Bacteria
What are bacteria?
Bacteria are tiny microscopic single celled organisms.
They can live on different sites. Tehse sites can be
ocean, soil and also can livein huan gut.
There are some bacteria that are harmful but mostly of
them are beneficial to humans.
They support in mmany areas. They are used in medical
and industrial zone.
Bacteria are thought to be evolved the first organism
on earth. Estimated 4 billion years ago. A gram soil can contain about 40million
bacterial cells.
Bacteria classification
Bacteria can be classified on the basis of
1.
Staining
2.
On the base of their shape.
3.
On the base of their nutrition and mode
of growth.
4.
Their flagella.
5.
Their motility.
Let’s describe these processes
Staining
There are two types of staining.
·
Gram positive
·
Gram negative
·
Acid fast staining
·
Albert’s staining
Gram positive bacteria
1.
Bacilli, clostridium, cisteria, corgnebacterium.
2.
Cocci , streptococcas ,
stephylococcas.
Gram negative
Bacilli animal source
Brucellia
Yersinia
Cocci
Neisseria meningitides
Neisseriagonorr
The primary stain in staining is crystal violet. The
mordant is iodine. The decolorizing agent is alcohol or acetone. The counterstain
is safranin.
Acid fast staining
Principle of acid fast staining. The priary stain used
will bind the cell wall to mycolic acids. The color of the AFB will be based on
the primary stain used. If we use counterstain it provides counteracting background.
Examples of acid fast bacilli
Actinomycetes
Mycobacterium tuberculosis.
Mycobacterium leprae.
Albert’s stain
Albert’s stain involves toluidine blue and malachite
green. They are highly acidic in nature so they can selectively stain acidified
basic dyes.
Malachite stains the cytoplasm while the toludin blue
stain volutine granules. The molecules are fixed with the help of
precipitation.
Example
Corynebacterium diphtheria
On the basis of shape.
Cocci
These bacteria’s are oval or spherical inn shape. These
can be arranged in pairs such as pneumococci, meningococci (chains) .
Streptococci
Clusters staphylococci.
Bacilli
These are rod shaped bacteria. There arrangements are
like
Cocco bacilli
Streptobacilli.
Comma shaped
Spirella
Spino chetes
These are slender, flexious and spiral shaped.
Acitinomytes
These are like branching filamentous. On the basis of
growth and nutrition
Oxygen requirements
Aerobic
Anaerobic
Carbon dioxide requirement
Temperature
On the basis of temperature, bacteria have different
kind which can survive in different temperatures
Psychrophiles
These grow in temperature between 0 to 20 degree centigrade.
Mesophiles
These can grow between 25 to 40 degree centigrade.
Thermophiles
These can grow within 55 to 80 degree centigrade.
pH
ph is also can an important factor.
Acidophile
These can grow in acidic ph which is below 4.
Alkaliphile
These can grow at alkaline ph which is 8.2 to 8.9.
Neutrophile
These can grow at neutral ph which is 7.2 to 7.6
Light
Photoautotrophs
These bacteria make their own food by using the
sunlight.
Chemoautrophs
These bacteria uses chemical, reactions to make energy
resources
0 Comments