1. Metabolic Terms. Important Metabolic Terms 9/13/2016. Chapter 11 PROKARYOTES: Survey of the Bacteria & Archaea. 1. Metabolic Terms 2.

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1 Chapter 11 PROKARYOTES: Survey of the Bacteria & Archaea 1. Metabolic Terms 2. The Bacteria A. Phototrophic Bacteria B. Gram-Positive Bacteria C. Gram-Negative Bacteria 3. The Archaea 1. Metabolic Terms Chapter Reading pp Important Metabolic Terms Oxygen tolerance/usage: aerobic requires or can use oxygen (O 2 ) anaerobic does not require or cannot tolerate O 2 Energy usage: phototroph uses light as an energy source all photosynthetic organisms chemotroph acquires energy from organic or inorganic molecules organotrophs get energy from organic molecules lithotrophs get energy from inorganic molecules 1

2 more Important Terms Carbon Source: autotroph uses CO 2 as a carbon source e.g., photoautotrophs or chemoautotrophs heterotroph requires an organic carbon source e.g., chemoheterotroph gets energy & carbon from organic molecules Facultative vs Obligate (or Strict): facultative able to, but not requiring e.g., facultative anaerobes can survive w/ or w/o O 2 obligate absolutely requires e.g., obligate anaerobes cannot survive in O 2 2. The Bacteria A. Phototropic Bacteria Chapter Reading pp Overview of the Bacterial Domain We will look at important genera from a variety of bacterial taxa classified largely based on rrna sequences (ribotyping): Phototropic bacteria Cyanobacteria Green & Purple Bacteria Gram-positive bacteria Firmicutes Actinobacteria Gram-negative bacteria Proteobacteria Spirochetes Chlamydiae Bacteroids 2

3 Cyanobacteria Gram-negative, oxygenic photoautotrophs produce vast amounts of oxygen gas via photosynthesis fix nitrogen (N 2 NH 4+ ) Anabaena carry out nitrogen fixation in non-photosynthetic heterocysts Vegetative cell Heterocyst Sheath Akinete Anabaena Oscillatora Purple & Green Bacteria Obligately anaerobic, anoxygenic photoautotrophs Green and Purple non-sulfur bacteria use organic molecules as a source of electrons (not H 2 O) Green and Purple sulfur bacteria use H 2 S as a source of electrons elemental sulfur is then released (green sulfur bacteria) or forms inclusions (purple sulfur bacteria) Purple sulfur bacteria B. Gram-Positive Bacteria Chapter Reading pp

4 Gram-Positive Bacteria Most known Gram-positive bacteria are found in 2 main phyla: Firmicutes low G + C content (less than 50%) many common pathogens Actinobacteria high G + C content (greater than 50%) characterized by branching filaments Firmicutes Streptococcus strep throat (S. pyogenes) Streptococcus Clostridium Staphylococcus MRSA (S. aureus) *Bacillus anthrax (B. anthracis) *Clostridium tetanus (C. tetani) botulism (C. botulinum) *produce endospores Lactobacillus other Firmicutes species used in fermented food products (e.g., yogurt, buttermilk, pickles) part of normal, healthy microbiota in human mouth, digestive tract, vagina Mycoplasma very small (less than 1 mm) no cell wall (are Gram-neg.) obligate intracellular pathogens colonies Mycoplasma 4

5 Actinobacteria Genera of ecological importance: Streptomyces important soil bacteria, recycle nutrients source of many antibiotics (e.g., erythromycin, tetracycline) Corynebacterium diphtheria (C. diphtheriae) Mycobacterium contain waxy mycolic acids in cell wall and thus stain acid fast tuberculosis (M. tuberculosis) Streptomyces leprosy (M. leprae) C. Gram-Negative Bacteria Chapter Reading pp Proteobacteria The phylum Proteobacteria contains most of the Gram-negative heterotrophs and is divided into 5 classes: Alphaproteobacteria Betaproteobacteria Gammaproteobacteria Deltaproteobacteria Epsilonproteobacteria 5

6 Alphaproteobacteria Genera of ecological importance: Azospirillum Rhizobium Nitrobacter nitrogen fixation nitrogen fixation nitrification Rickettsia intracellular pathogens typhus, Rocky Mountain spotted fever Brucella brucellosis in humans, cattle and other mammals Nitrosomonas Betaproteobacteria Genera of ecological importance: enrich soils through nitrification Thiobacillus oxidize H 2 S to sulfate important in sulfur cycle N. gonorrhoeae Neisseria gonorrhea (N. gonorrheae) Bordetella whooping cough (B. pertussis) Burkholderia opportunistic pathogens Gammaproteobacteria Largest & most diverse class of Proteobacteria. Genera of ecological importance: Methylococcus (metabolize methane) Some pathogenic genera: Vibrio cholera (V. cholerae) Pseudomonas opportunistic pathogens V. cholerae Salmonella typhoid fever, foodborne salmonellosis 6

7 Deltaproteobacteria Desulfovibrio H 2 S producing anaerobes important in the sulfur cycle Bdellovibrio unusual and interesting bacterial predator Epsilonproteobacteria Most are helical or vibriod. Helicobacter H. pylori peptic ulcers Campylobacter various species cause blood poisoning, intestinal illness (e.g., C. jejuni) H. pylori Other Gram-negative Phyla Spirochetes Treponema T. pallidum syphilis Borrelia B. burgdorferi Lyme disease Chlamydiae small intracellular pathogens with cell walls lacking peptidoglycan Bacteroides Chlamydia trachomatis most common STD obligate anaerobes, comprise ~1/3 of fecal bacteria aid in digestion of indigestible material (e.g., fiber) 7

8 3. The Archaea Chapter Reading pp The Domain Archaea Highly diverse group of prokaryotes first classified in 1977 by Carl Woese and George Fox: have metabolic processes, rrna sequences and other features more closely resembling eukaryotes e.g., initiate translation with methionine (as do eukaryotes) rather than N-formyl methionine as do the Bacteria cell walls made of material other than peptidoglycan have unusual membrane lipids many species inhabit extreme environments Crenarchaeota Two Main Phyla includes most thermophiles Euryarchaeota includes the methanogens, halophiles, a few thermophiles Geogemma (can survive at 130 o C!) Korarchaeota based on environmental RNA only **NO known archaeon causes disease in humans or animals!** Pyrodictium (found in acidic hot springs) 8

9 Key Terms for Chapter 11 aerobic vs anaerobic facultative vs obligate phototroph, chemotroph, organotroph, lithotroph autotroph vs heterotroph thermophile, halophile Relevant Chapter Questions T/F: 1-8 MC: 2-10 SA: 2-4, 6,