Natural Transformation of and Its Determinants.

In a previous study, it was shown that , a member of , is naturally competent. However, whether natural competence is universal in remains unknown. In this study, it was shown for the first time that was naturally competent in the laboratory condition; however, was not naturally competent under the same conditions.

The functional identification of Dps in oxidative stress resistance and virulence of Riemerella anatipestifer CH-1 using a new unmarked gene deletion strategy.

Excessive iron in the bacterial cytoplasm can potentiate the production of harmful reactive oxygen species (ROS). Riemerella anatipestifer (R. anatipestifer, RA), a gram-negative bacterium, encodes an iron uptake system, but its iron detoxification mechanism is unknown.

Role of LptD in Resistance to Glutaraldehyde and Pathogenicity in .

is a gram-negative bacterium that causes disease in ducks and other birds. Despite being an important pathogen in poultry, the pathogenesis and drug resistance mechanisms of this bacterium are poorly understood. An analysis of our unpublished RNA-Seq data showed that , a gene encoding one of the lipopolysaccharide transport components, is transcribed at higher levels in strain CH-1 than in strain ATCC11845.

New Perspectives on Galleria mellonella Larvae as a Host Model Using Riemerella anatipestifer as a Proof of Concept.

larvae have been used as a host model to study interactions between pathogens and hosts for several years. However, whether the model is useful to interrogate infection biology remained unknown. This study aimed to exploit the potential of larvae and reveal their limitations as a host model for infection.

DprA Is Essential for Natural Competence in and Has a Conserved Evolutionary Mechanism.

ATCC11845 (RA ATCC11845) is naturally competent. However, the genes involved in natural transformation in this species remain largely unknown. Bioinformatic analysis predicts that DprA of RA (DprA) has three domains: a sterile alpha motif (SAM), a Rossmann fold (RF) domain and a Z-DNA-binding domain (Zα).

Roles of B739_1343 in iron acquisition and pathogenesis in Riemerella anatipestifer CH-1 and evaluation of the RA-CH-1ΔB739_1343 mutant as an attenuated vaccine.

Iron is one of the most important elements for bacterial survival and pathogenicity. The iron uptake mechanism of Riemerella anatipestifer (R. anatipestifer, RA), a major pathogen that causes septicemia and polyserositis in ducks, is largely unknown.

Contribution of RaeB, a Putative RND-Type Transporter to Aminoglycoside and Detergent Resistance in .

is an important pathogenic bacterium that infects ducks. It exhibits resistance to multiple classes of antibiotics. Multidrug efflux pumps play a major role as a mechanism of antimicrobial resistance in Gram-negative pathogens and they are poorly understood in .

A novel resistance gene, lnu(H), conferring resistance to lincosamides in Riemerella anatipestifer CH-2.

The Gram-negative bacterium Riemerella anatipestifer CH-2 is resistant to lincosamides, having a lincomycin (LCM) minimum inhibitory concentration (MIC) of 128 µg/mL. The G148_1775 gene of R. anatipestifer CH-2, designated lnu(H), encodes a 260-amino acid protein with ≤41% identity to other reported lincosamide nucleotidylyltransferases.

Identifying the Genes Responsible for Iron-Limited Condition in CH-1 through RNA-Seq-Based Analysis.

One of the important elements for most bacterial growth is iron, the bioavailability of which is limited in hosts. (, RA), an important duck pathogen, requires iron to live. However, the genes involved in iron metabolism and the mechanisms of iron transport are largely unknown.

Identification of the ferric iron utilization gene B739_1208 and its role in the virulence of R. anatipestifer CH-1.

Riemerella anatipestifer is an important bacterial pathogen in ducks and causes heavy economic losses in the duck industry. However, the pathogensis of this bacterium is poorly understood. In this study, a putative outer membrane hemin receptor gene B739_1208 in R.

Use of Natural Transformation To Establish an Easy Knockout Method in Riemerella anatipestifer.

is a member of the family and a major causative agent of duck serositis. Little is known about its genetics and pathogenesis. Several bacteria are competent for natural transformation; however, whether is also competent for natural transformation has not been investigated.

Investigation of TbfA in Riemerella anatipestifer using plasmid-based methods for gene over-expression and knockdown.

Riemerella anatipestifer is a duck pathogen that has caused serious economic losses to the duck industry worldwide. Despite this, there are few reported studies of the physiological and pathogenic mechanisms of Riemerella anatipestifer infection. In previous study, we have shown that TonB1 and TonB2 were involved in hemin uptake.

The Detection of Hemin-Binding Proteins in Riemerella anatipestifer CH-1.

Riemerella anatipestifer (R. anatipestifer) is among the most prevalent duck pathogens, causing acute or chronic septicemia characterized by serositis. Riemerella anatipestifer can be grown on blood-enriched media, in vitro, which provides a hemin source essential for the sustainment of R.

TonB Energy Transduction Systems of Riemerella anatipestifer Are Required for Iron and Hemin Utilization.

Riemerella anatipestifer (R. anatipestifer) is one of the most important pathogens in ducks. The bacteria causes acute or chronic septicemia characterized by fibrinous pericarditis and meningitis.

Pyrophosphate-mediated iron acquisition from transferrin in Neisseria meningitidis does not require TonB activity.

The ability to acquire iron from various sources has been demonstrated to be a major determinant in the pathogenesis of Neisseria meningitidis. Outside the cells, iron is bound to transferrin in serum, or to lactoferrin in mucosal secretions. Meningococci can extract iron from iron-loaded human transferrin by the TbpA/TbpB outer membrane complex.

Managing iron supply during the infection cycle of a flea borne pathogen, Bartonella henselae.

Bartonella are hemotropic bacteria responsible for emerging zoonoses. Most Bartonella species appear to share a natural cycle that involves an arthropod transmission, followed by exploitation of a mammalian host in which they cause long-lasting intra-erythrocytic bacteremia. Persistence in erythrocytes is considered an adaptation to transmission by bloodsucking arthropod vectors and a strategy to obtain heme required for Bartonella growth.

The Bartonella henselae SitABCD transporter is required for confronting oxidative stress during cell and flea invasion.

Bartonella henselae is a zoonotic pathogen that possesses a flea-cat-flea transmission cycle and causes cat scratch disease in humans via cat scratches and bites. In order to establish infection, B. henselae must overcome oxidative stress damage produced by the mammalian host and arthropod vector.

Ctenocephalides felis an in vitro potential vector for five Bartonella species.

The blood-sucking arthropod Ctenocephalides felis has been confirmed as a vector for Bartonella henselae and is a suspected vector for Bartonella clarridgeiae, Bartonella quintana and Bartonella koehlerae in Bartonella transmission to mammals. To understand the absence of other Bartonella species in the cat flea, we have developed an artificial flea-feeding method with blood infected successively with five different Bartonella species. The results demonstrated the ability of these five Bartonella species to persist in C.

Heme binding proteins of Bartonella henselae are required when undergoing oxidative stress during cell and flea invasion.

Bartonella are hemotropic bacteria responsible for emerging zoonoses. These heme auxotroph alphaproteobacteria must import heme for their growth, since they cannot synthesize it. To import exogenous heme, Bartonella genomes encode for a complete heme uptake system enabling transportation of this compound into the cytoplasm and degrading it to release iron.

Heme degrading protein HemS is involved in oxidative stress response of Bartonella henselae.

Bartonellae are hemotropic bacteria, agents of emerging zoonoses. These bacteria are heme auxotroph Alphaproteobacteria which must import heme for supporting their growth, as they cannot synthesize it. Therefore, Bartonella genome encodes for a complete heme uptake system allowing the transportation of this compound across the outer membrane, the periplasm and the inner membranes.

Identification of a novel nanoRNase in Bartonella.

In Escherichia coli, only one essential oligoribonuclease (Orn) can degrade oligoribonucleotides of five residues and shorter in length (nanoRNA). In Bacillus subtilis, NrnA and NrnB, which do not show any sequence similarity to Orn, have been identified as functional analogues of Orn. Sequence comparisons did not identify orn, nrnA or nrnB homologues in the genomes of the Chlamydia/Cyanobacteria and Alphaproteobacteria family members.

The Trw type IV secretion system of Bartonella mediates host-specific adhesion to erythrocytes.

Bacterial pathogens typically infect only a limited range of hosts; however, the genetic mechanisms governing host-specificity are poorly understood. The alpha-proteobacterial genus Bartonella comprises 21 species that cause host-specific intraerythrocytic bacteremia as hallmark of infection in their respective mammalian reservoirs, including the human-specific pathogens Bartonella quintana and Bartonella bacilliformis that cause trench fever and Oroya fever, respectively. Here, we have identified bacterial factors that mediate host-specific erythrocyte colonization in the mammalian reservoirs.

The Hem and Has haem uptake systems in Serratia marcescens.

Serratia marcescens, like several other Gram-negative bacteria, possesses two functional haem uptake systems. The first, referred to as the Hem system, can transport haem present at a concentration equal to or above 10(-6) M. It requires an active outer-membrane receptor which uses proton-motive force energy transmitted by the inner-membrane TonB protein.