scholarly journals The Bacillus virulome in endophthalmitis

Microbiology ◽  
2021 ◽  
Vol 167 (5) ◽  
Author(s):  
Phillip S. Coburn ◽  
Frederick C. Miller ◽  
Morgan A. Enty ◽  
Craig Land ◽  
Austin L. LaGrow ◽  
...  
Keyword(s):  
Type Species ◽  
Manganese Superoxide Dismutase ◽  
Protein Gene ◽  
Rna Seq ◽  
Content Type ◽  
Link Type ◽  
Manganese Superoxide ◽  
Low Levels

Bacillus cereus is recognized as a causative agent of gastrointestinal syndromes, but can also cause a devastating form of intraocular infection known as endophthalmitis. We have previously reported that the PlcR/PapR master virulence factor regulator system regulates intraocular virulence, and that the S-layer protein (SlpA) contributes to the severity of B. cereus endophthalmitis. To better understand the role of other B. cereus virulence genes in endophthalmitis, expression of a subset of factors was measured at the midpoint of disease progression in a murine model of endophthalmitis by RNA-Seq. Several cytolytic toxins were expressed at significantly higher levels in vivo than in BHI. The virulence regulators codY, gntR, and nprR were also expressed in vivo. However, at this timepoint, plcR/papR was not detectable, although we previously reported that a B. cereus mutant deficient in PlcR was attenuated in the eye. The motility-related genes fla, fliF, and motB, and the chemotaxis-related gene cheA were detected during infection. We have shown previously that motility and chemotaxis phenotypes are important in B. cereus endophthalmitis. The sodA2 variant of manganese superoxide dismutase was the most highly expressed gene in vivo. Expression of the surface layer protein gene, slpA, an activator of Toll-like receptors (TLR)−2 and −4, was also detected during infection, albeit at low levels. Genes expressed in a mouse model of Bacillus endophthalmitis might play crucial roles in the unique virulence of B. cereus endophthalmitis, and serve as candidates for novel therapies designed to attenuate the severity of this often blinding infection.

scholarly journals The Bacillus Virulome in Endophthalmitis

2020 ◽  
Author(s):  
Phillip S. Coburn ◽  
Frederick C. Miller ◽  
Morgan A. Enty ◽  
Craig Land ◽  
Austin L. LaGrow ◽  
...  
Keyword(s):  
Murine Model ◽  
Manganese Superoxide Dismutase ◽  
Current Treatment ◽  
Treatment Modalities ◽  
Rna Seq ◽  
Expression Of Genes ◽  
Manganese Superoxide ◽  
New Treatment

AbstractBacillus cereus is recognized as a causative agent of gastrointestinal syndromes, but can also cause a devastating form of intraocular infection known as endophthalmitis. We have previously reported that the PlcR/PapR master virulence factor regulator system regulates intraocular virulence, and that the S-layer protein (SlpA) contributes to the severity of B. cereus endophthalmitis. To begin to better understand the role of other B. cereus virulence genes in endophthalmitis, expression levels of a subset of factors was measured at the midpoint of disease progression in a murine model of experimental endophthalmitis by RNA-Seq. Several cytolytic toxins were expressed at significantly higher levels in vivo than in BHI. The virulence regulators codY, gntR, and nprR were also expressed in vivo. However, at this timepoint, plcR/papR was not detectable, we previously reported that a B. cereus mutant deficient in PlcR was attenuated in the eye. The motility-related genes fla, fliF, and motB, and the chemotaxis-related gene cheA were detected during infection. We have shown previously that motility and chemotaxis phenotypes are important in B. cereus endophthalmitis. The sodA2 variant of manganese superoxide dismutase was the most highly expression gene in vivo, suggesting that this gene is criticial for intraocular survival, potentially through inhibition of neutrophil activity. Expression of the surface layer protein gene, slpA, an activator of Toll-like receptors (TLR) −2 and −4, and a potent contributor to intraocular inflammation and disease severvity, was also detected during infection, albeit at low levels. In summary, genes expressed in a mouse model of Bacillus endophthalmitis might prove to play crucial roles in the unique virulence of B. cereus endophthalmitis, and serve as candidates for novel therapies designed attenuate the severity of this often blinding infection.Impact statementB. cereus causes a potent and rapid infection of the eye that usually results in blindness or enucleation, even with the utilization of current treatment modalities. This necessitates the development of new treatment modalities based on new targets. To begin to better define those B. cereus factors with roles in intraocular infection, we analyzed the expression of genes with both known and hypothesized roles in intraocular infection at the midpoint of infection using a murine model of Bacillus endophthalmitis. Potentially targetable candidate genes were demonstrated to be expressed in vivo, which suggests that these genes might contribute to the unique virulence of B. cereus endophthalmitis. Importantly, our results begin to define the virulome of B. cereus in intraocular infections and identify previously uncharacterized factors with potential roles in the severity and outcome of Bacillus endophthalmitis.

The role of Akkermansia muciniphila in obesity, diabetes and atherosclerosis

2021 ◽  
Vol 70 (10) ◽  
Author(s):  
Alka Hasani ◽  
Saba Ebrahimzadeh ◽  
Fatemeh Hemmati ◽  
Aytak Khabbaz ◽  
Akbar Hasani ◽  
...  
Keyword(s):  
Type Species ◽  
Anaerobic Bacteria ◽  
Regulatory System ◽  
Content Type ◽  
Akkermansia Muciniphila ◽  
Link Type ◽  
Animal Trials ◽  
Obesity And Diabetes ◽  
Underlying Mechanisms

Alteration in the composition of the gut microbiota can lead to a number of chronic clinical diseases. Akkermansia muciniphila is an anaerobic bacteria constituting 3–5% of the gut microbial community in healthy adults. This bacterium is responsible for degenerating mucin in the gut; its scarcity leads to diverse clinical disorders. In this review, we focus on the role of A. muciniphila in diabetes, obesity and atherosclerosis, as well as the use of this bacterium as a next-generation probiotic. In regard to obesity and diabetes, human and animal trials have shown that A. muciniphila controls the essential regulatory system of glucose and energy metabolism. However, the underlying mechanisms by which A. muciniphila alleviates the complications of obesity, diabetes and atherosclerosis are unclear. At the same time, its abundance suggests improved metabolic disorders, such as metabolic endotoxemia, adiposity insulin resistance and glucose tolerance. The role of A. muciniphila is implicated in declining aortic lesions and atherosclerosis. Well-characterized virulence factors, antigens and cell wall extracts of A. muciniphila may act as effector molecules in these diseases. These molecules may provide novel mechanisms and strategies by which this bacterium could be used as a probiotic for the treatment of obesity, diabetes and atherosclerosis.

Rhizobium paknamense sp. nov., isolated from lesser duckweeds (Lemna aequinoctialis)

2013 ◽  
Vol 63 (Pt_10) ◽  
pp. 3823-3828 ◽  
Author(s):  
Chokchai Kittiwongwattana ◽  
Chitti Thawai
Keyword(s):  
Dna Hybridization ◽  
Type Species ◽  
Sequence Similarity ◽  
Housekeeping Genes ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
Low Levels ◽  
Sequence Similarity Analysis ◽  
Ph Range

A Gram-stain-negative, rod-shaped bacterium was isolated and designated strain L6-8T during a study of endophytic bacterial communities in lesser duckweed (Lemna aequinoctialis). Cells of strain L6-8T were motile with peritrichous flagella. The analysis of the nearly complete 16S rRNA gene sequence indicated that strain L6-8T was phylogenetically related to species of the genus Rhizobium . Its closest relatives were Rhizobium borbori DN316T (97.6 %), Rhizobium oryzae Alt 505T (97.3 %) and Rhizobium pseudoryzae J3-A127T (97.0 %). The sequence similarity analysis of housekeeping genes recA, glnII, atpD and gyrB showed low levels of sequence similarity (<91.5 %) between strain L6-8T and other species of the genus Rhizobium with validly published names. The pH range for growth was 4.0–9.0 (optimum 6.0–7.0), and the temperature range for growth was 20–45 °C (optimum 30 °C). Strain L6-8T tolerated NaCl up to 2 % (w/v) (optimum 1 % NaCl). The predominant components of cellular fatty acids were C19 : 0 cyclo ω8c (31.32 %), summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 25.39 %) and C16 : 0 (12.03 %). The DNA G+C content of strain L6-8T was 60.4 mol% (T m). nodC and nifH were not amplified in strain L6-8T. DNA–DNA relatedness between strain L6-8T and R. borbori DN316T, R. oryzae Alt505T and R. pseudoryzae J3-A127T was between 11.2 and 18.3 %. Based on the sequence similarity analyses, phenotypic, biochemical and physiological characteristics and DNA–DNA hybridization, strain L6-8T could be readily distinguished from its closest relatives and represents a novel species of the genus Rhizobium , for which the name Rhizobium paknamense sp. nov. is proposed. The type strain is L6-8T ( = NBRC 109338T = BCC 55142T).

scholarly journals Genetic regulation, biochemical properties and physiological importance of arginase from Sinorhizobium meliloti

Microbiology ◽  
2020 ◽  
Vol 166 (5) ◽  
pp. 484-497 ◽  
Author(s):  
Alejandra Arteaga Ide ◽  
Victor M. Hernández ◽  
Liliana Medina-Aparicio ◽  
Edson Carcamo-Noriega ◽  
Lourdes Girard ◽  
...  
Keyword(s):  
Type Species ◽  
Sinorhizobium Meliloti ◽  
Arginase Activity ◽  
Wild Type ◽  
Mobility Shift ◽  
Content Type ◽  
Link Type ◽  
Arginine Catabolism

In bacteria, l-arginine is a precursor of various metabolites and can serve as a source of carbon and/or nitrogen. Arginine catabolism by arginase, which hydrolyzes arginine to l-ornithine and urea, is common in nature but has not been studied in symbiotic nitrogen-fixing rhizobia. The genome of the alfalfa microsymbiont Sinorhizobium meliloti 1021 has two genes annotated as arginases, argI1 (smc03091) and argI2 (sma1711). Biochemical assays with purified ArgI1 and ArgI2 (as 6His-Sumo-tagged proteins) showed that only ArgI1 had detectable arginase activity. A 1021 argI1 null mutant lacked arginase activity and grew at a drastically reduced rate with arginine as sole nitrogen source. Wild-type growth and arginase activity were restored in the argI1 mutant genetically complemented with a genomically integrated argI1 gene. In the wild-type, arginase activity and argI1 transcription were induced several fold by exogenous arginine. ArgI1 purified as a 6His-Sumo-tagged protein had its highest in vitro enzymatic activity at pH 7.5 with Ni2+ as cofactor. The enzyme was also active with Mn2+ and Co2+, both of which gave the enzyme the highest activities at a more alkaline pH. The 6His-Sumo-ArgI1 comprised three identical subunits based on the migration of the urea-dissociated protein in a native polyacrylamide gel. A Lrp-like regulator (smc03092) divergently transcribed from argI1 was required for arginase induction by arginine or ornithine. This regulator was designated ArgIR. Electrophoretic mobility shift assays showed that purified ArgIR bound to the argI1 promoter in a region preceding the predicted argI1 transcriptional start. Our results indicate that ArgI1 is the sole arginase in S. meliloti , that it contributes substantially to arginine catabolism in vivo and that argI1 induction by arginine is dependent on ArgIR.

Halobaculum magnesiiphilum sp. nov., a magnesium-dependent haloarchaeon isolated from commercial salt

2013 ◽  
Vol 63 (Pt_3) ◽  
pp. 861-866 ◽  
Author(s):  
Hirokazu Shimoshige ◽  
Tomoaki Yamada ◽  
Hiroaki Minegishi ◽  
Akinobu Echigo ◽  
Yasuhiro Shimane ◽  
...  
Keyword(s):  
Type Species ◽  
Lipid Analysis ◽  
Halophilic Archaea ◽  
Single Species ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Content Type ◽  
Link Type ◽  
Physiological And Biochemical Characteristics ◽  
Low Levels

Two extremely halophilic archaea, strains MGY-184T and MGY-205, were isolated from sea salt produced in Japan and rock salt imported from Bolivia, respectively. Both strains were pleomorphic, non-motile, Gram-negative and required more than 5 % (w/v) NaCl for growth, with optimum at 9–12 %, in the presence of 2 % (w/v) MgCl2 . 6H2O. In the presence of 18 % (w/v) MgCl2 . 6H2O, however, both strains showed growth even at 1.0 % (w/v) NaCl. Both strains possessed two 16S rRNA genes (rrnA and rrnB), and they revealed closest similarity to Halobaculum gomorrense JCM 9908T, the single species with a validly published name of the genus Halobaculum , with similarity of 97.8 %. The rrnA and rrnB genes of both strains were 100 % similar. The rrnA genes were 97.6 % similar to the rrnB genes in both strains. DNA G+C contents of strains MGY-184T and MGY-205 were 67.0 and 67.4 mol%, respectively. Polar lipid analysis revealed that the two strains contained phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester derived from C20C20 archaeol. The DNA–DNA hybridization value between the two strains was 70 % and both strains showed low levels of DNA–DNA relatedness (48–50 %) with Halobaculum gomorrense JCM 9908T. Physiological and biochemical characteristics allowed differentiation of strains MGY-184T and MGY-205 from Halobaculum gomorrense JCM 9908T. Therefore, strains MGY-184T and MGY-205 represent a novel species of the genus Halobaculum , for which the name Halobaculum magnesiiphilum sp. nov. is proposed; the type strain is MGY-184T ( = JCM 17821T = KCTC 4100T).

scholarly journals SufT is required for growth of Mycobacterium smegmatis under iron limiting conditions

Microbiology ◽  
2020 ◽  
Vol 166 (3) ◽  
pp. 296-305 ◽  
Author(s):  
Tsaone Tamuhla ◽  
Lydia Joubert ◽  
Danicke Willemse ◽  
Monique J. Williams
Keyword(s):  
Mycobacterium Smegmatis ◽  
Type Species ◽  
Model Organism ◽  
Culture Conditions ◽  
Growth Defect ◽  
Content Type ◽  
Link Type ◽  
Targeted Gene Deletion ◽  
Accessory Factor

Iron-sulphur (FeS) clusters are versatile cofactors required for a range of biological processes within cells. Due to the reactive nature of the constituent molecules, assembly and delivery of these cofactors requires a multi-protein machinery in vivo. In prokaryotes, SufT homologues are proposed to function in the maturation and transfer of FeS clusters to apo-proteins. This study used targeted gene deletion to investigate the role of SufT in the physiology of mycobacteria, using Mycobacterium smegmatis as a model organism. Deletion of the sufT gene in M. smegmatis had no impact on growth under standard culture conditions and did not significantly alter activity of the FeS cluster dependent enzymes succinate dehydrogenase (SDH) and aconitase (ACN). Furthermore, the ΔsufT mutant was no more sensitive than the wild-type strain to the redox cycler 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), or the anti-tuberculosis drugs isoniazid, clofazimine or rifampicin. In contrast, the ΔsufT mutant displayed a growth defect under iron limiting conditions, and an increased requirement for iron during biofilm formation. This data suggests that SufT is an accessory factor in FeS cluster biogenesis in mycobacteria which is required under conditions of iron limitation.

scholarly journals Phosphate Transporter PstSCAB of Campylobacter jejuni Is a Critical Determinant of Lactate-Dependent Growth and Colonization in Chickens

2020 ◽  
Vol 202 (7) ◽  
Author(s):  
Ritam Sinha ◽  
Rhiannon M. LeVeque ◽  
Marvin Q. Bowlin ◽  
Michael J. Gray ◽  
Victor J. DiRita
Keyword(s):  
Stationary Phase ◽  
Campylobacter Jejuni ◽  
Phosphate Transporter ◽  
Rna Seq ◽  
Wild Type ◽  
Content Type ◽  
High Affinity ◽  
Polyphosphate Metabolism

ABSTRACT Campylobacter jejuni causes acute gastroenteritis worldwide and is transmitted primarily through poultry, in which it is often a commensal member of the intestinal microbiota. Previous transcriptome sequencing (RNA-Seq) experiment showed that transcripts from an operon encoding a high-affinity phosphate transporter (PstSCAB) of C. jejuni were among the most abundant when the bacterium was grown in chickens. Elevated levels of the pstSCAB mRNA were also identified in an RNA-Seq experiment from human infection studies. In this study, we explore the role of PstSCAB in the biology and colonization potential of C. jejuni. Our results demonstrate that cells lacking PstSCAB survive poorly in stationary phase, in nutrient-limiting media, and under osmotic conditions reflective of those in the chicken. Polyphosphate levels in the mutant cells were elevated at stationary phase, consistent with alterations in expression of polyphosphate metabolism genes. The mutant strain was highly attenuated for colonization of newly hatched chicks, with levels of bacteria at several orders of magnitude below wild-type levels. Mutant and wild type grew similarly in complex media, but the pstS::kan mutant exhibited a significant growth defect in minimal medium supplemented with l-lactate, postulated as a carbon source in vivo. Poor growth in lactate correlated with diminished expression of acetogenesis pathway genes previously demonstrated as important for colonizing chickens. The phosphate transport system is thus essential for diverse aspects of C. jejuni physiology and in vivo fitness and survival. IMPORTANCE Campylobacter jejuni causes millions of human gastrointestinal infections annually, with poultry a major source of infection. Due to the emergence of multidrug resistance in C. jejuni, there is need to identify alternative ways to control this pathogen. Genes encoding the high-affinity phosphate transporter PstSCAB are highly expressed by C. jejuni in chickens and humans. In this study, we address the role of PstSCAB on chicken colonization and other C. jejuni phenotypes. PstSCAB is required for colonization in chicken, metabolism and survival under different stress responses, and during growth on lactate, a potential growth substrate in chickens. Our study highlights that PstSCAB may be an effective target to develop mechanisms for controlling bacterial burden in both chicken and human.

scholarly journals Rhizobium yantingense sp. nov., a mineral-weathering bacterium

2015 ◽  
Vol 65 (Pt_2) ◽  
pp. 412-417 ◽  
Author(s):  
Wei Chen ◽  
Xia-Fang Sheng ◽  
Lin-Yan He ◽  
Zhi Huang
Keyword(s):  
Type Species ◽  
Novel Species ◽  
Sequence Similarity ◽  
Housekeeping Genes ◽  
Mineral Weathering ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
Pr China ◽  
Low Levels

A Gram-stain-negative, rod-shaped bacterial strain, H66T, was isolated from the surfaces of weathered rock (purple siltstone) found in Yanting, Sichuan Province, PR China. Cells of strain H66T were motile with peritrichous flagella. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain H66T belongs to the genus Rhizobium . It is closely related to Rhizobium huautlense SO2T (98.1 %), Rhizobium alkalisoli CCBAU 01393T (98.0 %) and Rhizobium cellulosilyticum ALA10B2T (98.0 %). Analysis of the housekeeping genes, recA, glnII and atpD, showed low levels of sequence similarity (<92.0 %) between strain H66T and other recognized species of the genus Rhizobium . The predominant components of the cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0. The G+C content of strain H66T was 60.3 mol%. Strain H66T is suggested to be a novel species of the genus Rhizobium based on the low levels of DNA–DNA relatedness (ranging from 14.3 % to 40.0 %) with type strains of species of the genus Rhizobium and on its unique phenotypic characteristics. The namehttp://dx.doi.org/10.1601/nm.1279 Rhizobium yantingense sp. nov. is proposed for this novel species. The type strain is H66T ( = CCTCC AB 2014007T = LMG 28229T).

scholarly journals Delivery of antibacterial silver nanoclusters to Pseudomonas aeruginosa using species-specific DNA aptamers

2020 ◽  
Vol 69 (4) ◽  
pp. 640-652 ◽  
Author(s):  
Jennifer Soundy ◽  
Darren Day
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Activity ◽  
Type Species ◽  
Galleria Mellonella ◽  
Host Cells ◽  
Silver Nanoclusters ◽  
Bacterial Cells ◽  
Content Type ◽  
Link Type

Introduction. The use of silver as an antimicrobial therapeutic is limited by its toxicity to host cells compared with that required to kill bacterial pathogens. Aim. To use aptamer targeting of DNA scaffolded silver nanoclusters as an antimicrobial agent for treating Pseudomonas aeruginosa infections. Methodology. Antimicrobial activity was assessed in planktonic cultures and in vivo using an invertebrate model of infection. Results. The aptamer conjugates that we call aptabiotics have potent antimicrobial activity. Targeted silver nanoclusters were more effective at killing P. aeruginosa than the equivalent quantity of untargeted silver nanoclusters. The aptabiotics have an IC50 of 1.3–2.6 µM against planktonically grown bacteria. Propidium iodide staining showed that they rapidly depolarize bacterial cells to kill approximately 50 % of the population within 10 min following treatment. In vivo testing in the Galleria mellonella model of infection prolonged survival from an otherwise lethal infection. Conclusion. Using P. aeruginosa as a model, we show that targeting of DNA-scaffolded silver nanoclusters with an aptamer has effective fast-acting antimicrobial activity in vitro and in an in vivo animal model.

scholarly journals Dyadobacter jiangsuensis sp. nov., a methyl red degrading bacterium isolated from a dye-manufacturing factory

2015 ◽  
Vol 65 (Pt_4) ◽  
pp. 1138-1143 ◽  
Author(s):  
Li Wang ◽  
Liang Chen ◽  
Qi Ling ◽  
Chen-chen Li ◽  
Yong Tao ◽  
...  
Keyword(s):  
Type Species ◽  
Phylogenetic Analyses ◽  
Major Fatty Acid ◽  
Rrna Gene ◽  
Methyl Red ◽  
Content Type ◽  
Link Type ◽  
Degrading Bacterium ◽  
Gene Sequence Analysis ◽  
Low Levels

A Gram-stain-negative, non-motile, rod-shaped bacterial strain, L-1T, which was capable of degrading methyl red was isolated from a dye-manufacturing factory in China. Phenotypic, chemotaxonomic and phylogenetic analyses established affiliation of the isolate to the genus Dyadobacter . Cells occurred in pairs in young cultures but became chains of coccoid cells in old cultures, and produced a flexirubin-like yellow pigment. Strain L-1T could not hydrolyse cellulose, and had a DNA G+C content of 51.3 mol%. The major cellular fatty acids were iso-C15 : 0, C16 : 1ω5c, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). C16 : 0, iso-C15 : 0 3-OH and C16 : 0 3-OH were the other major fatty acid components. Comparative 16S rRNA gene sequence analysis showed that strainL-1T was most closely related to Dyadobacter fermentans DSM 18053T (99.2 %), Dyadobacter soli JCM 16232T (98.9 %) and Dyadobacter beijingensis CGMCC 1.6375T (98.7 %). However, the new isolate exhibited relatively low levels of DNA–DNA relatedness with respect to JCM 16232T (41.2±1.8 %), DSM 18053T (38.6±2.6 %) and CGMCC 1.6375T (35.0±2.1 %). Strain L-1T could also be differentiated from its closest phylogenetic relatives based on differences in several phenotypic characteristics. These data suggest that strain L-1T represents a novel species of the genus Dyadobacter , for which the name Dyadobacter jiangsuensis sp. is proposed. The type strain is L-1T (DSM 29057T = CGMCC 1.12969T).

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