Ch. 12 - Eukaryotic Microbes

Examples of eukaryotic microbes

• Fungi

• Algae

• Protozoa

• Helminths

Forms of fungi

• Unicellular yeasts

• Multicellular molds

Functions of fungi

• Saprophytic (decompose dead materials)

• Symbiosis with plants (mycorrhizae)

• Food

• Medicines (antibiotics)

Septate hyphae

Vegetative fungal structure containing divisions

Coenocytic hyphae

Vegetative fungal structure with no divisions— one long tube

Pseudohyphae

Results from incomplete budding, no cytoplasmic connection— individual cells elongated

Asexual reproduction of fungi

Spore formation, fragmentation, budding—- germinates

Difference of spores to bacteria endospores

Endospores are a survival mechanism to survive harsh conditions where the cell is dormant

• When conditions are favorable, endospore germinates back to a vegetative state

How do yeasts reproduce?

Buddying yeasts divide asymmetrically

Dimorphic fungi

Meaning it can exist in 2 forms: yeast or mold in response to temperature changes

At what temperature is fungi yeast-like?

37 celsius

At what temperature is fungi mold-like?

25 celsius

Example of a yeast

Candida albicans

• Candidiasis

What are the problems associated with pathogenic fungi?

• Mycoses

• Mycotoxicosis

• Allergic reactions

Mycoses

Infection of body tissues

Mycotoxicoses

Fungi secondary metabolizes toxin

Example of mycoses

• Ringworm (tinea infections)

• Candida albicans (vaginitis)

• Cryptococcus neoformans (meningitis)

Example of mycotoxins

• Aflatoxins

• Fumonisins

What do fungal mycoses produce?

Keratinase—- degrades keratin in skin, nails, & hair

Tinea infections

• Trichophyton mentagrophyte

• Microsporum canis (major cause of ringworm)

• Epidermophyton floccosum (Athletes foot)

Definitive host

Protozoa using a host to reach maturity & reproductive stage

Intermediate host

Protozoa using a host but stays in a developmental stage

What are the 2 forms that protozoa take?

Cysts & trophzoite

Describe cysts

• Forms an endospore

• Survivor structure laying dormant

Describe trophzoites

• Protozoa in a vegetative state

• Unable to multiply

Protozoan reproduction

• Fission

• Budding

• Schizogony

What is schizogony?

Multiple fission of nucleus without dividing the cytoplasm

Giardia lamblia

• Infects intestines

• Giardiasis (beaver fever)

Trichomonas vaginalis

• STI

• Parasitic protozoan

• No cyst stage

• Most common pathogenic protozoan

Toxoplasma gondii in cats

• Definitive hosts

• Releases sporozoites > tachyzoites

Toxoplasma gondii in warm-blooded animals

• Intermediate hosts

• Tachyzoites > bradyzoites

What are plasmodiums

Obligate parasites to insects

Example of a plasmodium

Malaria

What is the definitive host of malaria?

Mosquitos

What are the intermediate hosts of malaria?

Humans

Characteristics of pathogenic helminths

• Reduced/lack of GI

• Reduced nervous system

• Reduced locomotion

• Differing reproduction

Diocious

Pathogenic helminths separated to male & female

Monoecious

Pathogenic helminths containing both male & female reproductive organs

Describe tapeworms

• Lives in the oral-fecal route

• Eggs in the feces ingested by other animals

• Attaches to the wall of intestines with hooks

Examples of tapeworms

• Taenia saginata (beef)

• Taenia solium (pork)

• Diphyllobothrium latum (fish)

Example of roundworms

Trichinosis spiralis

What are trichinosis

Roundworms—- eating undercooked meat with the larvae of a roundworm