Microbiology: An Introduction, Chapter 12 PDF

Microbiology: An Introduction Fourteenth Edition Chapter 12 The Eukaryotes: Fungi, Algae, Protozoa, and Helminths Copyright © 202...

Microbiology: An Introduction Fourteenth Edition Chapter 12 The Eukaryotes: Fungi, Algae, Protozoa, and Helminths Copyright © 2024 Pearson Education, Inc. All Rights Reserved Fungi Learning Objectives  List the defining characteristics of fungi.  Differentiate asexual from sexual reproduction, and describe each of these processes in fungi.  List defining characteristics of the four medically important phyla of fungi.  Identify two beneficial and two harmful effects of fungi. Reasons fungi are important  Earth’sbiggest recyclers Fungi make things rot, making space and nutrients for the rest of the living wor  They break down organic material, releasing carbon, oxygen, nitrogen, and ph  Symbiotic relationships with plants Fungi get sugars from plants, and the plant gets nutrients that are available in  important in the food industry They help make the stuff we like, like beer, wine, cheese, bread, yogurt, and m  beneficial to herbivores Found in the gut of cattle, sheep, and goats. High-fiber foods can be challengin Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Source of antibiotics. Penicillin, cephalosporins, cholesterol meds and cyclosporine which make organ transplants possible. These are just a few.  Many industrial uses They are being used in products such as plastics or synthetics. Also found in products that include clothing, skincare products, shoes, packing material and many more.  Used in spiritual and religious ceremonies Fungi are widely known for spiritual or sacred associations and play key roles in rituals, and ceremonies.  Provide a major carbon storage center Vast underground network stores 8 times more carbon compared to other vegetation. Makes soil richer and more stable from erosion. Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Characteristics of Fungi Molds and fleshy fungi – The fungal thallus (body) consists of hyphae filaments; a mass of hyphae is a mycelium – Septate hyphae: contain cross-walls – Coenocytic hyphae: do not contain septa – Vegetative hyphae obtain nutrients while aerial hyphae are involved with Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-3 Fungal Thallus Consists of a Mass of Hyphae For Long description, see slide 114: Appendix 2 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Characteristics of Fungi Vegetative Structures Yeasts – Nonfilamentous and unicellular – Budding yeasts divide unevenly – Fission yeasts divide evenly Dimorphic fungi Yeastlike at 37 C and moldlike at 25 C Copyright © 2024 Pearson Education, Inc. All Rights Reserved Life Cycle Fungi reproduce sexually and asexually via the formation of spores that detach from the parent and germinate into a new mold Asexual spores – Produced via mitosis and cell division; formed by the hyphae of one organism – Conidiospore: not enclosed in a sac – Arthroconidia: fragmentation of septate hyphae – Blastoconidia: buds of the parent cell – Chlamydoconidium: spore within a hyphal segment – Sporangiospore: enclosed in a sac Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-6 Representative Asexual Spores For Long description, see slide 117: Appendix 5 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Life Cycle Sexual spores – Fusion of nuclei from two opposite mating strains – Three phases of sexual reproduction: ▪ Plasmogamy: haploid donor cell nucleus (+) penetrates cytoplasm of recipient cell (  ) ▪ Karyogamy: + and  nuclei fuse and form diploid zygote ▪ Meiosis: diploid nucleus produces haploid nuclei (sexual spores) Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Environmental and Nutritional Adaptations Grow better at pH of 5 Oxic/anoxic requirements – Most molds are aerobic – Most yeasts are facultative anaerobes Grow in high sugar and salt concentration; resistant to osmotic pressure Can grow in low moisture content Fungi require less nitrogen than bacteria Can metabolize complex carbohydrates Cell walls contain chitin Copyright © 2024 Pearson Education, Inc. All Rights Reserved Check Your Understanding-1 Check Your Understanding 12-1 Assume you isolated a single-celled organism that has a cell wall. How would you determine that it is a fungus and not a bacterium? 12-2 Contrast the mechanism of sexual and asexual spore formation. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Medically Important Fungi Phyla: Mucoromycota Microsporidia Ascomycota Basidiomycota Copyright © 2024 Pearson Education, Inc. All Rights Reserved Mucoromycota Conjugation fungi Coenocytic hyphae Produced asexually: sporangiospore Produced sexually: zygospore – Forms when nuclei of two similar cells fuse Example – Rhizopus stolonifer (common black bread mold) Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-7 The Life Cycle of Rhizopus, a Mucoromycete For Long description, see slide 118: Appendix 6 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Microsporidia No sexual reproduction is observed, but probably occurs in a host No mitochondria Obligate intracellular parasites Some diseases caused by microsporidia: – chronic diarrhea – keratoconjunctivitis Copyright © 2024 Pearson Education, Inc. All Rights Reserved Ascomycota Sac fungi; septate hyphae Produce sexual and asexual spores Some are anamorphic – Lost ability to sexually reproduce Produced asexually: conidiospore Produced sexually: ascospore – Nuclei morphologically similar or dissimilar fuse in a saclike ascus Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-9 The Life Cycle of Penicillium, an Ascomycete For Long description, see slide 120: Appendix 8 (1 of 3) Copyright © 2024 Pearson Education, Inc. All Rights Reserved Basidiomycota Club fungi; septate hyphae Produced asexually: conidiospores Produced sexually: basidiospores – Formed externally on a base pedestal called a basidium Copyright © 2024 Pearson Education, Inc. All Rights Reserved Fungal Diseases Mycosis: fungal infection Five different types of mycoses: – Systemic mycoses: deep within the body, affect a number of tissues and organs – Subcutaneous mycoses: beneath the skin – Cutaneous mycoses: affect hair, skin, and nails ▪ Also known as dermatomycoses – Superficial mycoses: localized (e.g., hair shafts) – Opportunistic mycoses: fungi harmless in normal habitat but pathogenic in a compromised host Copyright © 2024 Pearson Education, Inc. All Rights Reserved Table 12-2 Characteristics of Some Pathogenic Fungi (1 of 4) Phylum Growth Asexual Spore Human Habitat Type of Mycosis Characteristics Types Pathogens Mucoromycota Coenocytic Sporangiospores Rhizopus Ubiquitous Systemic (Nonseptate Mucor Ubiquitous Systemic hyphae) Microsporidia No hyphae Nonmotile Encephalitozoon Humans, other Diarrhea spores Nosema animals keratoconjunctivitis Copyright © 2024 Pearson Education, Inc. All Rights Reserved Table 12-2 Characteristics of Some Pathogenic Fungi (3 of 4) Phylum Growth Asexual Spore Human Pathogens Habitat Type of Mycosis Characteristics Types Ascomycota Yeastlike, Chlamydoconidia Candida albicans Humans Cutaneous, pseudohyphae , blastoconidia mucocutaneous, systemic Ascomycota Unicellular Chlamydoconidia C. auris Humans Bloodstream infections None Pneumocystis Human lungs Pneumonia Copyright © 2024 Pearson Education, Inc. All Rights Reserved Economic Effects of Fungi Aspergillus niger: production of citric acid Aspergillus terreus: statins that inhibit cholesterol synthesis Saccharomyces cerevisiae: bread, wine, hepatitis B vaccine Trichoderma: cellulase Taxomyces: taxol Tolypocladium inflatum: cyclosporine Coniothyrium minitans: kills fungi on crops Paecilomyces: kills termites Copyright © 2024 Pearson Education, Inc. All Rights Reserved Economic Effects of Fungi Aspergillus niger: production of citric acid Aspergillus terreus: statins that inhibit cholesterol synthesis Saccharomyces cerevisiae: bread, wine, hepatitis B vaccine Trichoderma: cellulase Taxomyces: taxol Tolypocladium inflatum: cyclosporine Coniothyrium minitans: kills fungi on crops Paecilomyces: kills termites Copyright © 2024 Pearson Education, Inc. All Rights Reserved Check Your Understanding-2 Check Your Understanding 12-3 List the asexual and sexual spores made by mucoromycetes, ascomycetes, and basidiomycetes. 12-4 Why are microsporidia classified as fungi? 12-4 Are yeasts beneficial or harmful? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Algae Learning Objectives 12-7 List the defining characteristics of algae. 12-8 List the outstanding characteristics of the phyla that include algae discussed in this chapter. 12-9 Identify two beneficial and two harmful effects of algae. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Algae Not a taxonomic group Unicellular or filamentous photoautotrophs Lack roots, stems, and leaves Mostly aquatic – Water is necessary for growth and reproduction Copyright © 2024 Pearson Education, Inc. All Rights Reserved Characteristics of Algae Locations depend on nutrient availability, wavelengths of light, and surfaces to attach Vegetative structures – Thallus: body of multicellular algae ▪ Consists of holdfasts, stipes, and blades ▪ Cells covering thallus do photosynthesis ▪ Absorb nutrients or water over entire surface – Pneumocyst: floating gas filled bladder provides buoyancy Copyright © 2024 Pearson Education, Inc. All Rights Reserved Characteristics of Algae Life cycle – All can reproduce asexually – Multicellular algae can fragment or reproduce sexually via alternation of generations Nutrition – Most algae are photosynthetic ▪ Found throughout photic zone in bodies of water ▪ Chlorophyll a and accessory pigments are responsible for distinctive colors of algae – Oomycotes: chemoheterotrophic Copyright © 2024 Pearson Education, Inc. All Rights Reserved Selected Phyla of Algae Brown algae (kelp) – Cellulose and alginic acid cell walls – Multicellular and macroscopic ▪ Can reach lengths of 50 meters – Produce algin—thickener used in foods Copyright © 2024 Pearson Education, Inc. All Rights Reserved Selected Phyla of Algae Red algae – Have branched thalli – Most are multicellular – Able to live at greater depths than other algae – Harvested for agar and carrageenan – Some produce a lethal toxin Copyright © 2024 Pearson Education, Inc. All Rights Reserved Selected Phyla of Algae Green algae – Cellulose cell walls – Unicellular or multicellular – Chlorophyll a and b – Store starch – Gave rise to terrestrial plants Copyright © 2024 Pearson Education, Inc. All Rights Reserved Selected Phyla of Algae Euglenoids – Photoautotrophs in the Euglenozoa ▪ Have an eyespot and flagellum to seek out light Diatoms – Pectin and silica cell walls – Unicellular or filamentous – Store oil – Produce domoic acid—cause neurological disease Copyright © 2024 Pearson Education, Inc. All Rights Reserved Selected Phyla of Algae Dinoflagellates – Cellulose in plasma membrane – Unicellular – Component of plankton (large group of free-floating aquatic organisms) – Neurotoxins (saxitoxins) cause paralytic shellfish poisoning Copyright © 2024 Pearson Education, Inc. All Rights Reserved Selected Phyla of Algae Oomycota (water molds) – Cellulose cell walls – Chemoheterotrophic – Produce zoospores – More closely related to diatoms and dinoflagellates than to fungi – Decomposers and plant parasites ▪ Phytophthora infestans was responsible for Irish potato blight ▪ P. cinnamoni infects eucalyptus ▪ P. ramorum causes “sudden oak death” Copyright © 2024 Pearson Education, Inc. All Rights Reserved Roles of Algae in Nature Fix CO2 into organic molecules Produce 80% of Earth’s O2 Algal blooms are increases in planktonic algae that can result in toxin release or die and consume oxygen Oil production Symbionts of animals Copyright © 2024 Pearson Education, Inc. All Rights Reserved Check Your Understanding Check Your Understanding 12-7 How do algae differ from bacteria? From fungi? 12-8, 12-9 List the cell wall composition and diseases caused by the following algae: diatoms, dinoflagellates, oomycotes. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Protozoa Learning Objectives 12-10 List the defining characteristics of protozoa. 12-11 Describe the outstanding characteristics of the phyla of protozoa discussed in this chapter and give an example of each. 12-12 Differentiate an intermediate host from a definitive host. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Protozoa Unicellular eukaryotes Inhabit water and soil Over 50,000 species – Some are normal microbiota in animals – Some cause disease in humans and animals ▪ Plasmodium species: cause malaria Animal-like nutrition Complex life cycles Copyright © 2024 Pearson Education, Inc. All Rights Reserved Protozoa Life cycle Feeding and growing form is a trophozoite Asexual reproduction is by fission, budding, or schizogony (multiple fission) Sexual reproduction is by conjugation Some produce a cyst to survive adverse conditions Copyright © 2024 Pearson Education, Inc. All Rights Reserved Characteristics of Protozoa Require a large supply of water Many have an outer protective pellicle, requiring specialized structures to take in food – Ciliates wave cilia toward mouthlike cytosome – Amebae phagocytize food Food is digested in vacuoles and wastes eliminated through an anal pore Copyright © 2024 Pearson Education, Inc. All Rights Reserved Medically Important Protozoa Feeding grooves (Excavata) – Move by means of flagella and undulating membrane ▪ Diplomonads (Giardia intestinalis) ▪ Parabasalids (Trichomonas vaginalis) ▪ Euglenozoa (Trypanosoma spp) Amoebozoa (Ameba) – Move by means of pseudopods Apicomplexa – Nonmotile, obligate intracellular parasites Ciliates – Move by means of cilia Copyright © 2024 Pearson Education, Inc. All Rights Reserved Medically Important Protozoa Diplomonads – No mitochondria; multiple flagella Parabasalids – Undulating membrane; no cyst stage Euglenozoa – Photoautotrophs or facultative chemotrophs – Hemoflagellates—transmitted by bites of blood- feeding insects Copyright © 2024 Pearson Education, Inc. All Rights Reserved Amebae Move by extending pseudopods Entamoeba histolytica—causes amebic dysentery Acanthamoeba—infects corneas and causes blindness, may infect brain (encephalitis) Balamuthia—granulomatous amebic encephalitis Copyright © 2024 Pearson Education, Inc. All Rights Reserved Apicomplexa Nonmotile Obligate intracellular parasites Complex life cycles Toxoplasma gondii—transmitted by cats; causes fetal infections Cryptosporidium—transmitted via feces; causes waterborne illness Copyright © 2024 Pearson Education, Inc. All Rights Reserved Apicomplexa Plasmodium—causes malaria – Sexually reproduces in the Anopheles mosquito – A mosquito injects a sporozoite into its bite, and the sporozoite undergoes schizogony in the liver; merozoites are produced – Merozoites infect red blood cells, forming a ring stage inside the cell – Red blood cells rupture, and merozoites infect new red blood cells Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-20 Life Cycle of Plasmodium vivax For Long description, see slide 140: Appendix 24 The Life Cycle of Plasmodium Vivax, the Apicomplexan that Causes Malaria. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Check Your Understanding Check Your Understanding 12-10 Identify three differences between protozoa and animals. 12-11 Do protozoa have mitochondria? 12-12 Where does Plasmodium undergo sexual reproduction? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Helminths Learning Objectives 12-14 List the distinguishing characteristics of parasitic helminths. 12-15 Provide a rationale for the elaborate life cycle of parasitic worms. 12-16 List the characteristics of the two classes of parasitic platyhelminths, and give an example of each. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Helminths Learning Objectives 12-17 Describe a parasitic infection in which humans serve as a definitive host, as an intermediate host, and as both. 12-18 List the characteristics of parasitic nematodes, and give an example of infective eggs and infective larvae. 12-19 Compare and contrast platyhelminths and nematodes. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Helminths Parasitic worms Two phyla: – Platyhelminthes (flatworms) – Nematoda (roundworms) Copyright © 2024 Pearson Education, Inc. All Rights Reserved Characteristics of Helminths Multicellular eukaryotic animals Specialized to live in hosts – May lack digestive system – Reduced nervous system – Reduced or lacking locomotion – Complex reproductive system Copyright © 2024 Pearson Education, Inc. All Rights Reserved Life Cycle Dioecious – Separate male and female Monoecious (hermaphroditic) – Male and female reproductive systems in one animal Egg larva e  adult Copyright © 2024 Pearson Education, Inc. All Rights Reserved Check Your Understanding Check Your Understanding 12-14 Why are drugs for parasitic helminths often toxic to the host? 12-15 Of what value is the complicated life cycle of parasitic helminths? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Platyhelminths Trematodes (flukes) – Flat, leaf-shaped – Ventral and oral sucker – Absorb food through cuticle covering – Paragonimus spp.—lung fluke – Schistosoma—blood fluke Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-25 Flukes For Long description, see slide 144: Appendix 28 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-26 The Life Cycle of the Lung Fluke, Paragonimus spp For Long description, see slide 145: Appendix 29 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Platyhelminths Cestodes (tapeworms) – Scolex—head that has suckers for attachment – Absorb food through cuticle – Proglottids—body segments; contain male and female reproductive organs Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-27 General Anatomy of an Adult Tapeworm For Long description, see slide 146: Appendix 30 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Cestodes Humans as definitive hosts (harbor the adult, sexually reproducing worms) – Eggs from proglottids are ingested, hatch into larvae, and bore into the intestinal wall – Produce cysticerci – Taenia solium—pork tapeworm Copyright © 2024 Pearson Education, Inc. All Rights Reserved Cestodes Humans as intermediate hosts (harbor larval forms) – Eggs are ingested and hatch in the intestine – Larvae migrate to the liver or lungs and develop a hydatid cyst – Echinococcus granulosus Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-28 The Life Cycle of the Tapeworm, Echinococcus For Long description, see slide 147: Appendix 31 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Check Your Understanding Check Your Understanding 12-16 Differentiate Paragonimus and Taenia. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nematodes Roundworms – Cylindrical; complete digestive system – Dioecious; males contain spicules – Free-living species and parasitic species Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nematodes Eggs infective for humans – Ascaris lumbricoides—infects human intestines – Baylisascaris procyonis—raccoon roundworm – Trichuris trichiura—whipworm – Enterobius vermicularis—pinworm Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-29 The Pinworm, Enterobius vermicularis For Long description, see slide 148: Appendix 32 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nematodes Larvae infective for humans – Strongyloides—reemerging infection – Necator americanus and Ancylostoma duodenale —hookworms; enter the skin and are carried to the intestines – Dirofilaria immitis—spread by mosquitoes; causes heartworm Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-30 The Heartworm, Dirofilaria immitis Copyright © 2024 Pearson Education, Inc. All Rights Reserved Check Your Understanding Check Your Understanding 12-17 What is the definitive host for Enterobius? 12-18 What stage of Dirofilaria immitis is infectious for dogs and cats? 12-19 You find a parasitic worm in a baby’s diapers. How would you know whether it’s a Taenia or a Necator? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Arthropods as Vectors Learning Objectives 12-20 Define and identify arthropod vectors. 12-21 Differentiate a tick from a mosquito, and name a disease transmitted by each. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Arthropods as Vectors Arthropods are animals with segmented bodies, hard external skeletons, and jointed legs Vectors are arthropods that carry pathogenic microorganisms Representative classes: – Arachnida—eight legs (spiders, mites, ticks) – Crustacea—four antennae (crabs, crayfish) – Insecta—six legs (bees, flies, mosquitos, lice) Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-31 Blood-Sucking Mosquitoes and Ticks Copyright © 2024 Pearson Education, Inc. All Rights Reserved Figure 12-32 Arthropod Vectors For Long description, see slide 149: Appendix 33 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Arthropods as Vectors Mechanical transmission Biological transmission – Pathogen multiplies in the vector Definitive host – Microbe’s sexual reproduction takes place in the vector Copyright © 2024 Pearson Education, Inc. All Rights Reserved