Steffen Kari T, Cajthaml Tomás, Snajdr Jaroslav, Baldrian Petr
Division of Microbiology, Department of Applied Chemistry and Microbiology, University of Helsinki, FIN-00014 Helsinki, Finland.
Res Microbiol. 2007 Jun;158(5):447-55. doi: 10.1016/j.resmic.2007.04.002. Epub 2007 Apr 21.
Due to production of lignocellulose-degrading enzymes, saprotrophic litter-decomposing basidiomycetes can significantly contribute to the turnover of soil organic matter. The production of lignin and polysaccharide-degrading enzymes and changes in the chemical composition of litter was studied with Marasmius quercophilus, Mycena inclinata and Pholiota lenta, three basidiomycete species typical of oak (Quercus petraea) forests. Within 12weeks of incubation, M. inclinata decomposed 33%, M. quercophilus 36% and P. lenta 48% of the substrate dry mass. All fungi produced laccase and Mn-peroxidase and none of them produced lignin peroxidase or Mn-independent peroxidases. M. inclinata and M. quercophilus produced considerable laccase activity, while production by P. lenta was low. M. quercophilus and P. lenta produced most Mn-peroxidase at the beginning of the experiment, while the production by M. inclinata was more stable in time. Endo-1,4-beta-xylanase exhibited the highest activity among endocleaving glycosyl hydrolases while 1,4-beta-glucosidase was the main exocleaving enzyme. All fungi decreased the C:N ratio of the litter from 27 to 13-17 and M. inclinata and M. quercophilus also decreased the lignin content. Analytical pyrolysis of decayed litter showed changes in litter composition similar to those caused by white-rot fungi during wood decay, e.g. a decrease in the syringyl/guaiacyl lignin ratio. These changes were more pronounced in M. inclinata and M. quercophilus. The results indicate that different litter-decomposing fungi can cause substantial litter transformation despite considerable differences in the production of lignocellulose-degrading enzymes.
由于能产生木质纤维素降解酶，腐生型落叶分解担子菌可显著促进土壤有机质的周转。对栎生小皮伞、倾斜小菇和皱柄鳞伞这三种典型的栎林（岩栎）担子菌进行了研究，分析了它们木质素和多糖降解酶的产生情况以及落叶化学成分的变化。在培养12周内，倾斜小菇分解了33%的底物干质量，栎生小皮伞分解了36%，皱柄鳞伞分解了48%。所有真菌都产生漆酶和锰过氧化物酶，且均不产生木质素过氧化物酶或非锰依赖过氧化物酶。倾斜小菇和栎生小皮伞产生了相当高的漆酶活性，而皱柄鳞伞的漆酶产量较低。栎生小皮伞和皱柄鳞伞在实验开始时产生的锰过氧化物酶最多，而倾斜小菇的产量在时间上更稳定。内切-1,4-β-木聚糖酶在内切糖苷水解酶中活性最高，而1,4-β-葡萄糖苷酶是主要的外切酶。所有真菌都使落叶的碳氮比从27降至13 - 17，倾斜小菇和栎生小皮伞还降低了木质素含量。对腐烂落叶的分析热解显示，落叶成分的变化类似于木材腐烂过程中白腐真菌引起的变化，例如紫丁香基/愈创木基木质素比例降低。这些变化在倾斜小菇和栎生小皮伞中更为明显。结果表明，尽管木质纤维素降解酶的产生存在显著差异，但不同的落叶分解真菌仍可导致大量的落叶转化。
