Photocatalytic-Driven Antiviral Activities of Heterostructured BiOCl0.2Br0.8 - BiOBr Semiconductors.

Numerous methods for eliminating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are being extensively examined in recent years as a result of the COVID-19 pandemic and its adverse effects on society. Photocatalysis is among the most encouraging solutions since it has the capacity to fully annihilate pathogens, surpassing conventional disinfecting methods. A heterostructured photocatalytic composite of (70%W BiOCl0.2Br0.8 with 30%W BiOBr) was prepared via a simple synthetic route that yielded microspheres ∼3-4 µm in diameter. The composite was evidenced to inactivate stubborn enveloped viruses. By utilizing scanning electron microscopy, transmission electron microscopy, N2 sorption, and X-ray diffraction, the morphology and the chemical composition of the heterostructured composite was revealed. Full elimination of SARS-CoV-2 occurred 5 min following the light-activation of the photocatalytic mixture. Illumination absence bared a slower yet effective result of full viral decomposition at a time span of 25 min. A comparable efficacious outcome was observed in the study case of vesicular stomatitis virus with complete diminishing within 30 min of visible light exposure.

Remote Photocatalytic Eradication of Biorecalcitrant Microorganisms via BiOCl0.2Br0.8-The Applied Aspects of Visible Light-Driven Photocatalysis.

Photocatalysis has an exceptional capacity to eliminate a wide range of harmful microorganisms and is proven to be superior over commonly used disinfection methods. A visible light-induced photocatalyst, the BiOCl0.2Br0.8@gypsum hybrid composite, composed of microspheres (∼3 µm) molded with a gypsum composite as a honeycomb-shaped filter was proven to inactivate a large selection of bacteria including Salmonella typhi, Bacillus subtilis, and Listeria monocytogenes via remote photocatalysis. The chemical composition and morphology of the composite were unveiled with the help of scanning electron microscopy, transmission electron microscopy, N2 sorption, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. After 6 h under ambient conditions, our system declined the number of viable bacteria by fourfold. A similar effect was observed at a low temperature, where we rapidly and completely diminished L. monocytogenes inside a refrigerator within 24 h of visible light illumination.

The Bacterial Extracellular Matrix Protein TapA Is a Two-Domain Partially Disordered Protein.

Biofilms are aggregates of microbial cells that form on surfaces and at interfaces, and are encased in an extracellular matrix. In biofilms made by the soil bacterium Bacillus subtilis, the protein TapA mediates the assembly of the functional amyloid protein TasA into extracellular fibers, and it anchors these fibers to the cell surface. We used circular dichroism and NMR spectroscopy to show that, unlike the structured TasA, TapA is disordered. In addition, TapA is composed of two weakly interacting domains: a disordered C-terminal domain and a more structured N-terminal domain. These two domains also exhibited different structural changes in response to changes in external conditions, such as increased temperatures and the presence of lipid vesicles. Although the two TapA domains weakly interacted in solution, their cooperative interaction with lipid vesicles prevented disruption of the vesicles. These findings therefore suggest that the two-domain composition of TapA is important in its interaction with single or multiple partners in the extracellular matrix in biofilms.

Bacterial Model Membranes Reshape Fibrillation of a Functional Amyloid Protein.

Biofilms are aggregates of cells that form surface-associated communities. The cells in biofilms are interconnected with an extracellular matrix, a network that is made mostly of polysaccharides, proteins, and sometimes nucleic acids. Some extracellular matrix proteins form fibers, termed functional amyloid or amyloid-like, to differentiate their constructive function from disease-related amyloid fibers. Recent functional amyloid assembly studies have neglected their interaction with membranes, despite their native formation in a cellular environment. Here, we use TasA, a major matrix protein in biofilms of the soil bacterium Bacillus subtilis, as a model functional amyloid protein and ask whether the bacterial functional amyloid interacts with membranes. Using biochemical, spectroscopic, and microscopic tools, we show that TasA interacts distinctively with bacterial model membranes and that this interaction mutually influences the morphology and structure of the protein and the membranes. At the protein level, fibers of similar structure and morphology are formed in the absence of membranes and in the presence of eukaryotic model membranes. However, in the presence of bacterial model membranes, TasA forms disordered aggregates with a different ß sheet signature. At the membrane level, fluorescence microscopy and anisotropy measurements indicate that bacterial membranes deform more considerably than eukaryotic membranes upon interaction with TasA. Our findings suggest that TasA penetrates bacterial more than eukaryotic model membranes and that this leads to membrane disruption and to reshaping the TasA fiber formation pathway. Considering the important role of TasA in providing integrity to biofilms, our study may direct the design of antibiofilm drugs to the protein-membrane interface.