MEDICAL BOTANY - A.G. Serbin - 2003

SECTION 3. SYSTEMATICS

KINGDOM FUNGI — FUNGI

PHYLUM ASCOMYCOTA — ASCOMYCOTA

Class Ascomycetes, or sac fungi — Ascomycetes

Includes over 30,000 species found everywhere. These are multicellular (except for unicellular Yeasts) Saprophytes, less commonly parasites, featuring a septate mycelium embedded in a substrate. The segments are uninucleate, binucleate, or multinucleate, with central Pores in the septa. The life cycle is dominated by a mycelium consisting of haploid, smooth hyphae. They reproduce vegetatively by mycelial fragments, budding, and sclerotia; asexually by conidiospores; and sexually via ascospores. The Organs of sexual reproduction are the archicarp and antheridium. Following the fusion of the sex organs' protoplasts, dikaryotic (binucleate) ascogenous hyphae are formed. At their tips, organs of sexual sporulation develop—asci, or sacs—which contain haploid ascospores. In many species, the asci form a hymenial layer located on a fruiting body composed of a dense weave of hyphae. Fruiting bodies are divided into cleistothecia, which are closed and rounded; perithecia, which are semi-open and flask-shaped; and apothecia, which are open and cup- or saucer-shaped.

Yeasts and ergot are among the representatives of ascomycetes.

Family Saccharomycetaceae — Saccharomycetaceae

Genus Yeast — Saccharomyces. Belongs to the subclass Hemiascomycetidae, which is characterized by the absence of fruiting bodies and The formation of single sacs. It unites about 350 species of unicellular organisms living in sugary substrates (flower nectaries, fruits, milk). They reproduce by budding, less frequently by ascospores (Fig. 3.112). They are capable of causing Alcoholic Fermentation—The breakdown of glucose into ethanol and carbon dioxide. Wine yeast — S. ellipsoideus occurs naturally On the surface of fruits, causing the fermentation of grape juice, cocoa beans, etc. Brewer's or baker's yeast — S. cerevisiae (Fig. 3.112) is known only in culture, represented by hundreds of strains—wine, baking, brewing, distilling, etc. Under favorable conditions, they reproduce intensively. They are used in baking, and in The production of wine, beer, and alcohol through the fermentation of potatoes, cereal grains, molasses, wood, and Cellulose. In medicine, yeast is recommended for deficiencies of Vitamin D and the B-vitamin group, Metabolic Disorders, furunculosis, and general malaise. Certain strains are used for genetic research.

Class="center">Fig. 3.112. Structure and reproduction of yeast Cells: A — yeast Cell; B — budding cells; C — sexual process; 1 — Nucleus with nucleolus; 2 — vacuoles; 3 — Mitochondria; 4 — Glycogen

A promising direction in modern biotechnology is the creation of vitamin-Protein Complexes. Atoxic strains of Fusarium sambucinum and Rhodotorula gracilis are used as producers of protein and carotenoids with selective antibiotic activity.

The so-called "kombucha", which is a colony of yeast Fungi and acetic acid Bacteria, has also found medical application. The metabolic products of the fungus, accumulating in sweet tea as a nutrient medium, include: alcohol, sugar, acetic, oxalic, citric, and pyruvic acids, Enzymes, Vitamins C, B1, P, caffeine, as well as antibiotic, tanning, and other substances. Kombucha infusion and preparations based on it are recommended for lowering Blood pressure, treating dysentery, gargling the throat and rinsing the Mouth for tonsillitis, stomatitis, etc.

Family Clavicipitaceae — Clavicipitaceae

Ergot — Claviceps purpurea (Fig. 3.113). It parasitizes cereal crops most frequently. The life cycle includes 3 stages: the ascigerous (sac), conidial, and sclerotial stages. The ascigerous stage coincides in time with the flowering of cereals. A sexual process occurs in the fungus, and ascospores mature and disperse. They land on the feathery stigmas of flowers and germinate into the mycelium. This is followed by the conidial stage—conidiospores are formed on the conidiophores of the mycelium, and the hyphae produce a sugary, sticky fluid called honeydew, which attracts pollinators. Along with pollen, pollinators carry the ergot conidiospores and infect other plants. The conidia germinate, forming a dense mycelium in the Ovary that gradually develops into a sclerotium. By harvest time, the sclerotia mature, turn dark purple and very dense, and fall to the ground. This marks the beginning of the resting sclerotial stage. The sclerotia remain dormant all winter, nourished by accumulated nutrients, and in spring begin to germinate: red or dark pink structures called stromae appear on them, consisting of a thin stalk and a globular HEAD bearing open perithecia. Club-shaped asci develop inside them, containing 8 filamentous ascospores that are dispersed by wind, insects, animals, etc.

Fig. 3.113. Structure and Life cycle of ergot: A — asexual reproduction; B — sexual reproduction; M — Meiosis: 1 — septate mycelium; 2 — infected rye ear with honeydew; 3 — conidiophore with conidia; 4 — germination of conidia into sclerotium; 5 — rye ear with sclerotia; 6 — germinated sclerotium with capitate stromae on stalks; 7 — sexual process; 8 — stroma with perithecia in longitudinal section; 9 — perithecia with asci; 10 — ascust with ascospores; 11 — ascospore and its germination

Ergot sclerotia are known as ergot of rye (secale cornutum), contain toxic Alkaloids, and are used as a hemostatic agent in obstetrics and gynecology. Consuming flour containing ergot alkaloids causes Muscle spasms, historically known as " St. Anthony's fire" (convulsive ergotism).