Fungi characteristics

• Chapter 12 focuses on eukaryotes like fungi, algae, protozoa, and helminths.

Fungi Characteristics

• Fungi are important recyclers, breaking down organic material and releasing carbon, oxygen, nitrogen, and phosphorus.
• Fungi establish symbiotic relationships with plants, providing the plant with nutrients and receiving sugars in return.
• Several types of foods production relies on fungi, including beer, wine, cheese, and bread.
• Fungi can benefit herbivores, aiding in the digestion of high-fiber foods in cattle, sheep, and goats.
• Some fungi produce antibiotics like penicillin and cephalosporins, and other substances used to lower cholesterol and prevent transplant rejection.
• Fungi are utilized in the production of plastics, synthetics, clothing, skincare products, and packing materials.
• Spiritual and religious ceremonies use them.
• Fungi store 8 times more carbon which enriches soil, and stabilizes it from erosion.
• The fungal thallus, or body, is composed of hyphae filaments; a mass of hyphae is called a mycelium.
• Septate hyphae contain cross-walls, while coenocytic hyphae do not contain septa.
• Vegetative hyphae get nutrients, and aerial hyphae aid reproduction.
• Budding yeasts divide unevenly, whereas fission yeasts divide evenly.
• Dimorphic fungi are yeastlike at 37°C and moldlike at 25°C.
• Asexual reproduction results in spores via mitosis and cell division using:
• Conidiospores (not enclosed in a sac).
• Arthroconidia (fragmentation of septate hyphae).
• Blastoconidia (buds of the parent cell).
• Chlamydoconidium (a spore within a hyphal segment).
• Sporangiospores (enclosed in a sac).
• Sexual reproduction begins with the fusion of nuclei from two opposite mating strains.
• The three phases of sexual reproduction are:
• Plasmogamy is when a haploid donor cell nucleus (+) enters a recipient cell (-).
• Karyogamy is when + and - nuclei fuse, forming a diploid zygote.
• Meiosis is when a diploid nucleus produces haploid nuclei (sexual spores).
• Fungi grow better at a pH of 5 and they require oxic/anoxic conditions
• Most molds are aerobic, while most yeasts are facultative anaerobes.
• Fungi can grow with high sugar and salt concentrations which are resistant to osmotic pressure, and in low moisture content.
• They require less nitrogen than bacteria, they metabolize complex carbohydrates, and their cell walls contain chitin.

Medically Important Fungi

• Include the phyla Mucoromycota, Microsporidia, Ascomycota, and Basidiomycota.

Mucoromycota

• Includes conjugation fungi with coenocytic hyphae, which reproduce asexually via sporangiospores.
• It sexually reproduces via zygospores, which form when the nuclei of two similar cells fuse.
• Rhizopus stolonifer is an example (common black bread mold).

Microsporidia

• Does not undergo sexual reproduction in its host, it lacks mitochondria, and it acts as an obligate intracellular parasite.
• Diseases caused by microsporidia include chronic diarrhea and keratoconjunctivitis.

Ascomycota

• Includes sac fungi with septate hyphae that produce both sexual and asexual spores.
• Some Ascomycota are anamorphic, having lost the ability to sexually reproduce.
• It reproduces asexually via conidiospores.
• Sexually reproduces via ascospores, where nuclei, whether similar or dissimilar morphologically, fuse in a saclike ascus.

Basidiomycota

• Includes club fungi with septate hyphae that reproduce asexually via conidiospores.
• Sexually reproduces via basidiospores, which form externally on a base pedestal called a basidium.

Fungal Diseases

• Mycosis is any fungal infection. The five types of mycoses are:
• Systemic mycoses affect the number of tissues and organs located deep within the body.
• Subcutaneous mycoses occur beneath the skin.
• Cutaneous mycoses affect hair, skin, and nails, also known as dermatomycoses.
• Superficial mycoses are localized, affecting sections, such as localized hair shafts.
• Opportunistic mycoses are caused by fungi that are harmless in their normal habitat but pathogenic in a compromised host.
• Aspergillus niger which is used for the production of citric acid.
• Aspergillus terreus produces statins that inhibit cholesterol synthesis.
• Saccharomyces cerevisiae is used to produce bread, wine, and hepatitis B vaccine.
• Trichoderma produces cellulase.
• Taxomyces produces taxol.
• Tolypocladium inflatum produces cyclosporine.
• Coniothyrium minitans kills fungi on crops.
• Paecilomyces kills termites.

Algae

• Algae are unicellular or filamentous photoautotrophs that lack roots, stems, and leaves.
• Algae depend on nutrient availability, wavelengths of light, and surfaces to attach.
• The multicellular algae body is made up of the thallus.
• Thallus consists of holdfasts, stipes, and blades.
• Cells covering the thallus photosynthesize and absorb water over the entire surface.
• Pneumocyst's floating gas-filled bladder produces buoyancy.
• Reproduction can occur asexually and sexually via fragmentation with alternation of generations.
• Algae are photosynthetic except for the chemoheterotrophic oomycotes.
• Found through bodies of water, chlorophyll a and accessory pigments are responsible for distinctive colors of algae.
• Brown algae, such as kelp have cells walls made from cellulose and alginic acid that create multicellular and macroscopic bodies.
• Can reach lengths of 50 meters and produce algin, which is used for thickening food.
• Red Algae have branches, they are multicellular, are able to live at greater depths, and harvested for agar and carrageenan, and some can produce a lethal toxin.
• Green Algae has is cellulose cell ways, can be unicellular or multicellular, has chlorophyll A and b, stores starch, and gave rise to terresterial plants.
• Euglenoids are photoautotrophs with euglenozoa. They have an eyespt and flagellum to seek out light.
• Diatoms cell walls are made of of Pectin and silica, are unicelluar or filamentous, store oil, and produce domoic acid which can cause neurological disease.
• Dinoflagellates have a cellluso membrane, unicelluar, are a component of plankton, and neurotoxins (saxitoxins) can cause paralytic shellfish posioning.
• Oomycota (water molds) has cellulose cell walls, chemoherterophic, produces zoospores, related closely to diatoms and dinoflagellates than to fungi, they are decomposers and plant parasites.
• Fix CO2 into organic molecules, produce 80% of earth O2, algal blooms are increases in planktonic algae can can cause toxin release or death and oxygen depletion, oil production, symbionts of animals

Protozoa

• Are unicellular eukaryotes that inhabit water and soil.
• There are over 50,000 species where some are normal microbiota in animals and some cause disease.
• They have animal-like nutrition and complex life cycles.
• The feeding and growing form is a trophozoite.
• Asexual reproduction occurs by fission, budding, or schizogony (multiple fission).
• Sexual reproduction occurs through conjugation, and some species produce a cyst to survive adverse conditions.
• Protozoa require a large supply of water.
• Many have an outer protective pellicle, with cilia and cytosomes for prey capture and with processes for phagocytizing food with amebae.
• Food is digested in vacuoles and wastes are eliminated, throught an anal pore.
• Medically important protozoa include feeding grooves (Excavata), Amoebozoa (Ameba), Apicomplexa, and Ciliates.
• Feeding grooves (Excavata): move using flagella and have undulating membrane.
• Diplomonads is the feeding groove (Excavata) and contains Giardia intestinalis.
• Parabasalids feeding groove (Excavata) with Trichomonas vaginalis
• Amoebozoa (Ameba): Moves with means of pseudopods.
• Apicomplexa are nonmotile obligate intracellular parasites.
• Ciliates moves my means of cilia.
• Diplomondas have to mitochondria but multiple flagealla.
• Paralbasilads - Undulating membrane, no cyst stage.
• Euglenozoa which are photoautotrophs or facultative chemotrophs.
• hemoflagellates through bites of blood-feeding insects.
• Amoebae extend pseudopods:
• Entamoeba histolytica causes amebic dysentery.
• Acanthamoeba infects corneas, causes meningitis/encephalitis.
• Balamuthia causes granulomatous amebic encephalitis.

Apicomplexa

• Are nonmotile with complex life cycles, and includes these species:
• Toxoplasma gondii transmitted by cats causing fetal infection.
• Cryptosporidium is transmitted via feces and causes waterborne illness.
• Plasmodium causes malaria that sexually reproduces in the Anopheles mosquito.

Helminths

• These are parasitic worms.
• The two phyla are Platyhelminthes (flatworms) and Nematoda (roundworms).
• They are multicellular eukaryotic animals that are specialized to live in hosts. They may lack digestive system, reduce nervous systems, and reduced/lacking motion.
• They are Dioecious; with separate male and female. Monoecious (hermaphroditic) is with male and female reproductive systems in one animal.

Platyhelminths

• These are flatworms such as Trematodes (flukes)
• Flat, leaf-shaped
• Ventral and oral sucker
• Absorb food through cuticle covering
• Paragonimus spp lung fluke
• Schistosoma-blood fluke
• General Charateristics of Adult Tapeworm
• Scolex, neck, hooks/suckers
• Scolexhead that has suckers for attachment. Absorb food through cuticle.
• Proglottids body segments; contain male and female reproductive organs.
• Eggfrom Proglottids ingested, hatch into larvae, and bore into the intestinal wall.
• Produce cysticerci.
• Taenia solium pork tapeworm.
• Humans harbor larval forms, ingesting eggs that hatch.
• Larvae migrate to the liver or lungs and develop a hydatid cyst.
• Echinococcus granulosus

Nematodes

• These are roundworms with a complete digestive system. They are cylindrical in shape, and contain spicules. Includes free-living and parasitic species.
• In eggs, are infective to humans:
• Ascaris lumbricoides infects human intestines.
• Baylisascaris procyonis raccoon roundworm.
• Trichuris trichiura whipworm.
• Enterobius vermicularis pinworm.
• Larvae are infective for humans:
• Strongyloides reemerging infection.
• Necator americanus and Ancylostoma duodenale hookworms; enter the skin and are carried to the intestines.
• Dirofilaria immitis spreads by mosquitoes and causes heartworm.

Arthropods as Vectors

• These are animals with segmented bodies, hard external skeletons, and jointed legs. Vectors are the arthropods that carry pathogenic microorganisms.
• Three Classes: Arachnida –eight legs(spiders, mites, ticks).
• Crustacea fourantennae(crabs, crayfish).
• Insecta – sixlegs(beesfls,quitos,lice).
• Mechanical transmission
• Biological transmission happens when a pathogen multiplies the vector.
• Definitive host occurs, which is when Microbe's sexual reproduction takes place in the vector.