Microbiology of Fungi - Morphology & Characteristics

Fungi is a eukaryotic spore bearing organism with absorptive nutrition.
They lack chlorophyll.
They reproduced both sexually and asexually.
The branch of science that deals with study of fungi are called mycology.
The scientists who study fungi are called mycologists.
The study of fungal toxins and their effects is called mycotoxicology.
The disease caused by fungi in animals are known as mycoses.

1. Presented By Sijo A Ph.D. Research Scholar (Microbiology) School of Biosciences, MACFAST College Tiruvalla, Kerala, India FUNGI – MORPHOLOGY AND CHARACTERISTICS

2. Fungi is a eukaryotic spore bearing organism with absorptive nutrition. They lack chlorophyll. They reproduced both sexually and asexually. The branch of science that deals with study of fungi are called mycology. The scientists who study fungi are called mycologists . The study of fungal toxins and their effects is called mycotoxicology. The disease caused by fungi in animals are known as mycoses. FUNGI

3. They are mainly terrestrial organisms. But some of them are found in fresh water and marine. Many of them are pathogenic and they infect plants and animals. Fungi also form beneficial relationship with other organisms. The symbiotic association with fungi and roots of higher vascular plants is called mycorrhizae. The symbiotic association of fungi and either algae and cyanobacteria is called Lichens. FUNGI - DISTRIBUTION

4. FUNGI - IMPORTANCE Fungi act as decomposers. They degrade complex organic molecules into simple organic compounds and inorganic molecules. In this way carbon, nitrogen, phosphorous are released & made available for living organisms. Fermentation (especially yeast) Making of bread, wine, and beer Preparation of Cheese, Soy sauce Organic acids – Citric and Gallic acid Certain drugs – E rgometrine, Cortisone Antibiotics– Penicillin, Griseofulvin

5. The vegetative structure of fungus is called thallus. it varies in size from single cell microscopic yeasts to multicellular models, macroscopic puffballs and mushrooms. The fungal cell wall is made up of Chitin. Chitin is a strong flexible nitrogen containing polysaccharide composed of N- acetylglucosamine residues. A yeast is a unicellular fungus with single nucleus. FUNGI - STRUCTURE They reproduces either: Asexually by budding, Transverse division & Sexually through spore formation A mold consists of long, branched, thread like filaments of cells called hyphae. Hyphae forms tissue like aggregation called mycelium. In some fungi the protoplasm streams through hyphae and uninterrupted by cross walls. These are called coenocytic hyphae.

6. In some fungi the hyphae contain cross walls called septa with single or multiple pores. These hyphae are called septate hyphae. The fungi that cause disease in animals and humans are dimorphic in nature. i.e. they can change from: Yeast form in the animal Mold form in the external environment in response to changes in various environmental factors like nutrients, Co2 tension, oxidation-reduction potential, temperature. This shift is called YM Shift. Nutrition and Metabolism Most fungi are saprophytes. They obtain their nutrition from dead organic matter. They are chemoorganoheterotrophs and uses organic compounds as a source of carbon, electron and energy. Glycogen is the primary storage polysaccharide in fungi. Most fungi are aerobic. However facultative anaerobe get energy through fermentation of glucose into ethyl alcohol. Obligate anaerobic fungi found in rumen of cattle. FUNGI - STRUCTURE

7. Based on sexual reproduction, Fungi are classified into 4 divisions. Zygomycota Ascomycota Basidiomycota Deuteromycota CLASSIFICATION OF FUNGI

8. 1. Division Zygomycota It contain fungi called Zygomycetes. They are mostly living in soil, or on decaying plant or animal material. The hyphae are coenocytic with many haploid nuclei. Sexual spores are called zygospores. The bread mold Rhizopus stolonifer is an example. This fungus grows on moist, carbohydrate rich foods such as breads, fruits and vegetables. The zygomycetes have economic importance. Rhizopus is used in Indonesia to produce a food called tempeh from boiled, skinless soybeans. Another zygomycete called mucor spp is used with soybean to make a cheese called sufu . Some of them are used for the commercial production of birth control agents, industrial alcohols and meat tenderizers. CLASSIFICATION OF FUNGI

9. CLASSIFICATION OF FUNGI

10. 2 . Division Ascomycota It contain fungi called Ascomycetes. They commonly known as sac fungi. They are the largest group of fungi with 35,000 species. Its reproductive structure is called ascus. Thousands of ascus packed together to form ascocarp. The sexual spores are called ascospores . Yeasts are come under this category. Neurospora crassa is an important research tool in genetics and biochemistry. CLASSIFICATION OF FUNGI

11. 1. Division Ascomycota – Diseases caused by Fungi CLASSIFICATION OF FUNGI Powdery mildew that attack plant leaves Chest nut blight disease Ergotism is a toxic condition in humans and animals who eat grain infected with the fungus. The pharmacological activities of ergot are due to its active ingredient called Lysergic acid diethylamide (LSD). Its controlled dosage is used to treat blood pressure, induce labour and migraine headaches.

12. CLASSIFICATION OF FUNGI

13. 3. Division Basidiomycota It contain fungi called Basidiomycetes. They commonly known as club fungi. Its reproductive structure is called basidium . Basidia held within fruiting bodies are called basidiocarps. The sexual spores are called Basidiospores . Benefits of Basidiomycota Most are saprophytes that decompose plant debris especially cellulose and lignin. Agaricus campestris is used as a food through out the world CLASSIFICATION OF FUNGI

14. 3. Division Basidiomycota Harmful effects of Basidiomycota many mushrooms produces alkaloids that act as either poisons or hallucinogens. Eg: destroying angel mushrooms ( Amanita creata ), Amanita phalloides The toxins isolated from these two species are phalloidin and alpha- amanitin . Phalloidin : It attacks liver cells where it binds to plasma membrane. As a result membrane ruptures & leaking of content occur. Alpha- amanitin It attacks cells lining the stomach and small intestine & causes severe gastrointestinal symptoms. CLASSIFICATION OF FUNGI

15. 3. Division Basidiomycota Harmful effects of Basidiomycota Cryptococcus neoformans is an important human pathogen. It causes a disease called cryptococcosis. It causes systemic infection primarily involving lungs and central nervous system. Smuts and rusts causes damage to cereal crops. CLASSIFICATION OF FUNGI

16. CLASSIFICATION OF FUNGI

17. CLASSIFICATION OF FUNGI Gorgonzola cheese Camembert cheese Roqueforti cheese Aspergillus flavus Mycotoxin production on maize and pea nut

18. Antifungal drugs : Used to kill or stop the growth of fungi. A good antifungal drug : Selectively targets and eliminates fungal pathogens with minimal harm to the host . Challenges with antifungal drugs : Fungal cells are eukaryotes, like human cells, making it harder to target fungi without affecting the host . Fungi grow slowly and are often multicellular, which complicates treatment and measurement . Mechanism of action : Most antifungal drugs target ergosterol, a key component of fungal cell membranes . Mammalian cells have cholesterol instead of ergosterol, making it easier to target fungal cells . Fungistatic agent : Inhibits the growth and reproduction of fungi but does not kill them. Fungal growth can resume when the agent is removed . Fungicidal agent : Directly kills fungi . ANTIFUNGAL DRUGS

19. Ergosterol inhibitors Two main types of antifungal compounds : Polyenes : Produced by Streptomyces species. Bind to ergosterol, disrupting the membrane, causing increased permeability, and leading to cell death . Eg : Amphotericin B, Nystatin Azoles and Allylamines : Azoles : Synthetic agents that inhibit ergosterol biosynthesis, leading to damaged membranes and altered membrane transport functions . Eg : Ketoconazole Allylamines : Also inhibit ergosterol biosynthesis but are mainly used topically as they are not easily absorbed by animal tissues . Eg : Terbinafine ANTIFUNGAL DRUGS

20. 2. Echinocandins Work by inhibiting 1,3-β-D-glucan synthase , an enzyme responsible for forming glucan polymers in the fungal cell wall . Since mammalian cells lack this enzyme and cell walls , echinocandins specifically target fungal cells, leading to selective fungal cell death . Primarily used to treat fungal infections caused by Candida and some fungi that are resistant to other antifungal agents . Eg : Caspofungin ANTIFUNGAL DRUGS

21. 3. Other antifungal drugs Polyoxins : Inhibit chitin biosynthesis and, therefore, fungal cell wall formation . It is used as agricultural fungicides , not for clinical use . Eg : Polyoxin A & Polyoxin B Nucleoside analog : Interfere with DNA replication by affecting DNA topology . Eg : 5-Fluorocytosine (flucytosine ) Aromatic antibiotic disrupt microtubule aggregation during mitosis . Eg : Griseofulvin Antifungal drugs with other applications : Vincristine and vinblastine are effective as antifungal agents and also used in cancer treatment . ANTIFUNGAL DRUGS

22. The use of antifungal drugs has led to the emergence of resistant fungi and opportunistic fungal pathogens . Candida species (normally non-pathogenic) can cause diseases in immunocompromised individuals . Drug-resistant Candida strains have developed, with some strains now resistant to all current antifungal agents. Antifungal resistance

23. THANK YOU