Linkages between enhanced soil cellobiohydrolase activity and nutrient status-driven shifts in cbhI-harboring fungal community under long-term swine manure fertilization

Manure fertilization can enhance the activity of soil enzymes involved in cellulose degradation, thereby generating positive legacy effects on soil organic carbon sequestration when crop residue incorporation is implemented. However, it remains unclear how manure fertilization regulates the cellobiohydrolase (CBH)-producing microbial community and the linkages between this regulation and the enhanced soil CBH activity. This study investigated the relationship between soil cellulose degradation potential, CBH activity, chemical properties, and the cbhI -harboring fungal community in an upland Ultisol subjected to four long-term fertilization treatments (no fertilization, mineral fertilization, swine manure fertilization, and mineral plus swine manure fertilization). The soil cellulose degradation potential and CBH activity in the manure treatment increased by 108 % and 233 % compared to the no-fertilization control, respectively. Those in the mineral plus manure treatment increased by 107 % and 108 % compared to the mineral treatment, respectively. Manure fertilization significantly increased the abundance of cbhI -harboring fungal community and altered its composition, while exerting no significant influence on its diversity. Sordariomycetes and Leotiomycetes were dominant and indictor taxa within the functional fungal community under manure fertilization. The co-occurrence networks within the cbhI -harboring fungal community showed greater complexity and stability across the manure-amended soils compared to the non-manure-amended soils. Soil CBH activity was closely associated with the abundance and composition of cbhI -harboring fungal community, both of which were strongly influenced by soil pH and nutrient content and stoichiometric ratios. The structural equation modeling revealed that the shifts in the functional fungal community outcompeted soil pH in influencing soil CBH activity. The findings of this study collectively suggest that the enhanced soil CBH activity following long-term application of swine manure is primarily attributed to the proliferation of r-strategist cbhI -harboring fungi, which is driven by the improvement in soil nutrient status. • Swine manure boosted soil cellulose degradation potential via enhanced CBH activity. • Swine manure increased cbhI fungal abundance and altered their community composition. • Swine manure enhanced co-occurrence network complexity of cbhI fungal community. • Soil nutrient content and stoichiometry drove cbhI fungal abundance and composition. • Shifts in cbhI fungal community closely linked to enhanced CBH activity.