Filtration effect of Cordyceps chanhua mycoderm on bacteria and its transport function on nitrogen

ABSTRACT Cordyceps chanhua is a kind of entomopathogenic fungus that has a long medicinal history in traditional Chinese medicine. In this study, we aimed to explore the role of C. chanhua mycoderm. Our results showed that C. chanhua mycoderm has a certain ability to transfer nitrogen, which can transfer nitrogen from the insect body to the external environment and transfer nitrogen from the environment to C. chanhua . By studying the filtration of bacterial mycoderm, it was found that the mycoderm of C. chanhua was able to filter out most of the bacteria in the environment. Using the high-throughput sequencing methods, we found that the abundance of bacterial community first increased and then decreased during the growth and development of C. chanhua . The bacterial richness and diversity of mycoderm of C. chanhua cultivated in sterile glass bottles were significantly lower than those cultivated in soil mulching. In addition, this study also found that the mycoderm of C. chanhua formed under both soil mulching cultivation and sterile glass bottle cultivation was hydrophobic. The mycoderm of C. chanhua , which occurred under sterile glass bottle cultivation, was closely and orderly arranged, while the mycoderm of C. chanhua cultivated in soil was quite the opposite. The density and thickness of the C. chanhua membrane in aseptic glass bottle culture were higher than those in soil-covered culture, but the dry/fresh weight was lower than those in soil-covered culture. IMPORTANCE During the natural growth of Cordyceps chanhua , it will form a mycoderm structure specialized from hyphae. We found that the bacterial membrane of C. chanhua not only filters environmental bacteria but also absorbs and transports nitrogen elements inside and outside the body of C. chanhua . These findings are of great significance for understanding the stable mechanism of the internal microbial community maintained by C. chanhua and how C. chanhua maintains its own nutritional balance. In addition, this study also enriched our understanding of the differences in bacterial community composition and related bacterial community functions of C. chanhua at different growth stages, which is of great value for understanding the environmental adaptation mechanism, the element distribution network, and the changing process of symbiotic microbial system after Cordyceps fungi infected the host. At the same time, it can also provide a theoretical basis for some important ecological imitation cultivation technology of Cordyceps fungi.