Heavy metal tolerance and removal efficiency of the Rhodotorula mucilaginosa and Saccharomyces boulardii planktonic cells and biofilm

The impact of heavy metals, cadmium (Cd2+), zinc (Zn2+) and nickel (Ni2+) on planktonic cells and biofilm of Rhodotorula mucilaginosa and Saccharomyces boulardii was examined. The metal tolerance testing was performed by MBECTM-HTP assay. The minimum inhibitory concentration (MICp) and minimum lethal concentration (MLCp) were determined as well as the minimum biofilm eradication concentration (MBEC). Biofilm was more tolerant on the presence of heavy metals than the planktonic cells. The planktonic cells of R. mucilaginosa were tolerant to high concentrations of Cd2+, Zn2+ and Ni2+, while the planktonic cells of S. boulardii tolerated Zn2+, exclusively. The R. mucilaginosa biofilm was tolerant to all of the tested metal concentrations and the obtained results were confirmed by fluorescence microscopy. S. boulardii did not show ability of biofilm formation. Metal removal efficiency of the R. mucilaginosa planktonic cells and biofilm were also tested. The R. mucilaginosa biofilm showed higher efficiency in metals removing compared to the planktonic cells. Until now, the heavy metal tolerance and the removal efficiency (Cd2+, Zn2+ and Ni2+) analyzes were performed solely on planktonic cells of Rhodotorula species. In this study, we investigated the metal removal efficiency of R. mucilaginosa planktonic cells and biofilm and compared the obtained results

Difference in influence of commercial industrial paints on microbial biofilms and planktonic cells

This study compares the effect of commercial industrial paints on the Escherichia coli PMFKG-F2, Proteus mirabilis PMFKG-F4 and Saccharomyces cerevisiae PMFKG-F6 planktonic cells and biofilms. A MBECTM-HTP assay and standard 96 microtiter plate assay were used to test the levels of resistance of planktonic cells and biofilms. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) of the tested substances, which affects planktonic cells and biofilms, were determined and the results were confirmed by fluorescence microscopy. Results obtained for planktonic cells were compared between them and with the results obtained for biofilms. Noticeable difference in the resistance between the biofilms and the planktonic cells on paints, was observed. The E. coli PMFKG-F2 planktonic cells showed the highest resistance in the presence of the tested substance 2 (MICp 2.5 μl/ml), while the P. mirabilis PMFKG-F4 planktonic cells showed the highest resistance in the presence of the tested substance 2 (MICp 5 μl/ml). The S. cerevisiae PMFKG-F6 planktonic cells showed the same level of resistance in the presence of the tested substances 1, 2 and 5 (MICp 0.62 μl/ml). The E. coli PMFKG-F2, P. mirabilis PMFKGF4 and S. cerevisiae PMFKG-6 biofilms showed the highest resistance in the presence of the tested substance 5 (MICb 125 μl/ml, MICb 125 μl/ml and MICb 62.5 μl/ml). The obtained results suggest that the biofilm may have a potential to be used in bioremediation of wastewater contaminated with industrial paints

Zn2+/Poly(2-Hydroxyethyl Acrylate/Itaconic Acid) Hydrogels as Potential Antibacterial Wound Dressings

Antibacterial hydrogels, as an advanced approach, can create optimal conditions for wound healing, even in the fight against stubborn and difficult-to-treat wound infections. Interestingly, pH is an often neglected clinical parameter, although it has a significant impact on the wound healing process. At different stages of wound healing, the pH in the wound bed changes from slightly alkaline to neutral to acidic. To develop novel pH-sensitive antibacterial hydrogel dressings, Zn2+-loaded poly(2-hydroxyethyl acrylate/itaconic acid) hydrogels were synthesized. The hydrogels exhibit pH-sensitive swelling in the physiologically relevant pH range, with a pronounced swelling ability at neutral pH. The controlled release of Zn2+ occurs in a buffer of pH 7.40 at 37°C. The liquid transport mechanism and release kinetics are evaluated using the specific kinetic models of Ritger-Peppas and Peppas-Sahlin. The effect of Zn2+ on structural, thermal, swelling, cytocompatibility, and antibacterial properties is evaluated by Fourier transform infrared spectroscopy, differential scanning calorimetry, swelling studies, MTT, and antibacterial tests. The hydrogels show excellent antibacterial activity against Escherichia coli. The research opens new perspectives for efficient wound healing management, and the extension of the study will be orchestrated by optimising the hydrogel composition to achieve improved performance. This article is protected by copyright. All rights reserve