Microbiology: Introduction Chapter 11 (PDF)

Microbiology an Introduction Thirteenth Edition, Global Edition Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Copyright © 2021 Pea...

Microbiology an Introduction Thirteenth Edition, Global Edition Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Prokaryotes: Domains Bacteria and Archaea One circular chromosome, not in a membrane No organelles Peptidoglycan cell walls Binary fission (reproduction) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Proteobacteria From the mythological Greek god Proteus, who could assume many shapes Gram-negative Chemoheterotrophic Largest taxonomic group of bacteria Five classes – Alphaproteobacteria – Betaproteobacteria – Gammaproteobacteria – Deltaproteobacteria – Episilonproteobacteria Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Alphaproteobacteria Most are capable of growing with very low levels of nutrients Many have stalks or buds known as prosthecae Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Alphaproteobacteria Rickettsia – Obligate intracellular parasites – Cause spotted fevers ▪ R. prowazekii: epidemic typhus ▪ R. typhi: endemic murine typhus ▪ R. rickettsii: Rocky Mountain spotted fever – Transmitted by insect and tick bites Ehrlichia – Transmitted by ticks – Cause ehrlichiosis Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Alphaproteobacteria Bartonella – Human pathogen – B. henselae: cat-scratch disease Brucella – Obligate parasite of mammals; survives phagocytosis – Causes brucellosis Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Betaproteobacteria Bordetella – Non-motile rods – B. pertussis: causes whooping cough Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Betaproteobacteria Neisseria – N. gonorrhoeae: cause of gonorrhoea – N. meningitidis: cause of meningococcal meningitis Bacteria Host-cell membrane Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Pseudomonadales – Pseudomonas ▪ Opportunistic pathogens; nosocomial infections ▪ Metabolically diverse ▪ Polar flagella; common in soil ▪ P. aeruginosa: wound and urinary tract infections Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Pseudomonadales (cont’d) – Moraxella ▪ M. lacunata: causes conjunctivitis – Acinetobacter ▪ A. baumanii: respiratory pathogen; resistant to antibiotics Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Vibrionales – Found in aquatic habitats ▪ V. cholerae causes cholera ▪ V. parahaemolyticus causes gastroenteritis Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Enterobacteriales – Commonly called enterics—inhabit the intestinal tract; ferment carbohydrates – Facultative anaerobes – Peritrichous flagella Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Enterobacteriales (cont’d) – Escherichia ▪ E. coli: indicator of fecal contamination; causes foodborne disease and urinary tract infections – Salmonella ▪ 2,500 serovars ▪ Common form of foodborne illness ▪ Salmonella typhi causes typhoid fever Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Enterobacteriales (cont’d) – Shigella ▪ Causes bacillary dysentery – Klebsiella ▪ K. pneumoniae causes pneumonia – Serratia ▪ Produces red pigment ▪ Common cause of nosocomial infections Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Enterobacteriales (cont’d) – Proteus ▪ Swarming motility; colonies form concentric rings – Yersinia ▪ Y. pestis causes plague ▪ Transmitted via fleas Flagella Proteus mirabilis with A swarming colony of peritrichous flagella Proteus mirabilis, showing concentric rings of growth Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Enterobacteriales (cont’d) – Enterobacter ▪ E. cloacae and E. aerogenes cause urinary tract infections and nosocomial infections – Cronobacter ▪ Discovered in 2007 ▪ C. sakazakii causes meningitis; found in a variety of environments and foods Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gammaproteobacteria Pasteurellales – Pasteurella ▪ Pathogen of domestic animals ▪ P. multocida is transmitted to humans via animal bites – Haemophilus ▪ Require X factor (heme) and V factor (NAD+ , NADP+) in media ▪ H. influenzae causes meningitis, earaches, and epiglottitis (it does NOT cause influenza—that disease is caused by the influenza virus, not by bacteria) Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Deltaproteobacteria Bdellovibrio – Attacks other gram-negative bacteria Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Epsilonproteobacteria Helical or curved; microaerophilic Campylobacter – One polar flagellum – C. jejuni causes foodborne intestinal disease Helicobacter – Multiple flagella – Cause peptic ulcers and stomach cancer Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 11.12 Helicobacter Pylori on Stomach Cells Flagella Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Nonproteobacteria (Gram- Negative Bacteria) Differentiate planctomycetes, chlamydias, Bacteroidetes, Cytophaga, and Fusobacteria Copyright © 2021 Pearson Education Ltd. All Rights Reserved Cyanobacteria (The Oxygenic Photosynthetic Bacteria) Carry out oxygenic photosynthesis 2H 2O + CO 2 ⎯⎯⎯ light →(CH 2O) + H 2O + O 2 Many contain heterocysts that can fix nitrogen Gas vesicles that provide buoyancy Unicellular or filamentous Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 11.13 Cyanobacteria Heterocysts Filamentous cyanobacterium The unicellular, nonfilamentous showing heterocysts, in which cyanobacterium Prochlorococcus nitrogen-fixing activity is located may be the world’s most abundant photosynthetic organism. (Electron micrograph courtesy of Claire Ting, Williams College) Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Phyla Chlorobi and Chloroflexi (The Anoxygenic Photosynthetic Bacteria) Carry out anoxygenic photosynthesis 2H 2S + CO 2 ⎯⎯⎯ light →(CH 2O) + H 2O + 2S0 Green sulfur: phylum Chlorobi Green nonsulfur: phylum Chloroflexi Purple sulfur and purple nonsulfur photosynthetic bacteria are proteobacteria Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 11.14 Purple Sulfur Bacteria Copyright © 2021 Pearson Education Ltd. All Rights Reserved TABLE 11.2 Selected Characteristics of Photosynthesizing Bacteria Copyright © 2021 Pearson Education Ltd. All Rights Reserved Chlamydiae No peptidoglycan in the cell wall; grow intracellularly Chlamydia and Chlamydophila – Form an elementary body that is infective – Chlamydia trachomatis causes trachoma and urethritis – Chlamydophila psittaci causes respiratory psittacosis – Chlamydophila pneumoniae causes a mild form of pneumonia prevalent in young adults Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 11.15a Chlamydias The elementary bodies Elementary body The bacterium’s infectious are released from the form, the elementary host cell. body, attaches to a host cell. Nucleus The reticulate bodies begin to convert back to The host cell phagocytizes elementary bodies. the elementary body, Host cell housing it in a vacuole. Vacuole forming Vacuole Reticulate body The reticulate body divides The elementary body successively, producing reorganizes to form a multiple reticulate bodies. reticulate body. Life cycle of the chlamydias, which takes about 48 hours to complete Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 11.15b Chlamydias Micrograph of Chlamydophila psittaci in the cytoplasm of a host cell. The elementary bodies are the infectious Elementary stage; they are dense, dark, body and relatively small. Reticulate bodies, the form in which chlamydias reproduce within the host Reticulate cell, are larger with a body speckled appearance. Intermediate bodies, a Intermediate stage between the two, have body a dark center. Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Nonproteobacteria (Gram- Negative Bacteria) Bacteroidetes – Anaerobic ▪ Bacteroides are found in the mouth and large intestine ▪ Cytophaga degrade cellulose in soil Fusobacteria – Anaerobic – Are found in the mouth; cause dental abscesses Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 11.17 Fusobacterium Copyright © 2021 Pearson Education Ltd. All Rights Reserved Spirochaetes Coiled and move via axial filaments Treponema – T. pallidum causes syphilis Borrelia – Causes relapsing fever and Lyme disease Leptospira – Excreted in animal urine Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 11.18 Spirochetes (b) The end of an axial filament (endoflagellum) is attached to the cell and extends through most of the length of the cell. Another axial filament is attached to the opposite end of the cell. These axial filaments do not extend away from the cell but remain between the body of the cell and the external sheath. Their contractions and relaxations cause the helical cell to rotate in a corkscrew fashion. Copyright © 2021 Pearson Education Ltd. All Rights Reserved Deinococcus-Thermus Deinococcus radiodurans – More resistant to radiation than endospores Thermus aquaticus – Found in a hot spring in Yellowstone National Park – Source of Taq polymerase Copyright © 2021 Pearson Education Ltd. All Rights Reserved The Gram-Positive Bacteria Firmicutes (low G + C ratios) Tenericutes (low G + C ratios) Actinobacteria (high G + C ratios) Copyright © 2021 Pearson Education Ltd. All Rights Reserved Firmicutes (Low G + C Gram-Positive Bacteria) Clostridiales – Clostridium ▪ Endospore-producing ▪ Obligate anaerobes ▪ Includes disease-causing C. tetani, C. botulinum, C. perfringens, and C. difficile Copyright © 2021 Pearson Education Ltd. All Rights Reserved Firmicutes (Low G + C Gram-Positive Bacteria) Bacillales – Bacillus ▪ Endospore-producing rods ▪ B. anthracis causes anthrax ▪ B. thuringiensis is an insect pathogen ▪ B. cereus causes food poisoning – Staphylococcus ▪ Grapelike clusters ▪ S. aureus causes wound infections, is often antibiotic resistant, and produces an enterotoxin Copyright © 2021 Pearson Education Ltd. All Rights Reserved  Toxin Figure 11.21 Bacillus Endospore Copyright © 2021 Pearson Education Ltd. All Rights Reserved Figure 11.22 Staphylococcus Aureus Copyright © 2021 Pearson Education Ltd. All Rights Reserved Firmicutes (Low G + C Gram-Positive Bacteria) Lactobacillales – Aerotolerant anaerobes; produce lactic acid from simple carbohydrates – Lactobacillus colonize the body and are used commercially in food production Copyright © 2021 Pearson Education Ltd. All Rights Reserved Firmicutes (Low G + C Gram-Positive Bacteria) Lactobacillales – Streptococcus ▪ Spherical in chains ▪ Produce enzymes that destroy tissue ▪ Beta-hemolytic streptococci hemolyze blood agar; includes S. pyogenes ▪ Non-beta-hemolytic streptococci include S. pneumoniae and S. mutans, which causes dental caries Copyright © 2021 Pearson Education Ltd. All Rights Reserved Firmicutes (Low G + C Gram-Positive Bacteria) Lactobacillales—important members of the Streptococcus genus – S. pyogenes and S. agalactiae are beta-hemolytic ▪ Beta-hemolytic streptococci subdivided into Groups A through G – S. pneumoniae and S. mutans often exhibit alpha- hemolysis Copyright © 2021 Pearson Education Ltd. All Rights Reserved Firmicutes (Low G + C Gram-Positive Bacteria) Lactobacillales – Enterococcus ▪ Found in intestinal tract; hospital contaminants ▪ E. faecalis and E. faecium infect surgical wounds and the urinary tract – Listeria ▪ L. monocytogenes contaminates food Copyright © 2021 Pearson Education Ltd. All Rights Reserved Tenericutes (Low G + C Gram-Positive Bacteria) Mycoplasma – Lack a cell wall; pleomorphic – M. pneumoniae causes mild pneumonia Copyright © 2021 Pearson Education Ltd. All Rights Reserved Actinobacteria (High G + C Gram- Positive Bacteria) High G + C Gram-positive Copyright © 2021 Pearson Education Ltd. All Rights Reserved Actinobacteria (High G + C Gram- Positive Bacteria) Often pleomorphic; branching filaments Often common inhabitants of soil Mycobacterium – Outermost layer of mycolic acids that is waxy and water-resistant – Often slow-growing – M. tuberculosis causes tuberculosis – M. leprae causes leprosy Copyright © 2021 Pearson Education Ltd. All Rights Reserved Actinobacteria (High G + C Gram- Positive Bacteria) Corynebacterium – C. diphtheriae causes diphtheria Propionibacterium – Forms propionic acid – P. acnes causes acne Gardnerella – G. vaginalis causes vaginitis Copyright © 2021 Pearson Education Ltd. All Rights Reserved Actinobacteria (High G + C Gram- Positive Bacteria) Streptomyces – Isolated from soil; produce most antibiotics Actinomyces – Form filaments in the mouth and throat; destroy tissue Nocardia – Form fragmenting filaments; acid-fast – N. asteroides causes pulmonary infections Copyright © 2021 Pearson Education Ltd. All Rights Reserved Diversity within the Archaea Distinct taxonomic grouping; lack peptidoglycan Extremophiles – Halophiles ▪ Require salt concentration >25% – Thermophiles ▪ Require growth temperature >80°C Methanogens ▪ Anaerobic and produce methane Copyright © 2021 Pearson Education Ltd. All Rights Reserved Microbial Diversity Bacteria size range – Thiomargarita (diameter of 750 μm) – Carsonella ruddii (182 genes) PCR indicates perhaps 10,000 or more bacterial species per gram of soil Many bacteria have not been identified – Have not been cultured – Are a part of complex food chains requiring the products of other bacteria Copyright © 2021 Pearson Education Ltd. All Rights Reserved