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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 117 (1978), S. 277-285 
    ISSN: 1432-072X
    Keywords: White-rot fungi ; Nutrient nitrogen metabolism ; Fungus physiology ; Mycelial pellets ; pH ; Growth substrate ; Wood decay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Culture parameters influencing metabolism of synthetic14C-lignins to14CO2 in defined media have been studied in shallow batch cultures of the ligninolytic wood-destroying HymenomycetePhanerochaete chrysosporium Burds. Study of the effect of O2 concentration in the gas phase above non-agitated cultures indicated essentially complete absence of attack on the lignin polymer at 5% O2 in N2, and a 2- to 3-fold enhancement by 100% O2 as compared to air (21% O2). Agitation of the cultures resulting in the formation of mycelial pellets greatly suppressed lignin decomposition. The optimum culture pH for lignin decomposition was 4 to 4.5, with marked suppression above 5.5 and below 3.5. The source of nutrient nitrogen (NO 3 − , NH 4 + , amino acids) had little influence on lignin decomposition, but the concentration of nitrogen was critical; decomposition at 24 mM was only 25–35% of that at 2.4 mM N. Thiamine was the only vitamin required for growth and lignin decomposition. Under the optimum conditions developed, decomposition of 5 mg of synthetic lignin was accompanied by utilization of approximately 100 mg of glucose. The influence of the various culture parameters was analogous for metabolism of synthetic lignin labeled in the ring-,side chain-, and methoxyl carbon atoms.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: White-rot fungi ; Secondary metabolism ; Wood decay ; Mycelial pellets ; Fungus physiology ; l-Glutamic acid repression ; Phenylalanine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lignin-degrading basidiomycete Phanerochaete chrysosporium synthesizes veratryl alcohol (3,4-dimethoxybenzyl alcohol) via phenylalanine, 3,4-dimethoxycinnamyl alcohol and veratrylglycerol. Study of the conversion of 3,4-dimethoxycinnamyl alcohol to veratrylglycerol and veratryl alcohol showed is to be (a) catalyzed by a secondary metabolic system, (b) markedly suppressed by culture agitation, and (c) strongly inhibited by l-glutamate. The amount of veratryl alcohol synthesized de novo was positively correlated with the O2 concentration after primary growth. Other work has shown that the cinnamyl alcohol terminal residue in a lignin substructure model compound is degraded via arylglycerol and benzyl alcohol structures in ligninolytic cultures of P. chrysosporium, and that the ligninolytic system exhibits traits (a)-(c) above. Ligninolytic activity is also strongly and positively correlated with O2 concentration. The results here suggest, therefore, that the actual biosynthetic secondary metabolic product is 3,4-dimethoxycinnamyl alcohol, but that this is degraded by the ligninolytic system to veratryl alcohol via veratrylglycerol. Veratryl alcohol is only slowly metabolized by the fungus, and accumulates.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 130 (1981), S. 66-71 
    ISSN: 1432-072X
    Keywords: Wood decay ; White-rot fungi ; Lignin biodegradation ; Fungus physiology ; Repression by glutamate ; Glutamate dehydrogenase ; Glutamine synthetase ; Intracellular amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous research showed that addition of nutrient nitrogen to ligninolytic (stationary, nitrogen-starved) cultures of the wood-decomposing basidiomycete Phanerochaete chrysosporium causes a suppression of lignin degradation. The present study examined early effects on nitrogen metabolism that followed addition of NH 4 + and l-glutamate at concentrations that yield similar patterns of suppression. Both nitrogenous compounds were rapidly assimilated (〉80% in 6 h). Both caused an initial 80% or greater increase in the intracellular glutamate pool and had similar effects in increasing the specific activities of NADP- and NAD-glutamate dehydrogenases and glutamine synthetase. Differences between the effects of added NH 4 + and glutamate showed that suppression was not correlated with intracellular pools of arginine or glutamine, nor was the maintenance of an elevated glutamate pool required to maintain the suppressed state. While a portion of the initial glutamate suppression could be attributed to an effect on central carbon metabolism through glutamate catabolism by NAD-glutamate dehydrogenase, the long term suppression by glutamate and the suppression by NH 4 + were more specific. Suppression by NH 4 + or glutamate in the presence or absence of protein synthesis (cycloheximide) followed essentially identical kinetics during 12 h. These results indicate that nitrogen additions cause a biochemical repression of enzymes associated with lignin degradation. Results are consistent with the hypothesis that nitrogen metabolism via glutamate plays a role in initiation of repression.
    Type of Medium: Electronic Resource
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