Differences in the Propensity of Different Antimicrobial Resistance Determinants to Be Disseminated via Transformation in and .

and are leading zoonotic foodborne pathogens, and the drugs of choice for human campylobacteriosis are macrolides (e.g., erythromycin) and fluoroquinolones.

Interaction of Copper Toxicity and Oxidative Stress in Campylobacter jejuni.

Copper is both a required micronutrient and a source of toxicity in most organisms, including Two proteins expressed in (termed CopA and CueO) have been shown to be a copper transporter and multicopper oxidase, respectively. We have isolated strains with mutations in these genes, and here we report that they were more susceptible to both the addition of copper in the growth media and to induced oxidative stress. Both mutant strains were defective in colonization of an avian host, and copper in the feed exacerbated the colonization deficiency.

Complete Genome Sequence of subsp. ATCC 35925.

Here, we report the complete genome sequence of ATCC 35925, an avian isolate from Sweden. The genome gives insight into the ATCC 35925 strain's remarkable ability to tolerate copper and its permissiveness to plasmid transformation.

Identification of a Campylobacter coli methyltransferase targeting adenines at GATC sites.

Campylobacter coli can infect humans and colonize multiple other animals, but its host-associated genes or adaptations are poorly understood. Adenine methylation at GATC sites, resulting in MboI resistance of genomic DNA, was earlier frequently detected among C. coli from swine but not among turkey-derived isolates.

Aerobic Hydrogen Production via Nitrogenase in Azotobacter vinelandii CA6.

The diazotroph Azotobacter vinelandii possesses three distinct nitrogenase isoenzymes, all of which produce molecular hydrogen as a by-product. In batch cultures, A. vinelandii strain CA6, a mutant of strain CA, displays multiple phenotypes distinct from its parent: tolerance to tungstate, impaired growth and molybdate transport, and increased hydrogen evolution.

The impairment of methylmenaquinol:fumarate reductase affects hydrogen peroxide susceptibility and accumulation in Campylobacter jejuni.

The methylmenaquinol:fumarate reductase (Mfr) of Campylobacter jejuni is a periplasmic respiratory (redox) protein that contributes to the metabolism of fumarate and displays homology to succinate dehydrogenase (Sdh). Since chemically oxidized redox-enzymes, including fumarate reductase and Sdh, contribute to the generation of oxidative stress in Escherichia coli, we assessed the role of Mfr in C. jejuni after exposure to hydrogen peroxide (H2 O2 ).

Respiratory proteins contribute differentially to Campylobacter jejuni's survival and in vitro interaction with hosts' intestinal cells.

Background: The genetic features that facilitate Campylobacter jejuni's adaptation to a wide range of environments are not completely defined. However, whole genome expression studies showed that respiratory proteins (RPs) were differentially expressed under varying conditions and stresses, suggesting further unidentified roles for RPs in C. jejuni's adaptation.

Upstream process optimization of polyhydroxybutyrate (PHB) by Alcaligenes latus using two-stage batch and fed-batch fermentation strategies.

This research focused on optimizing the upstream process time for production of polyhydroxybutyrate (PHB) from sucrose by two-stage batch and fed-batch fermentation with Alcaligenes latus ATCC 29714. The study included selection of strain, two-stage batch fermentations with different time points for switching to nitrogen limited media (14, 16 or 18 h) and fed-batch fermentations with varied time points (similar to two stage) for introducing nitrogen limited media. The optimal strain to produce PHB using sucrose as carbon source was A.

Barriers to Horizontal Gene Transfer in Campylobacter jejuni.

Campylobacter jejuni is among the most frequent agent of foodborne gastroenteritis in the world, but its physiology and pathogenesis is less well understood than other bacterial enteric pathogens. This is due in part to the incompatibility of the molecular tools that have enabled advances in the characterization of other bacterial species. Most notably, the dearth of plasmid-based complementation, reporter assays, and plasmid-based unmarked mutagenesis procedures in many of the type strains has hindered research progress.

Molybdenum and tungsten in Campylobacter jejuni: their physiological role and identification of separate transporters regulated by a single ModE-like protein.

Campylobacter jejuni is an important human pathogen that causes millions of cases of food-borne enteritis each year. The C. jejuni respiratory chain is highly branched and contains at least four enzymes predicted to contain a metal binding pterin (MPT), with the metal being either molybdenum or tungsten.

The dual-functioning fumarate reductase is the sole succinate:quinone reductase in Campylobacter jejuni and is required for full host colonization.

Campylobacter jejuni encodes all the enzymes necessary for a complete oxidative tricarboxylic acid (TCA) cycle. Because of its inability to utilize glucose, C. jejuni relies exclusively on amino acids as the source of reduced carbon, and they are incorporated into central carbon metabolism.

The role of respiratory donor enzymes in Campylobacter jejuni host colonization and physiology.

The human pathogen Campylobacter jejuni utilizes oxidative phosphorylation to meet all of its energy demands. The genome sequence of this bacterium encodes a number of respiratory enzymes in a branched electron transport chain that predicts the utilization of a number of electron transport chain donor and acceptor molecules. Three of these electron donor enzymes: hydrogenase, formate dehydrogenase, and 2-oxoglutarate:acceptor oxidoreductase (OOR), oxidize hydrogen, formate and alpha-ketoglutarate as electron donors, respectively.

Role of Campylobacter jejuni respiratory oxidases and reductases in host colonization.

Campylobacter jejuni is the leading cause of human food-borne bacterial gastroenteritis. The C. jejuni genome sequence predicts a branched electron transport chain capable of utilizing multiple electron acceptors.

The Campylobacter jejuni NADH:ubiquinone oxidoreductase (complex I) utilizes flavodoxin rather than NADH.

Campylobacter jejuni encodes 12 of the 14 subunits that make up the respiratory enzyme NADH:ubiquinone oxidoreductase (also called complex I). The two nuo genes not present in C. jejuni encode the NADH dehydrogenase, and in their place in the operon are the novel genes designated Cj1575c and Cj1574c.

Role of a bacterial organic hydroperoxide detoxification system in preventing catalase inactivation.

In the gastric pathogen Helicobacter pylori, catalase (KatA) and alkyl hydroperoxide reductase (AhpC) are two highly abundant enzymes that are crucial for oxidative stress resistance and survival of the bacterium in the host. Here we report a connection unidentified previously between the two stress resistance enzymes. We observed that the catalase in ahpC mutant cells in comparison with the parent strain is inactivated partially (approximately 50%).

Helicobacter pylori FlgR is an enhancer-independent activator of sigma54-RNA polymerase holoenzyme.

Helicobacter pylori FlgR activates transcription with sigma54-RNA polymerase holoenzyme (sigma54-holoenzyme) from at least five flagellar operons. Activators of sigma54-holoenzyme generally bind enhancer sequences located >70 bp upstream of the promoter and contact sigma54-holoenzyme bound at the promoter through DNA looping to activate transcription. H.

Characterization of Helicobacter pylori nickel metabolism accessory proteins needed for maturation of both urease and hydrogenase.

Previous studies demonstrated that two accessory proteins, HypA and HypB, play a role in nickel-dependent maturation of both hydrogenase and urease in Helicobacter pylori. Here, the two proteins were purified and characterized. HypA bound two Ni(2+) ions per dimer with positive cooperativity (Hill coefficient, approximately 2.

Association of Helicobacter pylori antioxidant activities with host colonization proficiency.

To assess the importance of two separate antioxidant activities in Helicobacter pylori, we tested the abilities of strains with mutations in either tpx (encoding thiolperoxidase) or ahpC (encoding alkyl hydroperoxide reductase [AhpC]) to colonize the stomachs of mice. The tpx strain was clearly more sensitive than the parent strain to both oxygen and cumene hydroperoxide. The strain colonized only 5% of the inoculated mice.

Molecular hydrogen as an energy source for Helicobacter pylori.

The gastric pathogen Helicobacter pylori is known to be able to use molecular hydrogen as a respiratory substrate when grown in the laboratory. We found that hydrogen is available in the gastric mucosa of mice and that its use greatly increased the stomach colonization by H. pylori.

Oxidative-stress resistance mutants of Helicobacter pylori.

Within a large family of peroxidases, one member that catalyzes the reduction of organic peroxides to alcohols is known as alkyl hydroperoxide reductase, or AhpC. Gene disruption mutations in the gene encoding AhpC of Helicobacter pylori (ahpC) were generated by screening transformants under low-oxygen conditions. Two classes of mutants were obtained.