Microbiology-Ch. 11 Study Guide-Prokayotes
Coxiella
C. burnetii is only characterized species Obligate intracellular bacterium; can survive outside host cell as spore-like structures called small-cell variants (SCVs) formed during intracellular growth Not as resistant as endospores to heat, disinfectants
Obligate Intracellular Parasites
Cannot reproduce outside a host cell: host cells supply compounds they would otherwise need to synthesize Most have lost ability to synthesize needed substances Multiple bacterial examples; all are tiny Gram-negative rods or coccobacilli
Oxygenic phototrophs-cyanobacteria
Earliest oxygenic phototrophs, primary producers; Anabaena Use water as source of electrons for reducing power
Proteus
Implicated in many infections of the urinary tract and in wounds
Obligate aerobes
Microorganisms that can survive only in the presence of oxygen. To obtain energy, these organisms metabolize substances like sugar or fats through cellular respiration. Oxygen acts as the terminal electron acceptor. They gather at the top of the tube where the oxygen concentration is highest
Aerotolerant anaerobes
Organisms cannot use oxygen for growth but tolerate its presence. Use fermentation to produce ATP eg Strep
Obligate anaerobes
Organisms that cannot live where molecular oxygen is present Gather at the bottom of the tube where the oxygen concentration is lowest
Aerobic chemoorganotrophs
Oxidize organic compounds for energy; use oxygen as TEA Some inhabit specific environments, others ubiquitous Gram-positive cocci Found in soil, dust particles, inanimate objects, skin Pigmented colonies Tolerate dry, salty conditions
Hyperthermophiles
Pyrodictium (barophile) Sulfolobus (Thermoacidophilic) Domain: Archaea
Describe the contribution of Cornelis B. van Neil.
Studied photosynthetic purple bacteria Demonstrated requirement of light for growth No evolution of oxygen Oxidize hydrogen sulfide during CO2 fixation Noted remarkable similarity of photosynthetic reactions in all photosynthetic organisms
Enterococcus
Grows in low oxygen like intestinal tract and vagina and also in human stool They persist as contaminants in a hospital environment like hands and bedding Leading cause of hospital infections due to high resistance to antibiotics
Rhizobia
Bacteria that Associate with Plants Gram-negative rods that often fix nitrogen
Gram negative rods
Bacteria that Inhabit Mucous Membranes
Gram positive rods
Bacteria that Inhabit Mucous Membranes Purple
How many genera and species of bacteria are classified currently?
950 genera
Gram positive irregular rods
Bacteria that Inhabit Mucous Membranes Respiratory, genitourinary, intestinal tracts inhabited by numerous kinds of bacteria
M. pneumoniae
A type of "atypical" bacteria that commonly causes mild infections of the respiratory system Antibiotics that target peptidoglycan synthesis not effective Medically important Genus: Mycoplasma
Gram positive cocci_
Bacteria that Inhabit the Skin
Streptomyces G+
Aerobic Gram-positive bacteria Terrestrial Growth resembles fungi: form mass of branching hyphae called mycelium Chains of spores (conidia) develop at tips Conidia resistant to drying; easily spread by air currents Produce extracellular enzymes, geosmins
Anaerobic chemoorganotrophs-fermentation
Aka: Chemoheterotrophs Oxidize glucose to obtain energy (use organics for energy and carbon) Numerous anaerobic bacteria ferment, different organic energy sources, end products. E.g. Clostridium, lactic acid bacteria
Salmonella
Almost all members are potentially pathogenic, gram negative rod Inhabit intestines of poultry and cattle Salmonella typhi- causative agent of typhoid fever Other members of this genus causes salmonellosis, one of the most common foodborne illness
Facultative anaerobes
An organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent. They use oxygen as electron acceptor. They gather mostly at the top because aerobic respiration generates more ATP than either fermentation or anaerobic respiration.
Microaerophiles
An organism that need oxygen because they cannot ferment or respire anaerobically. However, they are poisoned by high concentrations of oxygen. They gather in the upper part of the test tube but not the very top. Eg H. Pylori or Campylobacter
Treponema
Are obligate anaerobes or microaerophiles; often inhabit mouth, genital tract
Bifidobacteria
Are used in treatment as so-called "probiotics," Used to treat skin infections, excema
Agrobacterium
Bacteria that Associate with Plants Gram-negative rods Genetically modify plants via plasmid to form tumors DNA encodes ability to synthesize plant growth hormone; results in tumor Also encodes synthesis of unusual amino acid derivative opine Use opine as nutrient
Yersinia
Bubonic plague, transmitted by fleas
What causes Q fever and is most often acquired by inhaling bacteria shed from infected animals?
C. burnetii
Facultative anaerobes
Can live with or without oxygen Enterics Gram negative rods , E.coli Obtain energy from fermentation reactions, use organics as energy source Various end products
B. recurrentis and B. hermsii
Cause relapsing fever Genus: Borrelia
B. burgdorferi
Causes Lyme disease Genus: Borrelia
S. mutans
Causes cavities (dental caries) Genus: Streptococcus
C. diphtheriae
Causes diphtheria Toxin producing strain Genus: Corynebacterium
S. pyogenes
Causes scarlet fever, sore throat (pharyngitis), rheumatic fever Genus: Streptococcus
T. pallidum
Causes syphilis, difficult to culture Genus: Treponema
H. pylori
Causes ulcers, produces urease(breaks down to CO2 and NH3<-alkalizes, which breaks down urea to ammonia to neutralize local pH Multiple flagella Peptic ulcers Stomach cancer
Name the features common to most bacteria.
Cell wall Flagella Capsule Pili Fimbre
Anaerobic chemolithotrophs
Chemolithotrophs oxidize reduced inorganic chemicals to obtain energy; E.g., H2, CO2, sulfur Anaerobes use alternative electron acceptor
Anaerobic chemoorganotrophs-respiration
Chemoorganotrophs oxidize organic compounds (e.g., glucose) to obtain energy Sulfur- and Sulfate-Reducing Bacteria; sulfur cycle *Anaerobes often use sulfur, sulfate as electron acceptor *Hydrogen sulfide (rotten-egg smell) ;Gram-negative curved rods & some archaea
Archaea
Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan Thrive in extremes High heat, acidity, alkalinity, salinity Many others detected in non-extreme environments using molecular techniques
B. anthracis
Facultative anaerobe Causative agent of anthrax Genus: Bacillus
Klebsiella
Found in soil or water K. pneumonia: contains a capsule; causes a serious form of pneumonia in humans 50% mortality rate Facultative Anerobic Gram negative rod
Shigella
Found only in humans Second only to E. coli as a cause of traveler's diarrhea
Aerobic chemolithotrophs
Gain energy by oxidizing inorganic chemicals(S); but use O2 as TEA *Energy from oxidation of sulfur, sulfur compounds including H2S, thiosulfate; responsible for sulfur cycles Sulfur-oxidizing bacteria: Gram-negative rods, spirals; Beggiatoa
Pseudomonas
Gram-Negative Rods Aerobic rods Fluoresce under UV light Motile by flagella Metabolically diverse P. aeruginosa Infects urinary tract, burns, wounds Can grow on antiseptics and are resistant to most antibiotics Responsible for 1 in 10 hospital infections
Bacillus
Gram-Positive Rods Endospore forming Few are pathogenic
Clostridium
Gram-Positive Rods Obligate anaerobes Common in soils; vegetative cells live in anaerobic microenvironments created by aerobes consuming O2 Endospores tolerate O2, survive long periods of heat, drying, chemicals, irradiation; Germinate when conditions improve (eg ingested makes anaerobic environment) Diverse metabolism; some cause diseases Endospore-producing: C. tetani: tetanus C. botulinum: botulism C. perfringens: foodborne diarrhea
Neisseria
Gram-negative cocci with fimbrae, typically kidney bean-shaped cocci found in pairs Aerobic cocci
Haemophilus
Gram-negative coccobacilli "Blood-loving": require hematin and/or NAD blood Many common microbiota of respiratory tract H. influenzae causes ear infections, respiratory infections, meningitis Greatest cause of childhood meningitis before Hib vaccine Encapsulated forms from csf H. ducreyi causes STD chancroid
Bacteroides
Gram-negative rods and coccobacilli Small; strict anaerobes that inhabit mouth, intestinal tract, genital tract of humans and other animals B. fragilis and related species comprise ~1/3 of bacteria in human feces Pleomorphic Non endospore formers Opportunistic infections
Purple bacteria
Gram-negative; appear red, orange, or purple Photosynthetic apparatus in cytoplasmic membrane
Green bacteria
Gram-negative; typically green or brownish
Staphylococci
Gram-positive cocci Facultative anaerobes; catalase-positive Most harmless (e.g., S. epidermidis)
Micrococcus
Gram-positive cocci Found in soil, dust particles, inanimate objects, skin Pigmented colonies Tolerate dry, salty conditions
Streptococci
Gram-positive cocci that occur in chains. Generally aerotolerant anaerobes Responsible for more illness than any other group Produce products that destroy phagocytic cells Some digest connective tissue which causes it to spread
Bifidobacterium
Gram-positive irregular rods Anaerobes; reside primarily in intestinal tract of humans and other animals Predominant members of intestinal microbiota of breast-fed infants; thought to exclude pathogens
Corynebacterium
Gram-positive pleomorphic rods Obligate Aerobes Wide-spread Often club-shaped and form V shapes or palisades Referred to as coryneforms or diphtheroids Generally facultative anaerobes; some strict aerobes Many harmless
Green Sulfur Bacteria
Habitats similar to purple sulfur bacteria Form granules outside of cell Accessory pigments located in chlorosomes Lack flagella May have gas vesicles Strict anaerobes None are chemotrophic Representatives include: Chlorobium, Pelodictyon
Halophiles
Halobacterium Domain: Archaea
Dichotomous key
Identification scheme Paired questions; answering one question leads to another paired question until Identification of organisms
Borrelia
Includes three pathogens, transmitted by ticks and lice Genome is linear chromosome and many linear and circular plasmids
Why is Nitrogen-fixing cyanobacteria critical ecologically?
Incorporate N2 and CO2 into organic material Form usable by other organisms
Mycoplasma
Lack cell wall, gives flexibility Pleomorphic 0.1 - 0.24 µm Most have sterols for added strength and rigidity Among smallest forms of life; genomes thought to be minimum size encoding essential functions Colony growth produces characteristic "fried egg" appearance
What is the major metabolic end product of Streptococcus species?
Lactic acid
Purple sulfur bacteria
Large cells; some motile May have gas vesicles to control depth Most store sulfur in intracellular granules Preferentially use H2S to generate reducing power Some can grow aerobically in absence of light
Geosmins
Metabolic products in soil from the microbes Medically useful antibiotics including streptomycin, tetracycline, erythromycin
Methanogens
Methanobacterium Domain: Archaea
Campylobacter
Microaerophilic Gram Negative Curved Rods C. jejuni (causes diarrhea in humans)
Purple Non-Sulfur Bacteria
Moist soils, bogs, paddy fields Preferentially use organic molecules instead of H2S as source of electrons Lack gas vesicles May store sulfur; granules form outside cell Remarkably diverse metabolism
Current methods to classify bacteria.
Morphological characteristics: Useful for identifying eukaryotes Differential staining: Gram staining, acid-fast staining Biochemical tests: Determines presence of bacterial enzymes
S. pneumoniae
Most common cause of pneumonia Genus: Streptococcus
E.coli
Most common inhabitant of human intestinal tract Most well characterized organism in microbiology Main cause of traveler's diarrhea
Lactobacillus species are common members of the normal microbiota of which human body sites?
Mouth Intestinal tract Vagina
Metabolic Diversity in the prokaryotes
Numerous approaches to harvesting energy to produce ATP PCR indicates up to 10,000 bacteria/gm of soil. Many bacteria have not been identified or characterized because they: Haven't been cultured Need special nutrients Are part of complex food chains requiring the products of other bacteria Need to be cultured to understand their metabolism and ecological role
Mycobacterium
Obligate Aerobes Acid-fast bacteria Mycolic acid in cell wall prevents Gram-staining Special staining used; resist destaining Generally pleomorphic rods Notable pathogens: M. tuberculosis, M. leprae More resistant to disinfectants, differ in susceptibility to antimicrobial drugs Related Nocardia species also acid-fast
Oxygen requirements.
Obligate Aerobes eg Micrococcus Obligate Anaerobes eg Clostridium Facultative anaerobes eg most common in your ecoli
Name the four features common to all bacteria.
Plasma membrane Cytoplasm Ribosomes DNA
Cyanobacteria
Produce oxygen Use water as source of electrons for reducing power Still play essential role as primary producers: Harvest sunlight to convert CO2 into organic compounds Diverse group of Gram-negative bacteria
What roles do hydrogen gas and carbon dioxide play in the metabolism of methanogens?
Produces methane
Obligate aerobes
Require O2 for cellular respiration Micrococcus
Previous methods to classify bacteria.
Shape Gram Stain Metabolism (growth in oxygen)
S. aureus
Skin and wound infections; food poisoning Medically important Genus: Staphylococcus
Rickettsia
Slime layer Rocky Mountain spotted fever Obligate Intracellular Parasite Include species responsible for several serious arthropod-transmitted human diseases
Bergeys Manual of Bacteriology
The main resource for determining the identity of prokaryotic organisms, emphasizing bacterial species, using every characterizing aspect.
Acidophiles
Thermoplasma Domain: Archaea
Gram negative Spirochetes
Treponema and Borrelia
G-rods Enterobacteriaceae
Typically found in intestinal tract of humans, other animals; some thrive in soil Facultative anaerobes that ferment glucose Normal intestinal microbiota include Enterobacter, Klebsiella, Proteus, most E. coli strains Those that cause diarrheal disease include Shigella, Salmonella enterica, and some E. coli strains Life-threatening systemic diseases include typhoid fever (Salmonella enterica serotype Thyphi) and bubonic and pneumonic plague (Yersinia pestis) Lactose fermenters termed coliforms
S. saprophyticus
Urinary tract infections Medically important Genus: Staphylococcus
Vibrio
vibrio-lowercase; shape Vibrio-uppercase; genus Gram-Negative Curved Rods Facultative anaerobic curved rods Found in coastal water; transmitted by raw shellfish Causes cholera (profuse diarrhea)