prokaryotes they’re everywhere!. references bergey’s manual of determinative bacteriology...
TRANSCRIPT
Prokaryotes
They’re Everywhere!
References
•• Bergey’s Manual of Determinative Bacteriology•Provides identification schemes for identifying bacteria and archaea
•Morphology, differential staining, biochemical tests
•• Bergey’s Manual of Systematic Bacteriology•Provides phylogenetic information on bacteria and archaea
•Based on rRNA sequencing
•• Approved Lists of Bacterial Names•Lists species of known prokaryotes
•Based on published articles
Pokaryota Overview
They’re (Almost) Everywhere! Most prokaryotes are microscopic
But what they lack in size they more than make up for in numbers
The number of prokaryotes in a single handful of fertile soil Is greater than the number of people who
have ever lived
Prokaryotes thrive almost everywhere
Including places too acidic, too salty, too cold, or too hot for most other organisms
Figure 27.1
Themes in the Diversification of Bacteria and Archaea
Morphological Diversity Metabolic Diversity
Cellular Respiration: Variation in Electron Donors and Electron Acceptors
Fermentation Photosynthesis Pathways for Fixing Carbon
NumbersTotal number alive today
5 1030
As much carbon in these cells as in all of the plants on Earth More living on a single person than number of people alive in the world
Prokaryotic Cells
Size Smallest of living cells
0.2 to 2.0 μm in diameter 2 to 8 μm in length
Most eukaryotes bigger Viruses much smaller
Two of the Three Domains
Prokaryote vs Eukaryote Overview
Prokaryote or “before nucleus” no membrane-bound
nucleus no other membrane-
bound organelles DNA not associated with
histones cell walls almost always
contain peptidoglycan 70s ribosomes Largest about size of
smallest eukaryote
Eukaryote or “true nucleus” membrane bound
nucleus many other membrane-
bound organelles DNA associated with
histones cell walls never contain
peptidoglycan 80s ribosomes Smallest about size of
largest prokaryote
BacteriaCell walls made of peptidoglycan Plasma membranes similar to those of eukaryotes Distinct ribosomes and RNA polymerase.
Archea Extreme environments
High heatHigh Salt ConcentrationHigh Acid Concentration
Call walls made of polysaccharides
unique plasma membranes
Ribosomes and RNA polymerase similar to those of eukaryotes.
Table 27.1
Major nutritional modes in prokaryotes
Oxygen (O2)
The Requirements for Growth: Chemical Requirements
obligate aerobes
Faultative
anaerobes
Obligate anaerobes
Aerotolerant anaerobes
Microaerophiles
Cyanobacteria Photosynthetic bacteria
first organisms to perform oxygenic (oxygen-producing) photosynthesis
Once oxygen was common in the oceans, aerobic respiration became possible.
Changed the Earth’s Atmosphere
From one dominated by nitrogen gas and carbon dioxide
To one dominated by nitrogen gas and oxygen.
Nitrate Pollution Use of ammonia fertilizers
serious pollution problems Releasing nitrate
by-product of bacterial ammonia metabolism
Nitrate may cause cancer decrease oxygen of aquatic systems
anaerobic “dead zones” to develop
Study of Bacteria and Archaea
Our understanding of the Bacteria and Archaea domains is advancing more rapidly now than at any time during the past 100 years—and perhaps faster than our understanding of any other lineages on the tree of life.
Enrichment Culture
•Media with specific growing conditions
• Used to isolate new bacteria and archea
Direct Sequencinga strategy for documenting the presence of bacteria and archaea that cannot be grown in culture
Direct sequencing has been used to discover a new lineage of Archaea called the Korarchaeota
Bacteria NOT Closely Related to
Archea The first lineage to diverge from the common ancestor of all living organisms was the BacteriaArchaea and Eukarya are more closely related to each other than to the Bacteria.
How the Major Clades are Related
Themes in the Diversification of Bacteria and Archaea
Bacteria and Archaea diversified Hundreds of thousands of distinct
species 3.4 billion years
Metabolic Diversity Produce ATP in different ways Obtain carbon in diverse ways
Microbial Growth and Cell Division
Increase in mass Increase in cell numbers
Mitosis in most eukaryotes Budding in yeasts Fragmentation in filamentous fungi Binary fission in bacteria and archea
Steps in Binary Fission
Chromosome replication Chromosome attachment to cell
membrane. Chromosomal segregation Septum formation
Inward movement of cell wall and cell membrane dividing daughter cells
Wall Elongation
Binary Fission
Plasmids
Figure 8.29
Conjugation
Figure 8.27a
Conjugation
Figure 8.27b
Conjugation
Figure 8.27c
Cellular Respiration
A molecule with high potential energy serves as an electron donor
is oxidized, A molecule with low potential energy serves as a final electron acceptor
is reduced Potential energy difference is converted into ATP
Exploit a Wide Variety of Electron Donors and Acceptors
Typical Bacterial Cell
Common Bacterial Shapes
Cocci - spherical Bacilli – rods
Spirillum - spiral
Other, Less Common Shapes
Vibrio – comma
Coccobacillus -
Square
Star
Common Cell arrangements
Cocci Bacilli
Bacterial Anatomy from the Outside In
Glycocalyx Appendages Cell Wall Bacterial Cell Membranes Inside the Cell
Glycocalyx Sticky substances that surround cells
Firmly attached = capsule Loosely attached = slime layer
Composition varies with species Polysaccharides Polypeptides Both
Function Protect cell from phagocytosis and dehydration Aid in attachment to various surfaces May inhibit movement of nutrients from cell
Appendages
Flagella Tail-like structures extending out from
glycocalyx Functions in movement of the bacterial
cell Complex structure
Structure of Flagella Filament
Long tail-like region Constant diameter Made of protein
Hook Filament
attachment Basal body
Small central rod inserted into a series of rings
Cell Wall
Rigid Composed mostly of peptidoglycan
Found only in bacterial cell walls Amount differs in gram+ and gram- cells
Protects cell in environments with osmotic pressures
Peptidoglycan Glycan portion
NAG N-acetylglucosamine
NAM N-acetylmuramic
acid Linked in rows of
10-65 sugars Peptide portion
Adjacent rows are linked by polypeptides
Gram+ Cell Wall
Gram – Cell Wall
Gram Stain The Gram Stain is the single most
important test in microbiology. The principal utility of the Gram Stain rests on its speed and simplicity. Most bacteria may be divided in two groups by this procedure
developed by the Danish physician Hans Christian Gram to differentiate pneumococci from Klebsiella pneumonia
difference between Gram-positive and Gram-negative bacteria is in the structure of the cell wall
ResultsG+ cocci G- rods
Websites with more samples of gram stained bacteria
GRAM STAINED IMAGES OF MEDICALLY IMPORTANT BACTERIALoyola University Medical Center
http://www.meddean.luc.edu/lumen/DeptWebs/microbio/med/gram/slides.htm
GRAM STAIN TUTORIALhttp://www.courses.ahc.umn.edu/pharmacy/5825/GSPage05.html
Atypical Cell Walls Mycoplasmas
Lack cell wall Smallest known bacteria
Archea Cell walls contain pseudomurein rather than
peptidoglycan Lacks D-amino acids found in bacteria
L-forms Tiny mutant bacteria with defective cell walls Just enough material to prevent lysis in dilute
environments
Bacteria There are at least 14 major lineages (phyla) of bacteria.
PCR indicates up to 10,000 bacteria/gm of soil. Many bacteria have not been identified or characterized because they: Haven't been cultured Need special nutrients Are part of complex food chains requiring
the products of other bacteria Need to be cultured to understand their
metabolism and ecological role
Microbial Diversity
Spirochetes
Spirochetes are distinguished by their corkscrew shape and unusual flagella
Borrelia Leptospira Treponema
Spirochaetes
Figure 11.23
Chlamidiae
Chlamydiaeare spherical and very tiny. They live as parasites inside animal cells
C. trachomatis Trachoma STD, urethritis
C. pneumoniae C. psittaci
Causes psittacosis
Chlamydiae
In Bergey's Manual, Volume 5
Figure 11.22b
In Bergey's Manual, Volume 5
Figure 11.22a
High-GC (guanine and cytosine) Gram-positive bacteria have various shapes, and many soil-dwelling species form mycelia (branched filaments)
Actinomyces Corynebacterium Frankia Gardnerella Mycobacterium Nocardia Propionibacteriu
m Streptomyces
Actinobacteria
Figure 11.20b
Cyanobacteria
Cyanobacteria dominate many marine and freshwater environments. They produce much of the oxygen and nitrogen, as well as many organic compounds, that feed other organisms in freshwater and marine environments
Cyanobacteria Oxygenic
photosynthesis Gliding motility Fix nitrogen
Low-GC Gram-positive bacteria cause a variety of diseases including anthrax, botulism, tetanus, gangrene, and strep throat. Lactobacillus is used to make yogurt.
Clostridium Endospore-
producing Obligate
anaerobes
Clostridiales
Figure 11.14 & 15
Bacillus Endospore-
producing rods
Bacillales
Figure 11.16b
Staphylococcus Cocci
Bacillales
Figure 1.17
Generally aerotolerant anaerobes, lack an electron-transport chain Lactobacillus Streptococcus Enterococcus Listeria
Lactobacillales
Figure 11.18
Wall-less, pleomorphic
0.1 - 0.24 µm M. pneumoniae
Mycoplasmatales
Figure 11.19a, b
Proteobacteria Large group
Cause Legionnaire’s disease, cholera, dysentery, and gonorrhea. Certain species can produce vinegars. Rhizobium can fix nitrogen.
Human pathogens: Bartonella B. hensela Cat-scratch disease Brucella Brucellosis
The (alpha) Proteobacteria
Wolbachia. Live in insects and other animals
The (alpha) Proteobacteria
Nitrogen-fixing bacteria: Azospirillum
Grow in soil, using nutrients excreted by plants
Fix nitrogen Rhizobium
Fix nitrogen in the roots of plants
The (alpha) Proteobacteria
Figure 27.5
Produce acetic acid from ethyl alcohol: Acetobacter Gluconobacter
The (alpha) Proteobacteria
Thiobacillus Chemoautotrophic, oxidize sulfur: H2S
SO42–
Sphaerotilus Chemoheterotophic, form sheaths
The (beta) Proteobacteria
Figure 11.5
Neisseria Chemoheterotrophic
, cocci N. meningitidis N. gonorrhoeae
Spirillum Chemoheterotrophic
, helical
The (beta) Proteobacteria
Figure 11.4 & 6
Bordetella Chemoheterotrophic, rods B. pertussis
Burkholderia. Nosocomial infections Zoogloea. Slimy masses in aerobic
sewage-treatment processes
The (beta) Proteobacteria
Pseudomonadales: Pseudomonas
Opportunistic pathogens
Metabolically diverse
Polar flagella Azotobacter and
Azomonas.
Nitrogen fixing Moraxella.
Conjunctivitis
The (gamma) Proteobacteria
Figure 11.7
Legionellales: Legionella
Found in streams, warm-water pipes, cooling towers
L. pneumophilia Coxiella
Q fever transmitted via aerosols or milk
The (gamma) Proteobacteria
Figure 24.15b
Vibrionales: Found in coastal
water Vibrio cholerae
causes cholera V. parahaemolyticus
causes gastroenteritis
The (gamma) Proteobacteria
Figure 11.8
The (gamma) Proteobacteria Enterobacteriales (enterics):
Peritrichous flagella, facultatively anaerobic Enterobacter Erwinia Escherichia Klebsiella Proteus Salmonella Serratia Shigella Yersinia
The (gamma) Proteobacteria
Bdellovibrio. Prey on other bacteria Desulfovibrionales. Use S instead of O2
as final electron acceptor Myxococcales. Gliding. Cells aggregate
to form myxospores
The (delta) Proteobacteria
The (delta) Proteobacteria
Figure 11.10a
The (delta) Proteobacteria
Figure 11.1b
Campylobacter One polar
flagellum Gastroenteritis
The (epsilon) Proteobacteria
Figure 11.1a
Helicobacter Multiple flagella Peptic ulcers Stomach cancer
The (epsilon) Proteobacteria
Figure 11.1b
Extremophiles Some archaea
Live in extreme environments Extreme thermophiles
Thrive in very hot environments hot springs at the bottom of the ocean, where
water as hot as 300°C emerges Extreme halophiles
Live in high saline environmentsMethanogens Live in swamps and marshes Produce methane as a waste product
Extremophiles Methanogens
Live in swamps and marshesProduce methane as a waste product
Low-temperature High-pressure habitats
Are of commercial interest enzymes that function at low temperature or high temperature may be useful in industrial processes
Model organisms in the search for extraterrestrial life
Extreme Halophiles
Figure 27.14
Prokaryotes play crucial roles in the biosphere
Prokaryotes are so important to the biosphere that if they were to disappear The prospects for any other life surviving would
be dim Continual recycling of chemical elements function as decomposers
Corpses, dead vegetation, and waste products Symbiotic Relationships
mutualism, commensalism, parasitism
The Nitrogen Cycle Molecular nitrogen (N2) is abundant in the atmospheremost organisms cannot use All eukaryotes and many bacteria and archaea must obtain their nitrogen from ammonia (NH3) or nitrate (NO3).
Nitrogen Metabolism
Prokaryotes can metabolize nitrogen In a variety of ways
In a process called nitrogen fixation Some prokaryotes convert atmospheric
nitrogen to ammonia Redox reactions
Nitrogen Fixing Organisms Species of cyanobacteria bacteria
Land Live in close association with plants
often in nodules
Pathogenic Prokaryotes Prokaryotes cause about half of all
human diseases Lyme disease is an example
5 µmFigure 27.16
Pathogenic Prokaryotes
Pathogenic prokaryotes typically cause disease By releasing exotoxins or endotoxins
Many pathogenic bacteria Are potential weapons of bioterrorism
Also cause other animal and plant diseases
Bioremediation Prokaryotes are the principal agents in
bioremediation The use of organisms to remove pollutants
from the environment
Figure 27.17
Bioremediation Some of the most serious pollutants in soils, rivers, and ponds
organic compounds originally used as solvents or fuels leaked or were spilled into the environment
Sediments where these types of compounds accumulate become anoxic Use bacteria and archaea to degrade pollutants
fertilizing contaminated sites to encourage the growth of
existing bacteria that degrade toxic compounds adding specific species of bacteria to contaminated sites
Prokaryotes in Research and Technology
Experiments using prokaryotes Have led to important advances in DNA
technology
Other Contributions
Prokaryotes are also major tools in Mining The synthesis of vitamins Production of antibiotics, hormones, and
other products