1. Classification of bacteria Mrs. Dalia Kamal Eldien MSC in Microbiology Mrs. Dalia Kamal Eldien MSC in Microbiology Lecture NO: 3

2. Questions for revision the previous lecture  What are the function of bacterial cell wall?  The movement organ in bacterial cell is ……  Define the germination process in bacteria?  What are the function of bacterial cell wall?  The movement organ in bacterial cell is ……  Define the germination process in bacteria?

3. Objectives At the end of this lecture, the student should know:-  The types of bacteria classified depending on different methods  Emphasis on morphological& staining classification

4. Introduction  Based on the difference in cellular organization and biochemistry, the kingdom protista has been divided into two groups namely prokaryotes and eukaryotes.  Bacteria and blue-green algae are prokaryotes, while fungi, other algae, fungi and parasite are eukaryotes.  Bacteria are prokaryotic microorganisms that do not contain chlorophyll.  They are unicellular and do not show true branching, except in higher bacteria like actinomycetales.

5. Classification  The bacteria are classified depending on different methods, include:-  Morphology  Staining reactions  Growth Requirements(Cultural characteristics)  Biochemical reactions  Antigenic structure  Increasingly by their genetic composition using specialized molecular biology techniques. Mrs.:Dalia Kamal Eldien MSC in microbiology

6. Morphological Classification of bacteria Bacteria are classified according to morphology in to:-  Cocci: are spherical or oval cells  Bacilli: rod shaped cells  Cocobacilli  Vibrios: comma shaped curved rods  Spiral: rigid spiral forms  Spirochetes: flexuous spiral forms Mrs.:Dalia Kamal Eldien MSC in microbiology

7. Basic shapes of bacteria  Cocci (Singular: coccus) are spherical or oval cells  Bacteria sometime show characteristic cellular arrangement or grouping Mrs.:Dalia Kamal Eldien MSC in microbiology

8.  According to the plane of cellular division, cocci may be arranged in  Pairs (diplococci)  Chains (streptococci)  Grape like clusters (staphylococci).  Groups of four (tetrads) or eight (sarcina) Mrs.:Dalia Kamal Eldien MSC in microbiology

10. Cocci in pairs

11. Cocci in cluster

12. Cocci in chain

13. Cocci in tetra

14. Cocci in sarcina

15. Basic shapes of bacteria  Bacillus (Singular: bacillus) stick-like bacteria, also name rod shaped  Bacilli are arrange in fewer groups, or singly, or in short chain Mrs.:Dalia Kamal Eldien MSC in microbiology

16. Bacilli arrangement

17. Bacilli in chain

19. Bacilli in single

20. Vibrios  Vibrios (Singular: vibrio) are small slightly curved rods, comma shape Mrs.:Dalia Kamal Eldien MSC in microbiology

21. Vibrio (Helicobacter pylori)

22. Spiral  Spiral (Singular: spirillum) are small, regularly coiled, rigid organisms Mrs.:Dalia Kamal Eldien MSC in microbiology

23. Spiral bacteria

24. Spirochetes  Spirochetes (Singular: spirochaete) have a helical shape and flexible bodies Mrs.:Dalia Kamal Eldien MSC in microbiology

25. Spirochetes

26. Identify the following bacteria structure?

27. Bacterial Classification Staining reaction  Classification according to staining reactions depend in different type of stains  The main stain is Gram stain  The Gram staining method is named after the Danish bacteriologist Hans Christian Gram (1853 – 1938) who originally devised it in 1882 (but published in 1884), to discriminate between pneumococci and Klebsiella pneumoniae bacteria in lung tissue Mrs.:Dalia Kamal Eldien MSC in microbiology

28. Principle of Gram stain  The procedure is based on the ability of microorganisms to retain color of the stains used during the gram stain reaction.  Gram-negative bacteria are decolorized by the alcohol, losing the color of the primary stain, purple.  Gram-positive bacteria are not decolorized by alcohol and will remain as purple.  After decolorization step, a counter stain is used to impart a pink color to the decolorized gram-negative organisms.

29. Gram stain  Gram staining consists of four components:  Primary stain (Crystal violet, methyl violet or Gentian violet)  Mordant (Gram's Iodine)  Decolourizer (ethyl alcohol, acetone or 1:1 ethanol-acetone)  Counter stain (safranin or neutral red, dilute carbol fuchsin)

30. Technique of Gram stain  Flood the slide with crystal violet solution for one minute. Wash off briefly with tap water  Flood slide with Gram's Iodine solution, and allow to act (as a mordant) for about one minute. Wash off with tap water.  Flood slide with 95% alcohol for 10 seconds and wash off with tap water. It is most important step  Flood slide with safranin solution and allow to counterstain for 30 seconds. Wash off with tap water  All slides of bacteria must be examined under the oil immersion lens of light microscope

31. Set of Gram stain

32. Results of Gram stain  The results of Gram stain will depend on the cell wall  Gram-positive bacteria have a thick mesh-like cell wall which is made up of peptidoglycan (50-90% of cell wall), so it stains as violet.  Gram-negative bacteria have a thinner layer of peptidoglycan (10% of the cell wall) and lose the crystal violet-iodine complex during decolorization with the alcohol rinse, but retain the counter stain Safranin, so it stains as red

33. Cell wall of Gram positive& negative bacteria

34. Classification of bacteria according to Gram stain  According to Gram stain, bacteria classify into large groups:-  Gram-positive bacteria (violet color)  Gram-negative bacteria (red color)

35. Gram-positive bacteria

36. Gram-negative bacteria

37. Identify ???