PowerPoint® Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R 11 Characterizing and Classifying Prokaryotes © 2014 Pearson Education, Inc. Bacteria as Plastic Recyclers http://www.cnn.com/2016/03/11/world/b acteria-discovery-plastic/index.html http://www.the- scientist.com/?articles.view/articleNo/4 5556/title/Microbial-Recycler-Found/ © 2014 Pearson Education, Inc. 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. Figure 11.3 Binary fission. 1 Cell replicates its DNA. Cell wall Cytoplasmic Nucleoid 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 11.6 Budding Parent cell retains its identity © 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 based on rRNA sequences PHYLUM CHLOROFLEXI Size of disc = # species BACTERIA (green nonsulfur) Closer = more similiar Thermophilic PHYLUM DEINOCOCCUS-THERMUS bacteria Deeply branching bacteria GRAM-NEGATIVE BACTERIA PHYLUM PROTEOBACTERIA PHYLUM AQUIFICAE Rickettsias () Purple nonsulfur () Nitrifying () Nitrogen fixing () Myxobacteria () PHYLUM CHLOROBI Campylobacteria () (green sulfur) Gammaproteobacteria () Neisserias () PHYLUM CYANOBACTERIA PHYLUM FIBROBACTERES PHYLUM BACTEROIDETES PHYLUM CHLAMYDIAE PHYLUM SPIROCHAETES PHYLUM ARCHAEA PLANCTOMYCETES PHYLUM EURYARCHAEOTA Methanogens Low G+C Gram-positive PHYLUM PHYLUM FIRMICUTES PHYLUM FUSOBACTERIA CRENARCHAEOTA Clostridia Halophiles Mycoplasmas Selenomonas Bacilli, lactobacili, cocci Streptomyces Atopobium Arthrobacter Corynebacterium Thermophilic Mycobacterium archaea Nocardia PHYLUM ACTINOBACTERIA GRAM-POSITIVE BACTERIAHigh G+C Gram-positive © 2014 Pearson Education, Inc. Survey of Archaea • Common features • Lack true peptidoglycan • Cell membrane lipids have branched hydrocarbon chains • AUG codon codes for methionine like eukaryotes • 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. Geogemma 130 degrees 2 hrs © 2014 Pearson Education, Inc. Survey of Archaea • Extremophiles (some) • 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. Solar evaporation ponds to concentrate salt for seasoning/fertilizer production © 2014 Pearson Education, Inc. Survey of Archaea • Methanogens (obligate anaerobe) e.g. Methanopyrus • 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 – environmental importance • 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 (radiation resistant) • 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 Nitrogen fixation Oxygenic Akinete Chlorophyll a Sheath (glycocalyx) © 2014 Pearson Education, Inc. Figure 11.14 Deposits of sulfur within purple sulfur bacteria. Anoxygenic bacteriocholorphylls Reduce H2S to Sulphur Internal – purple sulphur External – green sulphur Nonsuphur types reduce organic compounds © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Survey of Bacteria • Low G + C Gram-Positive Bacteria • Similar rRNA seqs • Clostridia (1/3) • Rod-shaped, obligate anaerobes • Important in medicine (toxins) and industry (endospores) • Clostridium botulinum/tetani/perfringes/difficile © 2014 Pearson Education, Inc. Survey of Bacteria • Low G + C Gram-Positive Bacteria • Mycoplasmas (2/3) • Facultative or obligate anaerobes • Lack cell walls • Smallest free-living cells - pleomorphic • Colonize mucous membranes of the respiratory and urinary tracts © 2014 Pearson Education, Inc. Survey of Bacteria • Low G + C Gram-Positive Bacteria • Other low G + C bacilli and cocci (3/3) • 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 Bacillus thuringiensis Kills caterpillars © 2014 Pearson Education, Inc. Survey of Bacteria • Low G + C Gram-Positive Bacteria • Other low G + C bacilli and cocci (no endospores) • 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 – yogurt/buttermilk/pickle © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Survey of Bacteria • High G + C Gram-Positive Bacteria • Corynebacterium (C diptheriae) • Pleomorphic aerobes and facultative anaerobes • Produces metachromatic granules (phosphates) • Mycobacterium (M leprae/M tuberculosis) • 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. 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 (N2 to NH3) • Two genera important to agriculture • Grow in association with the roots of plants • Azospirillum • Rhizobium © 2014 Pearson Education, Inc. Figure 11.19 Nodules on pea plant roots. © 2014 Pearson Education, Inc. Figure 11.18 A prostheca. Flagellum Prostheca Attachment and increase surface area for absortion superglue © 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 Survey of Bacteria • Gram-Negative Proteobacteria • Alphaproteobacteria • Nitrifying bacteria (NH3 to NO3) • (NH3 - to NO2 - to NO3) – 2 step nitrification step • Oxidation of nitrogenous compounds provides electrons • Important in the environment and agriculture • Nitrobacter (2nd step) © 2014 Pearson Education, Inc. Survey of Bacteria • Gram-Negative Proteobacteria • Alphaproteobacteria • Pathogenic alphaproteobacteria • Rickettsia • Transmitted through bite of an arthropod (fleas/lice) • Cause several human diseases (typhus/spotted fever) • Brucella • Causes brucellosis (spontaneous abortion, sterility) © 2014 Pearson Education,