CHAPTER 1 Overview of Mushroom Cultivation and Utilization as Functional Foods artmentofeic The Chinese University of Hong Kong.Hong Kong.China CONTENTS 1.1 Introduction 1.2 What Are Mushrooms? 1.4 Mushroom Cultivation 1.5 World Mushroom Production 1.6 Mushroom Biotechnology 1.8 Concluding Remarks References 1.1 INTRODUCTION o two Mycophiles-Those who love and know their mushrooms intimatelv. Mycophobes-Those who fear,dislike,and do not know their mushrooms I think all readers of this book belong to the former and not the latter. hroom species has accumulated through e as been reported to earth (Hawksworth,2001).China is estimated to have about 1500-2000 edible mushroom species with 981 species identified.By 2002,92 species have beer domesticated while 60 of these have been commercially cultivated(Mau et al
CHAPTER 1 Overview of Mushroom Cultivation and Utilization as Functional Foods Shu-Ting Chang Department of Biology, The Chinese University of Hong Kong, Hong Kong, China CONTENTS 1.1 Introduction 1.2 What Are Mushrooms? 1.4 Mushroom Cultivation 1.5 World Mushroom Production 1.6 Mushroom Biotechnology 1.8 Concluding Remarks References 1.1 INTRODUCTION In 1957, R. Gordon Wasson, a world known amateur mycologist, proposed the division of people into two classes for which he coined the following terms: Mycophiles—Those who love and know their mushrooms intimately. Mycophobes—Those who fear, dislike, and do not know their mushrooms. I think all readers of this book belong to the former and not the latter. Knowledge of numerous new mushroom species has accumulated through time. The number of recognized mushroom species has been reported to be 14,000, which is about 10% of the total estimated mushroom species on the earth (Hawksworth, 2001). China is estimated to have about 1500–2000 edible mushroom species with 981 species identified. By 2002, 92 species have been domesticated while 60 of these have been commercially cultivated (Mau et al., Mushrooms as Functional Foods, Edited by Peter C. K. Cheung Copyright 2008 John Wiley & Sons, Inc. 1
2 OVERVEW OF MUSHROOM CULTIVATION AND UTILIZATION AS FUNCTIONAL FOODS 2004).However,mushrooms have nearly always been around,with a very long and interesting history.Mushrooms have been found in fossilized wood that is estimated to b 0 and almo certainly prehistor nc man use in histo arnenri,was described in the Bible as"bread from heaven"and also"manna of the Israelites"(Pegler,2002). It may be interesting to have a charming mushroom poem as a beginning for his chapte aves without flov rs,yet,they 9301345 me the entire (Ch ng an oms while the second stat ritio inal properties of mushrooms. Our attitudes to the phenomenon of nature are seldom based on simple observation.There are,however exa mples throughout history where certain are nities.bats.snakes piders.toads and owls have all been as the devil or regarded as harbingers of illness and even of death.This is one of the reasons why some refer to the e poisonous m Actually as no ent and sho any sit 686 e or even op or a mush of d in the n.Inse certainly are intere It cannot be denied tha than about 1%of the s a more likely expla rthe wide pre strange and mysteri of or nlants In s ancient communities,the seemingly miraculous manner of its growth without seed, without leaf,and without bud,its fruiting body's sudden appearance after rain. ing and thunderstorms,its qually rapid di appe ce,and e gave e to 山o funs ther funei requires the availability of more nutrients than are requ ired for the produetion of asexual spores by microfungi.Nevertheless.in damp places.such as tree-fern gul- plentiful moisture leads to mushroom formation and mush or the year re may be a particul it ms the er m although there are perennial fruiting bodies that persist during the winter.But in drier regions mushrooms occur only after seasonal rains.Formation of mushroom
2 OVERVIEW OF MUSHROOM CULTIVATION AND UTILIZATION AS FUNCTIONAL FOODS 2004). However, mushrooms have nearly always been around, with a very long and interesting history. Mushrooms have been found in fossilized wood that is estimated to be 300 million years old, and almost certainly prehistoric man used mushrooms collected in the wild as food. Recently, the importance of the role of mushrooms in history was evidenced by the fact that the desert truffle, Terfezia arnenari, was described in the Bible as “bread from heaven” and also “manna of the Israelites” (Pegler, 2002). It may be interesting to have a charming mushroom poem as a beginning for this chapter: “Without leaves, without buds, without flowers, yet, they form fruit; as a food, as a tonic, as a medicine, the entire creation is precious” (Chang and Miles, 1989, p. 345). The first part describes the morphological and physiological characteristics of mushrooms while the second states the nutritional and medicinal properties of mushrooms. Our attitudes to the phenomenon of nature are seldom based on simple observation. There are, however, examples throughout history where certain living things have inspired fear and loathing simply because they are regarded as ugly species with peculiar behavior and supposedly evil. For example, in some communities, bats, snakes, spiders, toads, and owls have all been associated with the devil or regarded as harbingers of illness and even of death. This is one of the reasons why some refer to the poisonous mushroom as a “toadstool.” Actually, the name has no scientific basis at all and should not be used in any situations, although it is possible to find a toad sitting beside or even on top of a mushroom. Mushrooms attract toads, not due to the mushroom itself, but because of the various insects which are harbored in them. Insects certainly are interested in mushrooms as a source of food (Chang, 2005). It cannot be denied that some mushrooms, even though they represent less than about 1% of the world’s known mushrooms, are dangerous if eaten. Some are deadly poisonous. But perhaps a more likely explanation for the widespread abhorrence of wild mushrooms in communities is that they are by nature a rather strange and mysterious group of organisms, quite unlike the green plants. In some ancient communities, the seemingly miraculous manner of its growth without seed, without leaf, and without bud, its fruiting body’s sudden appearance after rain, especially after lightning and thunderstorms, its equally rapid disappearance, and its curious umbrellalike shape gave rise to a wealth of illusions and mythologies. Fungi are found just about everywhere. Mushrooms, a special group of macrofungi, are rather more selective than other fungi in that the size of the fruiting body requires the availability of more nutrients than are required for the production of asexual spores by microfungi. Nevertheless, in damp places, such as tree-fern gullies and areas of rain forest, plentiful moisture leads to mushroom formation and mushrooms can be collected during most of the year. There may be a particular flora of mushroom species associated with the seasons of autumn, summer, and spring. Relatively few mushrooms are produced during the cold winter months, although there are perennial fruiting bodies that persist during the winter. But in drier regions mushrooms occur only after seasonal rains. Formation of mushroom
WHAT ARE MUSHROOMS?3 ey yn一 of int est in mushrooms not only as a health vegetable(food)which is rich in protein but also as a source of biologically active compounds of medicinal value Uses include complementary medicine/dietary hypocho estero em (Chane and Buswell.1996)are extractable from either the mushroom mycelium or fruiting body and represent an important component of ing mushr oom biotechnology indu try.It h been shown that constan mushr also hel to convert agricultural and forest wastes into useful matter and reduce pollutior in the environment.Therefore,mushroom cultivation can make three importan ：product1oI th food,manufacture of nutriceuticals,anc 1.2 WHAT ARE MUSHROOMS? 1.2.1 Definition of a Mushroom Musoomsalohhfmethinb They h naw (M to differe (Chang and Miles,1992)that specialized studies and the economic value of mush rooms and their products had reached a point where a clear definition of the term a more can be cithe large enouh to be seen with naked eye and to be picked by hand(Chang and Miles 1992】 Thus,mushrooms need not be Basidion mycetes,or aerial,or fleshy or edible.Mush .grow undergrour nd,have e pted as p to es mate the nume shrooms on the (Hawksworth,2001).The most common type of mushrooms is umbrella shaped th a pileu (cap)and a stipe hat is,Lentinula edodes.Othe ve a v mushrooms are in the form of pliable cups:others are round like golf balls.Some are in the shape of small clubs;some resemble c jellylike glob mushroom is in reality only the fruiting body of the fungus.The vegetative part of the fungus,called the mycelium,comprises a system of branching threads and cordlike strands that branch out through soil,compost
WHAT ARE MUSHROOMS? 3 fruiting bodies depends very much on the pattern of rain and, in some years, there may be virtually a complete lack of fruiting. There has been a recent upsurge of interest in mushrooms not only as a health vegetable (food) which is rich in protein but also as a source of biologically active compounds of medicinal value. Uses include complementary medicine/dietary supplements for anticancer, antiviral, immunopotentiating, hypocholesterolemic, and hepatoprotective agents. This new class of compounds, termed mushroom nutriceuticals (Chang and Buswell, 1996), are extractable from either the mushroom mycelium or fruiting body and represent an important component of the expanding mushroom biotechnology industry. It has been shown that constant intake of either mushrooms or mushroom nutriceuticals (dietary supplements) can make people fitter and healthier. In addition, mushroom cultivation can also help to convert agricultural and forest wastes into useful matter and reduce pollution in the environment. Therefore, mushroom cultivation can make three important contributions: production of health food, manufacture of nutriceuticals, and reduction of environmental pollution. 1.2 WHAT ARE MUSHROOMS? 1.2.1 Definition of a Mushroom Mushrooms along with other fungi are something special in the living world, being neither plant nor animal. They have been placed in a kingdom of their own, called Myceteae (Miles and Chang, 1997). But what are mushrooms? The word mushroom may mean different things to different people and countries. It was reported (Chang and Miles, 1992) that specialized studies and the economic value of mushrooms and their products had reached a point where a clear definition of the term mushroom was warranted. In a more broad sense “mushroom is a macrofungus with a distinctive fruiting body, which can be either epigeous or hypogeous and large enough to be seen with naked eye and to be picked by hand” (Chang and Miles, 1992). Thus, mushrooms need not be Basidiomycetes, or aerial, or fleshy, or edible. Mushrooms can be Ascomycetes, grow underground, have a nonfleshy texture, and need not be edible. This definition is not a perfect one but can be accepted as a workable term to estimate the number of mushrooms on the earth (Hawksworth, 2001). The most common type of mushrooms is umbrella shaped with a pileus (cap) and a stipe (stem), that is, Lentinula edodes. Other species additionally have a volva (cup), that is, Volvariella volvacea, or an annulus (ring), that is, Agaricus campestris, or both, that is, Amanita muscaria. Furthermore, some mushrooms are in the form of pliable cups; others are round like golf balls. Some are in the shape of small clubs; some resemble coral; others are yellow or orange jellylike globs; and some even very much resemble the human ear. In fact, there is a countless variety of forms. The structure that we call a mushroom is in reality only the fruiting body of the fungus. The vegetative part of the fungus, called the mycelium, comprises a system of branching threads and cordlike strands that branch out through soil, compost
4 OVERVEW OF MUSHROOM CULTIVATION AND UTILIZATION AS FUNCTIONAL FOODS wood log.or other lignocellulosic material on which the fungus may be growing After a period o or gro lshed (mature cn we c n.Acco 1) and edible fall into the edible mushroom category ()) mushrooms which are considered to have medicinal applications are referred toa edicinal mus me umher of mushrooms whose properties remain less w ogethe ras“other mushroom "Certainly,this approach of classifying mushro rooms are not only 1.2.2 Ecological Classification of Mushrooms There few parasitic mushrooms.Most of the cultivated gourmet c fungi.Some are mycorrhizal mushrooms,for mhe (u orum)and n sutake mushroom into culti ymbiotic relationshin with some ve etation.particularly trees.that is.there is relationship of mutual need.Therefore.the substratum (host)should be carefully th hen be ure in idenuinca ion and in merohremh r om is a owing on a living plant or on dead par cognizable as belonging to a nearby plant,flowers,fruits,or other parts of the plant. should be collected for identification of the host or substrate if its phytes obtain nutrients from dead organic materials;p arasites derive food substances from living plants and animals,causing harm to the hosts;and mycor rhiza live in a close physiological ation with host plants and a However some mushrooms do not fall peatly within these man-made cat and can share two of these categories (Figure 1.1).For example some Gnd spp..including G. e common saprophytes but can be pathogenic to 1.2.3 Identification of Mushrooms Successful identification of wild mushrooms requires a basic knowledge of the structure of fungi and of the way in which they live.To identify a given mushroom
4 OVERVIEW OF MUSHROOM CULTIVATION AND UTILIZATION AS FUNCTIONAL FOODS wood log, or other lignocellulosic material on which the fungus may be growing. After a period of growth and under favorable conditions, the established (matured) mycelium could produce the fruit structure which we call the mushroom. Accordingly mushrooms can be grouped into four categories: (1) those which are fleshy and edible fall into the edible mushroom category (e.g., Agaricus bisporus); (2) mushrooms which are considered to have medicinal applications are referred to as medicinal mushrooms (e.g., Ganoderma lucidum); (3) those which are proven to be or suspected of being poisonous are named poisonous mushrooms (e.g., Amanita phalloides); and (4) a miscellaneous category, which includes a large number of mushrooms whose properties remain less well defined, may tentatively be grouped together as “other mushrooms.” Certainly, this approach of classifying mushrooms is not absolute and not mutually exclusive. Many kinds of mushrooms are not only edible but also possess tonic and medicinal qualities. 1.2.2 Ecological Classification of Mushrooms Mushrooms can be ecologically classified into three categories: saprophytes, parasites, and mycorrhiza. There are only a few parasitic mushrooms. Most of the cultivated gourmet mushrooms are saprophytic fungi. Some are mycorrhizal mushrooms, for example, Perigold black truffle (Tuber melanosporum) and matsutake mushroom (Tricholoma matsutake). It is difficult to bring these pricey wild gourmet species into cultivation because they are mycorrhiza. These mushroom species have a symbiotic relationship with some vegetation, particularly trees, that is, there is a relationship of mutual need. Therefore, the substratum (host) should be carefully recorded, as this can be an important feature in identification and in classification, for example, whether the mushroom is growing on dung, wood, bark, living trees, litter, or soil. If the mushroom is growing on a living plant or on dead parts recognizable as belonging to a nearby plant, flowers, fruits, or other parts of the plant, these should be collected for identification of the host or substrate if its name is not known. Saprophytes obtain nutrients from dead organic materials; parasites derive food substances from living plants and animals, causing harm to the hosts; and mycorrhiza live in a close physiological association with host plants and animals, thereby forming a special partnership where each partner enjoys some vital benefits from the other. However, some mushrooms do not fall neatly within these man-made categories and can share two of these categories (Figure 1.1). For example, some Ganoderma spp., including G. lucidum, are common saprophytes but can be pathogenic too; also T. matsutake, while initially appearing to be mycorrhizal on young roots, soon becomes pathogenic and finally exhibits some saprophytic ability. 1.2.3 Identification of Mushrooms Successful identification of wild mushrooms requires a basic knowledge of the structure of fungi and of the way in which they live. To identify a given mushroom
WHAT ARE MUSHROOMS?5 Mycorrhizal Saprobe Pathogen Figure 1.1 Modified triangular model for ecological classification of mushrooms (Hall etal..2003b). eA one. Ag00 d refe ce mat ial,usually a be h color,picture 200 Mao,1995;Fuhrer,2005:Shepherd and Totterdell,1988;van der Westhuizen and Eicker,1994). that one know ome specific charact of theng ideed are (e coor and stalk;(3)spore color in mass;and(4)chemical tests or reactions. Although the e gills is a good in tion of the spo e co there instances ill h nto dete of th with a distinct cap and stem,the cap is removed and placed fertile-side down preferably on a mic paper.or cel with a bowl or si ct to preven useful deposit usually requires longer time up to 2 bours or more).The print is necessary to determine overall spore color.It is also a source of mature spores for on and meas 0 genu mushro e th room is cut longitudinally through the cap.exposing the point of attachment of the gills to the stem The envir is n which the mush oom was picke hould al o be noted.I ing wood.on a living tree trunk.or on co e should not overlook the species of those on which the mushrooms are found growng or the type of grasses or moss present in the area where the mushrooms are collected
WHAT ARE MUSHROOMS? 5 Saprobe Pathogen Mycorrhizal Cantharellus cibarius Tricholoma matsutake; Tubur melanosporum Ganoderma species including G. lucidum Figure 1.1 Modified triangular model for ecological classification of mushrooms (Hall et al., 2003b). it is necessary to examine the fruiting bodies with the utmost care. A fresh fruiting body is much easier to identify than a pickled (preserved in formalin) or a dried one. A good reference material, usually a book with color, pictures of the different mushrooms known, is a basic requirement. A key is usually provided to simplify identification in most reference texts (Arora, 1986; Carlucccio, 2003; Chang and Mao, 1995; Fuhrer, 2005; Shepherd and Totterdell, 1988; van der Westhuizen and Eicker, 1994). In using the reference, it is essential that one knows some specific characteristics of the mushroom being identified. These characteristics are (1) size, color, and consistency of the cap and the stalk; (2) mode of attachment of the gills to the stalk; (3) spore color in mass; and (4) chemical tests or reactions. Although the color of the gills is a good indication of the spore color, there are instances when the experienced mycologist will have to resort to what is called “spore print” examination to determine the real color of the spores. For specimens with a distinct cap and stem, the cap is removed and placed fertile-side down, preferably on a microscope slide, but in the absence of such, on white paper, black paper, or cellophane. Then it is covered with a bowl or similar object to prevent air currents. A thin spore print is often visible after as little as a half hour, but a useful deposit usually requires longer time (up to 2 hours or more). The print is necessary to determine overall spore color. It is also a source of mature spores for microscopic examination and measurements. The mode of gill attachment to the stem indicates the genus of the mushroom and should be carefully noted. To determine the mode of attachment, the mushroom is cut longitudinally through the cap, exposing the point of attachment of the gills to the stem. The environment in which the mushroom was picked should also be noted. It is important to know whether the mushroom grows directly on the ground, on decaying wood, on a living tree trunk, or on compost. One should not overlook the species of those on which the mushrooms are found growing or the type of grasses or moss present in the area where the mushrooms are collected