Characterizing and Classifying Prokaryotes

Transcription

1 CSLO2. Provide examples of the impact of microorganisms on agriculture, environment, ecosystem, energy, and human health, including biofilms. CSLO5. Describe evidence for the evolution of cells, organelles and major metabolic pathways from early prokaryotes and how phylogenetic trees reflect evolutionary relationships. PowerPoint Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R 11 Characterizing and Classifying Prokaryotes

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3 amazing bacteria do amazing things Found/ Important Environmental Role of Microorganisms Act as Recyclers of Nature - Recycling of chemicals (carbon, nitrogen, and sulfur) 1406 CONCEPT 11.1

4 Recycling capability can be used for our benefit Bioremediation uses living bacteria, fungi, and algae to detoxify polluted environments FACT 11.1 Kill the Spill

5 How do Prokaryotic Organisms Reproduce? All reproduce asexually using one of 3 methods 1) Binary fission (most common) 2) Snapping division 3) Budding CONCEPT 11.2

6 2) Snapping division - a variation of binary fission. Older, outer portion of cell wall Corynebacterium Newer, inner portion of cell wall Rupture of older, outer wall palisades is bacterial arrangements which is the result of snapping division Hinge CONCEPT 11.2

7 3) Budding - Parent cell retains its identity daughter cell Is smaller CONCEPT 11.2

8 cause of shape is because of shape of cell wall CONCEPT 11.3 Morphology = coccus Arrangement = streptococcus cause of arrangement is because of two aspects of division during binary fission 1) Planes in which cells divide 2) Separation of daughter cells

9 Figure 11.7 Arrangements of cocci. Plane of division Diplococci CONCEPT ) Planes in which cells divide Streptococci Tetrads 2) Separation of cells Sarcinae Staphylococci

10 Figure 11.8 Arrangements of bacilli. CONCEPT 11.3 Single bacillus Corynebacterium Diplobacilli Streptobacilli palisades is bacterial arrangements of bacilli which is the result of snapping division Palisade V-shape

11 Modern Prokaryotic Classification CONCEPT 11.4 Classification based on genetic relatedness of ribosomal RNA sequences Three domains Archaea Bacteria Eukarya

12 Figure 11.9 Prokaryotic taxonomy based on rrna sequences BACTERIA PHYLUM CHLOROFLEXI (green nonsulfur) CONCEPT 11.4 Thermophilic bacteria PHYLUM DEINOCOCCUS-THERMUS Deeply branching bacteria GRAM-NEGATIVE BACTERIA Rickettsias ( ) PHYLUM CHLOROBI (green sulfur) PHYLUM BACTEROIDETES PHYLUM PLANCTOMYCETES Low G+C Gram-positive PHYLUM PROTEOBACTERIA PHYLUM FIRMICUTES Mycoplasmas Nitrogen fixing ( ) Clostridia Purple nonsulfur ( ) Nitrifying ( ) Myxobacteria ( ) Campylobacteria ( ) Gammaproteobacteria ( ) Neisserias ( ) PHYLUM FIBROBACTERES PHYLUM CHLAMYDIAE PHYLUM SPIROCHAETES PHYLUM FUSOBACTERIA PHYLUM AQUIFICAE How to read the chart Size of disc = # species Closer = more similar PHYLUM CYANOBACTERIA evolutionarily ARCHAEA PHYLUM CRENARCHAEOTA PHYLUM EURYARCHAEOTA Methanogens Halophiles Bacilli, lactobacili, cocci Streptomyces Atopobium Arthrobacter Corynebacterium Mycobacterium Nocardia PHYLUM ACTINOBACTERIA GRAM-POSITIVE BACTERIAHigh G+C Gram-positive Selenomonas Thermophilic archaea

13 Classification of Archaea CONCEPT ) Common features 1) Lack true peptidoglycan 2) Genetic code similar to eukaryotes - AUG codon codes for methionine like eukaryotes 2) Two phyla: Crenarchaeota, Euryarchaeota Reproduce by binary fission, budding, or fragmentation Are cocci, bacilli, spirals, or pleomorphic Not known to cause disease

14 Survey of Archaea CONCEPT 11.6 A) Extremophiles - Require extreme conditions to survive A1) Thermophiles and Hyperthermophiles (over 80ºC) DNA, RNA, cytoplasmic membranes, and proteins do not function properly below 45ºC Pyrodictium

15 Figure Some hyperthermophilic archaea live in hot springs.

16 Classification of Archaea A2) Halophiles CONCEPT 11.7 Inhabit extremely saline habitats Require greater than 9% NaCl to maintain integrity of cell walls Most studied Halobacterium salinarium Many contain red or orange pigments (may protect from sunlight)

17 Classification of Archaea CONCEPT 11.8 B) Methanogens (obligate anaerobe) e.g. Methanopyrus 1) Largest group of archaea 2) Convert carbon dioxide, hydrogen gas, and organic acids to methane gas economic importance 3) Convert organic wastes in pond, lake, and ocean sediments to methane gas environmental importance 4) 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

18 Methanogens (obligate anaerobe) Where do you find them? Carbon dioxide Methane

19 4) Some live in colons of animals - one of primary sources of environmental methane 5) also used for gas production

20 Classification of Bacteria

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22 Classification of Bacteria CONCEPT ) Deeply Branching and 2) Phototrophic Bacteria 1) Deeply branching bacteria Autotrophic Scientists believe these organisms are similar to earliest bacteria Live in habitats similar to those thought to exist on early Earth e.g. Aquifex Considered to represent earliest branch of bacteria

23 Aquifex Considered to represent earliest branch of bacteria

24 Classification of Bacteria 2) Phototrophic bacteria CONCEPT Autotrophic - contain photosynthetic lamellae 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

25 Function of Bacterial Cytoplasmic Membranes FACT ) Energy storage Harvest light energy in photosynthetic bacteria cytoplasmic membrane infoldings cyanobacteria Purple Sulphur bacteria

26 Oxygenic Photosynthesis Electron Donor is Water oxygen (uses Chlorophyll a Same as in plants) Figure cyanobacteria CONCEPT Vegetative cell Heterocyst Nitrogen fixation Akinete FACT 11.2 Figure Deposits of sulfur within purple sulfur bacteria. Anoxygenic Photosynthesis (uses bacteriocholorphylls) Electron Donor is H 2 S Sulphur Sulphur types Internal storage purple sulphur External storage green sulphur Nonsulphur types Electron Donor is organic compounds

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28 Classification of Bacteria based on Analysis of nucleic acids CONCEPT 4.12 Nucleic acid sequence can be used to classify and identify microbes 1) rrna sequences domains based on it 2) Prokaryotic taxonomy also includes the G + C content of an organism's DNA

29 FACT 11.3 CONCEPT Phylum Class Low G+C High G+C

30 Classification of Bacteria CONCEPT ) Low G + C Gram-Positive Bacteria (plus Similar rrna seqs) (Fermicutes-Clostridia) Clostridium (1/3) make endospores and toxins Rod-shaped, obligate anaerobes FACT 11.4 Important in medicine and industry Clostridium botulinum/tetani/perfringes/difficile Clostridium botulinum bacteria makes powerful neurotoxin Clostridium difficile (C diff) Opportunistic pathogen Clostridium difficile colitis results from disruption of normal healthy bacteria in the colon, often from antibiotics. Symptoms include diarrhea, belly pain, and fever.

31 Classification of Bacteria CONCEPT ) Low G + C Gram-Positive Bacteria (plus Similar rrna seqs) FACT 11.5 (Fermicutes-Mollicutes) Mycoplasma (2/3) Lack cell walls - pleomorphic Colonize mucous membranes of the respiratory and urinary tracts Mycoplasma pneumoniae Smallest freeliving cells

32 Classification of Bacteria 1) Low G + C Gram-Positive Bacteria (plus Similar rrna seqs) (Fermicutes- Bacilli) Bacillus (3/3) Bacillus make endospores and toxins CONCEPT FACT 11.6 Bacillus thuringiensis toxin used by farmers and gardeners as an insecticide Bacillus anthracis produces anthrax toxin Spores used as bioweapon

33 Classification of Bacteria CONCEPT ) Low G + C Gram-Positive Bacteria (plus Similar rrna seqs) (Fermicutes- Bacilli) Listeria (3/3) Listeria Contaminates milk and meat products Capable of reproducing under refrigeration Can cross the placenta in pregnant women FACT 11.7 (Fermicutes- Bacilli) Lactobacillus (3/3) Lactobacillus Grows in the body but rarely causes disease Used in the production of various foods yogurt/buttermilk/pickle

34 Phylum Class Low G+C High G+C CONCEPT 11.12

35 Classification of Bacteria High G + C Gram-Positive Bacteria CONCEPT FACT ) Mycobacterium (M. leprae/m. tuberculosis) Aerobic rods with slow growth partly due to mycolic acid in its cell walls 2) Actinomycetes (some are sources of antibiotic) Form branching filaments resembling fungi Important genera include Actinomyces, Nocardia, Streptomyces

36 Classification of Bacteria CONCEPT Gram-Negative Proteobacteria Largest and most diverse group of bacteria Five classes of proteobacteria FACT 11.9 Alphaproteobacteria Betaproteobacteria Many contain prostheca Gammaproteobacteria Deltaproteobacteria Epsilonproteobacteria

37 Figure Growth and reproduction of Caulobacter. Rock or other substrate 1 Prostheca Flagellum CONCEPT FACT Swarmer cell Cell doubles in size 3 4a For adhesion and increase area for absorption 4b or Rosette

38 Agrobacterium Figure A plant gall.

39 Gram-Negative Proteobacteria Alphaproteobacteria CONCEPT FACT Important in the environment and agriculture 1) Nitrogen fixers (N 2 to NH 3 ) Grow in association with plant roots Azospirillum Rhizobium 2) Nitrifying bacteria (NH 3 to NO 3 ) Nitrobacter

40 Gram-Negative Proteobacteria FACT Alphaproteobacteria Pathogenic alphaproteobacteria 1) Rickettsia Transmitted through bite of an arthropod (tick/fleas) Cause several human diseases (typhus/spotted fever) 2) Brucella Causes brucellosis Source is unpasteurized dairy product, meat

41 Gram-Negative Proteobacteria Gammaproteobacteria CONCEPT FACT ) Glycolytic facultative anaerobes Catabolize carbohydrates by glycolysis and the pentose phosphate pathway Divided into three families 1) Enterobacteriacea

42 Gram-Negative Proteobacteria Gammaproteobacteria FACT ) Pseudomonads Break down numerous organic compounds Important pathogens of humans and animals Pseudomonas causes urinary tract, ear, nail and lung infections

43 Deltaproteobacteria CONCEPT Figure Bdellovibrio, a Gram-negative pathogen of other Gram-negative bacteria. 1 Bdellovibrio Bacterial prey 10 minutes Cell wall Periplasmic space vampire-bacteria seconds Cytoplasmic membrane 20 minutes minutes 3 20 minutes

44 Deltaproteobacteria Figure Life cycle of myxobacteria. CONCEPT Myxobacteria are soil-dwelling and form stalked fruiting bodies containing resistant, dormant myxospores that can survive for a decade or more before germinating and becoming vegetative cells. multicellular behavior

45 Classification of Bacteria Gram-Negative Proteobacteria FACT Epsilonproteobacteria (rods, vibrios, or spirals) Campylobacter causes blood poisoning and inflammation of the intestinal tract Helicobacter causes ulcers

46 Classification of Bacteria Other Gram-Negative Bacteria FACT Spirochetes are motile helical bacteria which move in a corkscrew motion e.g. Treponema (syphilis) and Borrelia (Lyme disease) Chlamydias Intracellular obligate parasites Grow intracellularly in mammals, birds, and some invertebrates Most common sexually transmitted bacteria in the United States

47 Classification of Bacteria Other Gram-Negative Bacteria: Bacteroids CONCEPT Treatment of sewage before release in waterways Bacteroides Inhabit digestive tracts of humans and animals Some species cause infections Cytophaga Aquatic, gliding bacteria Important in the degradation of raw sewage consume biodegradable soluble organic contaminants (e.g. sugars, fats, and organic short-chain carbon molecules from human waste, food waste etc)