2. 1.Flagella curved filament made of flagellin protein: travels through hollow tube, assembles at external end. 1.polar flagellation: flagella attached at one (monopolar) or both (bipolar) ends. Ex: Pseudomonas aeruginosa 2.peritrichous flagellation: flagella attached at many sites around cell periphery. Ex: E. coli

5. Electron micrograph of pili 1.fimbriae & pili short, rigid protein rods, similar in size to flagella, but not involved in motility. function in adhesion, formation of pellicles at liquid surfaces. Function not entirely clear. Pili sometimes involved in pathogenic adhesion (e.g. gonorrhea) Sex pili in conjugation.

6. Endospores Produced by gram positive bacteria(Bacillus, Closteridia, Sporosarcinia) and Coxiella bunetii. Sporulation Occurs at the end of the log phase Germination - Activation - Initiation – Outgrowth. Properties 1- Core 2- Spore wall 3-Cortex 4- Coat 5- Exosporium

8. Centrally (left), terminally (center), and subterminally (right) located endospores. Pictures from Brock Biology of Microorganisms (lecture textbook) Endospore Pi cures

9. SPORE FORMING BACTERIA Spores from woodland pond. Image taken using a phase contrast Some G+ bacteria form resistant structures called SPORES under adverse conditions. Spores are the most RESISTANT life form known. They are able to survive boiling in water at 100 o C for long periods. Spores are resistant to UV-light, to drying and many harmful chemicals. We know spores can live for 100s of yr. and recently spores several million yr. old have been revived from insects trapped in amber. Some disease organisms like anthrax and botulism form spores that reside in the soil. The size, shape, and location of a spore in the cell are all identifying genetic characteristics.

10. Bacteria reproduce by binary fission in which one bacterial cell divides into two cells. Following elongation of the cell, a transverse cell membrane is formed and, subsequently, a new cell wall. The new transverse membrane and wall grow inward from the outer layers, a process in which the septal mesosomes are intimately involved. The nucleoid, which have doubled in number preceding the division, are distributed equally to the two daughter cells.

12. Size, and Morphology of Bacteria Size: 1 u. Some bacteria such as Chlamydia and Rickettsia are o.25 u in size. Morphology and Arrangement: - Cocci: clusters, diploes, chains, tetrads. - Bacilli - Spiral - Filamentous - Coccobacilli

14. Bacterial arrangement and Morphology

15. Staining Dye Properties Dyes used to stain bacterial cells are organic compounds, which have affinity for specific cellular components. The many types of dyes have two features in common: 1) they have chromophore groups, groups with conjugated double bonds that give the dye its color and 2) they can bind with cells by ionic, covalent, or hydrophobic bonding. Dyes also contain an auxochrome group, which in itself does not produce color but gives the dye its acidic or basic properties. Since the surfaces of bacterial cells are negatively charged such as nucleic acids and acidic polysaccharides, basic dyes are most often used in bacteriology. Acidic dyes, because of their negative charge, bind to positively charged cell structures such as proteins. Commonly used basic dyes are methylene blue, crystal violet, safranin, basic fuchsin, and malachite green. Some common acidic dyes are eosin,. rose bengal, and acid fuchsin. Basic stains have colored cation and cololess anion(stain bacteria). Acidic stains have cololess cation and colored anion(negative stain stains the background). Gram stain

16. Acid Fast Stain Differential - measures the resistance of a cell to decolorization by acids acid fastness attributed to high lipid content of the cell Important genera are Mycobacterium and actinomycetes Mycobacterium tuberculosis - causative agent of TB Mycobacterium leprae - causative agent of leprosy Staining mechanism is similar to Gram Stain Carbol fuscin will not easily rinse away in positive cells Acid alcohol is used as decolorizer Counterstain is methylene blue :Structural Stain based on differences in a structure compared to rest of cell can selectively stain one part of a bacterial cell take advantage of special property of cell structure ex. capsules are resistant to staining Examples of structural stains 1.Endospore Stain 2.Capsule Stain 3.Flagellar Stain

17. An acid fast a long filamentous organism in stain demonstrates the center that is dark red. This is typical for Nocardia

18. Fig.1: Structure of an Acid-Fast Cell Wall In addition to peptidoglycan, the acid-fast cell wall of Mycobacterium contains a large amount of glycolipids such as mycolic acid, arabinogalactan-lipid comlex, and lipoarabinomannan.

19. Acid-fast stained tissue

20. Nomenclature of Bacteria Bacteria are named according to different criteria: 1- Morphology – Staphylococcus aureus. 2- Discoverer – Brucella abortus. 3- Disease - Vibrio cholera. 4- Site – Staphylococcus epidermidis. 5- Growth requirment – Haemophilus influenzae. The first letter of the genus name is capitalized, while the first letter of the species name is not capitalized. Both the genus and the species names are underlined or written in italics. Staphylococcus aureus.

21. Classification of Bacteria According to the character of the cell wall, bacteria are classified into 1- Gram positive Eubacteria that have a cell wall. 2- Gram negative Eubacteria that have a cell wall. 3- Eubacteria lacking a cell wall. Mycoplasma pneumoniae. 4- Archaebacteria.