Microbial Diversity - 2 Chapters PDF

Basic Comparison of Microbes  Microbe Categories Cellular Acellular Prokaryotes Viruses – Bacteria Prions – Archaeans Eukaryotes – Certain algae – Certain fungi – Protozoa Acellular Microbes Viruses Virus es Doesn’t belong...

Basic Comparison of Microbes  Microbe Categories Cellular Acellular Prokaryotes Viruses – Bacteria Prions – Archaeans Eukaryotes – Certain algae – Certain fungi – Protozoa Acellular Microbes Viruses Virus es Doesn’t belong to any kingdom -It’s not a plant or an animal. -It’s not a fungi, protist, or bacteria. A virus is an infectious agent made up of nucleic acid (DNA or RNA) a protein wrapped in coat called a capsid. Bacterioph Influenza age (Flu) DNA = Genetic material = RNA Tail sheath Capsid (Protein Coat) Envelope Tail (Lipids & fiber Glycoproteins)  Viruses vs. Cells (structure) v DNA or RNA Capsid (protein coat) s. DNA and RNA Organelles No organelles Cytoplasm No cytoplasm  Are viruses alive? Made of one or more Non-cellular - NOT cells? Grow and develop? No organisms Eat for energy? No Metabolize nutrients? No Respond to stimuli? No Maintain No homeostasis? Adapt to Yes – viruses can environment? mutate (change). (change over Reproduce?Yes time)Ex. Influenza-new vaccine every year Reproduce on their No – need a own? share some characteristics Viruses host. of living things, but need to meet all  How many characteristics of life do viruses TWO possess? *Genetic Material *Change over time Are viruses living? N  Viruses are parasites What is a parasite? Parasite is an organism that depends entirely upon another living organism (a host) for its existence in such a way that it harms that organism. Ex. A flea is a parasite to a dog and is harmful to the dog.  Viruses are parasites Viruses must have a living host to reproduce. Viruses hijack a living cell’s machinery and use it to reproduce more virus particles. 5 Properties that distinguish viruses from living cells DNA or RNA only Unable to replicate on their own Do not divide by mitosis, meiosis or binary fussion Lack the genes and enzymes for energy production Depend on host cell  Classification Type of genetic material (DNA or RNA) Shape of the capsid Number of capsomeres Size of the capsid Presence or absence of an envelope Type of host it infects Type of disease it produces Target cell Immunologic or antigenic properties Lytic vs. Lysogenic Cycles  LYTIC CYCLE Viral DNA is Viral DNA is injected into cell. Virus copied & Bacterial DNA is attaches to viral parts destroyed. Step Step cell. Step are made. 2 3 1 Viral parts Cell bursts are (lyses) and assembled releases new Step Step viruses. 4 5 Viruses spread.  LYTIC CYCLE A virus CANNOT reproduce by itself—it must invade a host cell and take over the cell activities, eventually causing destruction of the cell and killing it. (The virus enters a cell, makes copies of itself and causes the cell to burst releasing more viruses.) LYSOGENIC CYCLE Some viruses like HIV do NOT go straight into the lytic cycle. These viruses enter a long (dormant) period - between an infection and the onset off disease. = prophage (viral DNA)  LYSOGENIC CYCLE Virus enters a long (dormant) period between an infection and the onset off disease. Viral genetic material (DNA) incorporates into a host’s DNA and called a prophage. Virus replicates its genetic material without destroying the host. Every time the host divides, it copies the viral DNA and passes the copies. Various factors such as UV light can trigger a virus to enter the LYTIC CYCLE  cell bursts  Lytic vs. Lysogenic Cycles Lytic Lysogenic Rapid: Causes Long period between disease right away infection and onset off Ex. Influenza disease (dormant period). Ex. HIV Does NOT involve integration of viral Involves integration of genetic material into viral genetic material the host genetic into the host’s genetic material. material forming a prophage. Result in host Eventually enters the destruction: Lytic Cycle and host cell Bacteria Taxonomy and Classification Traditional Cell wall – 23 phyla characteristics – 32 classes – Gram positive – 5 subclasses – Gram negative – 77 orders – Cell-wall less – 14 suborders – 182 families – 871 genera – 5,007 species  Bacterial Characteristics Morphology Nutritional – Cellular morphology requirements – Colonial Metabolism morphology Pathogenicity Motility Genetics Atmospheric requirements  Morphology Basic shapes and arrangement: – Coccus (pl. cocci) Singly, diplococci, streptococci, staphylococci, tetrads and octads – Bacillus (pl. bacilli) Singly, diplobacilli, streptobacilli and palisades Coccobacilli – Spirillum (pl. spirilla) – Pleomorphic Cocci Bacilli Spirilla  Colonial Morphology Bacterial colony – Mound or pile of bacteria – Millions of cells Size, color, shape, elevation and appearance of the margin Generation time Generation Time and Microbial Growth Curve  Motility Flagella or axial filaments Gram negative bacteria Determined by: – Turbidity in semisolid medium – Hanging-drop preparation  Atmospheric Requirements Oxygen requirements – Obligate aerobes (20 to 21% O2) – Microaerophiles (5% O2) – Anaerobes Obligate Aerotolerant – grow better anaerobically but survive in the presence of O2 Facultative – grow regardless of atmospheric O2 conditions  Atmospheric Requirements Carbon dioxide requirements – Capnophiles: 5 to 10% CO2 – Capnophilic anaerobes Bacteroides and Fusobacterium species – Capnophilic aerobes Neisseria, Campylobacter and Haemophilus species  Nutritional Requirements Basic elements Fastidious – – Carbon, hydrogen, microbes having oxygen, sulfur, special nutritional phosphorus and nitrogen needs Special elements Examples: – Potassium, calcium, – Neisseria spp. iron, manganese, – Haemophilus spp. magnesium, cobalt, copper, zinc and uranium Vitamins  Metabolism Specific enzymes – Catalase – Urease  Pathogenicity Ability to cause disease Factors: – Capsules, pili, or endotoxins, exotoxins and enzymes  Atypical Bacteria AKA “unique” or “rudimentary” bacteria – Rickettsias, chlamydias and closely related bacteria Gram negative, obligate intracellular pathogens In vitro culture requires embryonated chicken eggs. – Mycoplasmas Cell-wall less Archaea Taxonomy and Classification Traditional Previously referred – 2 phyla to as – 8 classes archaeobacteria or – 12 orders ancient bacteria – 21 families Cocci, bacilli or – 69 genera long filaments – 217 species Majority are extremophiles Live at ocean bottom, geysers and hot springs  Characteristics pH – Acidophiles and alkaliphiles Temperature – Thermophiles and psychrophiles Salinity – Halophiles Atmospheric pressure – Piezophiles (formerly barophiles) Plant-like Protists : Unicellular Algae Algae – plant-like protists that perform photosynthesis. A. Characteristics of Algae 1. Algae contain chlorophyll in their chloroplasts to produce food & O2 through photosynthesis. Photosynthesis – the process by which autotrophs convert sunlight into a usable form of energy. 2. Have no specialized tissues/organs. 3. Are classified based on differences in structure & type of pigments that they contain. 4. Can be unicellular or multicellular. 7 major groups of plant-like protists : 1. Euglenophy tes 2. Chrysophyt es 3. Diatoms 4. Dinoflagella tes 5. Red algae Unicellular algae include : 1. Euglenophytes (Euglenophyta) plant-like protists that have 2 flagella but no cell wall Ex, Euglena. -Have characteristics of both plants & animals. Plant-like characteristics include : -Photosynthetic pigments Animal-like characteristics  Characteristics of Euglena : 1. Are single-celled. 2. Have 2 flagella : A. Large one for movement. B. Small one that is inactive. 3. Have a large central nucleus. 4. Are primarily photosynthetic but  Chrysophytes 2. Chrysophytes (Chrysophyta) – the diverse group of plant- like protists that have gold-colored chloroplasts. -Chrysophyta means “golden plants”. Chrysophyta includes : a. Yellow-green algae b. Golden-brown algae -Cell walls sometimes contain pectin instead of cellulose. -Store food in the form of  Diatoms 3. Diatoms (Bacillariophyta) – protists that produce thin, delicate cell walls rich in silicon. They look glass-like. -Are among the most abundant & beautiful organisms on Earth. -Cell walls fit together like a Petri dish. -Remains of diatoms  Dinoflagellates 4. Dinoflagellates (Pyrrophyta) - type of algae with 2 flagella that spin the cell in a corkscrew fashion. -The name Pyrrophyta means “fire plants”, after some dinoflagellates that are luminescent when disturbed. -Have an armor-like cell wall with plates made of cellulose & silicon. -Can be autotrophic or heterotrophic. -Are a major source of food for aquatic animals. Phytoplankton – population of small, photosynthetic organisms found near the surface of the ocean. 70% of our oxygen comes from them. -Cause red tide – Release of toxins that poison shellfish. Protozoa Fungi  Fungal Structures Yeast Aerial Vegetati ve Myceli um Septum Septa Aseptat te e Kingdom Fungi About 100,000 species Uses: medicine food Ecological value: major decomposers symbiotic relationships (N2 fixers) Problems: some strains are deadly athletes foot destroy library books destroy crops  Some fungi are pathogens About 30% of the 100,000 known species of fungi are parasites, mostly on or in plants. – American elms: – American chestnut: Dutch Elm Disease chestnut blight Was once one of America's most dominant trees  Some fungi are pathogens Other fungi, such as rusts and ergots, infect grain crops, causing tremendous economic losses each year.  Some fungi are pathogens Curse of the Mummy Some fungi are persistant Athletes Foot Fungi as Decomposers Kingdom Fungi Eukaryotic, absorptive Mostly multicellular (except few, e.g. yeast) Heterotrophic (decomposers & parasitic) Mycelium (body of hyphae) Kingdom Fungi Firm cell walls (generally of “chitin”) “Spores” as reproductive bodies Unique chromosomes and nuclei Includes molds, yeasts, rusts, and mushrooms  hyphae - the vegetative bodies of most fungi, constructed of tiny filaments mycelium -an interwoven mat of hyphae Human hair Fungal hypha Septate hypha: Ceonocytic hypha: multicellular continuous walls divided by septa cytoplasm mass multinucleate no septa Haustoria: Modified hyphae found in parasitic fungi Function: absorb nutrients from host Some fungi even have hyphae adapted for preying on animals. Kingdom Fungi Division Chytridiomycota Division Ascomycota Division Glomeromycota Division Basidiomycota Division Zygomycota Division Deuteromycota Fig. 31-11 Hypha 25 e µm Chytrids (1,000 species) Fungu Zygomycet es (1,000 s-like species) protis Fungal hypha t Glomeromyce tes (160 species) Ascomycetes (65,000 species) Basidiomycet ? es (30,000 species) Deuteromycota  The five fungal phyla can be distinguished by their reproductive features.  Division Chytridiomycota mainly aquatic. Some are saprobes, while others parasitize protists, plants, and animals. chitinous cell wall flagellated zoospores the most primitive fungi Division Zygomycota “Zygote fungi” (bread molds) Zygote = “mated” hyphal strands Live in soil, water Some are parasites 600 species Mated hyphal strands  The zygosporangia are resistant to freezing and drying. When conditions improve, the zygosporangia release haploid spores that colonize new substrates. – Pilobolus aiming its spores.  The zygomycete Rhizopus can reproduce either asexually or sexually.  PHYLUM GLOMEROMYCOTA Previously With Zygomycota Small Monophyletic Clade Endomycorrhizae – Arbuscular Mycorrhizae Produce branching Arbuscules Fig. 31-15 2.5 µm Plant-Fungal Relationships Mycorrhizae (“fungus roots”) 90% of tree species have this association Very important to absorption of water and nutrients Soil surface Plant roots Mycorrhizae Increases s.a. for absorption Division Ascomycota “Sac fungi” (truffles, yeast) Beer > 6,000 years Wine > 8,000 years Lichens Decomposers, pathogens “yeast” describes a form of fungi (i.e., non- 60,000 species Division Ascomycota Scarlet cup Morchella truffles  Division Ascomycota Close up of cheese showing blue-green mycelium of Roquefort cheese Penicillium roqueforti. Yeast  LICHENS Crusrose Foliose Fruticose Lichen Lichen Anatomy  Ascomycetes are characterized by an extensive heterokaryotic stage during the formation of ascocarps. Division Basidiomycota “Club fungi” (mushrooms) Club-shaped reproductive structure Food Plant diseases 25,000 species Fairy Ring  The life cycle of a club fungus usually includes a long-lived dikaryotic mycelium. PHYLUM DEUTEROMYCOTA No Longer Exist!! 22,000 species. No known sexual stage. Saprophytic, parasitic and predatory. Many produce conidia. Most classified as Ascomycota. Fusarium wilt of tomato, potato and cotton. Athletes foot, ring worm Division Deuteromycota “Imperfect fungi” (penicillin) Unrelated group Asexual No info on sexual cycle 25,000 species  Penicillin Woops… now Ascomycota Candida albicans “yeast infection” Botrytis: “Noble Rot” Protozoa  General Concepts Eukaryotic Organisms Generally unicellular Found in every conceivable damp habitat Approximately 60,000 living species Largest visible to the naked eye Smallest only seen with the EM have all necessary life activities.  Protozoa are one-celled animals found worldwide in most habitats. Most species are free living, but all higher animals are infected with one or more species of protozoa. Infections range from asymptomatic to life threatening, depending on the species and strain of the parasite and the resistance of  Structure Protozoa are microscopic unicellular eukaryotes that have a relatively complex internal structure and carry out complex metabolic activities. Some protozoa have structures for propulsion or other types of movement.  Classification On the basis of light and electron microscopic morphology, the protozoa are currently classified into seven phyla. Most species causing human disease are members of the phyla Sacromastigophora and Apicomplexa.  Classification Phylum: Class Genera: Sarcomastigop Zoomastigophor Trypanosoma, Leishmania, Giardia, hora a Trichomonas Entamoeba, Naegleria, Lobosea Acanthamoeba Plasmodium,Toxoplasma, Apicomplexa Sporozoea Cryptosporidium, Isospora Kinetofragminopho Ciliophora rea Balantidium  Reproduction Binary fission, the most common form of reproduction, is asexual; multiple asexual division occurs in some forms. Both sexual and asexual reproduction occur in the Apicomplexa.  Nutrition All parasitic protozoa require preformed organic substances that is, nutrition is holozoic as in higher animals.  Life Cycle Stages The stages of parasitic protozoa that actively feed and multiply are frequently called trophozoites; in some protozoa, other terms are used for these stages. Cysts are stages with a protective membrane or thickened wall. Protozoan cysts that must survive outside the host usually have more resistant walls than cysts that form in tissues.  Basic structure 1. Cell membrane 2. Cytoplasm organelles: pseudopodium(-dia- amoeba); flagellum(-lla- flagellate); cilium(cilia-ciliate) 3. Nucleus: two kinds of nuclei: vesicular; compact  Characteristics of Pathogenesis 1. proliferation 2. Diffusion (disperse ) 3. Opportunistic parasitosis Ecological Niches in the Human Body: 1. Skin: Leishmania 2. Eye: Acanthamoeba 3. Mouth: Amoebae and flagellates (usually non-pathogenic) 4.Gut: Giardia, Entamoeba (and invasion to liver), Cryptosporidium, Isospora, Balantidium 5. G.U. tract: Trichomonas Ecological Niches in the Human Body: 6. Bloodstream: Plasmodium, Trypanosoma 7. Spleen: Leishmania 8. Liver: Leishmania, Entamoeba 9. Muscle: Trypanosoma cruzi 10. CNS: Trypanosoma, Naegleria, Toxoplasma, Plasmodium Taxonomy and Classification Classified under kingdom Protista Classified into phyla based on method of locomotion – Ciliates – Amoeba – Flagellates – Sporozoa  Characteristics Life stages: Additional – Trophozoite – organelles motile, feeding, – Pellicles – cell wall- dividing like; for protection – Cyst – non-motile, – Cytostomes – food dormant , survival ingestion – Contractile vacuoles – pump water out of cell – Pseudopodia Viruses  Virus Components Very small (measured in nanometers) Components – Nucleic acid core, capsid and envelope  Classification Genetic material Type of host (either DNA or RNA) infected Shape of the capsid Type of disease Number of produced capsomeres Target cell Size of capsid Immunologic Presence or properties absence of envelope FIN