Ultra structure of bacteria and nutritional requirements for growth Presentation_3.pptx

Ultra structure of bacteria
Nutritional requirements for growth of bacteria

1. Microbiology Ultra structure and morphology of bacteria nutritional requirements Ms. Ayodhya Pardhe ( M Pharmacy) Sudhakar Rao Naik institute of pharmacy Pusad

2. Contents Introduction of bacteria Classification of bacteria Ultra structure of bacteria Nutritional requirements for growth of bacteria

3. Pili or fimbriae Pili are hair like microfibrils 0.5 to 2 micrometer in length and 5to7 nm in diameter They are thinner, shorter and more numerous than flagella Present only n gram – ve bacteria Fimbriae are composed of protein known as pillin and it’s molecular weight is 18000D Fimbriae can be seen only under the electron microscope They are found on motile and nonmotile cells Fimbriae distributed over the entire surface of the cell of bacteria Each bacterium possesses 100- 200 fimbriae

4. Pili longer than fimbriae and no. Only one or two per cell They join bacterial cells in preparation for the transfer of DNA from one cell to another cell and hence called as sex pili Functions: Play major role in attachment to surfaces Sex pili used for the transfer of genetic material from donor to the recipient cell Many Fimbriated cells agglutinate red blood cells of guinea pigs, horse, pigs Fimbriae are antigenic

5. Functions of capsule Capsule protect the bacteria from antibacterial agents such as lytic enzymes They inhibit phagocytosis Provide protection against temporary drying by binding water molecules Inhibit attachment of bacteriophage Promote the stability of bacterial suspension by preventing the cells from aggregation and settling May promote attachment of bacteria to surfaces

6. Cell wall It is a rigid structure which gives definite shape to the cell Situated between the capsule and cytoplasmic membrane 10-20 nm in thick and constitutes 20-30% of dry weight of the cell Can not been seen by light microscopy and does not stain easily by different staining reagents It can demonstrated by differential staining, plasmolysis, electron microscopy and by using specific antibodies Cell wall of bacteria contain diaminopimelic acid (DAP), muramic acid and teichoic acid These substances joined together to give rise a complex polymeric structure known as peptidoglycan or mucopeptide

7. Peptidoglycan consist of three parts: a backbone composed of alternating N- acetyal glucosamine and N- acetyl muramic acid 2. A set of tetrapeptide side chains attached to N- acetyl muramic acid 3. A set of pentapeptide cross- bridges tetrapeptide side chains and pentapeptide cross- bridges vary from species to species but most commonly found side chains contain four amino acids as L- alanine, D- alanine, D- glutamic acid and diaminopimelic acid(DPA)

8. Comparison of cell walls of gram positive and gram negative bacteria Components Gram positive Gram negative Thickness Thick( 20-25nm) Thin( 10-15nm) Peptidoglycan More(50-90%) Less(5-10%) Teichoic acid Present Absent Polysaccharides Present Absent Lipids Less or absent More Cell wall Simple Complex Outer membrane and periplasmic space Absent Present Types of amino acids Few Several

9. Components Gram positive Gram negative Effect of lysozyme Easily destroy Resistance Example Bacillus anthracis , staphylococcus aureus, E. Coli, salmonella typhi , vibrio cholerae , H. Influenzae

10. Functions of cell wall Gives definite shape to cell Involved in growth and cell division of bacteria Gives protection to the internal structure and acts as supporting layer Provide attachment to complement It contains receptor sites for pages and colicin It shows resistance to the harmful effects of environment

11. Plasma membrane is thin 5-10nm layer lining the inner surface of the cell walland separating it from cytoplasm Composed of phospholipid -20-30% and proteins 60-70% Phospholipid form bilayer in which most of the proteins are tenaciously held and called integral proteins Phospholipid molecule arrange in two parallel rows called phospholipid bilayer Each phospholipid molecule contains a polar head composed of phosphate group and glycerol Nonpolar tails are in the interior of the bilayer And polar heads on the two surfaces of the phospholipid bilayer Head is a hydrophilic region Tail is a hydrophobic region

12. Functions of cell membrane Acts as semipermeable membrane controlling inflow and outflow of metabolites Provide mechanical strength to the bacterial cell Helps in DNA replication It contains the enzymes, permease which plays an important role in the passage of selective nutrients through membrane It contains the enzymes involved in the biosynthesis of membrane lipids and various other macromolecules of the bacterial cell wall

13. Nutritional requirements

14. Thank you!