scholarly journals Erwinia tasmaniensis sp. nov., a non-phytopathogenic bacterium from apple and pear trees

2006 ◽  
Vol 56 (12) ◽  
pp. 2937-2943 ◽  
Author(s):  
Klaus Geider ◽  
Georg Auling ◽  
Zhiqiang Du ◽  
Vladimir Jakovljevic ◽  
Susanne Jock ◽  
...  

Bacteria were isolated from flowers and bark of apple and pear trees at three places in Australia. In Victoria, Tasmania and Queensland, strains with white colonies on nutrient agar were screened for dome-shaped colony morphology on agar with sucrose and were found to be closely related by several criteria. The isolates were not pathogenic on apples or pears. They were characterized by a polyphasic approach including microbiological and API assays as well as fatty acid methyl ester analysis, DNA–DNA hybridization and DNA sequencing. For molecular classification, the 16S rRNA cistron and the conserved genes gpd and recA of these bacteria were investigated. Together with other taxonomic criteria, the results of these studies indicate that the bacteria belong to a novel separate species, which we propose to name Erwinia tasmaniensis sp. nov., with the type strain Et1/99T (=DSM 17950T=NCPPB 4357T). From DNA–DNA hybridization kinetics, microbiological characteristics and nucleotide sequence analyses, this species is related to pathogenic Erwinia species, but also to the epiphytic species Erwinia billingiae.

2013 ◽  
Vol 103 (3) ◽  
pp. 237-244 ◽  
Author(s):  
R. S. Donahoo ◽  
J. B. Jones ◽  
G. H. Lacy ◽  
V. K. Stromberg ◽  
D. J. Norman

A comprehensive analysis of 175 Xanthomonas axonopodis pv. dieffenbachiae strains isolated from 10 Araceae hosts was done to identify pathogen variation. The strains were subjected to repetitive extragenic palindromic sequence polymerase chain reaction and four major phylogenetic clusters were generated. A subset of 40 strains isolated from Anthurium, Dieffenbachia, and Syngonium was further defined by amplified fragment length polymorphism and fatty acid methyl ester analysis and the same four phylogenetic clusters were observed. Comparison of representative strains in the first three clusters using DNA-DNA hybridization and multilocus sequence analysis supports the previous reclassification of strains in cluster I, including the X. axonopodis pv. dieffenbachiae pathovar reference strain (LMG695), to X. citri. Our research findings indicate that strains in cluster I, isolated primarily from anthurium, probably represent an undescribed pathovar. Other phylogenetic subclusters consisting primarily of strains isolated from xanthosoma and philodendron in clusters III and IV, respectively, may yet represent other undescribed species or pathovars of Xanthomonas.


2015 ◽  
Vol 65 (Pt_7) ◽  
pp. 2071-2077 ◽  
Author(s):  
Pavel Švec ◽  
Annelies De Bel ◽  
Ivo Sedláček ◽  
Petr Petráš ◽  
Tereza Gelbíčová ◽  
...  

Seven coagulase-negative, oxidase-negative and novobiocin-susceptible staphylococci assigned tentatively as Staphylococcus petrasii were investigated in this study in order to elucidate their taxonomic position. All strains were initially shown to form a genetically homogeneous group separated from remaining species of the genus Staphylococcus by using a repetitive sequence-based PCR fingerprinting with the (GTG)5 primer. Phylogenetic analysis based on 16S rRNA gene, hsp60, rpoB, dnaJ, gap and tuf sequences showed that the group is closely related to Staphylococcus petrasii but separated from the three hitherto known subspecies, S. petrasii subsp. petrasii, S. petrasii subsp. croceilyticus and S. petrasii subsp. jettensis. Further investigation using automated ribotyping, MALDI-TOF mass spectrometry, fatty acid methyl ester analysis, DNA–DNA hybridization and extensive biotyping confirmed that the analysed group represents a novel subspecies within S. petrasii, for which the name Staphylococcus petrasii subsp. pragensis subsp. nov. is proposed. The type strain is NRL/St 12/356T ( = CCM 8529T = LMG 28327T).


2015 ◽  
Vol 61 (1) ◽  
pp. 89-92 ◽  
Author(s):  
Manisha Karani ◽  
Ravindranath Shashidhar ◽  
Aarti Kakatkar ◽  
Raj Kamal Gautam ◽  
Shibani Sukhi ◽  
...  

A radiation-resistant bacterial isolate from gamma-radiation-processed (5 kGy) semidried prawns was identified as a new strain of Macrococcus caseolyticus and was designated as M. caseolyticus (A) on the basis of morphological and biochemical characterization and 16S rRNA sequencing. DNA–DNA hybridization studies with M. caseolyticus DSM 20597T further confirmed the isolate as M. caseolyticus. Major fatty acids present in M. caseolyticus (A) were C14:0, C16:1ω11c, and C18:1ω9c, whereas C15:0anteiso, C16:0iso, and C18:0iso were absent. The closest match for the isolate, as per fatty acid methyl ester analysis, was M. caseolyticus DSM 20597T. However, the similarity index was significantly low (0.112), which indicates that the isolate could be a new strain of M. caseolyticus. The decimal reduction dose (D10) for M. caseolyticus (A), M. caseolyticus JCSC5402, and Staphylococcus aureus MTCC96 was 1.18, 0.607, and 0.19 kGy, respectively. This is the first report on radiation resistance of M. caseolyticus. Macrococcus caseolyticus (A) is more resistant to gamma and UV radiation stress than are M. caseolyticus JCSC5402 and S. aureus MTCC96; however, it is sensitive to heat as well as desiccation stress.


2013 ◽  
Author(s):  
Jr Morris ◽  
Shardo Robert W. ◽  
Higgins James ◽  
Cook Kim ◽  
Tanner Rhonda ◽  
...  

2020 ◽  
Vol 16 (4) ◽  
pp. 556-567
Author(s):  
Asma Khalil ◽  
Zubair Ahmad ◽  
Farid Touati ◽  
Mohamed Masmoudi

Background: The photo-absorption and light trapping through the different layers of the organic solar cell structures are a growing concern now-a-days as it affects dramatically the overall efficiency of the cells. In fact, selecting the right material combination is a key factor in increasing the efficiency in the layers. In addition to good absorption properties, insertion of nanostructures has been proved in recent researches to affect significantly the light trapping inside the organic solar cell. All these factors are determined to expand the absorption spectrum and tailor it to a wider spectrum. Objective: The purpose of this investigation is to explore the consequence of the incorporation of the Ag nanostructures, with different sizes and structures, on the photo absorption of the organic BHJ thin films. Methods: Through a three-dimensional Maxwell solver software, Lumerical FDTD, a simulation and comparison of the optical absorption of the three famous organic materials blends poly(3- hexylthiophene): phenyl C71 butyric acid methyl ester (P3HT:PCBM), poly[N-9″-heptadecanyl-2,7- carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]: phenyl C71 butyric acid methyl ester (PCDTBT:PCBM) and poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt- 4,7-(2,1,3-benzothiadiazole)]: phenyl C71 butyric acid methyl ester (PCDPDTBT:PCBM) has been conducted. Furthermore, FDTD simulation study of the incorporation of nanoparticles structures with different sizes, in different locations and concentrations through a bulk heterojunction organic solar cell structure has also been performed. Results: It has been demonstrated that embedding nanostructures in different locations of the cell, specifically in the active layer and the hole transporting layer had a considerable effect of widening the absorption spectrum and increasing the short circuit current. The effect of incorporation the nanostructures in the active layer has been proved to be greater than in the HTL. Furthermore, the comparison results showed that, PCDTBT:PCBM is no more advantageous over P3HT:PCBM and PCPDTBT:PCBM, and P3HT:PCBM took the lead and showed better performance in terms of absorption spectrum and short circuit current value. Conclusion: This work revealed the significant effect of size, location and concentration of the Ag nanostructures while incorporated in the organic solar cell. In fact, embedding nanostructures in the solar cell widen the absorption spectrum and increases the short circuit current, this result has been proven to be significant only when the nanostructures are inserted in the active layer following specific dimensions and structures.


Sign in / Sign up

Export Citation Format

Share Document