Characterizing and Classifying prokaryotes chapter 11

Prokaryotes Most diverse group of organisms Habitats All possible habitats are exploited by some sort of prokaryote Only a few capable of colonizing humans and causing disease

Morphology of Prokaryotic Cells Figure 11.1

Arrangements of Prokaryotic Cells Result from two aspects of division during binary fission Planes in which cells divide Separation of daughter cells

Arrangements of Cocci: Diplococci Figure 11.6a

Arrangements of Cocci: Streptococci Figure 11.6b

Arrangements of Cocci: Tetrads Figure 11.6c

Arrangements of Cocci: Staphylococci Figure 11.6e

Arrangements of Bacilli: Single Bacillus Figure 11.7a

Arrangements of Bacilli: Diplobacilli Figure 11.7b

Arrangements of Bacilli: Streptobacilli Figure 11.7c

Arrangements of Bacilli: V-Shape and Palisade Figure 11.7d

Endospores Produced by Gram-positive bacteria Bacillus and Clostridium are examples Each vegetative cell transforms into one endospore Each endospore germinates to form one vegetative cell Constitute a defensive strategy against hostile or unfavorable conditions Endospores are not reproductive structures

Modern Prokaryotic Classification Three domains of Life Archaea (prokaryote) Bacteria (prokaryote) Eukarya (eukaryote)

Archaea

Features of Archaea Prokaryotes (no membrane bound nucleus) Lack Peptidoglycan in their cell walls Genome is circular DNA Histone proteins are present Ribosomes are more similar to bacteria than eukaryotes Many occupy "extreme' environments. Extremophiles Not known to cause disease in humans or animals

Halophiles Inhabit extremely saline habitats Depend on greater than 9% NaCl to maintain integrity of cell walls Many contain red or orange pigments; protection from visible and UV light Extreme Halophiles… require very high salt (not just tolerant) Most require at least 9 % NaCl Most require 12-23% NaCl for optimal growth Almost all can grow at 32% NaCl Most studied – Halobacterium salinarium

Extreme Halophiles Great salt lake Seawater evaporation ponds African “soda lake” high alkalinity, high salinity SEM of halophiles

Methanogens Convert carbon dioxide, hydrogen gas, and organic acids to methane gas Largest group of archaea Convert organic wastes in pond, lake, and ocean sediments to methane Some live in colons of animals; are one of primary sources of environmental methane

Methanogens CH4 (methane producers) Strict anaerobes Example genus: Methanococcus

Methanogens Methanogen habitats

Hyperthermophiles Most are obligate anaerobes Most require S as part of their metabolic scheme Example Genera: Sulfolobus Thermococcus Pyrolobus Hyperthermophiles – require temperatures over 80ºC Heat stable biomolecules

Hyperthermophile Habitats

Bacterial groups

Phototrophic Bacteria Photoautotrophs Five groups … (often grouped by color) Blue-green bacteria (cyanobacteria) Chlorophyll a (oxygenic photosynthesis) Green sulfur bacteria bacteriochlorophyll Green nonsulfur bacteria “ Purple sulfur bacteria “ Purple nonsulfur bacteria “

Phototrophic Bacteria Table 11.1

Low G + C Gram-Positive Bacteria Clostridia Mycoplasma Bacillus Listeria Lactobacillus Streptococcus Staphylococcus

High G + C Gram-Positive Bacteria Includes rod-shaped cells and filamentous bacteria Corynebacterium Mycobacterium Actinomycetes Actinomyces Nocardia Streptomyces

Actinomycetes Figure 11.17

Gram-Negative Proteobacteria Largest and most diverse group of bacteria More diseases are caused by this group than any other. Five distinct classes Alphaproteobacteria Betaproteobacteria Gammaproteobacteria Deltaproteobacteria Epsilonproteobacteria

Alphaproteobacteria Nitrogen fixers Nitrifying bacteria Azospirillum Rhizobium Nitrifying bacteria Nitrobacter Purple nonsulfur phototrophs Pathogenic alphaproteobacteria Rickettsia Brucella Ehrlichia Caulobacter

Betaproteobacteria Pathogenic betaproteobacteria Neisseria Bordetella Nonpathogenic betaproteobacteria Thiobacillus Spirillum

Gammaproteobacteria Purple sulfur bacteria Intracellular pathogens Legionella Coxiella Methane oxidizers Facultative anaerobes Family Enterobacteriaceae Pseudomonads Pseudomonas Azotobacter Azomonas

Deltaproteobacteria Bdellovibrio Myxobacteria

Epsilonproteobacteria Campylobacter Helicobacter

Other Gram-Negative Bacteria Chlamydias Chlamydia Spirochetes Treponema Borrelia Bacteroids Bacteroides