Classification of fungi Mrs. Dalia Kamal Eldien Msc in Microbiology Lecture NO (2)

Objectives Classification of fungi according to method of reproduction & type of hyphae Identification of the different classes of fungi Zygomycetes (phycomycetes) Ascomycetes Basidiomycetes Deuteromycetes

Classification of fungi There are many ways for fungi classification, but the most practical approaches based on: Method of reproduction Type of hyphae Basing on those criteria they classify the fungi in to four groups Zygomycetes (phycomycetes) Ascomycetes Basidiomycetes Deuteromycetes (Fungi imperfecti)

Zygomycetes (phycomycetes)

Scientific classification Kingdom: Fungi Phylum: Zygomycota Class: Zygomycetes

Zygomycetes (phycomycetes) Commonly known as bread moulds Zygomycetes are fast growing Hyphae are aseptate Reproduce sexual and asexual . Asexual reproduction produce the sporangiospores, found within sac like structure known as sporangia, sporangia are borne on special hyphae called sporangiophore. This endogenous process of spore formation within a sac is known as Sporogenesis.

Zygomycetes under light microscope

Identify the different parts?

Zygomycetes (phycomycetes) Sexual reproduction involves producing a thick-walled spore called a zygospore. Example: Rhizopus, Mucor, Rhizomucor

ASCOMYCETES

Scientific classification Kingdom: Fungi Subkingdom:Dikarya Phylum: Ascomycota Class : Ascomycetes

Ascomycetes The Hyphae of ascomycetes are septate with simple septal pores Reproduce sexual and asexual . Asexual reproduction produce the conidia. Conidia arise by budding of conidiogenous hyphae Conidia are borne on specialized structures called conidiophore (hyphae that bear conidia)

Asexual reproduction of ascomycetes

Conidia of ascomycetes

Sexual reproduction is by the formation of endogenous ascospores, are the largest sexual spore usually are eight in number, present in an ascus sac, group of asci found in ascocarp.

Sexual reproduction of ascomycetes 2-The female portion usually enlarges and gametangia fuse.  The fusion cell enlarges into a sac 1-Two gametangia arise on adjacent cells and nuclei migrate  3-Meiosis takes place to produce many nuclei

Fungus with Ascospores (8 in number)

BASIDIOMYCETES

Scientific classification Kingdom: Fungi Subkingdom:Dikarya Phylum: Basidiomycota Class: Basidomycetes

Basidomycetes Less medically important group Have septated hyphe and reproduce sexually only The sexual spore known as basidospore found in the tip of hyphe typically, four on a basidium Example: Mushrooms

Sexual reproduction of basidomycetes

DEUTEROMYCETES

Deuteromycetes Also name as Fungi imperfecti or imperfect fungi Are the most medically important group Have septated hyphe Reproduce sexually and asexually, but mostly asexually, result in formation of 3 types of spore:- Thallospore Conidiospore Sporingiospore

Thallospore:- are formed with in the hyphe, are two types Arthrospore: by fragmentation of the terminal part of hyphe, seen in pathological specimen not culture b) Chlamydospore: formed by migration of content of two adjacent cells

Arthrospore

Chlamydospore

Conidiophore Conidia are asexual spore, important in identification of some fungi, have different shape, size & arrangement: Macroconidia: large& multicellular Microconidia: small& unicellular Sporingiospore Similar to zygomcytes but the hypha is septated

Pathogenesis of fungi Most fungi are saprophytic or parasitic to plants and are adapted to their natural environment. Infection in humans is a chance event, occurring only when conditions are favorable. Except for few fungi such as the Dimorphic fungi that cause systemic mycoses and Dermatophytes, which are primary pathogens, the rest are only opportunistic pathogens.

Fungal Diseases (Mycoses) Mycosis is the infection cause by fungi, classify according to the tissue levels of infection to: 1. Superficial mycoses are limited to the outermost layers of the skin I. Superficial phaeohyphomycosis II. Tinea versicolor III. Black piedra IV. White piedra 2- Cutaneous mycoses extend deeper into the epidermis, and also include invasive hair and nail disease I. Dermatophytosis

3- Subcutaneous mycoses involve the dermis, subcutaneous tissues, muscle and fascia. I. Chromoblastomycosis II. Rhinosporidiasis III. Mycetoma 4- Systemic (deep) mycoses due to primary pathogens originate primarily in the lungs and may spread to many organ systems, In general primary pathogens that cause systemic mycoses are dimorphic. I. Blastomycosis II. Histoplasmosis

I. Candidiasis II. Aspergillosis 5- Opportunistic mycoses Systemic mycoses due to opportunistic pathogens are infections of patients with immune deficiencies I. Candidiasis II. Aspergillosis

Factors predispose fungal infection Prolonged antibiotic therapy Underlying disease (HIV infection, cancer, diabetes, etc.) Age Surgical procedures Immunosuppressive drugs Irradiation therapy Indwelling catheters Obesity Drug addiction Organ transplants