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Classifying Bacteria • Bergey’s Manual of Systematic Bacteriology – Classifies bacteria via evolutionary or genetic relationships. • Bergey’s Manual of Determinative Bacteriology – Classifies bacteria by cell wall composition, morphology, biochemical tests, differential staining, etc. Prokaryotic Organisms • Prokaryotic-means pre-nucleus. – Genetic material not enclosed in a special nuclear membrane. – What are the other differences between Prokaryotic and Eukaryotic organisms. • Prokaryotic organisms are split into two Domains. – Bacteria – Archaea The Prokaryotes Domain Bacteria • Phylum Proteobacteria – Contains most of the gram negative bacteria. – Relationships have been put together via Ribosomal RNA studies. – Split up into five classes. – Alpha, beta, gamma, delta, and epsilon Alphaproteobacteria • The Alphaproteobacteria contain many bacteria that are capable of nitrogen fixation in symbiosis with plants. – What is nitrogen fixation? • Also includes several plant and human pathogens. The Alphaproteobacteria • Human pathogens – Bartonella • B. hensela: Cat-scratch disease – Brucella: Brucellosis • Can survive phagocytosis, an important element of the body’s defense against bacteria. The Alphaproteobacteria • Obligate intracellular parasites – Rickettsia: Arthropod-borne, spotted fevers • R. rickettsii: Rocky Mountain spotted fever The Alphaproteobacteria • Plant pathogen – Agrobacterium: Insert a plasmid into plant cells, inducing a tumor Figure 9.19 The Alphaproteobacteria • Nitrogen-fixing bacteria – Rhizobium • Fix nitrogen in the roots of plants Figure 27.5, step 5 The Betaproteobacteria • Neisseria – Usually inhabit the mucous membranes of mammals. – N. meningitidis – N. gonorrhoeae Figures 11.4, 11.6 The Gammaproteobacteria Pseudomonas • Opportunistic pathogens • Metabolically diverse • Polar flagella Figure 11.7 The Gammaproteobacteria Legionella • Found in streams, warm-water pipes, cooling towers • L. pneumophilia • Legionellosis or legionaire’s disease Figure 24.15b Enteric Bacteria Genera • Escherichia-Very commonly found in human intestines. Known for its ability to cause very serious food-borne disease. • Salmonella-Almost all members of this genera are potential pathogens. • Serratia-Can be found on catheters, in saline irrigation solutions, and in other supposedly sterile situations. • Proteus-very motile genera, many flagella, can cause UTI’s or wound infections. The Epsilonproteobacteria • Helicobacter – Multiple flagella – Peptic ulcers – Stomach cancer Figure 11.12 Cyanobacteria • Oxygenic photosynthesis • Heterocysts-specialized cells that fix nitrogen. Firmicutes • Low G + C ratio-Guanine and cytosine bases in DNA. • Gram-positive bacteria. Clostridiales • Clostridium – Endospore-producing – Obligate anaerobes C. tetani- tetanus, C. Botulinum- Botulism C. perfringens- gas gangrene, C. difficile- serious diarrhea, Especially when undergoing Antibiotic therapy. Figures 11.15, 11.16 Bacillales • Bacillus – Endospore-producing rods – B. anthracis –cause anthrax Figure 11.17b Bacillales • Staphylococcus – S. aureus-cause a lot of hospital infection. MRSA- methicillin resistant S. aureus. Figure 11.18 StreptococcusMembers of this genus are probably responsible for more Diseases than any other group of bacteria. Pneumonia, strep throat, cavities, scarlet fever. Figure 11.19 Actinobacteria • High G + C-guanine and cytosine levels in DNA. • Gram-positive Important Genera • Mycobacterium – M. tuberculosis – M. leprae-causes leprosy. • Propionibacterium-Some species help make swiss cheese, others cause acne. • Streptomyces-produce a a large number of antibiotics. Figure 11.21b Phylum Spirochaetes • Treponema – T. pallidum is the cause of syphilis. Figure 11.24 Domain Archaea • Hyperthermophiles – Pyrodictium – Sulfolobus • Methanogens – Methanobacterium • Extreme halophiles – Halobacterium Figure 11.26 Homework • Write a few sentences about the difference between gram positive cell walls and gram negative cell walls, and how the gram stain came about. • Also define: • Nitrogen fixation • Plasmids • Diseases • Rocky Mountain Spotted fever • Legionellosis • MRSA • Scarlet Fever • Cat-scratch disease • Brucellosis • Peptic Ulcers (Helicobacter)