Isolation and characterization of mutants of Rhizobium meliloti unable to synthesize poly-β-hydroxybutyrate

1994 ◽  
Vol 40 (10) ◽  
pp. 823-829 ◽  
Author(s):  
Silvana Povolo ◽  
Riccardo Tombolini ◽  
Antonella Morea ◽  
Alistair J. Anderson ◽  
Sergio Casella ◽  
...  
Keyword(s):  
Rhizobium Meliloti ◽  
Tn5 Transposon ◽  
Transposon Insertion ◽  
Isolation And Characterization ◽  
Transmission Electron ◽  
Genome Level ◽  
Acetylene Reducing Activity ◽  
Phb Synthase ◽  
Dna Profiles

The isolation and characterization of four mutants of Rhizobium meliloti unable to synthesize poly-β-hydroxybutyrate (PHB) are reported. The mutants were independently obtained via Tn5 transposon mutagenesis and exhibited physiological and cytomorphological characteristics similar to those of the parental strain, as well as overlapping DNA profiles. These were assessed at both the plasmid and total genome level, using for the latter the sensitive technique of pulsed-field gel electrophoresis in a contour-clamped homogeneous electric field. With respect to the parental PHB+ strain, the loss of PHB-synthesizing ability in the four mutants was demonstrated by gas chromatography, transmission electron microscopy, and enzymatic tests. Localization studies of Tn5 insertion showed that the PHB− phenotype had, in all mutants, a transposon insertion in the same region, although not in the same position. The symbiotic traits (nodule-inducing ability on Medicago sativa and acetylene-reducing activity of nodules) of the mutants did not differ significantly from those of the parental R. meliloti.Key words: Rhizobium meliloti, poly-β-hydroxybutyrate (PHB), PHB synthase.

scholarly journals Isolation and characterization of pathogenic Escherichia coli bacteriophages from chicken and beef offal

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Celosia Lukman ◽  
Christopher Yonathan ◽  
Stella Magdalena ◽  
Diana Elizabeth Waturangi
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
High Efficiency ◽  
Multiplicity Of Infection ◽  
Isolation And Characterization ◽  
Transmission Electron ◽  
Pathogenic Escherichia Coli ◽  
Family Based

Abstract Objective This study was conducted to isolate and characterize lytic bacteriophages for pathogenic Escherichia coli from chicken and beef offal, and analyze their capability as biocontrol for several foodborne pathogens. Methods done in this research are bacteriophage isolation, purification, titer determination, application, determination of host range and minimum multiplicity of infection (miMOI), and bacteriophage morphology. Results Six bacteriophages successfully isolated from chicken and beef offal using EPEC and EHEC as host strain. Bacteriophage titers observed between 109 and 1010 PFU mL−1. CS EPEC and BL EHEC bacteriophage showed high efficiency in reduction of EPEC or EHEC contamination in meat about 99.20% and 99.04%. The lowest miMOI was 0.01 showed by CS EPEC bacteriophage. CI EPEC and BL EPEC bacteriophage suspected as Myoviridae family based on its micrograph from Transmission Electron Microscopy (TEM). Refers to their activity, bacteriophages isolated in this study have a great potential to be used as biocontrol against several foodborne pathogens.

scholarly journals Isolation and Characterization of Cellulose Nanofibers fromGigantochloa scortechiniias a Reinforcement Material

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Chaturbhuj K. Saurabh ◽  
Asniza Mustapha ◽  
M. Mohd. Masri ◽  
A. F. Owolabi ◽  
M. I. Syakir ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cellulose Nanofibers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Isolation And Characterization ◽  
Transmission Electron ◽  
Reinforcement Material ◽  
Bamboo Fibers ◽  
Ft Ir

Cellulose nanofibers (CNF) were isolated fromGigantochloa scortechiniibamboo fibers using sulphuric acid hydrolysis. This method was compared with pulping and bleaching process for bamboo fiber. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis were used to determine the properties of CNF. Structural analysis by FT-IR showed that lignin and hemicelluloses were effectively removed from pulp, bleached fibers, and CNF. It was found that CNF exhibited uniform and smooth morphological structures, with fiber diameter ranges from 5 to 10 nm. The percentage of crystallinity was significantly increased from raw fibers to cellulose nanofibers, microfibrillated, along with significant improvement in thermal stability. Further, obtained CNF were used as reinforcement material in epoxy based nanocomposites where tensile strength, flexural strength, and modulus of nanocomposites improved with the addition of CNF loading concentration ranges from 0 to 0.7%.

scholarly journals Genome sequence and characterization of five bacteriophages infecting Streptomyces coelicolor and Streptomyces venezuelae: Alderaan, Coruscant, Dagobah, Endor1 and Endor2

2020 ◽  
Author(s):  
Aël Hardy ◽  
Vikas Sharma ◽  
Larissa Kever ◽  
Julia Frunzke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Streptomyces Coelicolor ◽  
Morphological Differentiation ◽  
Viral Diversity ◽  
Isolation And Characterization ◽  
Phage Evolution ◽  
Transmission Electron ◽  
Family Based

AbstractStreptomyces are well-known antibiotic producers, and are also characterized by a complex morphological differentiation. Streptomyces, like all bacteria, are confronted with the constant threat of phage predation, which in turn shapes bacterial evolution. However, despite significant sequencing efforts recently, relatively few phages infecting Streptomyces have been characterized compared to other genera. Here, we present the isolation and characterization of five novel Streptomyces phages. All five phages belong to the Siphoviridae family, based on their morphology as determined by transmission electron microscopy. Genome sequencing revealed that four of them were temperate phages, while one had a lytic lifestyle. Moreover, one of the newly sequenced phages shows very little homology to already described phages, highlighting the still largely untapped viral diversity. Altogether, this study expands the number of characterized phages of Streptomyces and sheds light on phage evolution and phage-host dynamics in Streptomyces.

scholarly journals Yersinia enterocolitica ClpB Affects Levels of Invasin and Motility

2000 ◽  
Vol 182 (19) ◽  
pp. 5563-5571 ◽  
Author(s):  
Julie L. Badger ◽  
Briana M. Young ◽  
Andrew J. Darwin ◽  
Virginia L. Miller
Keyword(s):  
Yersinia Enterocolitica ◽  
Insertion Mutant ◽  
Gene Transcript ◽  
Null Mutant ◽  
Early Stationary Phase ◽  
Flagellin Gene ◽  
Transposon Insertion ◽  
Isolation And Characterization ◽  
Mutant Phenotypes

ABSTRACT Expression of the Yersinia enterocolitica inv gene is dependent on growth phase and temperature. inv is maximally expressed at 23°C in late-exponential- to early-stationary-phase cultures. We previously reported the isolation of a Y. enterocolitica mutant (JB1A8v) that shows a decrease in invasin levels yet is hypermotile when grown at 23°C. JB1A8v has a transposon insertion within uvrC. Described here is the isolation and characterization of a clone that suppresses these mutant phenotypes of the uvrC mutant JB1A8v. This suppressing clone encodes ClpB (a Clp ATPase homologue). The Y. enterocolitica ClpB homologue is 30 to 40% identical to the ClpB proteins from various bacteria but is 80% identical to one of the two ClpB homologues ofYersinia pestis. AclpB::TnMax2 insertion mutant (JB69Qv) was constructed and determined to be deficient in invasin production and nonmotile when grown at 23°C. Analysis ofinv and fleB (flagellin gene) transcript levels in JB69Qv suggested that ClpB has both transcriptional and posttranscriptional effects. In contrast, a clpB null mutant, BY1v, had no effect on invasin levels or motility. A model accounting for these observations is presented.

scholarly journals Isolation and characterization of Rhizobium meliloti Tn5 mutants showing enhanced symbiotic effectiveness

Microbiology ◽  
1994 ◽  
Vol 140 (3) ◽  
pp. 463-470 ◽  
Author(s):  
L. A. Sharypova ◽  
O. P. Onishchuk ◽  
O. N. Chesnokova ◽  
J. G. Fomina-Eshchenko ◽  
B. V. Simarov
Keyword(s):  
Rhizobium Meliloti ◽  
Symbiotic Effectiveness ◽  
Isolation And Characterization ◽  
Tn5 Mutants

scholarly journals Isolation and Characterization of Rhizobium meliloti Isolated from Rhizosphere Soil and Roots of Fenugreek from Different Locations

2018 ◽  
Vol 7 (06) ◽  
pp. 1460-1467
Author(s):  
Satyadev Prajapati ◽  
M. S. Dadke ◽  
S. Surekha ◽  
S. Godika ◽  
V. Prasanna Krishna
Keyword(s):  
Rhizosphere Soil ◽  
Rhizobium Meliloti ◽  
Isolation And Characterization

scholarly journals Isolation and characterization of the recA gene of Rhizobium meliloti.

1983 ◽  
Vol 155 (1) ◽  
pp. 311-316 ◽  
Author(s):  
M Better ◽  
D R Helinski
Keyword(s):  
Rhizobium Meliloti ◽  
Reca Gene ◽  
Isolation And Characterization

scholarly journals Isolation and characterization of an R-prime plasmid from Rhizobium meliloti.

1980 ◽  
Vol 141 (1) ◽  
pp. 121-128 ◽  
Author(s):  
G B Kiss ◽  
K Dobo ◽  
I Dusha ◽  
A Breznovits ◽  
L Orosz ◽  
...  
Keyword(s):  
Rhizobium Meliloti ◽  
Isolation And Characterization

Isolation and characterization of the Rhizobium meliloti Tn5-mutants with impaired nodulation competitiveness

1994 ◽  
Vol 167 (2) ◽  
pp. 267-274 ◽  
Author(s):  
O. P. Onishchuk ◽  
L. A. Sharypova ◽  
B. V. Simarov
Keyword(s):  
Rhizobium Meliloti ◽  
Isolation And Characterization ◽  
Nodulation Competitiveness ◽  
Tn5 Mutants
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