Mold is a general term for fungi that form mycelium. It is not a noun of taxonomy, and it belongs to each sub-gate of the fungal door. The basic unit constituting the mold is called hyphae, which is long tubular and has a width of 2 to 10 μm. It can continuously grow and branch from the front end. No septum or septum, with 1 to more nuclei. The cell wall is divided into three layers: the outer layer of amorphous β-glucan (87 nm); the middle layer is glycoprotein, the protein network is filled with dextran (49 nm); the inner layer is chitin microfiber, and the amorphous protein is contained (20 nm). ). When growing on a solid substrate, part of the hyphae penetrates into the matrix to absorb nutrients, called matrix hyphae or vegetative hyphae; the aerial hyphae extending into the air can further develop into hyphae and produce spores. A large number of hyphae are interwoven into a villus, floc or mesh, etc., called mycelium. The mycelium is often white, brown, gray, or in a bright color (the mold is white hairy, it is mucor, the green is penicillium, the yellow is yellow Aspergillus), and some can produce pigment to color the substrate. Molds breed rapidly, often causing a lot of mildew and spoilage of foods and utensils, but many beneficial types have been widely used, and they are the first kind of microorganisms that are used and recognized in human practice activities.
Mold is a common name for filamentous fungi, meaning "mold fungi", which often form branched mycelium, but do not produce large fruiting bodies like mushrooms. In wet and warm places, many items grow on the surface. A viable, flocculent or arachnoid colony visible to the naked eye, that is mold. The main component of its cell wall is chitin, pay attention to the characteristics of mold colonies distinguished from Streptomyces (actinomycetes):
A. The shape is large, the texture is loose, the appearance is dry, opaque, and the shape is loose or tight.
B. The connection between the colony and the culture medium is tight and difficult to pick. The color and structure of the front and back of the colony are often inconsistent with the color and structure of the edge and the center.
C. The mycelium of mold has the differentiation of vegetative hyphae and aerial hyphae, while the aerial hyphae have no capillary water, so their colonies must be different from bacteria or yeast, and closer to actinomycetes.
Mycelium of mold. The basic unit that constitutes a mold vegetative is hyphae. The hyphae is a tubular filament, which is observed under a microscope, much like a transparent hose. Its diameter is generally 3 to 10 microns, which is several times to several tens of times larger than that of bacteria and actinomycetes. Times. The hyphae can be elongated and produce branches, and many of the branched hyphae are intertwined with each other, which is called mycelium.
According to the presence or absence of a septum in the hyphae, the mycelium can be divided into two types: no hyphae and no hyphae. There is no membrane in the hyphae without hysteresis, and the whole mycelium is a single cell containing multiple nuclei. This is the type of hyphae that lower fungi have. There is a septum in the hyphae, and a hyphae separated by a septum is a cell, and the mycelium is composed of a plurality of cells, each cell having one or more nuclei. There are 1 or more small holes in the membrane to allow the cytoplasm and nutrients between the cells to communicate with each other. This is the type of hyphae that higher fungi have.
In order to adapt to different environmental conditions and more effective intake of nutrients to meet the needs of growth and development, many mold hyphae can be differentiated into some special forms and tissues, this specialized form is called hyphal metamorphosis.
The mycelial hyphae grown on the solid medium can be divided into three parts: 1 vegetative hyphae: hyphae for absorbing nutrients in the deep medium; 2 aerial hyphae: hyphae growing in the air by the vegetative hyphae; 3 reproductive hyphae: some aerial hyphae develop to a certain stage, differentiate into reproductive hyphae, and produce spores.
Suction device. Hyphae produced by obligate parasitic molds such as rust, downy mildew and powdery mildew, which are the side branches produced from the hyphae, which invade the cells and differentiate into roots, fingers, spheres and bergamot. Used to absorb nutrients in the host cells.
rhizoid. The root structure differentiated between the hyphae of the moldy mold and the nutrient substrate has the function of fixing and absorbing nutrients.
The strain net and the fungus ring. The hyphae of some predatory molds are metamorphosed into a ring or a network, and are used to capture other small organisms such as nematodes and paramecium.
Sclerotia. The dense tissue formed by a large number of hyphae is a dormant body that resists adverse environmental conditions. The outer layer is hard and dark in color; the inner layer is loose and mostly white. For example, medicinal sputum and ergot are sclerotia.
Child entity. It is made up of a large number of aerial mycelium, which refers to any structure with a certain shape that can produce spores inside or above. For example, there are three types of structurally complex fruiting bodies that can produce spores, called closed capsules, ascospores, and ascospods.
Because the mycelium of the mold is thick and long, the colonies of the mold are large, and the hyphae of some molds spread, there is no limitation, the colonies can be extended to the whole culture dish, and some species have certain limitations, diameter 1 ~ 2 cm or less. The colony texture is generally looser than the actinomycetes, and the appearance is dry and opaque, showing a tight or loose arachnoid, villous or cotton-like shape; the colonies are tightly connected to the medium and are difficult to pick; the color and edge and center of the colony The colors are often inconsistent.
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