Diversity and Co-Occurrence Patterns of Soil Bacterial and Fungal Communities of Chinese Cordyceps Habitats at Shergyla Mountain, Tibet: Implications for the Occurrence

Abstract

Chinese <i>Cordyceps</i> is a well-known medicinal larva-fungus symbiote distributed in the Qinghai-Tibetan Plateau and adjacent areas. Previous studies have involved its artificial cultivation but commercial cultivation is difficult to perform because the crucial factors triggering the occurrence of Chinese <i>Cordyceps</i> are not quite clear. The occurrence of Chinese <i>Cordyceps</i> is greatly affected by the soil environment, including the soil's physicochemical and microecological properties. In this study, the effects of these soil properties on the occurrence of Chinese <i>Cordyceps</i> were investigated. The results show that the physicochemical properties, including easily oxidizable organic carbon (EOC), soil organic carbon (SOC), humic acid carbon (HAC), humin carbon (HMC), and pH, might be negatively related to the occurrence of Chinese <i>Cordyceps</i>, and soil water content (SWC) might be positively related. Several soil physicochemical parameters (pH, SOC, HMC, HAC, available potassium (APO), available phosphorus (APH), microbial biomass carbon (MBC), and the ratio of NH₄⁺ to NO₃^- (NH₄⁺/NO₃^-)) and microbial properties interact and mix together, which might affect the occurrence of Chinese <i>Cordyceps</i>. Soil microbial community structure was also a possible factor, and a low level of bacterial and fungal diversity was suitable for the occurrence of Chinese <i>Cordyceps</i>. The intra-kingdom network revealed that a closer correlation of the bacterial community might help the occurrence of Chinese <i>Cordyceps</i>, while a closer correlation of the fungal community might suppress it. The inter-kingdom network revealed that the occurrence rate of Chinese <i>Cordyceps</i> might be negatively correlated with the stability of the correlation state of the soil habitat. In conclusion, this study shows that soil physicochemical properties and microbial communities could be greatly related with the occurrence of Chinese <i>Cordyceps</i>. In addition, soil physicochemical properties, the level of bacterial and fungal diversity, and correlations of bacterial and fungal communities should be controlled to a certain level to increase the production of Chinese <i>Cordyceps</i> in artificial cultivation.