Effect of chitin from mushroom waste in the composting process of organic residues: compost characteristics and occurrence of biological control agents
Composting is a biological process that transforms organic wastes into valuable products, the composts, to be used in agriculture. Chitin, which is present in some organic residues, may increase microbial diversity, enhancing compost's suppressive capacity, responsible for the biological control of plant diseases. Two composts, P1 and P2, were produced in piles, with turning for aeration and moisture adjustment. Composting mixes included orange fruit wastes, grape marc and grass clippings for P1 (0.9:1:1.1 v/v), plus mushroom production waste for P2 (1.8:1.5:0.2:0.5 v/v). Identical mixtures of organic residues were composted three times, with six months intervals. Physical, chemical, and biological parameters were monitored to control the composting processes. Microbial activity was compared at the main composting stages, by enumeration of fungi, aerobic bacteria, actinomycetes and chitinolytic microorganisms. To study the antagonistic capacity of composts microorganisms, fungi from both composts were isolated from samples collected after the thermophilic phase (samples were collected every two weeks), and at the end of the composting process. The isolates were identified through morphologic and molecular characteristics. Composts presented neutral pH, somewhat higher in P2. Nitrogen content was higher in P1. P2 showed higher organic matter content, microbial populations and enzymatic activity. In total, 190 fungi species were isolated. From these, 31 species (31/190) showed antagonistic capacity, against Rhizoctonia solani, Sclerotium rolfsii and Clarireedia spp. Fourteen (14/31) isolated from P1, and 17 (17/31) from P2. The presence of residues rich in chitin in the composted mixture seems to have contributed to the higher microbiological diversity and enzymatic activity in P2 compost.
Coelho, L., Bueno-Pallero, F., Guerrero, C., Dionísio, L. and Reis, M. (2021). Effect of chitin from mushroom waste in the composting process of organic residues: compost characteristics and occurrence of biological control agents. Acta Hortic. 1305, 155-162
antagonistic potential, fungi, suppressiveness, Trichoderma