Ganoderma Neo-Japonicum

Ganoderma Neo-Japonicum

 

Ganoderma Neo-Japonicum

 

Ganoderma Neo-Japonicum

 

Mushroom cultivation benefits humankind as it deliberately encourages wild mushrooms to be commercially propagated while recycling agricultural wastes. Ganoderma neo-japonicum is a rare polypore mushroom found growing on decaying Schizostachyum brachycladium (a tropical bamboo) clumps in Malaysia. The Malaysian indigenous tribes including the Temuans and Temiars use the basidiocarps of G. neo-japonicum to treat various ailments including diabetes. In this study, the domestication of G. neo-japonicum in artificial logs of different agricultural residues was investigated. Sawdust promoted the mycelia spawn colonisation in the shortest period of 38 ± 0.5 days. However, only sawdust and bamboo dust supported the primodia formation. Complex medium supported mycelium growth in submerged cultures and 27.11 ± 0.43 g/L of mycelia was obtained after 2 weeks of cultivation at 28 °C and 200 rpm. Antioxidant potential in mushroom may be influenced by different cultivation and extraction methods. The different extracts from the wild and cultivated basidiocarps as well as mycelia were then tested for their antioxidant properties. Aqueous and ethanol extracts of mycelia and basidiocarps tested had varying levels of antioxidant activities. To conclude, domestication of wild G. neo-japonicum using agroresidues may ensure a continuous supply of G. neo-japonicum for its medicinal use while ensuring the conservation of this rare species.

Introduction
Ganoderma spp., in particular G. lucidum (Curtis: Fr.) P. Karst have a long history in traditional Chinese medicine. The mushroom, also known as Lingzhi has been widely prescribed for prevention and treatment of many chronic diseases including hypertension, bronchitis, arthritis, neurasthenia and neoplasia1. The curative effects of Ganoderma spp. are attributed to their superior antioxidant properties2. Natural products and food-derived antioxidants have received great attention because of their chemoprevention properties against oxidative damages such as inflammation3. Inflammation of normal cells caused by over-production of reactive oxygen species (ROS) has been identified as the main factor causing nearly all life-threatening diseases such as cancer, cardiovascular and neurological disorders4. Therefore, antioxidants that can remove excess ROS are important to protect the human body against oxidative stress. Moreover, natural antioxidants are considered safer when compared to synthetic antioxidants. In this regards, Ganoderma mushrooms are good candidates as antioxidative agents because they are natural and rich in polysaccharides, bioactive components such as terpenes, ganoderic acids and phenolic compounds5,6. Ganoderma lucidum has been well investigated and several of the ethnomycological claims of its curative properties have been scientifically validated7. There are, however, several neglected Ganoderma spp. which may add to the medicinal properties knowledge pool leading to new drug or nutraceutical discoveries8,9.

One such species available from the forest is Ganoderma neo-japonicum Imazeki which is a rare saprotrophic and annual Ganoderma species colonising decaying bamboo clumps. This mushroom is distributed in Asian countries including China, Korea, Japan, Taiwan and Malaysia. In Malaysia, G. neo-japonicum which grows in the forests and only on decaying clumps of tropical bamboo (Schizostachyum brachycladium) has been harvested by the indigenous people (Orang Asli) for its medicinal properties. Orang Asli is the term specifically used in referring to the indigenous people living in Peninsular Malaysia. There are three main groups namely the Negrito, Proto-Malays and Senoi. Each of these groups have six tribes and there are 150,000 Orang Asli in Malaysia10,11. The medicinal uses of G. neo-japonicum based on an on-going study to record the tacit knowledge of the use of mushrooms as food and medicine are summarised in Table 1 8,9,12,13,14,15,16,17,18,19,20. The basidiocarp was boiled in water and the decoction was consumed to treat fever, asthma, diabetes, joints and body aches as well as a tonic to improve body strength. The stipe was cut into bead-like pieces, strung and worn round the neck of children to treat epilepsy.

Table 1 The medicinal uses of Ganoderma neo-japonicum by different tribes in Peninsular Malaysia.
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However, the scientific validation of the medicinal value of this mushroom has not been extensively investigated. To date, G. neo-japonicum has been reported as a potent radical scavenger and showed hepatoprotective activity in vivo17. Hirotani et al.19 isolated and characterised two drimane sesquiterpenes, namely cryptoporic acids H and I from the basidiocarps of G. neo-japonicum. Two lanostanoids (ganoderal A and ganodermadiol), steroid (2β,3α,9α-trihydroxyergosta-7,22-diene) and four ergosteroids were also reported from this mushroom16. In our studies, we reported that wheat grains fermented by mycelia of G. neo-japonicum had enhanced antioxidant activities as well as enhanced adipogenesis; and that PPARγ expression in 3T3-L1 cells was modulated9,20. Further, the aqueous extracts of G. neo-japonicum had a significant (p < 0.001) effect on neurite outgrowth stimulatory activities when compared to nerve growth factor, the positive control8. Table 2 summarises the studies on the medicinal properties of G. neo-japonicum for the last two decades.

Table 2 Summary of research on Ganoderma neo-japonicum in the past two decades.
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Mushrooms can be artificially cultivated for mycelia biomass production21. There are, however, minimal reports on artificial cultivation for basidiocarp production21,22 and solid substrate fermentation (SSF) of G. neo-japonicum20. Besides the basidiocarp, mycelia of mushrooms can also be obtained via SSF. This process has been reported to enhance the phenolic content and antioxidant potential in fermented foods23. In SSF process, non specific hydrolytic enzymes were secreted to degrade lignocellulose, thus releasing various phenolic compounds. Chemical composition of Cordyceps sinensis and the bioactivity of stale rice were improved by SSF as reported by Zhang et al.24. The nutritional quality and antioxidant activity of different agro-residues such as cocoa pod husk, cassava peels and palm kernel cake were also enhanced by SSF16.

Ganoderma neo-japonicum is not abundantly available in the forest due to the annual growth cycle of this species in nature. Mycelium production via SSF may provide an alternative way to overcome the limited supply of G. neo-japonicum and for conservation of this invaluable, rare polypore both in and ex situ. Therefore, the aims of the study were to revisit G. neo-japonicum by optimising the cultivation conditions of G. neo-japonicum by different formulation of selected agricultural wastes as well as cultivation of the mycelium via fermentation. The antioxidant activities of the various extracts prepared from basidiocarp (wild and cultivated) and mycelium from submerged and solid substrate fermentation were also investigated.