1. Changes in bacterial traits Caused by: Changes in environmental conditions (only phenotypic changes) Changes in the genetic codes 1- Intermicrobial exchange 2- Mutations (point mutations, insertions, deletions)

2. Intermicrobial exchange Transformation (Capturing DNA from solution) Transduction (Phage-mediated) Conjugation (Bacterial Sex)

3. Original Transformation Exp. F. Griffith (1928) using pneumococci

4. DNA-Mediated Transformation

6. Intermicrobial exchanges by vectors

7. 7 Characteristics of genetic vectors must be capable of carrying a significant piece of donor DNA must be readily accepted by the host plasmids – small, well characterized, easy to manipulate & can be transferred into appropriate host cells through transformation bacteriophages – have the natural ability to inject their DNA into bacterial hosts through transduction

8. Transduction (madiated by phage)

9. Microbe Library, American Society for Microbiology www.microbelibrary.org

10. Lytic versus Lysogenic

11. Generalized Transduction

13. Transduction Types of transduction – Generalized - Transduction in which potentially any dornor bacterial gene can be transferred. – Specialized: Transduction in which only certain donor genes can be transferred.

14. Transduction (specialized)

15. Specialized Transduction (Lysogenic Phage) gal bio gal bio gal bio gal bio gal

16. Transduction Definition Types of transduction Significance – Common in Gram+ bacteria – Lysogenic (phage) conversion e.g. Corynebacterium diptheriae toxin – Toxin derived from lysogenic phage

17. Conjugation

18. Definition: Gene transfer from a donor to a recipient by direct physical contact between cells Mating types in bacteria – Donor F factor (Fertility factor) – F (sex) pilus Donor Recipient –Recipient Lacks an F factor

19. Conjugation Significance – Gram - bacteria Antibiotic resistance – Gram + bacteria Production of adhesive material by donor cells

20. Conjugation

21. Conjugation: Sex or F Pilus

22. Plasmids

23. Definition: Extrachromosomal genetic elements that are capable of autonomous replication (replicon) Episome - a plasmid that can integrate into the chromosome

24. Classification of Plasmids Transfer properties – Conjugative – Nonconjugative Phenotypic effects – Fertility – Bacteriocinogenic plasmid (or encoding some other toxins) – Resistance plasmid (R factors)

25. Structure of R Factors RTF – Conjugative plasmid – Transfer genes Tn 9 Tn 21 Tn 10 Tn 8 RTF R determinant –Resistance genes

26. Self-Transmissible R Plasmid

27. Conjugation: F Plasmid Transfer

28. Conjugation

29. F + and HFr cells Integrated (Hfr) (High Frequency of Recombination) F+F+ Hfr

30. Hfr and F’ cells Hfr F’

31. Mechanism of Hfr x F - Crosses HfrF-F- F-F- F-F- F-F-

33. Mechanism of F’ x F - Crosses F’ F-F- F-F-

34. Transposable Genetic Elements Definition: Segments of DNA that are able to move from one location to another (across the genome or from one genome to another) Properties – “Random” movement Transposase – Transposition may be accompanied by duplication

35. Types of Transposable Genetic Elements Transposons (Tn)/ Insertion elements (IS) – Definition: Elements that carry other genes in addition to those involved in transposition – Nomenclature - Tn10, IS6110 – Structure Composite Tns – Importance Antibiotic resistance Epidemiology and evolutionary studies IS Resistance Gene(s) IS Resistance Gene(s)