Comparison of the behavior of negative electrically charged E. coli and E. faecalis bacteria under electric field effect

Siphophage 0105phi7-2 of Bacillus thuringiensis: Novel Propagation, DNA, and Genome-Implied Assembly

Diversity of phage propagation, physical properties, and assembly promotes the use of phages in ecological studies and biomedicine. However, observed phage diversity is incomplete. Bacillus thuringiensis siphophage, 0105phi-7-2, first described here, significantly expands known phage diversity, as seen via in-plaque propagation, electron microscopy, whole genome sequencing/annotation, protein mass spectrometry, and native gel electrophoresis (AGE). Average plaque diameter vs. plaque-supporting agarose gel concentration plots reveal unusually steep conversion to large plaques as agarose concentration decreases below 0.2%. These large plaques sometimes have small satellites and are made larger by orthovanadate, an ATPase inhibitor. Phage head-host-cell binding is observed by electron microscopy. We hypothesize that this binding causes plaque size-increase via biofilm evolved, ATP stimulated ride-hitching on motile host cells by temporarily inactive phages. Phage 0105phi7-2 does not propagate in liquid culture. Genomic sequencing/annotation reveals history as temperate phage and distant similarity, in a virion-assembly gene cluster, to prototypical siphophage SPP1 of Bacillus subtilis. Phage 0105phi7-2 is distinct in (1) absence of head-assembly scaffolding via either separate protein or classically sized, head protein-embedded peptide, (2) producing partially condensed, head-expelled DNA, and (3) having a surface relatively poor in AGE-detected net negative charges, which is possibly correlated with observed low murine blood persistence.

Motility Suppression and Trapping Bacteria by ZnO Nanostructures

Regulating the swimming motility of bacteria near surfaces is essential to suppress or avoid bacterial contamination and infection in catheters and medical devices with wall surfaces. However, the motility of bacteria near walls strongly depends on the combination of the local physicochemical properties of the surfaces. To unravel how nanostructures and their local chemical microenvironment dynamically affect the bacterial motility near surfaces, here, we directly visualize the bacterial swimming and systematically analyze the motility of Escherichia coli swimming on ZnO nanoparticle films and nanowire arrays with further ultraviolet irradiation. The results show that the ZnO nanowire arrays reduce the swimming motility, thus significantly enhancing the trapping ability for motile bacteria. Additionally, thanks to the wide bandgap nature of a ZnO semiconductor, the ultraviolet irradiation rapidly reduces the bacteria locomotion due to the hydroxyl and singlet oxygen produced by the photodynamic effects of ZnO nanowire arrays in an aqueous solution. The findings quantitatively reveal how the combination of geometrical nanostructured surfaces and local tuning of the steric microenvironment are able to regulate the motility of swimming bacteria and suggest the efficient inhibition of bacterial translocation and infection by nanostructured coatings.