Biological Sciences
Saprophytic Fungi
Saprophytic fungi are organisms that obtain nutrients by decomposing and feeding on dead organic matter. They play a crucial role in the ecosystem by breaking down complex organic compounds into simpler forms, which can then be recycled by other organisms. Saprophytic fungi are important for nutrient cycling and the decomposition of organic material in various environments.
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10 Key excerpts on "Saprophytic Fungi"
eBook - PDF- J. W. Deacon(Author)
- 2009(Publication Date)
- Wiley-Blackwell(Publisher)
Chapter 11 Fungal ecology: saprotrophs This chapter is divided into the following major sections: • a theoretical model: the concept of life-history strategies • the biochemical and molecular toolbox for fungal ecology • a “universal” decomposition sequence • the fungal community of composts • fungal decomposers in the root zone • fungal communities in decaying wood The importance of fungi in ecosystem processes is unde- niable. Fungi are the main agents of decomposition in many terrestrial and aquatic environments. They are particularly important in the breakdown and recycl- ing of cellulose and hemicelluloses, which together account for nearly 70% of all the plant wall material that is recycled annually. In addition, fungi have a unique role in degrading woody substrates, which contain cellulose intimately complexed with lignin (lignocellulose). And, fungi degrade many other natural and manmade materials, causing serious economic losses. In previous chapters we dealt with the physiology, growth, genetics, and dispersal of fungi – the basis for understanding fungal ecology. But when we turn to fungi in natural environments we face a major problem, because natural communities are extremely complex: they contain many types of substrate, interacting species, and microhabitats. Therefore, at a practical level we need to find well-defined com- munities that can be dissected to provide key insights into fungal behavior. We will do this by focusing on a few natural “model” systems that have been well researched – the leaf zone, leaf litter, the root zone, self-heating composts, and wood decay. The principles derived from these natural model systems apply more generally across the fungal kingdom. We will also explore the biochemical and molecular toolbox that enables us to track and identify fungi in complex natural materials.
eBook - PDFSoil Fungi and Soil Fertility
An Introduction to Soil Mycology
- S. D. Garrett(Author)
- 2016(Publication Date)
- Pergamon(Publisher)
So I have to admit that some members of this natural ecological group of fungi that are pioneer colonizers of virgin plant tissues, usually alive at the time of fungal invasion, have been wrongly named as saprophytic sugar fungi; some of them, as Deacon (1979) has shown, have at least a limited power of cellulose decomposition; usually such fungi are invading fresh plant tissues as parasites rather than as saprophytes. Such difficulties should not deter us from improving our attempts at ecological grouping as a guide to understanding the behaviour of soil fungi. The history of ecological classification reveals the frequent inability of the human mind, SAPROPHYTIC SURVIVAL BY SOIL FUNGI 123 which craves for clear-cut boundaries, to cope with the infinite continuum of variation in the natural world. In every generation many biologists have had to re-learn, in frustration and disappointment, the lesson taught by Charles Darwin in The Origin of Species.
eBook - ePub- J. W. Deacon(Author)
- 2013(Publication Date)
- Wiley-Blackwell(Publisher)
Chapter 11
Fungal ecology: saprotrophs
This chapter is divided into the following major sections:- a theoretical model: the concept of life-history strategies
- the biochemical and molecular toolbox for fungal ecology
- a “universal” decomposition sequence
- the fungal community of composts
- fungal decomposers in the root zone
- fungal communities in decaying wood
The importance of fungi in ecosystem processes is undeniable. Fungi are the main agents of decomposition in many terrestrial and aquatic environments. They are particularly important in the breakdown and recycling of cellulose and hemicelluloses, which together account for nearly 70% of all the plant wall material that is recycled annually. In addition, fungi have a unique role in degrading woody substrates, which contain cellulose intimately complexed with lignin (lignocellulose). And, fungi degrade many other natural and manmade materials, causing serious economic losses.In previous chapters we dealt with the physiology, growth, genetics, and dispersal of fungi – the basis for understanding fungal ecology. But when we turn to fungi in natural environments we face a major problem, because natural communities are extremely complex: they contain many types of substrate, interacting species, and microhabitats. Therefore, at a practical level we need to find well-defined communities that can be dissected to provide key insights into fungal behavior. We will do this by focusing on a few natural “model” systems that have been well researched – the leaf zone, leaf litter, the root zone, self-heating composts, and wood decay. The principles derived from these natural model systems apply more generally across the fungal kingdom. We will also explore the biochemical and molecular toolbox that enables us to track and identify fungi in complex natural materials.A theoretical model: the concept of life-history strategies
Ecology lends itself to theoretical models as a basis for synthesizing complex information. The references at the end of this chapter cite some key publications in this field. Here we will briefly discuss one of these models, first developed by animal ecologists, then applied to plants and later to fungi – the concept of life-history strategies (Fig. 11.1
eBook - PDFEcology
From Individuals to Ecosystems
- Michael Begon, Colin R. Townsend, John L. Harper(Authors)
- 2009(Publication Date)
- Wiley-Blackwell(Publisher)
Finally, animal feces, whether pro- duced by detritivores, microbivores, herbivores, carnivores or parasites, are a further category of resource for decomposers and detritivores. They are composed of dead organic material that is chemically related to what their producers have been eating. The remainder of this chapter is in two parts. In Section 11.2 we describe the ‘actors’ in the saprotrophic ‘play’, and consider the relative roles of the bacteria and fungi on the one hand, and the detritivores on the other. Then, in Section 11.3, we consider, in turn, the problems and processes involved in the consumption by detritivores of plant detritus, feces and carrion. 11.2 The organisms 11.2.1 Decomposers: bacteria and fungi If scavengers do not take a dead resource immediately it dies (such as hyenas consuming a dead zebra), the process of decomposi- tion usually starts with colonization by bacteria and fungi. Other changes may occur at the same time: enzymes in the dead tissue may start to autolyze it and break down the carbohydrates and proteins into simpler, soluble forms. The dead material may also become leached by rainfall or, in an aquatic environment, may lose minerals and soluble organic compounds as they are washed out in solution. Bacteria and fungal spores are omnipresent in the air and the water, and are usually present on (and often in) dead material before it is dead. They usually have first access to a resource. These early colonists tend to use soluble materials, mainly amino acids and sugars that are freely diffusible. They lack the array of enzymes necessary for digesting structural materials such as cellulose, lignin, chitin and keratin. Many species of Penicillium, Mucor and Rhizopus, the so-called ‘sugar fungi’ in soil, grow fast in the early phases of decomposition. Together with bacteria having similar opportunistic physiologies, they tend to undergo population explosions on newly dead substrates.
eBook - PDF- Seyed Mahyar Mirmajlessi, Ramalingam Radhakrishnan, Seyed Mahyar Mirmajlessi, Ramalingam Radhakrishnan(Authors)
- 2020(Publication Date)
- IntechOpen(Publisher)
Environmental degradation of the soil is increasing worldwide at an alarming rate due to erosion, Biostimulants in Plant Science 124 acidity, salinization, compaction, depletion of organic matter, and water scarcity. On the contrary, in a healthy ecosystem, there is a balanced microbiota of the soil, in such a way that the potential of pathogenic and mycorrhizal fungi coexists in apparent harmony. Ectomycorrhizal fungi can survive in extreme habitats with high or low temperature [95, 96], salt and metal concentration [97, 98], drought [99], and other circumstances related to the degradation of the ecosystem. The importance of ECM fungi in the balance of the ecosystem can be enormous, since they can be used to increase the tolerance of plants against biotic or abiotic stresses, especially their capacity to fix heavy metals or to degrade a wide variety of persis-tent organic compounds; to interact with soil bacteria; to attack fungi, bacteria, and pathogenic nematodes; and to improve the vegetative growth and the nutritional status of its symbiont plant. It has been documented by several authors that mycorrhizal fungi improve the disease resistance of their host plant primarily by direct competition, enhanced or altered plant growth, nutrition and morphology, induced resistance, and develop-ment of antagonist microbiota. Direct competition or inhibition is reported to be due to the production and release of antibiotics and physical sheathing by the mantle of ECM [27, 100–102]. For example, ECM fungi have been shown to protect trees from Phytophthora cinnamomi infection along with supporting their survival and growth in comparison to non-mycorrhizal seedlings [35, 101, 102]. Thus, ECM fungi can also be used as a fungicide in nursery plantations for better growth, survival, and establishment of seedlings.
eBook - PDFThe Fungal Population
An Advanced Treatise
- G. C. Ainsworth, Alfred S. Sussman, G. C. Ainsworth, Alfred S. Sussman(Authors)
- 2013(Publication Date)
- Academic Press(Publisher)
In later stages of decomposition more organisms will be present in the substratum, and there may be a relatively high level of toxic substances residually present together with those concurrently being produced. Under such circumstances the fourth property listed will be of most importance, its possession being necessary for activity before any of the other three characters can be exhibited. The concept of competitive saprophytic ability has been much used recently and has stimulated a great deal of valuable work. Generalized statements of competitive saprophytic ability in respect of individual fungi can have broad validity. Thus it can be said that fungi of very low com-petitive saprophytic ability do not survive as saprophytes in soil generally, and therefore need some protection against the antagonism that prevents their successful activity there. Many such fungi depend upon a host for this protection, the host acting as suitable substratum and also excluding potential antagonists. The fungus has here exchanged tolerance to antago-nism for tolerance to host resistance. Such organisms have been described by Garrett (1956) as ecologically obligate parasites in that, like true obligate parasites, they have no soil ecology, apart from a declining phase after death of their host. Similarly, in a general way a spectrum of com-petitive saprophytic ability can be envisaged among terrestrial fungi, those with a low value occurring very early in substratum succession and being pioneer colonizers, those with a higher value being able to be active later when mixed culture conditions impose more intense antagonism. However, too often the concept has been used in a vague sense and applied as though each fungus could be assigned an invariable value to apply under all 1. The Ecology of Terrestrial Fungi 13 environmental conditions.
eBook - PDFAgroecology
The Ecology of Sustainable Food Systems, Third Edition
- Stephen R. Gliessman(Author)
- 2014(Publication Date)
- CRC Press(Publisher)
Other fungi produce enzymes that allow for the penetration of plant cell walls, enabling the fungi to absorb nutrients from the cells. Since the different enzymes produced by the vari-ous fungal species are so diverse, fungi as a group can digest compounds from a wide range of organic materials, living and dead. Further, fungi are very good at gaining access to these materials because of their incredibly extensive root-like hyphae, which form an interwoven mass called a mycelium. Combined, enzymes and hyphae make fungi remarkably efficient at water and nutrient absorption. Although the role of fungi in digesting and absorbing nutrients from dead or decaying plant matter is of considerable ecological impor-tance, our focus for the purpose of this chapter is on their role as heterotrophic consumers and their effects on plants. Fungi affect plants in two primary ways: as parasites and as mutualistic partners. Fungi that are parasitic on plants absorb nutrients from the cells of living plants. About 30% of the more than 100,000 known fungal species make their living as parasites, most of which are disease-causing (or pathogenic) to plants (Figure 13.3). Between 10% and 50% of the world’s fruit harvest is lost annually to fungal diseases, and grain crops can suffer major damage each year. Once infected, plants do not develop correctly, forming deformed or stunted parts. In addition, the compounds produced by the fungi—such as the aflotoxins produced by the ascomycete Aspergillus when it parasitizes peanuts or grain—can be toxic to humans. Fungi that form mutualisms with plants, on the other hand, create benefits for both organisms. This symbiotic relationship was presented as an important biotic interaction affecting plants in Chapter 12; the importance of these mutu-alisms in the design and management of crop communities will be described in detail in Chapter 16.
eBook - PDF- J. K. Misra, Jalpa P. Tewari, Sunil Kumar Deshmukh, Csaba Vágvölgyi, J. K. Misra, Jalpa P. Tewari, Sunil Kumar Deshmukh, Csaba Vágvölgyi(Authors)
- 2014(Publication Date)
- CRC Press(Publisher)
CHAPTER 7 CHAPTER 7 Microfungi from Deteriorated Materials of Cultural Heritage Filomena De Leo a, * and Clara Urzì b ABSTRACT Fungi possess a high metabolic versatility, hence are able to colonize several organic and even inorganic surfaces causing irreversible changes in their appearance and intrinsic properties. For this reason they may be considered as the major biodeteriogens of material of commercial and artistic value. The present work offers an overview on the main fungal species, both hyphomycetes and the so-called black meristematic fungi, associated with biodeteriorated materials. The patterns of alteration caused by fungi and the methodology that can be used for the diagnosis and prevention of fungal colonization have also been discussed. Introduction Fungi are chemoorganotrophic eukaryotic organisms with simple and versatile nutritional requirements. They present a wide range of adaptations to different climatic conditions being able to grow and/or survive in different environmental conditions such as high temperature or extremely low pH. Fungi are ubiquitous and thus are able to colonize a wide variety of substrates both, organic and inorganic including building materials. In fact, Department of Biological and Environmental Sciences, University of Messina, Viale F. Stagno d’Alcontres 31, 98166 Messina, Italy. a Email: [email protected] b Email: [email protected] * Corresponding author Microfungi from Deteriorated Materials of Cultural Heritage 145 these latter contain enough organic matter (dust, soil, airborne particles) to support their growth. They are widespread in nature and mainly abound in soils, and also occur as saprophytes or parasites of plants and animals including humans. Their dispersal in the environment occurs mainly by spores (conidia, sexual spores, chlamydospores, etc.) or hyphal fragments, conidiophores, free or associated with inorganic particles (Comtois, 1990).
- Shanthipriya Ajmera, B. Bhima, Krishnappa M., Shanthipriya Ajmera, B. Bhima, Krishnappa M.(Authors)
- 2002(Publication Date)
- Bentham Science Publishers(Publisher)
11 ].SOIL FUNGI
Soil fungi are microscopic plant-like cells that form the structures or hyphae of a long thread which forms a mass called mycelium. The mycelium consumes nutrients, surface organic matter, or soil from the roots it has colonized. Special hyphae that generate the reproductive spores are generated. Some fungi are single-celled (yeast). There are several structures for fungi, but they can function in similar ways and are thus not as plant-determined as other soil bacteria such as Rhizobia. Three functional classes of fungi exist, decomposers, mutualists, fungi mycorrhiza.Decomposers
Decomposers or Saprophytic Fungi turn dead organic matter into organic acids, carbon dioxide, and fungal biomass (i.e., their bodies). They play a vital role in immobilizing and preserving nutrients in the soil by eating nutrients in organic matter. The organic acids they manufacture as products help generate degradation-resistant organic matter. Some fungi are willing to degrade cellulose, lignin, and protein, and are highly resistant to breakdowns.
These fungi establish connections with plants that are mutually beneficial. They colonize the roots of plants, where they assist the plant to get nutrients from the soil, such as phosphorus.MutualistMycorrhizae
Mycorrhiza fungi are perhaps the most common of all mutualists. Mycorrhiza means fungus root, and within plant roots, mycorrhizal fungi emerge. From 1 g of soil, up to 5 m of living hyphae of mycorrhizal fungi can be removed. The four classes of mycorrhiza fungi are arbuscular, ectomycorrhizal, ericoid, and orchid mycorrhizal fungi. The most frequent type of mycorrhiza, particularly in agricultural plant associations, is arbuscular mycorrhiza (VAM). This fungus has arbuscles that are produced within the plant root that goes into the cells with several small projections.
eBook - PDFFungi
Experimental Methods In Biology, Second Edition
- Ramesh Maheshwari(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
71 CHAPTER 4 Fungi as Scavengers Lignin is the second most abundant constituent of the cell wall of vascular plants, where it protects cellulose towards hydrolytic attack by saprophytic and pathogenic microbes. Its removal represents a key step for carbon recycling in land ecosystems, as well as a central issue for industrial utilization of plant biomass. —Francisco J. Ruiz-Dueñas and Ángel T. Martínez (2009) Vast quantities of litter comprised mostly of dead plant cell walls are continuously decom-posed. The functioning of the ecosystem depends on this crucial process in which communities of microorganisms, with fungi being the principal player, break litter down into smaller mol-ecules. During this process the mineral ions required by living organisms are dissociated from the organic substances with which they were complexed and released into the soil. With their hyphal tips shaped as spears, the fungi penetrate through the pit apertures into the cell lumen, secreting enzymes that break pectin in the middle lamella and effecting separation of cells in dead plant material. Eventually, the cell wall is broken down into myriad small molecular substances for further decomposition into carbon dioxide and water. The fungi eke out a living by absorbing the released nutrients as a source of carbon and energy. Cellulose and hemicelluloses are the chief polysaccharide constituents of litter and wood. However, these polymeric substances are encrusted with lignin, a highly refractory insoluble compound resistant to microbial attack. Hence the key process in the recycling of carbon in nature is lignin biodegradation. The most striking lignin-degrading fungi are those that form fruiting bodies that project out from the woody trunk of trees (Figure 4.1). The isolation and identification of fungi from decomposing litter, their growth in pure cultures, and the characterization of the enzymes and of compounds have provided some insights into this process.
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