Quasi-Diamond Platelet-Shaped Zinc Oxide Nanostructures Display Enhanced Antibacterial Activity.

The current study compares the antibacterial activity of zinc oxide nanostructures (neZnO). For this purpose, two bacterial strains, Escherichia coli (ATCC 4157) and Staphylococcus aureus (ATCC 29213) were challenged in room light conditions with the aforementioned materials. Colloidal and hydrothermal methods were used to obtain the quasi-round and quasi-diamond platelet-shape nanostructures. Thus, the oxygen vacancy (VO ) effects on the surface of neZnO are also considered to assess its effects on antibacterial activity. The neZnO characterization was achieved by X-ray diffraction (XRD), a selected area electron diffraction (SAED) and Raman spectroscopy. The microstructural effects were monitored by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, optical absorption ultraviolet visible spectrophotometry (UV-Vis) and X-ray photoelectron spectroscopy (XPS) analyses complement the physical characterization of these nanostructures; neZnO caused 50 % inhibition (IC50 ) at concentrations from 0.064 to 0.072 mg/mL for S. aureus and from 0.083 to 0.104 mg/mL for E. coli, indicating an increase in activity against S. aureus compared to E. coli. Consequently, quasi-diamond platelet-shaped nanostructures (average particle size of 377.6±10 nm) showed enhanced antibacterial activity compared to quasi-round agglomerated particles (average size of 442.8±12 nm), regardless of Vo presence or absence.

Virulence variations between clonal complexes of Melisococcus plutonius and the possible causes.

Melissococcus plutonius is a pathogenic bacterium that affects honeybee brood triggering colony collapse in severe cases. The bacterium causes a European foulbrood (EFB) disease in the honeybee populations, impacting beekeeping and agricultural industries. The pathogenesis, epidemiology, and variants of M. plutonius have been studied, but the virulence factors involved in larval infection are still unknown. Recently, an in-silico study suggested putative genes that might play a role in the pathogenesis of EFB. However, studies are required to determine their function as virulence factors. In addition, the few studies of clonal complexes (CCs), virulence factors, and variation in the honeybee larvae mortality have interfered with the development of more efficient control methods. The research, development, and differences in virulence between genetic variants (CCs) of M. plutonius and potential virulence factors implicated in honeybee larval mortality are discussed in this review.

Prevalence, typing and phylogenetic analysis of Melissococcus plutonius strains from bee colonies of the State of Chihuahua, Mexico.

European foulbrood (EFB) caused by Melissococcus plutonius is an important bee brood disease but, in Mexico, information about this bacterium is limited. We evaluated the prevalence of typical and atypical strains in beehives of seven apicultural regions of the state of Chihuahua, Mexico. We performed MLST and phylogenetic analysis to characterize the isolates. Prevalence was highest 59%, in the region of Chihuahua, and lowest, 14%, in the regions of Cuauhtémoc and Nuevo Casas Grandes. Typical and atypical strains were identified in hives from all regions; however, in the regions of Parral, Cuauhtémoc and Aldama, the atypical strains were only detected in combination with typical strains. We obtained 81 isolates of M. plutonius and identified seven sequence types, of which three were new types. Additionally, we observed a relation between sequence type and the region where the strain was isolated. Phylogenetic analysis and multilocus sequence typing using goeBURST analysis showed that 97.5% of the isolates correspond to the Clonal Complex (CC) 12 and 2.5% to the CC3. Our work is the first molecular characterization of M. plutonius in Mexico and contributes to global information about the epidemiology of this pathogen.