Patterns of fungal community succession triggered by C/N ratios during composting

Accumulating evidence indicates that the functional rather than taxonomic composition of microbial communities is closely correlated to local environmental factors. While composting is a widely accepted practice, specific knowledge of how fungal functional groups interact during the composting process remains limited. To address this, the impact of the initial C/N ratio of composting material on fungal community was analyzed in order to reveal the succession of functional diversity. Compared with the raw materials, the final composting product significantly reduced the relative abundances of plant and animal pathogens. Abundances of plant and animal pathogens, as well as dung saprotrophs, were negatively correlated with compost maturity, while abundances of wood saprotrophs exhibited positive correlations. Specific OTUs that showing highly abundant in each treatment were expected to compete for environmental preferences (niches) and/or interact with each other in positive (facilitative) ways. OTU2 (wood saprotroph) exhibiting the highest occurrence was negatively related to OTU7 (animal pathogen) and OTU4 (plant pathogen) during the mesophilic phase. Taken together, high-efficiency composting is represented as pattern variations of fungal community with a process of gradual decline of plant and animal pathogens as well as dung saprotrophs.