová slova
• ampicillin, bio-artificial polymeric system, chitosan, health-care associated infections, polyvinyl alcohol,
• MeSH
• ampicilin * chemie   farmakologie   MeSH
• antibakteriální látky * chemická syntéza   chemie   farmakologie   MeSH
• chitosan * chemie   farmakologie   MeSH
• Escherichia coli růst a vývoj   MeSH
• polyvinylalkohol * chemie   farmakologie   MeSH
• Staphylococcus aureus růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ampicilin * MeSH
• antibakteriální látky * MeSH
• chitosan * MeSH
• polyvinylalkohol * MeSH