Assessment of Chinese Medicinal Herbal Wastes Compost Inoculated with Antagonistic Fungi: Nitrogen Retention and Microbial Community in Phytopathogenic Soil

Abstract

More and more non-medicinal wastes produced during the planting and processing of Chinese herbal medicine caused serious pollution. How to use these wastes efficiently and reasonably has become a popular topic with great interest. In this text, a new strain of antagonistic fungi Aspergillus niger was isolated from the root of the antimicrobial herb rhubarb, and the effect of its inoculation in Chinese medicinal herbal wastes (CMHWs) composting was investigated. Results suggested that the addition of CMHWs and A. niger could accelerate the composting process, improve the total N (TN) content (3.9%), the germination index (GI) value (132%) and the antibacterial activity against the phytopathogen Pectobacterium carotovorum (P. carotovorum) (zone of inhibition, 14.3 mm). Potting experiments suggested that a 15% dose of compost promotes the Chinese cabbage plant growth, and increases the soil TN content (0.3097%), and OM (organic matter, 74.49%), as well as the enzyme activities in the phytopathogen-contaminated rhizosphere soil. The abundance of soil Proteobacteria in compost treatments (38.2%-54.3%) was significantly higher. The highest relative abundance of Aspergillus, Pichia, and Fusarium in phytopathogen soil increased dramatically for the compost treatment, accounting for more than 65% of the microbial sequences at the fungal genus level. Redundancy analysis showed that the OM and TN were positively correlated with the Proteobacteria, Aspergillus and Fusarium, etc. Therefore, the CMHWs compost inoculated with endogenous fungi A. niger has great potential application in the waste resource utilization of Chinese herbal medicine and restoration of alkaline phytopathogenic soil.