Phage Tail Fiber Protein as a Specific Probe for Recognition of Shiga Toxin-Producing Escherichia coli O91, O103, and O111.

The ability to quickly identify specific serotypes of Shiga toxin-producing Escherichia coli (STEC) could facilitate the monitoring and control of STEC pathogens. In this study, we identified the receptors and receptor-binding proteins (RBPs) of three novel phages (pO91, pO103, and pO111) isolated from hospital wastewater. Recombinant versions of these RBPs (pO91-ORF43, pO103-ORF42, and pO111-ORF8) fused to a fluorescent reporter protein were then constructed. Both fluorescence microscopy and transmission electron microscopy showed that all three recombinant RBPs were bound to the bacterial surface. Indirect enzyme-linked immunosorbent assay was used to verify that each recombinant RBP bound specifically to E. coli O91, O103, or O111, but not to any of the 83 strains of E. coli with different O-antigens, nor to 10 other bacterial species that were tested. The recombinant RBPs adsorbed to their respective host bacteria within 10 min of incubation. The minimum concentration of bacteria required for detection by the recombinant RBPs was 33 colony-forming units (CFU)/mL (range: 3.3 × 10 to 3.3 × 108 CFU/mL). Furthermore, each recombinant RBP was also able to detect bacteria in lettuce, chicken breast meat, and infected mice, indicating that their usage will facilitate the detection of STEC and may help to reduce the spread of STEC-related infections and diseases.

Self-assembly of carbon nanodots induced by liquid-liquid phase separation in a surface microdroplet.

Evaporating a sessile drop of ternary solutions containing one hydrotrope (such as ethanol) and two immiscible fluids exhibiting fascinating phase separation behaviours, has opened up a new pathway for controlled nanomaterial assembly. In this work, we studied the influence of liquid-liquid phase separation (LLPS) on the assembly of carbon nanodots (C-dots), 2 nm fluorescent carbon-based nanomaterials with high water solubility. Through self-evaporation of a micro-sized droplet containing ethanol, C-dot-water solution and different oils on a hydrophobic surface, C-dots rearranged into film, porous and granular structures by controlling the properties of oil component in the tenary droplet. Vapour pressure, solubility, surface tension and compositions of the oil components were investigated systematically for their impacts on the evaporation process of C-dot-laden droplets. By using confocal microscopy, we clearly revealed that C-dot assembly was triggered by LLPS in these four oil-water-ethanol ternary systems. The corresponding evaporation and assembly processes were unravelled to be determined by how the ternary solutions pass through the liquid-liquid equilibrium curves in the phase diagrams during evaporation. Our findings deepen the understanding of phase-separation behaviours for nanomaterial assembly as well as provide a novel, simple, and well-controlled approach for depositing different C-dot based nanostructures onto surfaces, which will benefit a wide range of practical applications in the fields of energy, environment and health.

Genome sequence of Shiga toxin-producing Escherichia coli jumbo bacteriophage vB_EcoM_JNE01.

Bacteriophage vB_EcoM_JNE01 was isolated from chicken farm sewage using Escherichia coli O157:H7 as the host bacteria. The total length of the vB_EcoM_JNE01 genome is 355,583 bp, with 584 open reading frames and 36% G+C content. It shares an 80% nucleotide identity with 59% query coverage with the bacteriophage PBECO4 (NC_027364).

Surface chemistry altering electronic behaviour of liquid metal-derived tin oxide nanosheets.

Possessing excellent electronic properties and high chemical stability, semiconducting n-type two-dimensional (2D) tin dioxide (SnO2) nanosheets have been featured in sensing and electrocatalysis applications recently. Derived from non-layered crystal structures, 2D SnO2 has abundant unsaturated dangling bonds existing at the surface, providing interfacial activity. How the surface chemistry alters the electronic properties of 2D SnO2 nanomaterials remains unexplored. In this study, we synthesised ultra-thin 2D SnO2 nanosheets using a liquid metal (LM) touch printing technique and investigated experimentally and theoretically how the interactions of organic solvents composed of alkyl and hydroxyl groups with the surface of LM-derived 2D SnO2 modulate the electronic properties. It was found that alkane solvents can physically absorb onto the SnO2 surface with no impact on the material conductivity. Alcohol-based solvents on the other hand interact with the SnO2 surface via chemical absorptions primarily, in which oxygen atoms of hydroxyl groups in the alcohols form bonds with the surface atoms of SnO2. The binding stability is determined by the length and configuration of the hydrocarbon chain in alcohols. As representative long-chain alcohols, 1-octanol and 1-pentanol attach onto the SnO2 surface strongly, lowering the binding energy of Sn4+ and reducing the electron transfer ability of SnO2 nanosheets. Consequently, the electronic properties, i.e. conductivity and electronic mobility of SnO2 nanosheet-based electronic devices are decreased significantly.

Heavy Metal Content in Feedstuffs and Feeds in Hubei Province, China.

ABSTRACT: Heavy metal pollution threatens the health and life of animals and humans through the food chain. This study was performed to survey the heavy metal contamination in feedstuffs and feeds in Hubei Province, People's Republic of China, from 2012 to 2016. Samples were analyzed for cadmium (306 samples), mercury (117 samples), chromium (149 samples), and arsenic (4,358 samples) using atomic absorption spectrometry or atomic fluorescence spectrometry. The incidence rates of cadmium, mercury, chromium, and arsenic contamination of feedstuffs and feeds were high, and feeds were most often contaminated with chromium, followed by arsenic, cadmium, and mercury. The concentrations of heavy metals in samples positive for cadmium, mercury, chromium, and arsenic ranged from 0.001 to 1.200, 0.002 to 6.540, 0.060 to 8737.000, and 0.070 to 33.000 mg/kg, respectively. The mineral and additive samples had higher concentrations of heavy metals. The present study findings highlight the importance of monitoring heavy metals in feedstuffs and feeds and implementing feed management and bioremediation strategies to reduce heavy metal exposure.

Effects of dietary cadmium supplementation on production performance, cadmium residue in eggs, and hepatic damage in laying hens.

This study was conducted to investigate the adverse effects of cadmium (Cd) on the production performance, serum biochemistry, liver antioxidant status, histopathology, and egg residue in laying hens. A total of 72 healthy Hy-Line brown laying hens at 40-week-old were randomly assigned to four diets containing 0 (control diet), 15, 30, or 60 mg/kg Cd for 6 weeks. Laying hens exposed to 60 mg/kg Cd had lower egg production rate and worse feed to egg ratio (P < 0.05). Dietary Cd exposure (≥ 15 mg/kg) significantly decreased hepatic glutathione peroxide (GPX) activities, while increasing malondialdehyde (MDA) (P < 0.05). Hepatic histopathology and ultrastructure also showed damage and the symptoms were exacerbated in a dose-dependent manner. The residue of Cd in the yolk was increased with increasing dietary Cd concentration. The mRNA expression levels of mt4L, mt3, sod1, sod2, gpx1, gpx3, and gpx4 in the liver of laying hens exposed to 60 mg Cd/kg feed were significantly decreased (P < 0.05). In conclusion, dietary Cd exposure at ≥ 15 mg/kg induced hepatic damage in laying hens, indicating that the content of Cd in feed must be critically controlled.