Research Publications (Food Safety)

Edwardsiella tarda is a facultative intracellular pathogen in humans and animals. There is no effective way except vaccine candidates to eradicate intracellular E. tarda. In this study, four derivatives of marine peptide-N6NH2 were designed by an introduction of unnatural residues or substitution of natural ones, and their intracellular activities against E. tarda were evaluated in macrophages and in mice, respectively.

Macrolide–lincosamide–streptogramin B antibiotic resistance occurs through the action of erythromycin ribosome methylation (Erm) family proteins, causing problems due to their prevalence and high minimal inhibitory concentration, and feasibilities have been sought to develop inhibitors. Erms exhibit high conservation next to the N-terminal end region (NTER) as in ErmS, 64SQNF67.

Although the colorimetric methods can easily meet the demands of point-of-care and ease-of-use for antibiotic detection, they still face many challenges in the accuracy and stability of assay. Herein, a facile and stable colorimetric aptasensor is first developed for kanamycin residue detection based on the aptamer-enhanced peroxidase-mimicking activity of layered WS2 nanosheets.

Dalbavancin, vancomycin and chlorobiphenyl-vancomycin share a high degree of structural similarity and the same primary mode of drug action. All inhibit bacterial cell wall biosynthesis through complexation with intermediates in peptidoglycan biosynthesis mediated via interaction with peptidyl-d-alanyl–d-alanine (d-Ala–d-Ala) residues present at the termini of the intermediates.

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by Kimia Kardani, Azam Bolhassani

New anti-infective approaches are urgently needed to control multidrug-resistant (MDR) pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA). Sortase A (SrtA) is a membrane-bound cysteine transpeptidase that plays an essential role in the catalysis of covalent anchoring of surface proteins to the cell wall of Staphylococcus aureus (S. aureus).

Zinc is an essential micronutrient for mycobacteria, and its depletion induces multiple adaptive changes in cellular physiology, the most remarkable of which are remodeling and hibernation of ribosomes. Ribosome remodeling, induced upon relatively moderate depletion of zinc, involves replacement of multiple ribosomal proteins containing the zinc-binding CXXC motif (called C+ r proteins) by their motif-free C– paralogs.

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Author(s): P. Quintanilla, M.C. Beltrán, M.P. Molina, I. Escriche

Author(s): Annabel Mehl, Lena J. Schmidt, Laszlo Schmidt, Gertrud E. Morlock

It is commonly known that the widespread use of antibiotics has led to their existence in food products as residues and ingestion of these food products may create a selection pressure on bacteria inhabiting the human body.

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Residues of antibiotics such as oxytetracycline (OTC) in soil can affect microbial compositions and activities, thus affecting soil P availability, and consequently plant P uptake and growth.

Poultry meat and eggs are vital sources of protein for human consumption worldwide. The use of several nutritional and medicinal products, including antibiotics, is crucial for efficient and safe poultry production. Accumulation of drug residues in meat and eggs from inappropriate drug use is a major concern to public health. Recently, enrofloxacin was detected (2.4–3.8 ppb) in edible eggs produced in Jeju Island, Korea.

Author(s): Hae-Ni Jung, Da-Hee Park, Kyung-Hee Yoo, Hee-Jung Cho, Jae-Han Shim, Ho-Chul Shin, A.M. Abd El-Aty

Antibiotic residues in milk affects economics of dairy industry and poses health risks to consumers. This study aimed to assess health risks associated with presence of antibiotics in 173 raw and pasteurized milk sampled from northwestern Himalayan state of India. The oxytetracycline and amoxicillin were quantitatively analyzed using validated HPLC–DAD.

Aquatic products are favored by people all over the world, but the potential quality and safety issues cannot be ignored. In order to determine the risk of veterinary drug residues in aquatic products in the Yangtze River Delta, this paper used the Geographic Information System (GIS) method to analyze Chinese veterinary drugs in aquatic products in Shanghai, Jiangsu, Zhejiang, and Anhui (Yangtze River Delta Urban Agglomerations) from 2017 to 2019.

A simple methodology for the simultaneous determination of 67 pesticides, 25 veterinary drugs, and aflatoxin M1 in raw milk was developed and validated. After evaluating different combinations of sample preparation protocols, an extraction with acetonitrile:water (2:1) with QuEChERS citrate buffer salts and a combination of RP-C18 and anhydrous magnesium sulfate for the dispersive clean-up, using gas and liquid chromatography couples to mass spectrometry for determination, was selected.

Many bacterial pathogens utilize ADP-ribosyltransferases (ARTs) as virulence factors. The critical aspect of ARTs is their target specificity. Each individual ART modifies a specific residue of its substrates, which could be proteins, DNA, or antibiotics. However, the mechanism underlying this specificity is poorly understood. Here, we review the substrate recognition mechanism and target residue specificity based on the available complex structures of ARTs and their substrates.

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Tiamulin is a semi-synthetic derivative of the natural antibiotic pleuromutilin and is widely used as a veterinary drug for swine. Herein, we report the development of a sensitive and reliable method for determining 8α-hydroxymutilin as a marker residue for tiamulin in swine tissue using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Gold nanoparticles (AuNPs) are the most commonly used signal materials in lateral flow immunoassay (LFIA). However, the assay sensitivity of traditional AuNP-based LFIA is usually limited by the incomplete competition between free target analytes and immobilized antigens for the binding of AuNP-labeled antibodies. To unfreeze this limitation, here, asymmetric Au–SiO2 Janus NPs (about 66 nm) were designed and synthesized.

Majority of the cells in the bacterial populations exposed to lethal concentrations of antibiotics for prolonged duration succumbs to the antibiotics’ sterilizing activity. The remaining cells survive by diverse mechanisms that include reduced permeability of the antibiotics. However, in the cells surviving in the continued presence of lethal concentrations of antibiotics, it is not known whether any cell surface alterations occur that in turn may reduce permeability of the antibiotics.

We previously identified a small-molecule inhibitor of capsule biogenesis (designated DU011) and identified its target as MprA, a MarR family transcriptional repressor of multidrug efflux pumps. Unlike other proposed MprA ligands, such as salicylate and 2,4-dinitrophenol (DNP), DU011 does not alter Escherichia coli antibiotic resistance and has significantly enhanced inhibition of capsule expression.