Chia-Wei Phan

Potential uses of spent mushroom substrate and its associated lignocellulosic enzymes

Mushroom industries generate a virtually in-exhaustible supply of a co-product called spent mushroom substrate (SMS). This is the unutilised substrate and the mushroom mycelium left after harvesting of mushrooms. As the mushroom industry is steadily growing, the volume of SMS generated annually is increasing. In recent years, the mushroom industry has faced challenges in storing and disposing the SMS. The obvious solution is to explore new applications of SMS. There has been considerable discussion recently about the potentials of using SMS for production of value-added products. One of them is production of lignocellulosic enzymes such as laccase, xylanase, lignin peroxidase, cellulase and hemicellulase. This paper reviews scientific research and practical applications of SMS as a readily available and cheap source of enzymes for bioremediation, animal feed and energy feedstock.

Therapeutic potential of culinary-medicinal mushrooms for the management of neurodegenerative diseases: diversity, metabolite, and mechanism

Abstract Mushrooms have long been used not only as food but also for the treatment of various ailments. Although at its infancy, accumulated evidence suggested that culinary-medicinal mushrooms may play an important role in the prevention of many age-associated neurological dysfunctions, including Alzheimer’s and Parkinson’s diseases. Therefore, efforts have been devoted to a search for more mushroom species that may improve memory and cognition functions. Such mushrooms include Hericium erinaceus, Ganoderma lucidum, Sarcodon spp., Antrodia camphorata, Pleurotus giganteus, Lignosus rhinocerotis, Grifola frondosa, and many more. Here, we review over 20 different brain-improving culinary-medicinal mushrooms and at least 80 different bioactive secondary metabolites isolated from them. The mushrooms (either extracts from basidiocarps/mycelia or isolated compounds) reduced beta amyloid-induced neurotoxicity and had anti-acetylcholinesterase, neurite outgrowth stimulation, nerve growth factor (NGF) synthesis, neuroprotective, antioxidant, and anti-(neuro)inflammatory effects. The in vitro and in vivo studies on the molecular mechanisms responsible for the bioactive effects of mushrooms are also discussed. Mushrooms can be considered as useful therapeutic agents in the management and/or treatment of neurodegeneration diseases. However, this review focuses on in vitro evidence and clinical trials with humans are needed.

Neurite outgrowth stimulatory effects of culinary-medicinal mushrooms and their toxicity assessment using differentiating Neuro-2a and embryonic fibroblast BALB/3T3

BackgroundMushrooms are not only regarded as gourmet cuisine but also as therapeutic agent to promote cognition health. However, little toxicological information is available regarding their safety. Therefore, the aim of this study was to screen selected ethno-pharmacologically important mushrooms for stimulatory effects on neurite outgrowth and to test for any cytotoxicity.MethodsThe stimulatory effect of mushrooms on neurite outgrowth was assessed in differentiating mouse neuroblastoma (N2a) cells. Neurite length was measured using Image-Pro Insight processor system. Neuritogenesis activity was further validated by fluorescence immunocytochemical staining of neurofilaments. In vitro cytotoxicity was investigated by using mouse embryonic fibroblast (BALB/3T3) and N2a cells for any embryo- and neuro-toxic effects; respectively.ResultsAqueous extracts of Ganoderma lucidum, Lignosus rhinocerotis, Pleurotus giganteus and Grifola frondosa; as well as an ethanol extract of Cordyceps militaris significantly (p < 0.05) promoted the neurite outgrowth in N2a cells by 38.4 ± 4.2%, 38.1 ± 2.6%, 33.4 ± 4.6%, 33.7 ± 1.5%, and 35.8 ± 3.4%; respectively. The IC50 values obtained from tetrazolium (MTT), neutral red uptake (NRU) and lactate dehydrogenase (LDH) release assays showed no toxic effects following 24 h exposure of N2a and 3T3 cells to mushroom extracts.ConclusionOur results indicate that G. lucidum, L. rhinocerotis, P. giganteus, G. frondosa and C. militaris may be developed as safe and healthy dietary supplements for brain and cognitive health.

Gastroprotective Effects of Lion’s Mane Mushroom Hericium erinaceus (Bull.:Fr.) Pers. (Aphyllophoromycetideae) Extract against Ethanol-Induced Ulcer in Rats

Hericium erinaceus is a famous tonic in oriental medicine. The gastroprotective effects of aqueous extract of H. erinaceus against ethanol-induced ulcers in Sprague Dawley rats were investigated. The possible involvements of lipid peroxidation, superoxide dismutase, and catalase were also investigated. Acute toxicity study was performed. The effects of aqueous extract of H. erinaceus on the ulcer areas, ulcer inhibition, gastric wall mucus, gross and histological gastric lesions, antioxidant levels, and malondialdehyde (MDA) contents were evaluated in ethanol-induced ulcer in vivo. In acute toxicity study, a high dose of 5 g/kg did not manifest any toxicological signs in rats. The extract promoted ulcer protection as ascertained by a significant reduction of the ulcer area. Furthermore, it exhibited a significant protection activity against gastric mucosal injury by preventing the depletion of antioxidant enzymes. The level of MDA was also limited in rat stomach tissues when compared with the ulcer control group. Immunohistochemistry showed upregulation of HSP70 protein and downregulation of BAX protein in rats pretreated with the extract. The aqueous extract of H. erinaceus protected gastric mucosa in our in vivo model. It is speculated that the bioactive compounds present in the extract may play a major role in gastroprotective activity.

Pleurotus giganteus (Berk.) Karunarathna & K.D. Hyde: Nutritional value and in vitro neurite outgrowth activity in rat pheochromocytoma cells

BackgroundDrugs dedicated to alleviate neurodegenerative diseases like Parkinson’s and Alzheimer’s have always been associated with debilitating side effects. Medicinal mushrooms which harness neuropharmacological compounds offer a potential possibility for protection against such diseases. Pleurotus giganteus (formerly known as Panus giganteus) has been consumed by the indigenous people in Peninsular Malaysia for many years. Domestication of this wild mushroom is gaining popularity but to our knowledge, medicinal properties reported for this culinary mushroom are minimal.MethodsThe fruiting bodies P. giganteus were analysed for its nutritional values. Cytotoxicity of the mushroom’s aqueous and ethanolic extracts towards PC12, a rat pheochromocytoma cell line was assessed by using 3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Neurite outgrowth stimulation assay was carried out with nerve growth factor (NGF) as control. To elucidate signaling mechanisms involved by mushroom extract-induced neurite outgrowth, treatment of specific inhibitor for MEK/ERK and PI3K signalling pathway was carried out.ResultsThe fruiting bodies of P. giganteus were found to have high carbohydrate, dietary fibre, potassium, phenolic compounds and triterpenoids. Both aqueous and ethanolic extracts induced neurite outgrowth of PC12 cells in a dose- and time-dependant manner with no detectable cytotoxic effect. At day 3, 25 μg/ml of aqueous extract and 15 μg/ml of ethanolic extract showed the highest percentage of neurite-bearing cells, i.e. 31.7 ± 1.1% and 33.3 ± 0.9%; respectively. Inhibition treatment results suggested that MEK/ERK and PI3K/Akt are responsible for neurite outgrowth of PC12 cells stimulated by P. giganteus extract. The high potassium content (1345.7 mg/100 g) may be responsible for promoting neurite extension, too.ConclusionsP. giganteus contains bioactive compounds that mimic NGF and are responsible for neurite stimulation. Hence, this mushroom may be developed as a nutraceutical for the mitigation of neurodegenerative diseases.

Biodegradation of Crude Oil by Constructed Bacterial Consortia and the Constituent Single Bacteria Isolated From Malaysia

ABSTRACT Three bacterial isolates identified as Pseudomonas aeruginosa (UKMP-8T), Rhodococcus sp. M15-2 (UKMP-5T), and Rhodococcus sp. ZH8 (UKMP-7T) based on biochemical, physiological, and morphological characteristics and on 16S rDNA sequences were isolated from groundwater of a crude oil refinery plant. From these three isolates, four bacterial consortia were designed by mixing the single bacterial cultures in the following ratios: (P. aeruginosa:Rhodococcus sp. M15-2, 1:1), (P. aeruginosa:Rhodococcus sp. ZH8, 1:1), (Rhodococcus sp. M15-2: Rhodococcus sp. ZH8, 1:1), and (P. aeruginosa: Rhodococcus sp. ZH8:Rhodococcus sp. M15-2, 1:1:1), respectively. Bacterial isolates and consortia showed differing preferences for nitrogen source (0.01% ammonium chloride, 0.10% yeast extract, or 0.50% peptone) to reach optimum growth. When fortified with the preferred nitrogen sources and grown in minimal salt medium, within 7 days all three single isolates and the four bacterial consortia biodegraded 97.6-99.9% of Tapis Massa oil without any significant differences.

Polysaccharides-Rich Extract of Ganoderma lucidum (M.A. Curtis:Fr.) P. Karst Accelerates Wound Healing in Streptozotocin-Induced Diabetic Rats

Ganoderma lucidum (M.A. Curtis:Fr.) P. Karst is a popular medicinal mushroom. Scientific reports had shown that the wound healing effects of G. lucidum were partly attributed to its rich polysaccharides. However, little attention has been paid to its potential effects on wounds associated with diabetes mellitus. In this study, we evaluated the wound healing activity of the hot aqueous extract of G. lucidum in streptozotocin-induced diabetic rats. The extract of G. lucidum was standardised based on chemical contents (w/w) of total polysaccharides (25.1%), ganoderic acid A (0.45%), and adenosine (0.069%). Six groups of six rats were experimentally wounded in the posterior neck region. Intrasite gel was used as a positive control and aqueous cream as the placebo. Topical application with 10% (w/w) of mushroom extract-incorporated aqueous cream was more effective than that with Intrasite gel in terms of wound closure. The antioxidant activity in serum of rats treated with aqueous extract of G. lucidum was significantly higher; whereas the oxidative protein products and lipid damage were lower when compared to those of the controls. These findings strongly support the beneficial effects of standardised aqueous extract of G. lucidum in accelerating wound healing in streptozotocin-induced diabetic rats.

A Comparative Study on Biosurfactant Activity of Crude Oil–Degrading Bacteria and Its Correlation to Total Petroleum Hydrocarbon Degradation

ABSTRACT In this study, 11 bacteria isolated from Tapis crude oil–contaminated sites were identified by using biochemical tests and 16S rDNA gene sequencing. Their abilities to biodegrade Tapis crude oil was determined by gas chromatography before they were further screened for biosurfactant activity by employing qualitative (blood agar hemolysis, microplate assay, drop-collapse test), semiquantitative (emulsification formation), and quantitative (surface tension measurement) methods. Four isolates, namely, Acinetobacter baumanii UKMP-12T, Pseudomonas aeruginosa UKMP-14T, Rhodococcus sp. UKMP-5T, and Rhodococcus sp. UKMP-7T, exhibited high percentages in total petroleum hydrocarbon (TPH) degradation. A strong correlation between the emulsification index (E 24) and surface tension measurement (r s = +.866) as shown by Spearman rank correlation analysis suggested that these two methods were more reliable to predict biosurfactant activity. The TPH removal was also positively correlated to the ability of bacterial isolates to reduce the surface tension of growth medium, as revealed by Pearson correlation test (rp = +.886). In conclusion, not all the biosurfactant detection protocols employed were effective. Nevertheless, the measurement of surface tension and E 24 determination provided a rather rapid, easy, reproducible, and accurate result in identifying bacteria with biosurfactant-producing ability.

Restoration of sensory dysfunction following peripheral nerve injury by the polysaccharide from culinary and medicinal mushroom, Hericium erinaceus (Bull.: Fr.) Pers. through its neuroregenerative action

Peripheral nerves have the unique capability to regenerate after injury. Insights into regeneration of peripheral nerves after injury may have implications for neurodegenerative diseases of the nervous system. We investigated the ability of polysaccharide from Hericium erinaceus mushroom in the treatment of nerve injury following peroneal nerve crush in Sprague-Dawley rats by daily oral administration. In sensory functional recovery test, the time taken for the rats to withdraw its hind limb from contact with the hot plate was measured. The test revealed acceleration of sensory recovery in the polysaccharide group compared to negative controls. Further, peripheral nerve injury leads to changes at the remotely located DRG containing cell bodies of sensory neurons. Immunofluorescence studies showed that Akt and p38 MAPK were expressed in DRG and strongly upregulated in polysaccharide group after peripheral nerve injury. The intensity of endothelial cells antigen-1 that recognized endothelial cells in the blood vessels of distal segments in crushed nerves was significantly higher in the treated groups than in the negative control group. Our findings suggest that H. erinaceus is capable of accelerating sensory functional recovery after peripheral nerve injury and the effect involves the activation of protein kinase signaling pathways and restoration of blood-nerve barrier.

Oil Palm Empty Fruit Bunch and Sugarcane Bagasse Enhance the Bioremediation of Soil Artificially Polluted by Crude Oil

Contamination of soil by petroleum hydrocarbons is becoming prevalent in Malaysia. Infiltration of soil contamination into groundwater poses a great threat to the ecosystem and human health. Bioremediation can occur naturally or can be enhanced with supplementation of microorganisms and fertilizers. However, fertilizers are expensive and therefore alternative nutrient-rich biomaterials are required. In this study, two organic wastes from agricultural industry (i.e., sugarcane bagasse and oil palm empty fruit bunch) were investigated for possible enhanced bioremediation of soil contaminated with Tapis crude oil. Two bacterial strains isolated and characterized previously (i.e., Pseudomonas aeruginosa UKMP-14T and Acinetobacter baumannii UKMP-12T) were used in this study. Sugarcane bagasse (5% and 15%, w/w) and oil palm empty fruit bunch (20%, w/w) were mixed with soil (500 g) spiked with Tapis crude oil (3%, v/w). The treated soils as well as controls were incubated for 20 days under controlled conditions. Sampling was carried out every four days to measure the number of bacterial colonies (CFU/g) and to determine the percentage of oil degradation by gas chromatography. The two biostimulating agents were able to maintain the soil moisture holding capacity, pH, and temperature at 38-40% volumetric moisture content (VMC), 7.0, and 29–30°C; respectively. The growth of bacteria consortium after 20 days in the treatment with sugarcane bagasse and oil palm empty fruit bunch had increased to 10.3 CFU/g and 9.5 CFU/g, respectively. The percentage of hydrocarbon degradation was higher in the soil amended with sugarcane bagasse (100%) when compared to that of oil palm empty fruit bunch (97%) after 20 days. Our results demonstrated the potential of sugarcane bagasse and oil palm empty fruit bunch as good substrates for enhanced bioremediation of soil contaminated with petroleum crude oil.