Information and Example of Mushrooms – Fungi
The Fungi are the living beings that correspond to the Fungi Kingdom, according to the Taxonomy of Life. They contribute to many purposes such as the degradation of organic matter, or a participation in biological cycles. Some of them, only a few, are generators of diseases, that is, pathogens, of animals and plants.
At first, they had been placed in the classification as part of the Plantae Kingdom, because they were considered immobile organisms that developed structurally in the nutrient medium where they were found. However, upon further study, it was discovered that these organisms possess characteristics that lead them more to the Animalia Kingdom than to the Plantae.
Sub-classification of the Fungi Kingdom
In the Fungi Kingdom, fungi are subdivided into four “Phyla”, which are the official subdivisions in the Taxonomy.
The Ascomycota is the most extensive, comprising 50% of the known fungi, and contains at least 80% of the pathogenic fungi. There are also the Basidiomycota, the Zygomycota and the Chytridiomycota.
It is between Ascomycota, Basidiomycota and Zygomycota where the human pathogenic fungi are found.
The fungi whose sexual reproduction is still unknown, form a heterogeneous group called Deuteromycetos, imperfect or Mitosporic fungi, which represents the second largest group, and which also includes human pathogens.
Nature of the Fungi
The fungi, having cells with a defined nucleus, are typical eukaryotic organisms. Its nucleus contains several chromosomes and is delimited by a nuclear membrane, with a nucleic organelle rich in Ribonucleic Acid (RNA) and cytoplasmic organelles, such as mitochondria, vacuoles, endoplasmic reticulum, Golgi apparatus and Ribosomes.
Examples of the number of chromosomes in the nuclei are: Candida albicans with 7 chromosomes, Aspergillus nidulans with 8 chromosomes, Saccharomyces cerevisiae with 16 chromosomes.
The cells of fungi differ from those of plants in the constitution of the cell wall, and in that they do not have chlorophyll or chloroplasts.
The main differences between fungal and human cells is that they have a cell wall and there is presence of ergosterol in the cytoplasmic membrane.
On the surface of the cytoplasmic membrane, there is a cell wall that is made of polysaccharides and various proteins. The most important polysaccharides present are chitin, mannan and glucan.
Forms of Fungi
Fungi are found mainly in two forms or morphologies:
Filamentosa, which creates Filamentous Fungi, such as molds and myceliaries, and represents the most frequent growth of microscopic fungi. They develop in fruits and foods as a layer between whitish and greenish, of cottony or powdery appearance. If they are observed in the microscope, their tubular structures called hyphae will be noticed. Hyphae usually originate from spores, and grow thanks to the deposit of new materials at their end, branching so many times until they become entangled and make up the mycelium.
Levaduriforme, whose representative fungi give rise to smooth colonies that resemble those of bacteria. These colonies are formed by aggregates of individual cells called yeasts. The yeast fungi reproduce by budding or by binary fission.
Feeding the Fungi
The fungi obtain their nutrients by the mechanism of absorption, and they have a chemoheterotrophic metabolism, because they obtain the energy and the carbon of organic compounds synthesized by other organisms. In nature they are rooted in decaying organic matter, participating in the biogeochemical cycles of Carbon and other elements.
Fungi are capable of decomposing many components, since they possess powerful exoenzymes that in some cases may be useful as virulence factors in the host.
In the laboratory, fungi grow easily in most culture media, needing a source of organic carbon and ammonium or nitrate ions as nitrogen sources.
Filamentous fungi are aerobic, that is, their food operates only in the presence of oxygen. On the other hand, the Levaduriformes are facultative Anaerobes, that is to say, their feeding operates in the absence of Oxygen, but they can adapt to aerobic conditions.
Reproduction of the Fungi
The majority of the fungi present both mechanisms of reproduction: Sexual and Asexual.
The sexual mechanism is called Teleomorph or Meiosporic. The asexual mechanism is called Anamorph or Mitosporic. It is relatively common for one fungus to have two names, that of the Anamorph state, and that of the Teleomorph state.
In an important amount of fungi only the mechanism of asexual reproduction has been known, since the sexual conditions are not known in which they occur.
Examples of Fungi
Ganoderma lucidum or Lingzhi