Research Publications (Food Safety)

Applied and Environmental Microbiology, Ahead of Print. Microbe-mediated transformations of arsenic (As) often require As to be taken up into cells prior to enzymatic reaction. Despite the importance of these microbial reactions for As speciation and toxicity, understanding of how As bioavailability and uptake are regulated by aspects of extracellular water chemistry, notably dissolved organic matter (DOM), remains limited.

Sphingomonas wittichii RW1 is one of a few strains known to grow on the related compounds dibenzofuran (DBF) and dibenzo-p-dioxin (DXN) as the sole source of carbon. Previous work by others (B. Happe, L. D. Eltis, H. Poth, R. Hedderich, and K. N.

Strobilurin fungicides are widely used in agricultural production due to their broad-spectrum and fungal mitochondrial inhibitory activities. However, their massive application has restrained the growth of eukaryotic algae and increased collateral damage in freshwater systems, notably harmful cyanobacterial blooms (HCBs). In this study, a strobilurin fungicide-degrading strain, Hyphomicrobium sp. strain DY-1, was isolated and characterized successfully.

We investigated the prevalence and transmission of NDM-producing Enterobacteriaceae in fecal samples of geese and environmental samples from a goose farm in southern China. The samples were cultivated on MacConkey agar plates supplemented with meropenem. Individual colonies were examined for blaNDM, and blaNDM-positive bacteria were characterized based on whole-genome sequencing (WGS) data from the Illumina and Oxford Nanopore Technologies (ONT) platforms.

Within the landscape of globally distributed pathogens, populations differentiate via both adaptive and nonadaptive forces. Individual populations are likely to show unique trends of genetic diversity, host-pathogen interaction, and ecological adaptation. In plant pathogens, allopatric divergence may occur particularly rapidly within simplified agricultural monoculture landscapes.

The bacterial hydrolytic dehalogenation of 4-chlorobenzoate (4CBA) is a coenzyme A (CoA)-activation-type catabolic pathway that is usually a common part of the microbial mineralization of chlorinated aromatic compounds. Previous studies have shown that the transport and dehalogenation genes for 4CBA are typically clustered as an fcbBAT1T2T3C operon and inducibly expressed in response to 4CBA. However, the associated molecular mechanism remains unknown.

Enzymatic depolymerization of seaweed polysaccharides is gaining interest for the production of functional oligosaccharides and fermentable sugars. Herein, we describe a thermostable alginate lyase that belongs to polysaccharide lyase family 17 (PL17) and was derived from an Arctic Mid-Ocean Ridge (AMOR) metagenomics data set.

Rieske nonheme iron oxygenases (ROs) catalyze the oxidation of a wide variety of substrates and play important roles in aromatic compound degradation and polycyclic aromatic hydrocarbon degradation. Those Rieske dioxygenases that usually act on hydrophobic substrates have been extensively studied and structurally characterized. Here, we report the crystal structure of a novel Rieske monooxygenase, NagGH, the oxygenase component of a salicylate 5-monooxygenase from Ralstonia sp.

Fluorescent Pseudomonas spp. producing the antibiotic 2,4-diacetylphloroglucinol (DAPG) are ecologically important in the rhizosphere, as they can control phytopathogens and contribute to disease suppression. DAPG can also trigger a systemic resistance response in plants and stimulate root exudation and branching as well as induce plant-beneficial activities in other rhizobacteria.

Rhizodegradation is a promising cleanup technology where microorganisms degrade soil contaminants in the rhizosphere. A symbiotic relationship is expected to occur between plant roots and soil microorganisms in contaminated soils that enhances natural microbial degradation. However, little is known about how different initial microbiotas influence the rhizodegradation outcome.

Methomyl {bis[1-methylthioacetaldehyde-O-(N-methylcarbamoyl)oximino]sulfide} is a highly toxic oxime carbamate insecticide. Several methomyl-degrading microorganisms have been reported so far, but the role of specific enzymes and genes in this process is still unexplored. In this study, a protein annotated as a carbamate C-N hydrolase was identified in the methomyl-degrading strain Aminobacter aminovorans MDW-2, and the encoding gene was termed ameH.

Evolution of bacterial tolerance to antimicrobials precedes evolution of resistance and may result in cross-tolerance, cross-resistance, or collateral sensitivity to other antibiotics. Transient exposure of gut bacteria to glyphosate, the world’s most widely used herbicide, has been linked to the activation of the stress response and changes in susceptibility to antibiotics.

This study aimed to characterize in silico enterotoxigenic Escherichia coli F4- and F18-positive isolates (n = 90) causing swine postweaning diarrhea, including pathogenic potential, phylogenetic relationship, antimicrobial and biocide resistance, prophage content, and metal tolerance rates. F4 strains belonged mostly to the O149 and O6 serogroups and ST100 and ST48 sequence types (STs). F18 strains were mainly assigned to the O8 and O147 serogroups and ST10, ST23, and ST42.

Contamination of soil and water with heavy metals and metalloids is a serious environmental problem. Cadmium and arsenic are major environmental contaminants that pose a serious threat to human health. Although toxicities of cadmium and arsenic to living organisms have been extensively studied, the molecular mechanisms of cellular responses to cadmium and arsenic remain poorly understood.

The risk of petroleum spills coupled with the potential application of chemical dispersants as a spill response strategy necessitates further understanding of the fate of oil and dispersants and their interactive effects during biodegradation.

We sought to identify and study the antibiofilm protein secreted by the marine bacterium Pseudoalteromonas sp. strain 3J6. The latter is active against marine and terrestrial bacteria, including Pseudomonas aeruginosa clinical strains forming different biofilm types. Several amino acid sequences were obtained from the partially purified antibiofilm protein, named alterocin. The Pseudoalteromonas sp.

Ergot alkaloids are important specialized fungal metabolites that are used to make potent pharmaceuticals for neurological diseases and disorders. Lysergic acid (LA) and dihydrolysergic acid (DHLA) are desirable lead compounds for pharmaceutical semisynthesis but are typically transient intermediates in the ergot alkaloid and dihydroergot alkaloid pathways.

Biphenyl dioxygenase (BPDO), which is a Rieske-type oxygenase (RO), catalyzes the initial dioxygenation of biphenyl and some polychlorinated biphenyls (PCBs). In order to enhance the degradation ability of BPDO in terms of a broader substrate range, the BphAES283M, BphAEp4-S283M, and BphAERR41-S283M variants were created from the parent enzymes BphAELB400, BphAEp4, and BphAERR41, respectively, by a substitution at one residue, Ser283Met.

Anaerobic degradation of polycyclic aromatic hydrocarbons has been investigated mostly with naphthalene as a model compound.

According to the World Health Organization, arsenic is the water contaminant that affects the largest number of people worldwide. To limit its impact on the population, inexpensive, quick, and easy-to-use systems of detection are required. One promising solution could be the use of whole-cell biosensors, which have been extensively studied and could meet all these criteria even though they often lack sensitivity.

Carboxylesterase PytH, isolated from the pyrethroid-degrading bacterium Sphingobium faniae JZ-2, could rapidly hydrolyze the ester bond of a wide range of pyrethroid pesticides, including permethrin, fenpropathrin, cypermethrin, fenvalerate, deltamethrin, cyhalothrin, and bifenthrin. To elucidate the catalytic mechanism of PytH, we report here the crystal structures of PytH with bifenthrin (BIF) and phenylmethylsulfonyl fluoride (PMSF) and two PytH mutants.

Microbial production of the neurotoxin methylmercury (MeHg) is a significant health and environmental concern, as it can bioaccumulate and biomagnify in the food web. A chalkophore or a copper-binding compound, termed methanobactin (MB), has been shown to form strong complexes with mercury [as Hg(II)] and also enables some methanotrophs to degrade MeHg. It is unknown, however, if Hg(II) binding with MB can also impede Hg(II) methylation by other microbes.

Vibralactone, a hybrid compound derived from phenols and a prenyl group, is a strong pancreatic lipase inhibitor with a rare fused bicyclic β-lactone skeleton. Recently, a researcher reported a vibralactone derivative (compound C1) that caused inhibition of pancreatic lipase with a half-maximal inhibitory concentration of 14 nM determined by structure-based optimization, suggesting a potential candidate as a new antiobesity treatment.

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.

More than 10 years ago, we published the paper describing the mothur software package in Applied and Environmental Microbiology. Our goal was to create a comprehensive package that allowed users to analyze amplicon sequence data using the most robust methods available. mothur has helped lead the community through the ongoing sequencing revolution and continues to provide this service to the microbial ecology community.