Ziegenhagen D, Hofrichter M
Friedrich-Schiller Universität Jena, Institut für Mikrobiologie, Lehrstuhl für Technische Mikrobiologie, Germany.
J Basic Microbiol. 1998;38(4):289-99.
The depolymerization of humic acids (HAs) obtained from low-rank coal (lignite) to fulvic acids (FAs) was investigated in a cell-free system (in vitro) using manganese peroxidase (MnP) from the white-rot fungus Clitocybula dusenii b11. MnP was produced in surface cultures of C. dusenii which were induced with manganese (II) ions (Mn2+, 300 microM). The optimum conditions for the action of MnP were determined by varying following parameters of the enzyme assay: i) concentration of Mn2+, ii) concentration of hydrogen peroxide (H2O2), iii) pH value and iv) temperature. Optimum parameters determined were used in subsequent in vitro depolymerization studies of humic acids. For that purpose, following parameters of the reaction mixture were additionally varied: concentration of HAs, concentration of the thiol mediator glutathione (GSH), presence and concentration of organic solvents. As the result, following parameters were found to be optimal for the MnP-catalyzed in vitro depolymerization of HAs into low-molecular weight FAs (MnP activity 0.12 U/ml): 250 micrograms/ml HAs, 1 mM MnCl2, 46 microM/min H2O2 (continuously supplied by glucose oxidase), 600 microM GSH, 4% (v/v) N,N-dimethylformamide (DMF), pH 4.0, and 37 degrees C.
利用白腐真菌杜氏斜盖伞b11的锰过氧化物酶（MnP），在无细胞体系（体外）中研究了从低阶煤（褐煤）中获得的腐殖酸（HAs）向富里酸（FAs）的解聚过程。MnP是在杜氏斜盖伞的表面培养物中产生的，该培养物用锰（II）离子（Mn2 +，300微摩尔）诱导。通过改变酶测定的以下参数来确定MnP作用的最佳条件：i）Mn2 +浓度，ii）过氧化氢（H2O2）浓度，iii）pH值和iv）温度。确定的最佳参数用于随后的腐殖酸体外解聚研究。为此，还改变了反应混合物的以下参数：HAs浓度、硫醇介质谷胱甘肽（GSH）浓度、有机溶剂的存在和浓度。结果发现，以下参数对于MnP催化的HAs体外解聚为低分子量FAs（MnP活性0.12 U/ml）是最佳的：250微克/毫升HAs、1毫摩尔/升氯化锰、46微摩尔/分钟H2O2（由葡萄糖氧化酶持续供应）、600微摩尔GSH、4%（v/v）N，N-二甲基甲酰胺（DMF）、pH 4.0和37摄氏度。
