Promotion of Metabolite Synthesis in Isaria cicadae, a Dominant Species in the Cicada Flower Microbiota, by Cicada Pupae

Abstract

Cicada flowers, which are edible and medicinal mushrooms, are the fruiting bodies of Isaria cicadae, a fungus that is parasitic on the larvae of cicada pupae. We hypothesize that host factors might possess stimulatory activity on metabolite synthesis in Isaria cicadae. Here, we first compared the microbial community structures of different wild cicada flowers across geographical regions, compartments, and growth stages via high-throughput sequencing. Isaria cicadae TZC-3, an isolate of the most abundant operational taxonomic unit (OTU6782) in all the fungal communities, was isolated from wild cicada flowers. Furthermore, the effects of cicada pupae on metabolite synthesis in Isaria cicadae TZC-3 were studied in submerged culture. The contents of intercellular polysaccharides, adenosine, N6-(2-hydroxyethyl)-adenosine, free amino acids, and hydrolyzed monosaccharides in the mycelia cultured with cicada pupa powder (4%) were significantly increased as compared with the contents in the control group. This indicates that a cicada pupa can act as an elicitor for metabolite synthesis in Isaria cicadae.

Different Cultivation Environments Affect the Yield, Bacterial Community and Metabolites of Cordyceps cicadae

“…The relative abundance of bacteria related to carbohydrate metabolism and glycan biosynthesis and metabolism in CS decreased significantly than in CB, along with the content of carbon compound (mannitol and polysaccharides) in this cultivation environment. Researches showed culture conditions ( Cheng et al, 2012 ; Lee et al, 2019 ), nutrient sources ( Mao et al, 2005 ; Chunyu et al, 2019 ), different strains ( Kang et al, 2017 ), and hosts ( He Y. et al, 2019 ) can affect the level of metabolites, but these factors were consistent between two cultivation environment in this study. As a result, the main reason for different level of metabolite in two cultivation environment may be caused by the difference of microbial community composition and related functions ( Figures 5 , 6 ).…”

Analysis of Internal and External Microorganism Community of Wild Cicada Flowers and Identification of the Predominant Cordyceps cicadae Fungus

“…The samples were stored in sterile plastic bags and sent to the laboratory in an ice box. According to the morphological and anatomical characteristics, the wild cicada flowers were divided into two parts: (1) coremium, the aboveground part; and (2) sclerotium, the underground part (a cicada pupa filled with the mycelia of C. cicadae ) ( Chunyu et al, 2019 ). The processing and storage method of the collected wild cicada flowers were according to Xia et al (2015) .…”

“…The resulting seed culture was used to inoculate 100 ml of medium (inoculum amount: 5%) and cultured at 26°C and 140 rpm for 5 days. The composition of the seed culture/fermentation medium was extracted by a previous method with some modifications and contained (per liter) the following: 20 g of glucose, 10 g of peptone, 10 g of yeast extract, 2.0 g of KH 2 PO 4 , 0.5 g of MgSO 4 , and 0.5 g of ZnCl 2 ( Chunyu et al, 2019 ).…”

“…Chan hua, literally “cicada flowers” ( Dong et al, 2015 ), are the fruiting bodies of the fungus Cordyceps cicadae (syn. Isaria cicadae and Paecilomyces cicadae ) ( Chunyu et al, 2019 ), which is a parasitic complex fungus that grows inside cicada nymphs and larvae and forms fruiting bodies on the surface of the insect carcass ( Paterson, 2008 ). The medicinal value of cicada flower was firstly recorded in the Chinese medical text “Lei Gong Pao Zhi Lun” about 1,600 years ago ( Liu et al, 2019 ).…”

“…Although high-throughput sequencing has been used to explore the microbial community associated with Ophiocordyceps sinensis ( Zhang et al, 2010 ; Xia F. et al, 2016 ; Shao et al, 2019 ; Xia et al, 2019 ), only a few papers investigated the bacterial and fungal communities inhabiting cicada flower. Previous researches have revealed that cicada flowers enrich abundant microbial communities ( Chunyu et al, 2019 ; Qu et al, 2019 ; Mou et al, 2020 ; Zeng et al, 2021 ), and the microbial community composition varies with the geographic area ( Chunyu et al, 2019 ), and the endophytic bacteria in cicada flowers can influence the metabolite production ( Qu et al, 2019 ). These results suggested that wild cicada flower populations are ecologically linked to the surrounding soil through microorganisms, which may impact cicada flower growth and production of metabolites.…”