Influence of Rhizosphere Micro-organisms on the Virulence of Rhizobium trifolii

Nature ◽  
1953 ◽  
Vol 172 (4376) ◽  
pp. 507-508 ◽  
Author(s):  
J. R. HARRIS
Keyword(s):  
Rhizobium Trifolii ◽  
Micro Organisms

The effect of anti-fungal antibiotics on the nodulation of Trifolium subterraneum and the estimation of Rhizobium trifolii populations

1968 ◽  
Vol 8 (32) ◽  
pp. 327 ◽  
Author(s):  
AC Robinson
Keyword(s):  
Pure Culture ◽  
Culture Media ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Test Plant ◽  
Rhizobium Trifolii ◽  
Plant Infection ◽  
Micro Organisms ◽  
Anti Fungal ◽  
Test Plants

Three anti-fungal antibiotics (cycloheximide, griseofulvin, and mycostatin) were tested for their effects on inoculated Trifolium subterraneum (subterranean clover). All three influenced the growth and nodulation of the test plant, the effects being least with mycostatin. Mycostatin was further examined for its effect on a plant-infection technique for estimating Rhizobium numbers. The presence in culture media of mycostatin did not impair the accuracy of the plant-infection test for counting rhizobia in a pure culture. Moreover, when the plant-infection technique was used for counting rhizobia in soil, the antibiotic reduced the amount of infection of the test plant by miscellaneous soil micro-organisms, thereby improving nodulation. It is concluded that the incorporation of mycostatin into media (100 p.p.m.) used for growing test plants in plant-infection tests will improve the reliability of the method.

SOME FACTORS AFFECTING THE SURVIVAL OF RHIZOBIUM TRIFOLII ON WHITE CLOVER

1976 ◽  
pp. 182-186 ◽  
Author(s):  
C.N. Hale
Keyword(s):  
Seed Coat ◽  
White Clover ◽  
Inhibitory Effect ◽  
Water Soluble ◽  
Rhizobium Trifolii ◽  
Factors Affecting ◽  
Naturally Occurring ◽  
Clover Seed ◽  
Micro Organisms ◽  
Selection Of

Survival of Rhizobium trifolii on white clover seed before sowing is adversely affected by both drying and a water-soluble toxin which diffuses from the seed coat during the inoculation process. Survival of rhizobia is increased by removal of the toxin by seed washing or the suppression of its inhibitory effect by treatment of seed with phenolic adsorbents. Survival of rhizobia introduced into tbe soil on seed before the rhizosphere is capable of supporting growth and multiplication may be affected by the toxic diffusate and competition and/or antagonism from naturally occurring populations of soil micro-organisms, Selection of effective strains of rhizobia on criteria such as survival and competition abilities, as well as on the ability to nodulate and fix nitrogen, is considered to be extremely important.

Review of the Radiation Damage Problem of Organic Specimens in Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 476-477
Author(s):  
L. Reimer
Keyword(s):  
Electron Microscopy ◽  
Radiation Damage ◽  
Irradiation Time ◽  
Dose Effect ◽  
Primary Process ◽  
Thin Specimen ◽  
Secondary Damage ◽  
Small Doses ◽  
Micro Organisms ◽  
Damage Processes

Most information about a specimen is obtained by elastic scattering of electrons, but one cannot avoid inelastic scattering and therefore radiation damage by ionisation as a primary process of damage. This damage is a dose effect, being proportional to the product of lectron current density j and the irradiation time t in Coul.cm−2 as long as there is a negligible heating of the specimen.Therefore one has to determine the dose needed to produce secondary damage processes, which can be measured quantitatively by a chemical or physical effect in the thin specimen. The survival of micro-organisms or the decrease of photoconductivity and cathodoluminescence are such effects needing very small doses (see table).

Functional amyloid: widespread in Nature, diverse in purpose

2014 ◽  
Vol 56 ◽  
pp. 207-219 ◽  
Author(s):  
Chi L.L. Pham ◽  
Ann H. Kwan ◽  
Margaret Sunde
Keyword(s):  
Spider Silk ◽  
Epigenetic Inheritance ◽  
Fibrillar Structure ◽  
Cytoplasmic Polyadenylation ◽  
Functional Amyloid ◽  
Interacting Protein ◽  
Diverse Range ◽  
Element Binding Protein ◽  
Functional Amyloids ◽  
Micro Organisms

Amyloids are insoluble fibrillar protein deposits with an underlying cross-β structure initially discovered in the context of human diseases. However, it is now clear that the same fibrillar structure is used by many organisms, from bacteria to humans, in order to achieve a diverse range of biological functions. These functions include structure and protection (e.g. curli and chorion proteins, and insect and spider silk proteins), aiding interface transitions and cell–cell recognition (e.g. chaplins, rodlins and hydrophobins), protein control and storage (e.g. Microcin E492, modulins and PMEL), and epigenetic inheritance and memory [e.g. Sup35, Ure2p, HET-s and CPEB (cytoplasmic polyadenylation element-binding protein)]. As more examples of functional amyloid come to light, the list of roles associated with functional amyloids has continued to expand. More recently, amyloids have also been implicated in signal transduction [e.g. RIP1/RIP3 (receptor-interacting protein)] and perhaps in host defence [e.g. aDrs (anionic dermaseptin) peptide]. The present chapter discusses in detail functional amyloids that are used in Nature by micro-organisms, non-mammalian animals and mammals, including the biological roles that they play, their molecular composition and how they assemble, as well as the coping strategies that organisms have evolved to avoid the potential toxicity of functional amyloid.

X-ray Pictures of Micro-organisms

1913 ◽  
Vol 108 (5) ◽  
pp. 115-115
Author(s):  
Alfred Gradenwitz
Keyword(s):  
X Ray ◽  
Micro Organisms

The role of intracanal medicaments in inhibition of bacteria isolated from root canals of infected primary molars

2019 ◽  
Vol 14 (1) ◽  
pp. 92
Author(s):  
Dr. Maha Abdul- Kareem Mahmood ◽  
Dr. Huda Elias Ali ◽  
Dr. Haraa Khairi Abdul-Kadher
Keyword(s):  
Antimicrobial Activity ◽  
Streptococcus Mutans ◽  
Normal Saline ◽  
Root Canal ◽  
Primary Teeth ◽  
Primary Molars ◽  
Root Canals ◽  
Etiologic Agents ◽  
Micro Organisms

Microbes are considered as the primary etiologic agents in endodontic diseases.Disinfection of the root canal is obtained by the combined effect of biomechanicalpreparation, irrigation and intra canal medicament. The aim of the present study wasto assess the antimicrobial activity of intracanal medicaments (formocresol andEndosepton) against two micro organisms (Streptococcus mutans and staphylococcusaureus) isolated from 15 necrotic pulps of primary molars indicated for pulpectomyprocedure. The samples were cultured, and purified using microbiological evaluation.Broth dilution test was performed in our study by preparing test tubes containing10 ml of BHI broth (pH. 7) which then inoculated with strains of the tested bacteriaand incubated at 37 C° for 24 h. After over night incubaction, ten fold dilution weremade in test tubes containing 9 ml of normal saline by adding 1 ml of the inoculum tothe first tube . Then from dilution 10-1 , 0.1 ml of cell suspension was added to 9.9 mlof formocresol and endosepton, then 0.1 ml was taken and spread on duplicates ofBHI agar plates at different intervals and incubated aerobically for 24 h. at 37 C°.Colonies on the plates were counted after incubation and CFU/mL (colony formingunit) was calculated. Our results indicating that there were no significant differencesbetween the intracanal medicaments, but there were high significant differencesbetween the intervals time of the study. We concluded that both materials had greatantibacterial effect against the pathogens commonly isolated from necrotic pulpaltissue of primary teeth.

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