New insights into Peniophora crassitunicata and its co-inoculation with commercial microbial inoculant accelerating lignocellulose degradation and compost maturation during orchard wastes composting.

Lignocellulosic composting has been widely promoted in the utilization of agricultural wastes, while few focus on orchard lignocellulosic wastes in the fruit industry. Peniophora is a laccase hyper-producer highly efficient in lignin degradation, yet its application in lignocellulosic composting has not been investigated. Here, an aerobic composting experiment was conducted to investigate the effects of inoculation with Peniophora crassitunicata and a commercial microbial inoculant (mainly Bacillus and Aspergillus) on grape (Vitis Vinifera L.) orchard lignocellulosic wastes degradation and the underlying mechanisms. The inoculation with P. crassitunicata, both individually (H) and in combination with the commercial microbial inoculant (HS), enhanced lignocellulose degradation efficiency. Notably, the co-inoculation exhibited higher lignocellulose degradation ratios and higher lignocellulosic enzyme activities compared to other treatments. The compost piles with co-inoculation experienced a more rapid temperature rise, a longer duration (15 days) of high temperatures, lower pH, and lower electrical conductivity (EC). Firmicutes (e.g. Bacillus, Paenibacillus) and Ascomycota (e.g. Aspergillus) along with Bacteroidota, Actinobacteriota, and Basidiomycota (e.g. Peniophora) dominated the microbial community in compost; carbohydrate metabolism dominated microbial metabolic pathways at the thermophilic phase, highlighting an active microbial community. As compost processed, highly mature and non-toxic compost products were finally obtained for the co-inoculation, with a pH of 7.87, C/N ratio of 13.5, NH-N/NO-N ratio of 0.21-0.41, EC of 0.90 mS cm, and germination index of 149 %. The co-inoculation of P. crassitunicata with the commercial microbial inoculant effectively accelerated lignocellulose degradation and compost maturation, producing a friendly and non-toxic organic fertilizer for agricultural applications and thereby providing a new strategy for orchard wastes management and agricultural applications.