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  • Nitrogen regulation  (2)
  • ACV accumulation  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Relationship between nitrogen assimilation and cephalosporin synthesis inStreptomyces clavuligerus (1986)
    Springer
    Archives of microbiology 146 (1986), S. 46-51 
    Details
    ISSN: 1432-072X
    Keywords: Nitrogen assimilation ; Cephalosporin ; Nitrogen regulation ; Ammonium repression ; Streptomyces clavuligerus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The levels of three enzymes of the β-lactam antibiotic pathway and overall cephalosporin production were subject to nitrogen source repression inStreptomyces clavuligerus. The specific activities of isopenicillin N synthetase (“cyclase”) and deacetoxycephalosporin C synthetase (“expandase”) measured during the exponential phase depended on the nitrogen source employed, following a pattern that roughly correlated with the corresponding antibiotic production. The effects on isopenicillin N epimerase (“epimerase”) activities were less marked than those on the cyclase and expandase. Production of cephalosporins and enzymatic activities were not related to the growth rate of the cultures. Glutamate, glutamine and alanine inhibited production when added to resting cell systems, while lysine and α-aminoadipate were stimulatory. No clear relationship could be drawn between cephalosporin production or β-lactam synthetase activities and the activities of enzymes of ammonium assimilation (glutamine synthetase, glutamate synthase and alanine dehydrogenase). The intracellular pools of free glutamine, alanine and ammonium were the only ones markedly affected by the nitrogen source in the wild type and mutants, but these amino acids did not seem to play an obvious role as intracellular mediators of nitrogen control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690157
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A role for alanine in the ammonium regulation of cephalosporin biosynthesis inStreptomyces clavuligerus (1994)
    Springer
    Journal of industrial microbiology and biotechnology 13 (1994), S. 217-219 
    Details
    ISSN: 1476-5535
    Keywords: Cephalosporins ; Cephamycin ; Streptomyces clavuligerus ; Nitrogen regulation ; Antibiotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary It is known that excess ammonium supply decreases cephalosporin production and represses cephalosporin synthases. We wondered whether an additional important effect could be inhibition of synthase action by alanine. We had previously shown that ammonium addition induced alanine dehydrogenase and increased intracellular alanine and that alanine could inhibit resting cell synthesis of cephalosporins. In the present work we confirm the alanine inhibition of antibiotic production by resting cells. We foundl-alanine inhibited three of the four synthases tested: ACV synthetase, cyclase and expandase; the epimerase was not inhibited. These data suggest that interference in cephalosporin production by growth in ammonium salts involves synthase inhibition by intracellular alanine, in addition to the known role of ammonium in synthase repression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569751
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Methionine induction of ACV synthetase inCephalosporium acremonium (1987)
    Springer
    Journal of industrial microbiology and biotechnology 2 (1987), S. 251-255 
    Details
    ISSN: 1476-5535
    Keywords: Methionine effect ; ACV accumulation ; β-Lactam production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Methionine markedly stimulates the biosynthesis of penicillin N and cephalosporin C inCephalosporium acremonium. Examination of intra- and extracellular ACV tripeptide in non-producing mutant N-2 showed that growth in the presence of methionine increased ACV accumulation. Direct measurement of ACV synthetase activity in a cell-free system indicated that the methionine effect was mainly due to induction of this first enzyme of the β-lactam biosynthetic pathway, resulting in a corresponding increase in β-lactam production in both a low-producing strain and a high-producing mutant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569547
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    Paper (German National Licenses)
    Fulltext
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