Search Results (2)

Nanoparticles are proposed as alternatives to traditional antimicrobial agents. By manipulating a nanoparticle’s core and surface coating, antimicrobial effects against various microbial populations can be customized, known as the “designer effect”. However, the antimicrobial properties of nanoparticle core–coating combinations are understudied; little research exists on their effects on diverse bacteria. The antimicrobial effects of surface-stabilized zero-valent iron nanoparticles (FeNPs) are particularly interesting due to their stability in water and ferromagnetic properties. This study explores the impact of FeNPs coated with three surface coatings on six diverse bacterial species. The FeNPs were synthesized and capped with L-ascorbic acid (AA), cetyltrimethylammonium bromide (CTAB), or polyvinylpyrrolidone (PVP) using a bottom-up approach. Zone of inhibition (ZOI) values, assessed through the disc diffusion assay, indicated that AA-FeNPs and CTAB-FeNPs displayed the most potent antibacterial activity. Bacteria inhibition results ranked from most sensitive to least sensitive are the following: Bacillus nealsonii > Escherichia coli > Staphylococcus aureus > Delftia acidovorans > Chryseobacterium sp. > Sphingobacterium multivorum. Comparisons using ordinal regression and generalized linear mixed models revealed significant differences in bacterial responses to the different coatings and nanoparticle concentrations. The statistical model results are in agreement, thus increasing confidence in these conclusions. This study supports the feasibility of the “designer nanoparticle” concept and offers a framework for future research. Full article

Plant biomass offers great potential as a sustainable resource, and microbial consortia are primordial in its bioconversion. The wheat-straw-biodegradative bacterial strain w15 has drawn much attention as a result of its biodegradative potential and superior degradation performance in bacterial-fungal consortia. Strain w15 was originally assigned to the species Sphingobacterium multivorum based on its 16S ribosomal RNA (rRNA) gene sequence. A closer examination of this taxonomic placement revealed that the sequence used has 98.9% identity with the ‘divergent’ 16S rRNA gene sequence of S. multivorum NCTC 11343^T, yet lower relatedness with the canonical 16S rRNA sequence. A specific region of the gene, located between positions 186 and 210, was found to be highly variable and determinative for the divergence. To solve the identity of strain w15, genome metrics and analyses of ecophysiological niches were undertaken on a selection of strains assigned to S. multivorum and related species. These analyses separated all strains into three clusters, with strain w15, together with strain BIGb0170, constituting a separate radiation, next to S. multivorum and S. siyangense. Moreover, the strains denoted FDAARGOS 1141 and 1142 were placed inside S. siyangense. We propose the renaming of strains w15 and BIGb0170 as members of the novel species, coined Sphingobacterium paramultivorum. Full article