Review Article Diversity of Mushrooms and Their Metabolites of Nutraceutical and Therapeutic Significance
Total Page：16
File Type：pdf, Size：1020Kb
Hindawi Publishing Corporation Journal of Mycology Volume 2016, Article ID 7654123, 18 pages http://dx.doi.org/10.1155/2016/7654123 Review Article Diversity of Mushrooms and Their Metabolites of Nutraceutical and Therapeutic Significance Deepak K. Rahi and Deepika Malik DepartmentofMicrobiology,PanjabUniversity,Chandigarh160014,India Correspondence should be addressed to Deepak K. Rahi; [email protected] Received 31 August 2015; Accepted 5 November 2015 Academic Editor: Praveen Rao Juvvadi Copyright © 2016 D. K. Rahi and D. Malik. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Mushrooms are well known for their nutritional as well as therapeutic values worldwide. Interest in mushrooms has peaked because immunity and cellular protection are important issues for health conscious consumers and for those individuals who are dealing with serious health issues. Mushrooms generally belong to Basidiomycetes which harbors numerous mushroom species with diversity of metabolites of nutraceutical and therapeutic significance. They have been reported to be the most valuable ones for humans. Investigations on the therapeutic and nutritional properties of mushrooms are underway throughout the world. Researchers are providing crucial data on the array of bioactive compounds found within these fascinating fungi. People are now accepting mushrooms more as food and food supplements. Various academic and research institutes are all involved actively in research on bioactive metabolites of mushrooms. The present paper aims at reviewing the diversity of mushrooms and the types of metabolites especially of nutraceutical and therapeutic importance present in these mushrooms and their role as bioactive agents. 1. Introduction the face of the Earth. These records concern wild mushrooms, but there are stories of mushrooms being cultivated in Asia Manhaslivedinahunter-gatherersocietyformostofthe as far back as the early middle ages. Mushrooms are the time since their origin and has depended entirely on biodiver- macrofungi with fleshy, subfleshy, or sometimes leathery, sity for their sustenance. It is obvious that, during gathering umbrellalike sporophores that bear their fertile surfaces forays, fruiting bodies of larger fungi, or macromycetes, were either on lamellate or lining the tubes, opening out by also collected and early man must have sampled anything of meansofpores.Thelamellatemembersarecommonlycalled bitable nature. These fruiting bodies have been referred to “mushrooms” or “toadstool” depending upon whether they as mushrooms or toadstools for many centuries. The word are edible or poisonous and the tube bearing or poroid “truffle” has also been used in literature for some fruiting members as “boletes” [1]. Diversity of mushrooms varies bodies of edible fungi, but these are characterized as growing greatly ranging from the typical Agaricus mushrooms with below ground and must have been discovered subsequently a stalk and umbrella-shaped top to the polypores, Earth in these gathering forays. Theophrastus (300 BC) is the first Stars (Geastrum), the Stink Horns (phalloides), and Puff Balls writer to mention truffles and does so under several names. (Lycoperdon). Edible mushrooms are either collected from Since earliest times, mushrooms have been treated as a nature or more commonly cultivated and harvested under special kind of food. The Greeks believed that mushrooms defined conditions with rigorous quality control on size, provide strength for warriors in battle. The Pharaohs prized shape, tenderness, and palatability. Due to the high product mushroom as delicacy, and the Romans regarded mushrooms yield and the low reproducibility costs from fungi, major as the “Food of the Gods,” and they even had mushrooms interest has been shown in the respective markets for the on the menu which was served only on festive occasions. The metabolites derived from fungi. Both cellular components Chinese treasured mushrooms as a health food. Mushrooms and secondary metabolites of large number of mushrooms have probably been eaten for as long as people have walked have been shown to affect the immune system of host and 2 Journal of Mycology Mating of compatible hyphae Mycelium Spore germination Cap Fruiting body Spore liberation Primordia formation Gills Stem Fruit body development Vegetative mycelium Figure 1: Life cycle of Agaricus bisporus [7]. therefore could be used to treat variety of diseases. Secondary structurecalledbasidium.Althoughhaploid,basidiospores metabolites are generally produced following active growth, may be either uninucleate or binucleate at maturity. After and many have an unusual chemical structure. Interest in these basidiospores are released from mature fruiting bodies, these compounds is considerable, as many natural products theygerminatetoformhyphae.Collectively,hyphaemakeup are of medical, industrial, and/or agricultural importance. mycelium. Hyphae derived from the spores of two different Production of lipids, vitamins, and polysaccharides as well matingtypesthenfusetoformsecondarymyceliumwhich as intermediates in the synthesis of cell constituents such has two nuclei and is ultimately responsible for the formation as amino acids and nucleotides are also of great economic of fruiting bodies (Figure 1). importance in present-day industry [2–6]. Pure culture studies on mushrooms and related basid- 2. Diversity of Mushrooms of Nutraceutical iomycetous fungi have laid the foundation for several and Therapeutic Significance biotechnological innovations including mass cultivation for diverse purposes. Strain improvement and selection among It has become increasingly apparent in recent years that the edible mushrooms like Agaricus, preparation of mushroom organisms traditionally referred to as fungi are not all closely spawns and their application to composted natural substrates, related. This prompted some authors to use term “fungi” in and standardization of cultivation conditions to ensure a very general sense and the term “Fungi” with a capital proper mycelial colonization of the substrates to be followed “F” specifically for the so-called true fungi that appear to by differentiation of the fruit bodies which are the com- be related to one another. The true fungi are placed in the modities of commercial value are again well documented. kingdom Fungi. Modern systematics, based on morpholog- Relatively less attention has been given to the nutrient ical characters and analysis of rDNA sequences, divides the value of edible mushroom mycelia cultivated in submerged kingdom Fungi into four major phyla or divisions: Chytrid- culture. One of the pioneering efforts in this direction has iomycota, Zygomycota, Ascomycota, and Basidiomycota. The been that of Humfeld and Sugihara in USA who patented two fungal phyla that produce large, visible fruit bodies mass cultivation of Agaricus mycelia in submerged cultures are the Ascomycota and Basidiomycota. The Ascomycota and explored their potential as protein feed supplements in contains at least 40,000 different species worldwide, many animal and human nutrition. Whether the mycelium grown of them rather inconspicuous, but including such familiar in submerged culture has the same flavor and nutritional groups as the morels and truffles, the cup fungi, and most of aspectsasthatofthemushroomfruitbodieshasbeendebated the lichens, as well as many microscopic molds and yeasts. butbecauseoftheslowrateofgrowthofthemyceliain They all produce their spores within macroscopic cells called submerged culture and large volumes involved, the use of asci, which typically open under pressure when mature, mushroom mycelia as feed supplements to enhance feed shooting the spores out into the air currents [8]. The Basid- proteinvaluesinanimaldietsseemstobeeconomically iomycota contains at least 30,000 different species worldwide attractive. The basidiomycetes have some highly character- and includes many of our most familiar fungi, including istic features, which separate them from other fungi. They all the agarics (mushrooms and toadstools), puffballs and are the most evolutionarily advanced fungi, and even their stinkhorns, bracket fungi, chanterelles, and club and coral hyphae have a distinct “cellular” composition. Basidiomycetes fungi, as well as the plant-parasitic rusts and smuts [8]. All produce basidiospores that are produced on a specialized of them produce their spores on the external surface of Journal of Mycology 3 microscopic cells called basidia and their fruit bodies have hymenium is exposed while the spores are still immature. evolved in many ingenious ways in order to liberate these The major importance of the species of Aphyllophorales asa spores. The fungi comprising the phylum Basidiomycota whole is their saprobic activities as decomposers, particularly commonly are known as basidiomycetes. Basidiomycota in degradation of cellulose and lignin. Although most species includes classes Hymenomycetes, Ustilaginomycetes, and are saprobic in soil, litter, bark, and dead wood, some species Urediniomycetes. Hymenomycetes includes orders Agari- maybetrulyparasiticorpathogeniconforesttreesand cales, Aphyllophorales, Auriculariales, Dacrymycetales, Cer- nonwoody crops. The group also contains mycorrhizal forms atobasidiales, and Tuslasnellales. Among Hymenomycetes, associated with forest trees. A large number of species of mainly