Archaebacteria and Archaebacteria and EubacteriaEubacteria

Sarita BhatiaDepartment of Botany,DAVCG, Yamunanagar.

Bacteria are of Bacteria are of immense immense importance importance because of their because of their rapid growth, rapid growth, reproduction, and reproduction, and mutation rates, as mutation rates, as well as, their ability well as, their ability to exist under to exist under adverse conditions. adverse conditions.

The oldest fossils The oldest fossils known, nearly 3.5 known, nearly 3.5 billion years old, are billion years old, are fossils of bacteria-fossils of bacteria-like organisms.like organisms.

Bacteria can be autotrophs or Bacteria can be autotrophs or hetertrophs.hetertrophs.

Those that are classified as Those that are classified as autotrophs autotrophs are either photosynthetic, obtaining are either photosynthetic, obtaining energy from sunlight or energy from sunlight or chemosynthetic, breaking down chemosynthetic, breaking down inorganic substances for energyinorganic substances for energy . .

Bacteria classified as Bacteria classified as heterotrophs derive heterotrophs derive energy from breaking energy from breaking down complex organic down complex organic compoundscompounds in the in the environment. This environment. This includes includes saprobessaprobes, , bacteria that feed on bacteria that feed on decaying material and decaying material and organic wastesorganic wastes, as well , as well as those that live as as those that live as parasites, absorbing parasites, absorbing nutrients from living nutrients from living organisms.organisms.

Depending on the Depending on the species, bacteria species, bacteria can be can be aerobicaerobic which means they which means they require oxygen to require oxygen to livelive

or or

anaerobic anaerobic which which means oxygen is means oxygen is deadly to them.deadly to them.

Green patches are green sulfur bacteria.  The rust patches are colonies of purple non sulfur bacteria.  The red patches are purple sulfur bacteria.

ArchaebacteriaArchaebacteria

MethanogensMethanogens These Archebacteria are These Archebacteria are anaerobes. They make anaerobes. They make methane (natural gas) as methane (natural gas) as a waste product. They a waste product. They are found in swamp are found in swamp sediments, sewage, and sediments, sewage, and in buried landfills. In the in buried landfills. In the future, they could be future, they could be used to produce methane used to produce methane as a byproduct of sewage as a byproduct of sewage treatment or landfill treatment or landfill operation.operation.

HalophilesHalophilesThese are salt-loving Archaebacteria that These are salt-loving Archaebacteria that grow in places like the Great Salt Lake of grow in places like the Great Salt Lake of Utah or salt ponds on the edge of San Utah or salt ponds on the edge of San Francisco Bay. Large numbers of certain Francisco Bay. Large numbers of certain halophiles can turn these waters a dark halophiles can turn these waters a dark pink. Pink halophiles contain a pigment very pink. Pink halophiles contain a pigment very similar to the rhodopsin in the human retina. similar to the rhodopsin in the human retina. They use this visual pigment for a type of They use this visual pigment for a type of photosynthesis that does not produce photosynthesis that does not produce oxygen. Halophiles are aerobes, however, oxygen. Halophiles are aerobes, however, and perform aerobic respiration.and perform aerobic respiration.

Extreme halophiles can live in extremely salty environments. Most are photosynthetic autotrophs. The photosynthesizers in this category are purple because instead of using chlorophyll to photosynthesize, they use a similar pigment called bacteriorhodopsin that uses all light except for purple light, making the cells appear purple.

ThermophilesThermophilesThese are Archaebacteria from hot springs These are Archaebacteria from hot springs and other high temperature environments. and other high temperature environments. Some can grow above the boiling Some can grow above the boiling temperature of water. They are anaerobes, temperature of water. They are anaerobes, performing anaerobic respiration. performing anaerobic respiration.

Thermophiles are interesting because they Thermophiles are interesting because they contain genes for heat-stable enzymes that contain genes for heat-stable enzymes that may be of great value in industry and may be of great value in industry and medicine. An example is taq polymerase, medicine. An example is taq polymerase, the gene for which was isolated from a the gene for which was isolated from a collection of collection of Thermus aquaticusThermus aquaticus in a in a Yellowstone Park hot spring. Taq polymerase Yellowstone Park hot spring. Taq polymerase is used to make large numbers of copies of is used to make large numbers of copies of DNA sequences in a DNA sample. It is DNA sequences in a DNA sample. It is invaluable to medicine, biotechnology, and invaluable to medicine, biotechnology, and biological research. Annual sales of taq biological research. Annual sales of taq polymerase are roughly half a billion dollars.polymerase are roughly half a billion dollars.

EubacteriaEubacteria

CyanobacteriaCyanobacteriaThis is a group of bacteria This is a group of bacteria that includes some that that includes some that are single cells and some are single cells and some that are chains of cells. that are chains of cells. You may have seen them You may have seen them as "green slime" in your as "green slime" in your aquarium or in a pond. aquarium or in a pond.

CyanobacteriaCyanobacteria can do can do "modern photosynthesis", "modern photosynthesis", which is the kind that which is the kind that makes oxygen from makes oxygen from water. All plants do this water. All plants do this kind of photosynthesis kind of photosynthesis and inherited the ability and inherited the ability from the cyanobacteria. from the cyanobacteria.

Cyanobacteria were the first organisms on Cyanobacteria were the first organisms on Earth to do modern photosynthesis and they Earth to do modern photosynthesis and they made the first oxygen in the Earth's made the first oxygen in the Earth's atmosphereatmosphere..

Bacteria are often Bacteria are often maligned as the maligned as the causes of human causes of human and animal disease. and animal disease. However, certain However, certain bacteria, the bacteria, the actinomycetes, actinomycetes, produce antibiotics produce antibiotics such as such as streptomycin and streptomycin and nocardicin. nocardicin.

Other Bacteria live symbiotically in Other Bacteria live symbiotically in the guts of animals or elsewhere in the guts of animals or elsewhere in their bodies.their bodies.

For example, bacteria in your gut For example, bacteria in your gut produce vitamin K which is essential produce vitamin K which is essential to blood clot formation.to blood clot formation.

Still other Bacteria Still other Bacteria live on the roots of live on the roots of certain plants, certain plants, converting nitrogen converting nitrogen into a usable form.into a usable form.

Bacteria put the Bacteria put the tang in yogurt and tang in yogurt and the sour in the sour in sourdough bread.sourdough bread.

Saprobes help to Saprobes help to break down dead break down dead organic matter.organic matter.

Bacteria make up Bacteria make up the base of the food the base of the food web in many web in many environments.environments. Streptococcus thermophilus in yogurt

Bacteria are prokaryotic and unicellular.Bacteria are prokaryotic and unicellular.

Bacteria have cell walls.Bacteria have cell walls.

Bacteria have circular DNA called Bacteria have circular DNA called plasmidsplasmids

Bacteria can be anaerobes or aerobes.Bacteria can be anaerobes or aerobes.

Bacteria are heterotrophs or autotrophs.Bacteria are heterotrophs or autotrophs.

Bacteria are awesome!Bacteria are awesome!

Bacteria can reproduce Bacteria can reproduce sexuallysexually by by conjugationconjugation or or asexuallyasexually by by binary fissionbinary fission..

EndosporeEndospore

Bacteria can Bacteria can survive survive unfavorable unfavorable conditions by conditions by producing an producing an endosporeendospore..

Shapes of BacteriaShapes of Bacteria

Penicillin, an antibiotic, comes from molds of the genus Penicillium Notice the area of inhibition around the Penicillium.

Penicillin kills bacteria by making holes in their Penicillin kills bacteria by making holes in their cell cell walls. Unfortunately, many bacteria have . Unfortunately, many bacteria have developed resistance to this antibiotic.developed resistance to this antibiotic.

The The Gram stainGram stain, which divides most , which divides most clinically significant bacteria into two clinically significant bacteria into two main groups, is the first step in main groups, is the first step in bacterial identification. bacterial identification. 

Bacteria stained Bacteria stained purple are Gram + purple are Gram + - - their cell walls have thick petidoglycan their cell walls have thick petidoglycan and teichoic acid. and teichoic acid.

Bacteria stained Bacteria stained pink are Gram – pink are Gram – their their cell walls have have thin peptidoglycan cell walls have have thin peptidoglycan and lipopolysaccharides with and lipopolysaccharides with nono teichoic acid.teichoic acid.

In Gram-positive bacteria, the purple crystal violet stain is trapped by the layer of peptidoglycan which forms the outer layer of the cell. In Gram-negative bacteria, the outer membrane of lipopolysaccharides prevents the stain from reaching the peptidoglycan layer. The outer membrane is then permeabilized by acetone treatment, and the pink safranin counterstain is trapped by the peptidoglycan layer.

The Gram stain has four steps:The Gram stain has four steps: 1. 1. crystal violet,crystal violet, the the primary stainprimary stain: :

followed byfollowed by

2. 2. iodineiodine, which acts as a , which acts as a mordantmordant by forming a crystal violet-iodine by forming a crystal violet-iodine complex, thencomplex, then

3. 3. alcoholalcohol, which , which decolorizesdecolorizes, , followed byfollowed by

4. 4. safraninsafranin, the , the counterstaincounterstain..

Is this gram stain positive or negative? Is this gram stain positive or negative? Identify the bacteria.Identify the bacteria.

Is this gram stain positive or negative? Is this gram stain positive or negative? Identify the bacteria.Identify the bacteria.

Gram staining tests the bacterial cell wall's Gram staining tests the bacterial cell wall's ability to retain ability to retain crystal violetcrystal violet dye during dye during solvent treatment. solvent treatment.

Safranin is added as a mordant to form the Safranin is added as a mordant to form the crystal violet/safranincrystal violet/safranin complex in order to complex in order to render the dye impossible to remove. render the dye impossible to remove.

Ethyl-alcohol solvent acts as a decolorizer Ethyl-alcohol solvent acts as a decolorizer and dissolves the lipid layer from gram-and dissolves the lipid layer from gram-negative cells. This enhances leaching of negative cells. This enhances leaching of the primary stain from the cells into the the primary stain from the cells into the surrounding solvent.surrounding solvent.

Ethyl-alcohol will dehydrate the thicker Ethyl-alcohol will dehydrate the thicker gram-positive cell walls, closing the pores gram-positive cell walls, closing the pores as the cell wall shrinks.  as the cell wall shrinks. 

For this reason, the diffusion of the crystal For this reason, the diffusion of the crystal violet-safranin staining is inhibited, so the violet-safranin staining is inhibited, so the bacteria remain stained.  bacteria remain stained.