Biological Sciences
Mold Spores
Mold spores are tiny reproductive units produced by molds, which are a type of fungus. These spores are dispersed through the air and can settle on surfaces where they can grow and multiply under the right conditions. Mold spores are a common allergen and can cause respiratory issues in sensitive individuals.
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6 Key excerpts on "Mold Spores"
- David M. Carlberg(Author)
- 2004(Publication Date)
- CRC Press(Publisher)
Unlike spore-forming bacteria, where only one spore is formed per cell, a single mold hypha may produce thousands of spores, each of The Scope of Microbiology 19 which can be launched into the air with the slightest air movement. If the spore happens to land on a site where there are nutrients and moisture, it will germinate and eventually develop into a new mycelium. While Mold Spores are somewhat more resistant to harsh conditions than the cells that make up the hyphae, Mold Spores generally are nowhere as resistant to adverse environmental conditions as are bacterial endospores. Thus, chemical and physical means that destroy bacterial spores easily eliminate Mold Spores. People are most familiar with molds because of their association with food spoilage and the deterioration of materials and equipment through mildew and dry rot. In addition, a few species of molds are responsible for diseases in animals and plants. The destructive effects molds have on landscape plants, food crops, and consumer products cause billion dollar losses each year for farmers, manufacturers, and consumers. On the positive side, many of our most effective antibiotics, such as penicillin, griseofulvin, and gentamicin, are produced by molds. Also, many species of molds are necessary in the manufacture of important products such as corticosteroids and citric acid and dozens of foods like soy sauce, miso, and blue cheese. Molds are the second most common microbial contaminant in the cleanroom and, under certain circumstances, they can become a serious threat. Their nutritional requirements are generally simpler than those of bacteria, and many species can grow in the absence of significant amounts Figure 1.9 Tangled mycelium of the mold Microsporum. Conical structures are macroconidia or spore cases. (Photo: CDC Public Health Image Library ID #4325.) 20 Cleanroom Microbiology for the Non-Microbiologist of moisture.
eBook - PDF- Thad Godish(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
167 chapter six Biological contaminants — mold Biological contaminants were described in Chapter 5 in the context of illness syndromes and disease risks associated with exposure to airborne organisms and products of biological origin. Discussion of airborne bacteria and viruses was in the context of their role in causing infectious disease and potentially contributing to other problems; mites, insects and animal allergens, in the context of causing chronic allergic rhinitis and asthma. Because mold is such a significant indoor environment concern, this chapter is devoted to mold- related health concerns and risk factors for mold infestation. I. Biology of mold The terms mold and mildew are commonly used to describe the visible manifestations of the growth of a large number of organisms that are scien- tifically classified as fungi. Terms such as yeast and mushrooms are used to describe, respectively, single-celled fungi (widely used for baking and brew- ing) and the large reproductive structures of a major class of fungi that are used for food or are known for their high toxicity. Fungi form true nuclei, which distinguishes them from lower organisms such as bacteria. They differ from plants in that they do not produce chlo- rophyll and thus cannot manufacture their own food; from animals in that (except for reproductive cells in some species) they are not motile. Structurally, fungi exist as masses of threadlike filaments or hyphae. The collective mass of hyphal filaments is described as mycelium, the vegetative part of the organism that infests a substrate and extracts food for the organ- ism’s growth. Though hyphal filaments are microscopic, the mycelium is typically visible to the naked eye. Masses of mycelia can be distinguished as fungal colonies (Figure 6.1). In many species, the hyphae are colorless; in other species they contain pigments.
eBook - ePub- Christopher S. Cox, Christopher M. Wathes, Christopher S. Cox, Christopher M. Wathes(Authors)
- 2020(Publication Date)
- CRC Press(Publisher)
14Biological Analysis of Fungi and Associated Molds
T.M. Madelin and M.F. Madelin
INTRODUCTION
General Characteristics of Fungi and Associated Molds
Spores and hyphal fragments of fungi are ubiquitous in air, where they are sometimes the major pollutant and sources of infection or allergic reactions. For the great majority of dry-spored fungi, air is their natural dispersal medium, and accordingly they have evolved various mechanisms that enhance their effective dispersal and survival in air. From the aerobiological standpoint this is an important difference from bacteria and viruses. Fungal spores vary greatly in size, but most are in the range 2–50 μm they are bigger than actinomycete and other bacterial spores and generally smaller than pollens (see Figures 14.1 and 14.2 ).Figure 14.1. Scanning electron photomicrograph of conidiophores of Penicillium cam-embertii bearing chains of spores (courtesy of Dr. A. Beckett, University of Bristol). Scale bar 20 //m.Figure 14.2. Airborne fungal spores released from disturbed straw, and trapped with May/RE Cascade Impactor. Scale bar 20 μAirborne fungal spores cannot rise or move laterally in air except through wind and turbulence (see Chapter 4 ). Consequently they must first traverse the boundary layer of still air that adjoins the surface from which they have originated in order to reach a region of air movement, for otherwise they would not disperse far from their site of formation. Their introduction into the turbulent region is commonly achieved by mechanisms or structures that shoot them through the boundary layer (such as bursting asci) or drop them from a height into moving air (such as the fruit bodies of bracket fungi and toadstools), or simply raise them on microscopic stalks the millimeter or so required to expose them to wind or gusts. The dispersal of fungal spores is treated comprehensively by Ingold.1 Not infrequently, fragments of mycelium and sporophores also become blown away. Some of these remain viable and capable of instituting new growth.2
eBook - PDFBiological Risk Engineering Handbook
Infection Control and Decontamination
- Martha J. Boss, Dennis W. Day, Martha J. Boss, Dennis W. Day(Authors)
- 2016(Publication Date)
- CRC Press(Publisher)
Given appropriate growing conditions, fungi are dimorphic (having two forms of growth) and can be found as either mold or yeast. This dimorphism may be temperature dependent. Mold germinates with branching hyphae and reproduces using spores. Yeast germinate as unicellular organisms and reproduce by budding. 1.3.1 Typical Mold Life Story Molds develop from spores. When a spore settles on a hospitable surface, the spore swells and produces a germ tube (germination) that grows into a tiny, thread-like hypha (plural, hyphae). The hyphae form a tangled mass called a mycelium (Figure 1.10).The mycelium in turn produces aerial hyphae called stolons and root-like structures known as rhizoids . The rhizoids anchor the stolons in the substrate (living space and food source). As the mold matures, many upright fruiting bodies form above the rhizoids. For asexual reproduction, the end of each fruiting body has a spore case, called a sporangium . A sporangium looks like a miniature pinhead and contains thousands of spores. When the spore case matures and breaks open, air currents carry the spores away (Figure 1.11). The asexual spores are genetic copies of the parent. For sexual reproduction a variety of methods are used to unite Figure 1.9 Mycobacterium . (Courtesy of CDC Public Health Image Library.) 12 BIOLOGICAL RISK ENGINEERING HANDBOOK: INFECTION CONTROL AND DECONTAMINATION genetic material from two parent hyphae into a resultant spore. The sexual spores are genetically different from each parent. These spores may settle on damp food and grow, starting the reproductive cycle over again. Some molds, such as Penicillium , produce chains of spores at the tips of certain hyphae, called conidiophores (Figure 1.12). 1.3.2 Thallus and Hyphae Vegetative structures are defined as those involved in catabolism and growth, rather than reproduction.
eBook - PDFFungi
Experimental Methods In Biology, Second Edition
- Ramesh Maheshwari(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
47 CHAPTER 3 Spores Their Dormancy, Germination, and Uses If most of life were destroyed by a holocaust of natural or man-made origin, a residuum in the form of spores, cysts, or seeds might remain to serve as the raw material of further evolution. —P. Becquerel (1950) (in French, summary in Sussman and Halvorson, 1966) Fungal biology is inextricably linked with spores. Experiments on fungi almost always begin with spores and end when the culture has begun to produce spores. In the middle of the 17th century when fascination with looking at the microscopic-sized objects was developing, a French farmer named Mathieu Tillet (1714–1791) collected a black dusty mass from diseased grains of wheat and applied them to a plot sown with healthy wheat seed. He showed that the powdery mass caused the bunt of wheat, establishing that the disease is seed borne. The Italian botanist Micheli (1679–1737) collected spores of fungi, sowed them on organic substrate (pieces of melon), and put forth the view that fungi arose from their own spores. He described germination of powdery wheat bunt spores for the first time, and this was confirmed by Prevost (1755–1819). The Tulasne brothers, Louis (1815– 1885) and Charles (1817–1884), illustrated spores of several fungi. The German botanist Anton de Bary (1831–1888) traced the germination of spores, including those of the rust fungi (Figure 3.1), to mycelium inside the host plant tissue and its eventual external production of disseminative spores. It thus began to be understood that the vegetative mycelium of fungi is mostly hidden inside the substratum and that what is observed are only the externally produced colored spores. Most fungal spores are dark because of melanin pigment. Some fungi, however, produce colored spores. For example, Penicillium produces blue-green conidia, Fusarium puts forth pink conidia, and Puccinia forms pustules containing rust-colored urediospores, while the mushroom fungi discharge yellow-ish basidiospores.
eBook - PDF- J. W. Deacon(Author)
- 2009(Publication Date)
- Wiley-Blackwell(Publisher)
Chapter 10 Fungal spores, spore dormancy, and spore dispersal This chapter is divided into the following major sections: • general features of fungal spores • spore dormancy and germination • spore dispersal • dispersal and infection behavior of zoospores • zoospores as vectors of plant viruses • dispersal of airborne spores • spore sampling devices and human health Fungi are the supreme examples of spore-producing organisms. They produce millions of spores, with an astonishing variety of shapes, sizes, surface properties, and other features – all precisely matched to the specific requirements for dispersal and/or persistence in different environments. A small part of this diversity is illustrated in Fig. 10.1, for some of the more bizarrely shaped spores of the freshwater aquatic fungi that grow in fast-flowing streams. But even the common rounded spores of fungi have properties that determine whether they will be deposited on plant surfaces, or on soil, or in the human lungs, etc. In this chapter we discuss several examples of this fine-tuning, and we will see that the properties of a spore tell us much about the biology and ecology of a fungus. Fig. 10.1 Examples of tetraradiate, multiple-armed and sigmoid spores found in fast-flowing freshwater streams. Approximate spore lengths are shown in parentheses. (a) A single conidium of Dendrospora (150–200 mm); (b) conidium of Alatospora (30–40 mm); (c) conidium of Tetrachaetum (70–80 mm); (d) conidium of Heliscus (30 mm); (e) conidium of Clavariopsis (40 mm); (f) conidium of Lemonniera (60–70 mm); (g) conidium of Tetracladium (30–40 mm); (h) conidium of Anguillospora (150 mm). (a) General features of fungal spores Because of their extreme diversity we can define fungal spores in only a general way, as microscopic propagules that lack an embryo and are specialized for dispersal or dormant survival.
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