Prokaryotes They’re Everywhere!. References Bergey’s Manual of Determinative Bacteriology...

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


Nitrogen-fixing bacteria: Azospirillum

Grow in soil, using nutrients excreted by plants

Fix nitrogen Rhizobium

Fix nitrogen in the roots of plants


Figure 27.5

Produce acetic acid from ethyl alcohol: Acetobacter Gluconobacter


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


Figure 11.4 & 6

Bordetella Chemoheterotrophic, rods B. pertussis

Burkholderia. Nosocomial infections Zoogloea. Slimy masses in aerobic

sewage-treatment processes


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


Figure 24.15b

Vibrionales: Found in coastal

water Vibrio cholerae

causes cholera V. parahaemolyticus

causes gastroenteritis


Figure 11.8

The (gamma) Proteobacteria Enterobacteriales (enterics):

Peritrichous flagella, facultatively anaerobic Enterobacter Erwinia Escherichia Klebsiella Proteus Salmonella Serratia Shigella Yersinia


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


Figure 11.10a


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

Prokaryotes They’re Everywhere!. References Bergey’s Manual of Determinative Bacteriology...

Documents

Transcript of Prokaryotes They’re Everywhere!. References Bergey’s Manual of Determinative Bacteriology...