Fungi are recognized as efficient decomposers of biopolymers contained in soil or litter, but not all saprotrophic taxa are equally efficient in accessing various C sources. While many fungi may be considered generalists that are able to utilize complex biomass of plant, bacterial, and fungal origin, it is less clear which of the individual biopolymers that compose these substrates they utilize. Here we analysed fungal communities in forest topsoil enriched in bags with polymers composing plant (cellulose, xylan, glucomannan, pectin, lignin) and fungal (chitin, β-1,3-glucan, and β-1,3-1,6-glucan) biomass along with fungal abundance and the activity of enzymes. There was a high degree of specialization among saprotrophs, each biopolymer being preferred by distinct taxa. White-rot fungi and general saprotrophs were most common on cellulose and xylan, while pectin and lignin-associated communities were dominated by moulds, and animal pathogens were found almost exclusively on chitin. Although several enzymes were produced on all biopolymers, the composition of enzyme pools was significantly different among substrates and different from litter. Activity of endocellulase, β-galactosidase, β-mannosidase, and β-glucosidase significantly correlated with the fungal to bacterial biomass ratio indicating the important role of fungi in their production. The results indicate the high level of specialization among litter-inhabiting fungi and differences in the substrate preference across nutritional guilds of saprotrophic fungi. While most of the litter-inhabiting fungi utilize plant biopolymers, fungal biopolymers are also frequently targeted.

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枯枝落叶真菌对组成植物和真菌生物质的生物聚合物表现出高度的专业化

真菌被认为是土壤或凋落物中生物聚合物的有效分解者，但并非所有腐生类群在获取各种碳源方面都同样有效。虽然许多真菌可能被认为是能够利用植物、细菌和真菌来源的复杂生物质的通才，但尚不清楚它们利用构成这些底物的单个生物聚合物中的哪一种。在这里，我们分析了富含植物（纤维素、木聚糖、葡甘露聚糖、果胶、木质素）和真菌（几丁质、β-1,3-葡聚糖和β-1,3-1,6-葡聚糖）生物量以及真菌丰度和酶活性。腐生菌之间存在高度的专业化，每种生物聚合物都被不同的分类群所偏爱。白腐真菌和一般腐生菌在纤维素和木聚糖上最常见，而果胶和木质素相关群落则以霉菌为主，而动物病原体几乎只在几丁质上发现。尽管在所有生物聚合物上都产生了几种酶，但酶库的组成在底物和垃圾之间存在显着差异。内切纤维素酶、β-半乳糖苷酶、β-甘露糖苷酶和β-葡萄糖苷酶的活性与真菌与细菌的生物量比显着相关，表明真菌在其生产中的重要作用。结果表明，凋落物栖息的真菌具有高度的专业化水平，以及腐养真菌营养类群之间底物偏好的差异。虽然大多数栖息在垃圾中的真菌利用植物生物聚合物，但真菌生物聚合物也经常成为目标。