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  • 1
    Electronic Resource
    Electronic Resource
    Adenine requirement for nodulation of pea by an auxotrophic mutant of Rhizobium leguminosarum (1974)
    Springer
    Archives of microbiology 100 (1974), S. 219-238 
    Details
    ISSN: 1432-072X
    Keywords: Rhizobium ; Nodulation ; Symbiosis ; Adenine ; Thiamine ; Auxotroph ; Prototroph
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A non-nodulating auxotroph (L4-73) derived from an effective strain (L4) of Rhizobium leguminosarum has a growth requirement for adenine and thiamine. The auxotroph was able to infect the roots of the host plant Pisum sativum L. but formed root nodules (ineffective in nitrogen fixation) only when adenine and, to a lesser extent, thiamine were added to the plant substrate. Nodules formed in the presence of adenine were structurally abnormal, containing small cells in which infection threads appeared to have aborted. In the presence of thiamine the auxotroph produced a smaller number of nodules which were slightly more developed and were able to reduce trace amounts of acetylene to ethylene. The adenine effect predominated when both growth factors were added together or separately in different sequences. Adenine amendment was required during the first 6 days following inoculation to achieve the maximum number of nodules. The block in symbiosis could not be fully overcome by sequential addition or removal from the root medium of either compound or by addition of some other adeninecontaining compounds. Partial prototroph revertants requiring adenine but not thiamine induced a nodulation response similar to that of the original auxotroph in the presence of thiamine; partial prototrophs requiring thiamine only were almost fully effective. Bioassay of pea root tissue indicated the presence of significant amounts of both adenine and thiamine or related substances in the roots. The auxotroph was able to compete with the parent strain L4 in nodulation on roots of pea only in the presence of exogenous adenine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446319
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Degradation of the compatible solute trehalose in Ectothiorhodospira halochloris: isolation and characterization of trehalase (1990)
    Springer
    Archives of microbiology 153 (1990), S. 600-606 
    Details
    ISSN: 1432-072X
    Keywords: Ectothiorhodospira halochloris ; Osmoregulation ; Betaine ; Phototrophic bacteria ; Haloalkaliphilic bacteria ; Trehalase ; Trehalose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Trehalase, which hydrolyzes the disaccharide trehalose to α-d-glucose was isolated and partially purified (124-fold) from the phototrophic halo-alkaliphilic bacterium Ectothiorhodospira halochloris. The molecular mass was determined to be 480,000 and the isoelectric point pH 5.6. Temperature optimum was found to be 40°C and the pH-optimum 7.8–8.1. In spite of its high K m-value of 0.5 M, trehalase of E. halochloris was shown to be specific for trehalose. Trehalase is activated by phosphate which is, however, not involved in the reaction mechanism. The enzyme is activated by the compatible solute betaine and inhibited by salts. In the presence of betaine the K m-value is lowered from 0.5 M to 0.16 M; moreover, betaine partially protects enzymatic activity from salt inhibition. The findings indicate that betaine might regulate the trehalose level in the cells by affecting trehalase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245272
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The role of trehalose as a substitute for nitrogen-containing compatible solutes (Ectothiorhodospira halochloris) (1990)
    Springer
    Archives of microbiology 153 (1990), S. 607-613 
    Details
    ISSN: 1432-072X
    Keywords: Anaerobic phototrophic bacteria ; Halophilic eubacteria ; Osmoadaptation ; Betaine Ectoine ; Trehalose ; Compatible solutes ; Ectothiorhodospira halochloris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The halophilic phototrophic bacterium Ectothiorhodospira halochloris is able to synthesize both nitrogen-containing (betaine, ectoine) and nitrogen-free (trehalose) compatible solutes. In the absence of external ammonium and under nitrogen-limited growth conditions ectoine was metabolized and trehalose partly replaced betaine. The cytoplasmic trehalose concentration did not exceeded 0.5 mol/kg water (approx. 30% of total compatible solutes). A decreasing content of betaine in cells growing under nitrogen limitation is a result of decreased biosynthesis. Apparently, the betaine pool cannot be used as a nitrogen source, not even in a situation of total nitrogen depletion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245273
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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