Characterizing and Classifying Prokaryotes

PowerPoint® Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University

C H A P T E R 11

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/

• All reproduce asexually

• Three main methods

• Binary fission (most common)

• Snapping division

• Budding

2 The cytoplasmic membrane elongates, separating DNA molecules.

3 Cross wall forms; membrane invaginates.

4 Cross wall forms completely.

5 Daughter cells may separate.

Newer, inner portion of cell wall Rupture of older, outer wall

Hinge

• Result from two aspects of division during binary fission

• Planes in which cells divide

• Separation of daughter cells

Streptococci

Tetrads

Sarcinae

Staphylococci

Single bacillus

Diplobacilli

Streptobacilli

Palisade

V-shape

• 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 PHYLUM SPIROCHAETES 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

Geogemma 130 degrees 2 hrs

• Extremophiles (some)

• Require extreme conditions to survive

• Temperature, pH, and/or salinity

• Prominent members are thermophiles and halophiles

• Extremophiles

• Thermophiles

• DNA, RNA, cytoplasmic membranes, and proteins do not function properly below 45ºC

• Hyperthermophiles – require temperatures over 80ºC

• Two representative genera

• Geogemma

• Pyrodictium

• 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

Solar evaporation ponds to concentrate salt for seasoning/fertilizer production

• 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

• 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

• 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)

Reduce H2S to Sulphur Internal – purple sulphur External – green sulphur

Nonsuphur types reduce organic compounds

• 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

• 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

• 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

• 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

• 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

• Gram-Negative Proteobacteria

• Largest and most diverse group of bacteria

• Five classes of proteobacteria

• Alphaproteobacteria

• Betaproteobacteria

• Gammaproteobacteria

• Deltaproteobacteria

• Epsilonproteobacteria

• Gram-Negative Proteobacteria

• Alphaproteobacteria

• Nitrogen fixers (N2 to NH3) • Two genera important to agriculture

• Grow in association with the roots of plants

• Azospirillum

• Rhizobium

Attachment and increase surface area for absortion

superglue

1 Prostheca Flagellum

2 Swarmer cell

Cell doubles in size 3 4a

• 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)

• 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)

• Gram-Negative Proteobacteria

• Gammaproteobacteria

• Glycolytic facultative anaerobes

• Catabolize carbohydrates by glycolysis and the pentose phosphate pathway

• Divided into three families

• 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

• Gram-Negative Proteobacteria

• Deltaproteobacteria

• Desulfovibrio

• Bdellovibrio

• Myxobacteria

Bdellovibrio Bacterial prey

Cell wall Periplasmic 10 minutes 1 space

2 5 10 seconds Cytoplasmic membrane

20 minutes 4 3 20 minutes 150–210 minutes

Binary fission (nutrients plentiful) 1

Slime trail 5 Vegetative cells Myxospores germinate to form vegetative Mounding when cells once nutrients nutrients are are restored depleted

Myxospores

4 Sporangium

Myxospores Sporangium Mound of cells

2 Formation of fruiting body 3

Fruiting body