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PowerPoint® Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University CHAPTER 11 Characterizing and Classifying Prokaryotes © 2014 Pearson Education, Inc. General Characteristics of Prokaryotic Organisms • Prokaryotes • Most diverse group of cellular microbes • Thrive in various habitats • Only a few capable of colonizing humans and causing disease © 2014 Pearson Education, Inc. Figure 11.1 Typical prokaryotic morphologies. © 2014 Pearson Education, Inc. General Characteristics of Prokaryotic Organisms • Endospores • Produced by Gram-positive bacteria Bacillus and Clostridium • Each vegetative cell transforms into one endospore • Each endospore germinates to form one vegetative cell • Defensive strategy against unfavorable conditions • Concern to food processors, health care professionals, and governments © 2014 Pearson Education, Inc. Figure 11.2 Locations of endospores. Endospores © 2014 Pearson Education, Inc. Endospore General Characteristics of Prokaryotic Organisms • Reproduction of Prokaryotic Cells • All reproduce asexually • Three main methods • Binary fission (most common) • Snapping division • Budding © 2014 Pearson Education, Inc. Bacterial Growth: Overview PLAY © 2014 Pearson Education, Inc. Bacterial Growth: Overview Figure 11.3 Binary fission. 1 Cell replicates its DNA. Nucleoid Cell wall Cytoplasmic membrane Replicated DNA 2 The cytoplasmic membrane elongates, separating DNA molecules. 3 Cross wall forms; membrane invaginates. 4 Cross wall forms completely. 5 Daughter cells may separate. © 2014 Pearson Education, Inc. Figure 11.4 Snapping division, a variation of binary fission. Older, outer portion of cell wall Newer, inner portion of cell wall Rupture of older, outer wall Hinge © 2014 Pearson Education, Inc. Figure 11.5 Spores of actinomycetes. Spores © 2014 Pearson Education, Inc. Filamentous vegetative cells Figure 11.6 Budding. © 2014 Pearson Education, Inc. General Characteristics of Prokaryotic Organisms • Reproduction of Prokaryotic Cells • Epulopiscium and its relatives have unique method of reproduction • Live offspring emerge from the body of the dead mother cell (viviparity) • First noted case of viviparous behavior in prokaryotic world © 2014 Pearson Education, Inc. General Characteristics of Prokaryotic Organisms • Arrangements of Prokaryotic Cells • Result from two aspects of division during binary fission • Planes in which cells divide • Separation of daughter cells © 2014 Pearson Education, Inc. Figure 11.7 Arrangements of cocci. Plane of division Diplococci Streptococci Tetrads Sarcinae Staphylococci © 2014 Pearson Education, Inc. Figure 11.8 Arrangements of bacilli. Single bacillus Diplobacilli Streptobacilli Palisade V-shape © 2014 Pearson Education, Inc. Modern Prokaryotic Classification • Currently based on genetic relatedness of rRNA sequences • Three domains • Archaea • Bacteria • Eukarya © 2014 Pearson Education, Inc. Figure 11.9 Prokaryotic taxonomy. BACTERIA PHYLUM CHLOROFLEXI (green nonsulfur) Thermophilic bacteria PHYLUM DEINOCOCCUS-THERMUS Deeply branching bacteria GRAM-NEGATIVE BACTERIA PHYLUM PROTEOBACTERIA PHYLUM AQUIFICAE Purple nonsulfur () Nitrifying () Rickettsias () Nitrogen fixing () Myxobacteria () PHYLUM CHLOROBI (green sulfur) Campylobacteria () Gammaproteobacteria () Neisserias () PHYLUM CYANOBACTERIA PHYLUM FIBROBACTERES PHYLUM PHYLUM CHLAMYDIAE BACTEROIDETES PHYLUM SPIROCHAETES PHYLUM PLANCTOMYCETES Low G+C Gram-positive PHYLUM FIRMICUTES PHYLUM FUSOBACTERIA ARCHAEA PHYLUM EURYARCHAEOTA PHYLUM CRENARCHAEOTA Halophiles Clostridia Mycoplasmas Selenomonas Bacilli, lactobacili, cocci Arthrobacter Streptomyces Atopobium Corynebacterium Mycobacterium Nocardia PHYLUM ACTINOBACTERIA GRAM-POSITIVE BACTERIAHigh G+C Gram-positive © 2014 Pearson Education, Inc. Methanogens Thermophilic archaea Survey of Archaea • Common features • Lack true peptidoglycan • Cell membrane lipids have branched hydrocarbon chains • AUG codon codes for methionine • Two phyla: Crenarchaeota, Euryarchaeota • Reproduce by binary fission, budding, or fragmentation • Are cocci, bacilli, spirals, or pleomorphic • Not known to cause disease © 2014 Pearson Education, Inc. Figure 11.10 Archaea. © 2014 Pearson Education, Inc. Survey of Archaea • Extremophiles • Require extreme conditions to survive • Temperature, pH, and/or salinity • Prominent members are thermophiles and halophiles © 2014 Pearson Education, Inc. Survey of Archaea • Extremophiles • Thermophiles • DNA, RNA, cytoplasmic membranes, and proteins do not function properly below 45ºC • Hyperthermophiles – require temperatures over 80ºC • Two representative genera • Geogemma • Pyrodictium © 2014 Pearson Education, Inc. Figure 11.11 Some hyperthermophilic archaea live in hot springs. © 2014 Pearson Education, Inc. Survey of Archaea • Extremophiles • Halophiles • Inhabit extremely saline habitats • Depend on greater than 9% NaCl to maintain integrity of cell walls • Many contain red or orange pigments • May protect from sunlight • Most studied – Halobacterium salinarium © 2014 Pearson Education, Inc. Figure 11.12 The habitat of halophiles: highly saline water. © 2014 Pearson Education, Inc. Survey of Archaea • Methanogens • Largest group of archaea • Convert carbon dioxide, hydrogen gas, and organic acids to methane gas • Convert organic wastes in pond, lake, and ocean sediments to methane • Some live in colons of animals • One of primary sources of environmental methane • Have produced ~10 trillion tons of methane that is buried in mud on ocean floor © 2014 Pearson Education, Inc. Survey of Bacteria • Deeply Branching and Phototrophic Bacteria • Deeply branching bacteria • Scientists believe these organisms are similar to earliest bacteria • Autotrophic • Live in habitats similar to those thought to exist on early Earth • Aquifex • Considered to represent earliest branch of bacteria • Deinococcus • Has outer membrane similar to Gram-negatives, but stains Gram-positive © 2014 Pearson Education, Inc. Survey of Bacteria • Deeply Branching and Phototrophic Bacteria • Phototrophic bacteria • Phototrophs that contain photosynthetic lamellae • Autotrophic • Divided into five groups based on pigments and source of electrons for photosynthesis • Blue-green bacteria (cyanobacteria) • Green sulfur bacteria • Green nonsulfur bacteria • Purple sulfur bacteria • Purple nonsulfur bacteria © 2014 Pearson Education, Inc. Figure 11.13 Examples of cyanobacteria with different growth habits. Vegetative cell Heterocyst Akinete Sheath (glycocalyx) © 2014 Pearson Education, Inc. Figure 11.14 Deposits of sulfur within purple sulfur bacteria. © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Photosynthesis: Comparing Prokaryotes and Eukaryotes PLAY © 2014 Pearson Education, Inc. Photosynthesis: Comparing Prokaryotes and Eukaryotes Survey of Bacteria • Low G + C Gram-Positive Bacteria • Clostridia • Rod-shaped, obligate anaerobes • Important in medicine and industry • Microbes related to Clostridium include Epulopiscium, sulfate-reducing microbes, and Selenomonas © 2014 Pearson Education, Inc. Survey of Bacteria • Low G + C Gram-Positive Bacteria • Mycoplasmas • Facultative or obligate anaerobes • Lack cell walls • Smallest free-living cells • Colonize mucous membranes of the respiratory and urinary tracts © 2014 Pearson Education, Inc. Figure 11.15 The distinctive "fried egg" appearance of Mycoplasma colonies. © 2014 Pearson Education, Inc. Survey of Bacteria • Low G + C Gram-Positive Bacteria • Other low G + C bacilli and cocci • Bacillus • Many common in soil • Bacillus thuringiensis toxin used by farmers and gardeners as an insecticide • Bacillus anthracis causes anthrax © 2014 Pearson Education, Inc. Figure 11.16 Crystals of Bt toxin, produced by the endospore-forming Bacillus thuringiensis. Bt toxin © 2014 Pearson Education, Inc. Bacillus thuringiensis Survey of Bacteria • Low G + C Gram-Positive Bacteria • Other low G + C bacilli and cocci • Listeria • Contaminates milk and meat products • Capable of reproducing under refrigeration • Can cross the placenta in pregnant women • Lactobacillus • Grows in the body but rarely causes disease • Used in the production of various foods © 2014 Pearson Education, Inc. Survey of Bacteria • Low G + C Gram-Positive Bacteria • Other low G + C bacilli and cocci • Streptococcus and Enterococcus • Cause numerous diseases • Various strains of multi-drug-resistant streptococci • Staphylococcus • One of the most common inhabitants of humans • Produce toxins and enzymes that contribute to disease © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Survey of Bacteria • High G + C Gram-Positive Bacteria • Corynebacterium • Pleomorphic aerobes and facultative anaerobes • Produces metachromatic granules • Mycobacterium • Aerobic rods that sometimes form filaments • Slow growth partly due to mycolic acid in its cell walls • Actinomycetes • Form branching filaments resembling fungi • Important genera include Actinomyces, Nocardia, Streptomyces © 2014 Pearson Education, Inc. Figure 11.17 The branching filaments of actinomycetes. Spores © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Largest and most diverse group of bacteria • Five classes of proteobacteria • Alphaproteobacteria • Betaproteobacteria • Gammaproteobacteria • Deltaproteobacteria • Epsilonproteobacteria © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Alphaproteobacteria • Nitrogen fixers • Two genera important to agriculture • Grow in association with the roots of plants • Azospirillum • Rhizobium © 2014 Pearson Education, Inc. Figure 11.18 A prostheca. Flagellum © 2014 Pearson Education, Inc. Prostheca Figure 11.19 Nodules on pea plant roots. © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Alphaproteobacteria • Nitrifying bacteria • Oxidation of nitrogenous compounds provides electrons • Important in the environment and agriculture • Nitrobacter • Purple nonsulfur phototrophs • Grow at the bottom of lakes and ponds © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Alphaproteobacteria • Pathogenic alphaproteobacteria • Rickettsia • Transmitted through bite of an arthropod • Cause several human diseases • Brucella • Causes brucellosis © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Alphaproteobacteria • Other alphaproteobacteria • Acetobacter • Gluconobacter • Caulobacter © 2014 Pearson Education, Inc. Figure 11.20 Growth and reproduction of Caulobacter. Rock or other substrate 1 Prostheca Flagellum 2 Swarmer cell Cell doubles in size 3 4a or 4b © 2014 Pearson Education, Inc. Rosette Figure 11.21 A plant gall. © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Betaproteobacteria • Pathogenic betaproteobacteria • Neisseria • Inhabit mucous membranes of mammals • Causes numerous diseases • Bordetella • Causes pertussis • Burkholderia • Colonizes moist environmental surfaces and respiratory passages of cystic fibrosis patients © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Betaproteobacteria • Other betaproteobacteria • Thiobacillus • Recycles sulfur in the environment • Zoogloea • Form flocs that assist in the treatment of sewage • Sphaerotilus • Flocs impede flow of waste in treatment plants © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Gammaproteobacteria • Largest and most diverse class of proteobacteria • Divided into subgroups • Purple sulfur bacteria • Intracellular pathogens • Methane oxidizers • Glycolytic facultative anaerobes • Pseudomonads © 2014 Pearson Education, Inc. Figure 11.22 Purple sulfur bacteria. © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Gammaproteobacteria • Intracellular pathogens • Legionella • Causes Legionnaires' disease • Coxiella • Causes Q fever • Methane oxidizers • Use methane as a carbon and energy source • Inhabit anaerobic environments © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Gammaproteobacteria • Glycolytic facultative anaerobes • Catabolize carbohydrates by glycolysis and the pentose phosphate pathway • Divided into three families © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Gammaproteobacteria • Pseudomonads • Break down numerous organic compounds • Important pathogens of humans and animals • Pseudomonas causes urinary tract, ear, and lung infections • Azotobacter • Azomonas © 2014 Pearson Education, Inc. Figure 11.23 Two dividing Pseudomonas cells and their characteristic polar flagella. © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Deltaproteobacteria • Desulfovibrio • Bdellovibrio • Myxobacteria © 2014 Pearson Education, Inc. Figure 11.24 Bdellovibrio, a Gram-negative pathogen of other Gram-negative bacteria. Bdellovibrio Bacterial prey Cell wall 1 10 minutes Periplasmic space 2 5 10 seconds 20 minutes 3 20 minutes 4 150–210 minutes © 2014 Pearson Education, Inc. Cytoplasmic membrane Figure 11.25 Life cycle of myxobacteria. Binary fission (nutrients plentiful) 5 Myxospores germinate to form vegetative cells once nutrients are restored 1 Slime trail Vegetative cells Mounding when nutrients are depleted Myxospores 4 Sporangium Myxospores Sporangium Mound of cells 2 Formation of fruiting body 3 Fruiting body © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Epsilonproteobacteria • Campylobacter • Helicobacter © 2014 Pearson Education, Inc. Survey of Bacteria • Other Gram-Negative Bacteria • Chlamydias • Grow intracellularly in mammals, birds, and some invertebrates • Some are smaller than viruses • Most common sexually transmitted bacteria in the United States © 2014 Pearson Education, Inc. Survey of Bacteria • Other Gram-Negative Bacteria • Spirochetes • Motile bacteria that move in a corkscrew motion • Have diverse metabolism and habitats • Treponema and Borrelia both cause disease in humans © 2014 Pearson Education, Inc. Survey of Bacteria • Other Gram-Negative Bacteria • Bacteroids • Bacteroides • Inhabit digestive tracts of humans and animals • Some species cause infections • Cytophaga • Aquatic, gliding bacteria • Important in the degradation of raw sewage © 2014 Pearson Education, Inc.
