Microbial Community Dynamics in Casing Soil and Impact on Oudemansiella raphanipes during Cultivation

In this study, high-throughput sequencing (HTS) was used to demonstrate the microbial community diversity and succession of the casing soil during Oudemansiella raphanipes cultivation. The abundance and diversity of bacteria and fungi were the highest in the original sample of vegetable soil, and then decreased in casing soil, but they increased at the end of the mushroom formation. As the mushroom formation progressed, the abundance of some bacteria such as Massilia, Sphingomonas, and Cupriavidus increased, and they are often found in heavy metal contaminated soils. In terms of fungi, the dominant fungi in the vegetable soil and at the end of the mushroom formation stage were Thermoascus, and the abundance of some plant and animal pathogens increased in the first and second mushroom formation stages, such as Candida, Aspergillus, Trichoderma, and Chaetomium. The above results showed a decrease in the number of microbial species and an increase of harmful microorganisms, which might inhibit the growth of mushroom. Furthermore, we disinfected and sterilized the casing soil to investigate the effect of different treatments of casing soil on the growth and quality of Oudemansiella raphanipes. Results showed that the casing soil was beneficial for the cultivation of Oudemansiella raphanipes, but microorganisms in the casing soil might not be necessary for the growth of mushroom. Sterilization treatment of the casing soil could improve yield and quality more than conventional disinfection treatment. In future studies, different matrix materials can be explored to replace soil cover to achieve soilless cultivation which is more efficient and hygienic.