1 / 19

Review of Key Microbial Groups

Review of Key Microbial Groups. Domain Bacteria Domain Archaea Domain Eucarya. Domain Bacteria: General Features. Prokaryotic cell structure DNA organized in nucleoid; no nuclear membrane, nucleolus, or histones No complex membranous organelles (e.g. endoplasmic reticulum, golgi apparatus)

mannt
Download Presentation

Review of Key Microbial Groups

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Review of Key Microbial Groups • Domain Bacteria • Domain Archaea • Domain Eucarya

  2. Domain Bacteria: General Features • Prokaryotic cell structure • DNA organized in nucleoid; no nuclear membrane, nucleolus, or histones • No complex membranous organelles (e.g. endoplasmic reticulum, golgi apparatus) • Cell walls containing peptidoglycan found in most groups of bacteria • Some features of gene expression (mRNA, tRNA, RNA polymerase, ribosomes) are more similar to archaea; some are more similar to eucarya

  3. Domain Bacteria:General features • Metabolic strategies found in Bacteria: • Chemoheterotrophy • Chemolithotrophy • Photosynthesis

  4. Domain Bacteria:General features • Cell Wall Structures in Bacteria • Gram-negative cell wall • Outer membrane containing lipopolysaccharide • Thin layer of peptidoglycan • Periplasmic space • Gram-positive cell wall • Thick layer of peptidoglycan • Teichoic acids • “Acid-fast” bacteria • Bacteria in Phylum Actinomycetes with high concentrations of mycolic acid • Detected by acid-fast staining • Mycoplasmas • Bacteria in Phylum Firmicutes with no cell wall

  5. Domain Bacteria:General features • Other structural features found in Bacteria • Plasma membrane • Capsules • Pili or Fimbrae • Cytoplasmic inclusions • Bacterial DNA • Ribosomes • Flagella • Spores http://science.kennesaw.edu/~jhendrix/bio3340/handouts/microcells.ppt

  6. Domain Bacteria:General features • Identification of the Bacteria • Colony morphology • Cell shape & arrangement • Cell wall structure (Gram staining) • Special cellular structures • Biochemical characteristics • Serological tests • G+C content • DNA hybridization • DNA fingerprinting • Nucleic acid sequencing http://science.kennesaw.edu/~jhendrix/bio3340/handouts/microtaxonomy.ppt

  7. Domain Bacteria:Major Groups • Phylum Proteobacteria • “Gram-negative” type cell wall architecture • Outer membrane with lipopolysaccharide and porin protein • Thin layer of peptidoglycan • Notable periplasmic space containing transport proteins and hydrolases • A very large and metabolically diverse phylum; various groups utilizing chemoheterotrophy (both respiration & fermentation), chemolithotrophy, photosynthesis

  8. Domain Bacteria:Major Groups • Phylum Proteobacteria (cont.) • Major groups of proteobacteria • Enterobacteriacea: “Gram-negative enterics;” common intestinal flora and pathogens; both respiratory and fermentative metabolisms; facultatively anaerobic; oxidase negative; includes genera Escherichia, Klebsiella, Enterobacter, Citrobacter, Serratia, Proteus, Salmonella, Shigella, Yersinia • Pseudomonadaceae: Genus Pseudomonas and related genera; common soil and aquatic organism; usually aerobic; oxidase positive; use Entner-Douderoff glycolysis instead of EMP glycolysis; often can metabolize unusual carbon substrates such as aromatic hydrocarbons

  9. Domain Bacteria:Major Groups • Phylum Proteobacteria (cont.) • Major groups of proteobacteria (cont.) • Purple nonsulfur photosynthetic bacteria, e.g. Rhodospirillum • Green sulfur photosynthetic bacteria, e.g. Chlorobium • Nitifying bacteria: Nitrosomonas (oxidizes ammonium to nitrite) and Nitrobacter (oxidizes nitrite to nitrate) • Nitrogen fixing bacteria: Rhizobium (symbiotic in root nodules); Azotobacter (free-living) • Various human pathogens in phylum Proteobacteria: Neisseria, Vibrio, Haemophilus, Rickettsia, Coxsiella, Bordetella, Legionella, Camphylobacter, Helicobacter

  10. Domain Bacteria:Major Groups • Phylum Firmicutes • “Low G-C” Gram-positive bacteria • Cell walls consist of thick layers of extensively crosslinked peptidoglycan (exception: Mycoplasma) • Notable genera • Clostridium: Strictly anaerobic, spore-forming rods; common in soil; includes botulism & tetanus; significant contaminant in food industry & medicine • Bacillus: Facultatively anaerobic, spore-forming rods; common in soil; frequent contaminant; includes Bacillus anthracis • Mycoplasma: Have no cell walls; respiratory tract flora & pathogens of humans & other animals

  11. Domain Bacteria:Major Groups • Phylum Firmicutes • Notable genera • Lactobacillus: Facultatively anaerobic nonsporeforming rods; oral or intestinal flora; found in sevral dairy products such as yogurt • Staphylococcus: Catalase-positive cocci; common skin flora; virulent strains of Staph. aureus are associated with skin infections, food poisoning, and toxic shock syndrome • Streptococcus, Enterococcus, Lactococcus: Catalase-negative cocci; diverse group with numerous skin, oral, and intestinal flora as well as several important pathogens such as Streptococcus pyogenes (Group A pyogenic strep)

  12. Domain Bacteria:Major Groups • Phylum Actinomycetes • “High G-C” Gram-positive bacteria • Cell walls consist of thick layers of extensively crosslinked peptidoglycan • Notable genera • Corynebacterium: Facultatively anaerobic, irregular rods; coryneform arrangement; common soil & skin flora; common laboratory contaminant • Micrococcus: Facultatively anaerobic cocci; tetrads or sarcinae; yellow or pink pigmentation; common soil flora;common laboratory contaminants • Actinomyces, Streptomyces; Common soil organism; filamentous growth often mistaken for mold

  13. Domain Bacteria:Major Groups • Phylum Actinomycetes • Notable genera • Mycobacterium: Acid-fast rods; high concentration of mycolic acid in the cell wall make them difficult to gram stain; certain species are skin and soil flora; includes tuberculosis and leprosy

  14. Domain Bacteria:Major Groups • Phylum Bacteroidetes • A group of gram-negative, strictly anaerobic bacteria • Most are intestinal and oral flora in humans and animals; some are pathogens • Example: genus Bacteroides

  15. Domain Bacteria:Major Groups • Phylum Cyanobacteria • The “blue-green algae” • Carry out oxygenic photosynthesis • Have thylakoid membranes, chlorophyll a, and photosystem II

  16. Domain Bacteria:Major Groups • Phylum Chlamydiae • A group of gram-negative, obligately intracellular parasites • Genus Chlamydia • Phylum Spirochaetes • Characterized by flexible helical-shaped cells • Cells covered by an outer sheath and are motile by a modified flagellar structure called an axial filament • Example: Treponema pallidum (syphillis)

  17. Domain Archaea: General Features • Prokaryotic cell structure • Cell walls have no peptidoglycan; some archaea have pseudomurein or other polymers • Some features of gene expression (mRNA, tRNA, RNA polymerase, ribosomes) are more similar to bacteria; some are more similar to eucarya • Metabolic strategies found in Archaea: • Chemoheterotrophy • Chemolithotrophy

  18. Domain Archaea:Major Groups • Methanogenic archaea • Methanobacterium, Methanococcus • Extremely thermophilic archaea • Sulfate reducers, Archaeoglobus • Sulfur reducers, Desulfurococcus, Sulfolobus • Extremely halophilic archaea • Halobacterium, Halococcus • Cell wall deficient archaea • Thermoplasma

  19. Domain Eucarya: General Features • Eukaryotic cell structure • Cell walls vary; none in “animal-like” cells; cellulose in algae most others, with additional polysaccharides in different groups (e.g., chitin in many fungi) • Some features of gene expression (mRNA, tRNA, RNA polymerase, ribosomes) are more similar to bacteria; some are more similar to archaea • Metabolic strategies found in Eucarya: • Chemoheterotrophy (respiration in mitochondria) • Photosynthesis (in chloroplasts)

More Related