© 2012 Pearson Education Inc. Lecture prepared by Mindy Miller-Kittrell North Carolina State University Chapter 11 Characterizing and Classifying Prokaryotes

General Characteristics of Prokaryotic Organisms Prokaryotes –Most diverse group of cellular microbes –Habitats –From Antarctic glaciers to thermal hot springs –From colons of animals to cytoplasm of other prokaryotes –From distilled water to supersaturated brine –From disinfectant solutions to basalt rocks –Only a few capable of colonizing humans and causing disease © 2012 Pearson Education Inc.

Figure 11.1 Typical prokaryotic morphologies Coccus Coccobacillus Bacillus Vibrio Spirillum Spirochete Pleomorphic

General Characteristics of Prokaryotic Organisms Reproduction of Prokaryotic Cells –All reproduce asexually –Three main methods –Binary fission (most common) –Snapping division –Budding © 2012 Pearson Education Inc.

General Characteristics of Prokaryotic Organisms © 2012 Pearson Education Inc. ANIMATION Bacterial Growth: Overview

Figure 11.2 Binary fission Cell replicates its DNA. Nucleoid Cell wall Cytoplasmic membrane Replicated DNA The cytoplasmic membrane elongates, separating DNA molecules. Cross wall forms; membrane invaginates. Cross wall forms completely. Daughter cells may separate.

Figure 11.3 Snapping division-overview

Figure 11.4 Actinomycetes spores Spores

Figure 11.5 Budding DNA is replicated One daughter DNA molecule is moved into bud Young bud Daughter cell

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 –First noted case of viviparity in prokaryotic world © 2012 Pearson Education Inc.

General Characteristics of Prokaryotic Organisms Arrangement of Prokaryotic Cells –Result from two aspects of division during binary fission –Planes in which cells divide –Separation of daughter cells © 2012 Pearson Education Inc.

Figure 11.6 Arrangements of cocci-overview

Figure 11.7 Arrangements of bacilli-overview

General Characteristics of Prokaryotic Organisms Endospores –Produced by Gram-positive 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 © 2012 Pearson Education Inc.

Figure 11.8 Locations of endospores-overview

Modern Prokaryotic Classification Currently based on genetic relatedness of rRNA sequences Three domains –Archaea –Bacteria –Eukarya © 2012 Pearson Education Inc.

Figure 11.9 Prokaryotic taxonomy PHYLUM CHLOROFLEXI (green nonsulfur) Thermophilic bacteria PHYLUM DEINOCOCCUS-THERMUS Deeply branching bacteria PHYLUM AQUIFICAE GRAM-NEGATIVE BACTERIA PHYLUM PROTEOBACTERIA Rickettsias (  ) Rhodospirilla (  ) (purple nonsulfur) Rhizobium (  ) Nitrifying (  ) Myzobacteria (  ) Campylobacteria (  ) Pseudomonads (  ) PHYLUM CHLOROBI (green sulfur) Neisserias (  ) PHYLUM BACTEROIDETES PHYLUM FIBROBACTERES PHYLUM CHLAMYDIAE PHYLUM SPIROCHAETES PHYLUM PLANCTOMYCETES PHYLUM CYANOBACTERIA BACTERIA ARCHAEA PHYLUM FUSOBACTERIAPHYLUM FIRMICUTES Clostridia Mycoplasmas Bacilli-Lactobacilli Arthrobacter Streptomyces Atopobium Corynebacterium Mycobacterium Nocardia PHYLUM ACTINOBACTERIA GRAM-POSITIVE BACTERIA High G+C Gram-positive PHYLUM KORARCHAEOTA PHYLUM EURYARCHAEOTA PHYLUM CRENARCHAEOTA Thermophilic archaea Methanogens Halophiles

Survey of Archaea Common features –Lack true peptidoglycan –Cell membrane lipids have branched hydrocarbon chains –AUG codon codes for methionine Three phyla: Crenarchaeota, Euryarchaeota, Korarchaeota Reproduce by binary fission, budding, or fragmentation Most are cocci, bacilli, or spiral forms; pleomorphic forms exist Not known to cause disease © 2012 Pearson Education Inc.

Figure Archaea-overview

Survey of Archaea Extremophiles –Require extreme conditions to survive –Temperature, pH, and/or salinity –Prominent members are thermophiles and halophiles © 2012 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 © 2012 Pearson Education Inc.

Figure Orange archaea in Yellowstone National Park

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 visible and UV light –Most studied – Halobacterium salinarium © 2012 Pearson Education Inc.

Figure The habitat of halophiles: highly saline water

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 –Produced ~10 trillion tons of methane buried on ocean floor © 2012 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 –Outer membrane similar to Gram-negatives but stains Gram-positive © 2012 Pearson Education Inc.

Survey of Bacteria Deeply Branching and Phototrophic Bacteria –Phototrophic bacteria –Phototrophs that contain photosynthetic lamellae –Autotrophic –Divided into five groups –Blue-green bacteria (cyanobacteria) –Green sulfur bacteria –Green nonsulfur bacteria –Purple sulfur bacteria –Purple nonsulfur bacteria © 2012 Pearson Education Inc.

Figure Cyanobacteria-overview

Figure Deposits of sulfur within purple sulfur bacteria

Survey of Bacteria © 2012 Pearson Education Inc. ANIMATION 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 sulfate-reducing microbes and Veillonella © 2012 Pearson Education Inc.

Survey of Bacteria Low G+C Gram-Positive Bacteria –Mycoplasmas –Facultative or obligate anaerobes –Lack cell walls –Smallest free-living cells © 2012 Pearson Education Inc.

Figure The distinctive "fried egg" appearance of Mycoplasma colonies

Survey of Bacteria Low G+C Gram-Positive Bacteria –Low G+C bacilli and cocci –Bacillus–many common in soil –Listeria–contaminates milk and meat products –Lactobacillus–grows in the body but rarely causes disease –Streptococcus and Enterococcus–cause numerous diseases –Staphylococcus–one of the most common inhabitants of humans © 2012 Pearson Education Inc.

Figure Crystals of Bt toxin, produced by the endospore-forming Bacillus thuringiensis Bt toxinBacillus thuringiensis

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 © 2012 Pearson Education Inc.

Figure The branching filaments of actinomycetes

Survey of Bacteria Gram-Negative Proteobacteria –Largest and most diverse group of bacteria –Many have extensions called prosthecae –Used for attachment and to increase surface area for nutrient absorption © 2012 Pearson Education Inc.

Figure A prostheca Prostheca

Survey of Bacteria Gram-Negative Proteobacteria –Alphaproteobacteria –Nitrogen fixers –Azospirillum –Rhizobium –Rhodopseudomonas –Nitrifying bacteria –Nitrobacter –Purple nonsulfur phototrophs © 2012 Pearson Education Inc.

Figure Nodules on pea roots

Survey of Bacteria Gram-Negative Proteobacteria –Alphaproteobacteria –Pathogenic alphaproteobacteria –Rickettsia –Brucella –Other alphaproteobacteria –Acetobacter –Gluconobacter –Caulobacter © 2012 Pearson Education Inc.

Figure Growth and reproduction of Caulobacter Rock or other substrate Prostheca Flagellum Swarmer cell Cell doubles in size or Rosette

Figure A plant gall

Survey of Bacteria Gram-Negative Proteobacteria –Betaproteobacteria –Pathogenic betaproteobacteria –Neisseria –Bordetella –Burkholderia –Nonpathogenic betaproteobacteria –Thiobacillus –Zoogloea –Sphaerotilus © 2012 Pearson Education Inc.

Survey of Bacteria Gram-Negative Proteobacteria –Gammaproteobacteria –Purple sulfur bacteria –Intracellular pathogens –Legionella –Coxiella –Methane oxidizers –Glycolytic facultative anaerobes –Family Enterobacteriaceae –Pseudomonads –Pseudomonas –Azotobacter –Azomonas © 2012 Pearson Education Inc.

Figure Purple sulfur bacteria

Figure Two dividing Pseudomonas cells and their characteristic polar flagella

Survey of Bacteria Gram-Negative Proteobacteria –Deltaproteobacteria –Desulfovibrio –Bdellovibrio –Myxobacteria © 2012 Pearson Education Inc.

Figure Bdellovibrio, a Gram-negative pathogen of other Gram-negative bacteria-overview

Figure Myxobacteria-overview

Survey of Bacteria Gram-Negative Proteobacteria –Epsilonproteobacteria –Campylobacter –Helicobacter © 2012 Pearson Education Inc.

Survey of Bacteria Other Gram-Negative Bacteria –Chlamydias –Chlamydia –Spirochetes –Treponema –Borrelia –Bacteroids –Bacteroides –Cytophaga © 2012 Pearson Education Inc.