Industrial and medicinal application of Reishi and Lion’s Mane mushrooms
Van der Berg, Christina
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Medicinal mushrooms have had applications for centuries as an alternative treatment of various ailments. Their nutritional value adds to their popularity and has been extensively studied as a healthy source of food which are rich in protein. Two medicinal mushrooms, Ganoderma lucidum and Hericium erinaceus have been scrutinized in recent years due to the presence of bioactive compounds. Although a non-edible mushroom, G. lucidum is considered to possess the most medicinal properties and cultivation may have the potential of providing animal feed. The edible H. erinaceus is currently scrutinized as it may have application as a natural alternative to treat the symptoms associated with Alzheimer’s and cognitive decline. This study focused primarily on highlighting the advantages both mushrooms hold for humankind and pave the way for alternative medicinal applications. In chapter 2, the optimum growth conditions for the cultivation of G. lucidum and H. erinaceus have been investigated in order to allow exploitation of their medicinal and economic benefits. In this chapter, pure cultures of G. lucidum and H. erinaceus were required with the need for a single medium allowing cultivation of both species being imperative. Sorghum agar was developed and found to be a superior growth medium compared to MEA or YMA. For cultivation of G. lucidum, the encroaching tree species, Acacia mellifera, were used as substrate for cultivation in order to provide animal feed. Various factors, such as improved lighting and different lighting cycles, humidity control and CO2 regulation were taken in consideration and modified to improve yields. Cultivation of H. erinaceus was conducted on both A. mellifera wood and pecan nut shells, which proved to be a sustainable method for removal of these waste products. Factors such as humidity control resulted in high yields of H. erinaceus fruiting bodies. As running costs were reduced, both G. lucidum and H. erinaceus were used for the development of medicinal applied capsules in collaboration with the pharmaceutical company, Sfera Nutraceuticals. After optimization of growth conditions, extraction methods, antimicrobial activity and toxicity assays were investigated in chapter 3. Water, alcohol and a combined extract of water and alcohol were performed on the different growth stages of G. lucidum and H. erinaceus, namely mycelia, fruiting bodies and spent mushroom substrate (SMS). Various studies have been conducted on the applications of bioactive polysaccharides. Thin layer chromatography (TLC) was applied for preliminary separation of compounds. For the identification of compounds, separation and isolation of each extract using TLC should be undertaken in future while fingerprinting can be performed to identify and isolate compounds for further investigation. The antimicrobial activity of the extracts was investigated against 12 different pathogens. The hot water extracts showed no inhibitory effect against the various pathogens, but various factors have to be considered. The extraction times might have been too short while some of the compounds such as triterpenoids are water-insoluble and can only be extracted with alcohol. Alcohol extracts of G. lucidum fruiting bodies showed the best inhibitory effect. In addition, combined water and alcohol extracts were performed on the three growth phases of G. lucidum, with the combined extracts of G. lucidum fruiting bodies and spent mushroom substrate (SMS) showing the most promising results. It can be explained due to the extraction of both water-soluble and water-insoluble compounds, such as polysaccharides and triterpenoids. As a result, SMS have application as animal feed due to antimicrobial activity, thus utilizing waste. Pre-clinical and clinical trials are required to ensure safe use of herbal medicines. Human toxicity is poorly portrayed by animal models, resulting in the use of in vitro screening using human derived cells. Various parameters such as live/dead cells, lysosomes, mitochondrial dysfunction and steatosis can be investigated by staining cells followed by analysis with the ImageXpress Micro XLS Widefield High-Content Analysis System. Hepatotoxicity assays of the different extracts at different concentrations of were performed on HepG2 cells using above-mentioned parameters. Some of the extracts showed toxicity, with alcohol extracts proving to be more toxic when compared to water extracts. This study provided interesting data on the cytotoxicity of two South African macro-fungal species, G. lucidum and H. erinaceus. As hepatotoxicity assays are considered to be novel, further investigation is required as this was just a preliminary study in order to evaluate the antimicrobial effects and whether different extracts at different concentrations are highly toxic or not to human derived cells by making use of in vitro screening. By taking all of the results in account, none of the extracts proved to be highly toxic, paving the way for further investigations and improving health in a natural manner. New methods of waste disposal are required with the application of G. lucidum SMS as animal feed after delignification taking centre stage. The use of encroaching wood species such as A. mellifera following mushroom cultivation was investigated in chapter 4. Enzymes produced by mushrooms aid in the delignification process, resulting in degradation of lignocellulosic materials for growth and fruiting. Due to sufficient breakdown of lignin, A. mellifera wood had application as animal feed and SMS were added as supplement. Ruminants from experimental group showed improved and more consistent growth compared to the control groups fed on feed consisting only of lusern and corn. In addition, microbial analysis of stomach contents showed a significant increase in Lactobacilli counts for the experimental group compared to the control groups. Additionally, the effect of animal feed supplemented with SMS on ruminants was also investigated by weight gaining, % fat, total fatty acids, fatty acid ratios and colour of meat. In general, total fatty acids and fatty acid ratios of the experimental groups were considered to be more acceptable compared to the control groups. Furthermore, consumers considered meat from the experimental groups to be more favourable when various parameters (L*, a*, b*, hue and saturation index) were taken into consideration. As a result, meat from the experimental group were found to be the most in accordance with guidelines regarding acceptability for consumers. Consequently, the application of SMS as animal feed were considered to be successful and should be further investigated. It can therefore be concluded that feed supplemented with SMS have a positive effect when compared to traditional feed.