# Current Progress Regarding _Cordyceps militaris_, Its Metabolite Function, and Its Production
## 1 Introduction  
_Cordyceps militaris_, which is called Yong Chong Cao in Chinese, is a type of entomogenic fungus that belongs to the _Cordyceps_ genus in the phylum Ascomycota and family Cordycipitaceae [1]. It is most abundant in humid temperate and tropical regions, and is widely distributed throughout North America, Europe, and East and Southeast Asia [2]. _Cordyceps militaris_ grows parasitically on the larvae and pupae of arthropods, mainly lepidopteron and coleopteran species. As the cultivation period progresses, the spores of C. _militaris_ develop into hyphae, gradually growing into club-shaped, orange fruiting bodies measuring 2-5 cm in height. The morphology of mature C. _militaris_ consists of two parts, including the stalk (the grass part, also known as the fruiting body) and the sclerotium (the corpse part of the insect) [3]. The basal medium for cultivating C. _militaris_ typically consisted of 40 g of glucose (or other sugars), 10 g of peptone, 5 g of yeast extract, 1 g of K2 HPO4, 1 g of KCl, 1 g of MgSO4-7H2O, and 2 g of adenosine per liter [4], withoutpH control [5]. [PERSON] and [PERSON] [6] discovered that under the culture conditions of 20 \({}^{\circ}\)C temperature, 2.5% (_w/v_) glucose, and 0.8% (_w/v_) yeast extract, the maximal yield of the mycelial biomass reached 547 \(\pm\) 2.09 mg/100 mL. This yield was 1.95-fold higher than that obtained in the basal medium.  
All _Cordyceps_ species share a mechanism of invading and growing on their hosts to maintain their life cycles [7], but the main difference occurs in the hosts they infect [8]. The majority of known species in the _Cordyceps_ genus infect insects and other arthropods, with a few parasitizing fungi and plants. Most _Cordyceps_ species exhibit host specificity and are known to infect particular or closely related host species, with only a few having the ability to infect a wide range of hosts [9]. During the parasitic process, _Cordyceps_ has developed a complex survival mechanism to facilitate its attachment to a host and avoid clearance by the host's immune system. For this mechanism, _Cordyceps_ produces several unique secondary metabolites that aid in its parasitism and reproduction on its hosts [7], showing great promise as potential sources of new drugs.  
The _Cordyceps_ genus has a history of several hundred years of use as a traditional Chinese medicine, with _C. sinensis_ being the species with the longest history of use, exhibiting a wide range of biological activities. At present, the main source of _C. sinensis_ is wild collection, with its rarity and high price are due to its wild characteristics. Although artificial cultivation has been achieved in recent years, production costs remain high, and cultivation times are long. In contrast, artificial cultivation of _C. militaris_ yields lower production costs and shorter cultivation times compared to _C. sinensis_. _Cordyceps militaris_ also has a similar chemical composition and comparable medicinal properties to those of _C. sinensis_, and even contains higher levels of certain bioactive components. Therefore, it is regarded as a promising substitute for _C. sinensis_. Figure 1 displays both natural and cultured _C. militaris_ for comparison [10].