Research Publications (Food Safety)

Author(s): Yuming Hu, Yunpeng Shen, Jianlong Wang

Significance and Impact of the Study: Vibrio harveyi is a major pathogen of marine animals. The bacterium could enter into a viable but non‐culturable state (VBNC) state when exposed to harsh conditions, and retains its pathogenicity after resuscitation. In this work, we analysed the enzyme activities of a resuscitation‐promoting factor YeaZ and the relationship of protease activities with its promoting effect on the resuscitation of VBNC cells.

Multidrug resistance among Gram-negative bacteria is a major global public health threat. Metallo-β-lactamases (MBLs) target the most widely used antibiotic class, the β-lactams, including the most recent generation of carbapenems. Interspecies spread renders these enzymes a serious clinical threat, and there are no clinically available inhibitors.

Author(s): Dongmei Xu, Hua Pan, Jiachao Yao, Yixuan Feng, Panpan Wu, Kai Shao

Host defense peptides (HDPs), also known as antimicrobial peptides, are naturally occurring polypeptides (~12–50 residues) composed of cationic and hydrophobic amino acids that adopt an amphipathic conformation upon folding usually after contact with membranes. HDPs have a variety of biological activities including immunomodulatory, anti-inflammatory, anti-bacterial, and anti-biofilm functions.

Ebola virus (EBOV), the causative pathogen of the deadly EBOV disease (EVD), can be transmitted via sexual transmission. Seminal amyloid fibrils have been found enhancers of EBOV infection. Currently, limited preventive vaccine or therapeutic is available to block EBOV infection through sexual intercourse.

The burden of antibiotic resistance necessitates a continued search for new antimicrobials. We evaluated the antimicrobial activities of novel benzothiazoles synthesized by our group. Antibacterial activity was evaluated in vitro in Staphylococcus aureus, Bacillus subtilis, and Escherichia coli, while the antifungal activity was tested in Candida albicans and Aspergillus niger, and expressed as the minimum inhibitory concentration (MIC; µg/mL).

ABSTRACT

ABSTRACT

Ceftobiprole is an advanced-generation broad-spectrum cephalosporin antibiotic with potent and rapid bactericidal activity against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus, as well as susceptible Gram-negative pathogens, including Pseudomonas sp. pathogens. In the case of Pseudomonas aeruginosa, ceftobiprole acts by inhibiting P. aeruginosa penicillin-binding protein 3 (PBP3).

Levels of amphetamine, methamphetamine, cocaine, and benzoylecgonine (BE), the metabolite of cocaine, were quantitated by solid phase extraction and liquid chromatography with tandem mass spectrometry (LC/MS/MS) in Forester Creek in San Diego County, CA, and in raw wastewater from the region’s sewage treatment plant. Drug residues in these surface waters were detected with 100% frequency.

Avermectin (AVM) has been widely used in agriculture and animal husbandry for the treatment of broad spectrum parasitic diseases, but it has a harmful effect on human body through food chain. In this paper, on the basis of anti-AVM specific antibody, expanded mesoporous silica-encapsulated gold nanoparticles (EMSN-AuNPs)-based enzyme-linked immunosorbent assay (ELISA) for the detection of AVM was developed.

Promysalin is a small-molecule natural product that specifically inhibits growth of the Gram-negative pathogen Pseudomonas aeruginosa (PA). This activity holds promise in the treatment of multidrug resistant infections found in immunocompromised patients with chronic illnesses, such as cystic fibrosis. In 2015, our lab completed the first total synthesis; subsequent analogue design and SAR investigation enabled identification of succinate dehydrogenase (Sdh) as the biological target in PA.

Acetylation is a conserved modification used to regulate a variety of cellular pathways, such as gene expression, protein synthesis, detoxification, and virulence. Acetyltransferase enzymes transfer an acetyl moiety, usually from acetyl coenzyme A (AcCoA), onto a target substrate, thereby modulating activity or stability. Members of the GCN5-N-acetyltransferase (GNAT) protein superfamily are found in all domains of life and are characterized by a core structural domain architecture.

Development of probiotic-ineffective antimicrobial peptides (AMPs)-based coatings that can kill pathogenic bacteria at low concentrations but are essentially harmless (even high concentrations) to probiotic organisms is a relatively new trend for therapy against GI tract infections. In this study, a series of triplet-tryptophan-pivot peptides with various hydrophilic amino acids was constructed.

Lantibiotic salivaricins are polycyclic peptides containing lanthionine and/or β-methyllanthionine residues produced by certain strains of Streptococcus salivarius, which almost exclusively reside in the human oral cavity. The importance of these molecules stems from their antimicrobial activity towards relevant oral pathogens which has so far been applied through the development of salivaricin-producing probiotic strains.

Lactococcus lactis subsp. cremoris MG1363 is a model for the lactic acid bacteria (LAB) used in the dairy industry. The proteolytic system, consisting of a proteinase, several peptide and amino acid uptake systems, and a host of intracellular peptidases, plays a vital role in nitrogen metabolism and is of eminent importance for flavor formation in dairy products. The dipeptidase PepV functions in the last stages of proteolysis.

The ATP binding cassette (ABC) transporter LptB2FGC extracts LPS from the inner membrane and powers the transport of the glycolipid to the cell surface in Gram‐negative bacteria. Our study shows that changes to the LPS structure and the transporter can affect how the function of the cytoplasmic LptB ATPase is coupled to the extraction of LPS by LptFG by either promoting or interfering with the collapse of the substrate‐binding cavity.

Quinolone is a family of widely prescript antibiotics in veterinary medicine. Their excessive use can be causative of quinolone residues in foodstuffs of animal origin. Therefore, a magneto immunofluorescence assay in microwell plate has been developed and validated to screen quinolone in bovine milk. The assay is based on an indirect competitive method where the quinolone in the milk sample competed with the quinolone immobilized on magnetic beads for the anti-quinolone antibody.

Retroviral reverse transcriptases (RTs) have the ability to carry out strand displacement DNA synthesis in the absence of accessory proteins. Although studies with RTs and other DNA polymerases suggest that fingers subdomain residues participate in strand displacement, molecular determinants of this activity are still unknown.

Gram-negative bacteria expressing class A β-lactamases pose a serious health threat due to their ability to inactivate all β-lactam antibiotics. The acyl–enzyme intermediate is a central milestone in the hydrolysis reaction catalyzed by these enzymes. However, the protonation states of the catalytic residues in this complex have never been fully...

To investigate the drug residue situation in commercial liquid milk products in China, 190 samples, including ultra-high temperature (UHT) milk (n=168) and pasteurized (n=22) milk samples, were collected in 2019. Milk samples were analyzed for the presence of any of the sixty-one veterinary drugs in them by using a screening assay combined with a UPLC-MS/MS analysis.

In this study, the molecularly imprinted nano-polymer of minocycline was polymerized on the surface of a metal organic framework material to synthesize a novel composite. This composite was used as absorbent to develop a dispersive solid phase microextraction method for extraction of 7 tetracyclines in chicken muscle followed by determination with ultra performance liquid chromatography.

Antibiotic residues in chicken meat samples is a serious public health concern due to their harmful effects on consumers’ health. We conducted this research in 2017 to determine antibiotic residues in chicken meat samples and to describe the knowledge, attitude, and practice (KAP) of farmers on the antibiotic uses in poultry farms at Tay Ninh province.

Malaria is a tropical disease that kills about half a million people around the world annually. Enzymatic reactions within pyrimidine biosynthesis have been proven to be essential for Plasmodium proliferation. Here we report on the essentiality of the second enzymatic step of the pyrimidine biosynthesis pathway, catalyzed by aspartate transcarbamoylase (ATC).