Reuse of citrus peel to enhance the formation of bioactive metabolite-triterpenoid in solid-state fermentation of A. cinnamomea

• Few papers are published regarding solid-state fermentation of A. cinnamomea.
• Grapefruit was the most effective in enhancing the content of crude triterpenoid.
• With peel addition, crude triterpenoid content had more than a fourfold increase.
• HPLC analysis shows that the mycelia was similar to natural basidiomes.
• Some kinds of citrus peel could enhance the production of bioactive metabolites.

Antrodia cinnamomea has recently become popular as a drug remedy in Taiwan because of the mushroom's physiologically beneficial properties. However, because of its host specificity, slow growth rate and rarity in nature, the fruiting bodies of A. cinnamomea have become the most expensive mushrooms in Taiwan in recent years. Artificial cultivation of A. cinnamomea basidiomes to satisfy market demand is considered to be the most effective solution.In this study, solid-state fermentation was carried out in petri dishes for mycelia growth and basidiomatal formation of A. cinnamomea. Different kinds of citrus peel were added to the medium to investigate the feasibility of enhancing the production of bioactive compounds. The crude triterpenoid content of mycelia in the control test reached the highest level of 9.66 mg/g DW on day 30. Among various kinds of citrus peel, grapefruit peel was the most effective in enhancing the content of crude triterpenoid. Moreover, at the addition ratio of 4 g per petri dish, the amount of crude triterpenoid reached 47.10 mg/g DW on day 30, with more than a fourfold increase. Furthermore, compared with the mycelia of the control culture, the profiles of HPLC analysis show that the mycelia cultured with the grapefruit-peel addition contained more kinds of triterpenoid and was similar to natural basidiomes. This study demonstrates that additions of some kinds of citrus peel could effectively accelerate the formation of basidiomes and enhance the production of bioactive metabolites.