1. Microbial Biotechnology
Lecture:5
Microbial Biotechnology

2. 2- Bacteria

3. BACTERIA
Bacteria are unicellular prokaryotic microorganisms that multiply by binary fission.
Most are helpful or harmless. But some cause disease
Bacteria can reproduce outside of the body or within the body as they cause infections
They are found everywhere on earth, in the ocean, in rocks, in volcanoes, in our bodies and in the soil

4. The size of bacteria
The size of bacteria is measured in micrometer (m) or micron () (1 micron or micrometer is one thousandth of a millimeter) and varies from 0.1  to .
Most pathogenic bacteria measure from 0.1 to 10 .

6. Bacterial Structure Chromosome: DNA material of the cell
Cell Membrane
Chromosome
Cell wall
Cytoplasm
Chromosome: DNA material of the cell
Cell wall: Composed of peptidoglycan the cell wall maintains the overall shape of a bacterial cell
Cell membrane: Lining the inside of the cell wall it provides a boundary for the contents of the cell and a barrier to substances entering and leaving.
Cytoplasm: Describes the inside of the cell and the contents

7. Bacteria can be classified according to morphology, arrangement, and staining reaction into the following groups:
1- Filamentous bacteria: Streptomyces: antibiotic producers.
2- True bacteria:
Cocci: Gram positive: Staphylococcus, Streptococcus.
` Gram negative: Neisseria.
Bacilli: Gram positive: Bacillus, Clostridum, Corynebacterium.
Gram negative: Enterobacteriaceae, Brucella.
3- Spirochetes: Slender flexuous spiral bacteria.
Borrelia, Treponema, Leptospira.
4- Mycoplasma: The Smallest bacteria that lack of a rigid cell wall.
5- Rickettsiae and Chlamydiae: intracellular parasites.

8. Structure of bacterial cells: Size, Shape, and Arrangement of bacterial cells:
Morphology and arrangement of bacterial cells are criteria used for classification of bacteria into following groups: 1. Cocci (Singular: coccus). 2. Rods (bacilli), (Singular: rod, bacillus). 3. Vibrios (Singular: vibrio). 4. Spirilla (singular :Spirillum) 5. Spirochetes. (Singular: Spirochaete).

9. Spherical (cocci) bacteria
a. Micrococci
Diplococci
Streptococci
b. Tetracocci
c. Sarcine
d. Staphylococci

10. 2. Rods (bacilli):

11. 3-Vibrios:
-These are small slightly curved rods measuring 3-4 micrometer in length by 0.5 micrometers in width.

12. 4-Spirochetes:
-These are flexible, coiled, motile organism, 6-20 micrometer in length.

13. Cell wall
In addition to conferring rigidity upon bacteria, the cell wall protects against osmotic damage.
Chemically, the rigid part of the cell wall is peptidoglycan.
First described by Hans Christian Gram in It is' used to study morphologic appearance of bacteria. Gram's stain differentiates all bacteria into two distinct groups:
a. Gram-positive organisms
b. Gram-negative organisms

15. Bacteria are classified by the Gram stain.
Gram positive bacteria appear purple after Gram staining.
Gram negative bacteria appear pink after Gram staining.

16. Gram-positive bacteria are important in industry and medicine
Many antibiotics will kill Gram-positive bacteria
Examples include
Staphylococcus aureus, Mycobacterium tuberculosis,

17. Many species of Gram negative bacteria are pathogenic (not all)
Gram-negative bacteria are often tougher to kill, resisting common antibiotics
Examples include
Escherichia coli, Haemophilus influenzae

18. Morphology of Rickettsiae.
They are minute organisms having properties in between bacteria and viruses.
It contains both DNA and RNA.
Contains enzymes for metabolic functions.
It is coccobacilli 300x600 nm in size, non-motile, non-capsulated and is Gram-negative.
Sensitive to many antibiotics.
Can multiply only inside living cells.

19. Morphology of chlamydia.
Chlamydiae are Gram-negative.
They are intracellular parasites.