Lignin enrichment selects specialized fungal communities from contrasting soils

Despite growing interest in microbial lignin degradation, the ecological and taxonomic dynamics of fungal communities enriched under ligninolytic conditions remain poorly understood. We hypothesized that sequential enrichment on lignin would select specialized fungal communities, with assembly shaped by inoculum source, temperature, and lignin type. Fungal consortia from backyard compost soil and a commercial substrate were enriched on alkaline-extracted or Kraft lignin as the sole carbon source at 30°C or 37°C through six successive passages. Internal Transcribed Spacer amplicon sequencing assessed fungal diversity, taxonomic composition, and predicted ecological guilds. Richness and diversity progressively declined, indicating strong selective pressure and enrichment of specialized communities. Community composition was primarily influenced by temperature and inoculum source, whereas lignin type had limited and statistically nonsignificant effects at the genus level. Ascomycota dominated all enriched consortia, while several taxa initially detected in the source materials were progressively lost. Functional predictions indicated a predominance of saprotrophic guilds, although most assignments had moderate or low confidence. These findings highlight the importance of temperature and inoculum source in shaping fungal community assembly during lignin enrichment and provide guidance for designing and optimizing ligninolytic consortia for biotechnological applications.