1. Bacteria Growth in the laboratory (in vitro)

2. Bacterial nutrition and the design of culture media Based on bacterial metabolism* Culture pH Culture oxidation- reduction petencial Gaseous requirments –Oxzgen

3. Growth of bacteria Growth of bacterial cell Growth in batch culture

4. The lag fase The exponential fase The stationary fase

5. Growth in batch culture

6. Bacterial growth on solid surface Agar media –Colony forming units –Bacterial colony

7. Environmetal conditions optimal temperature, oxygen concentration, pH, water activity

8. Oxygen concentration Aerobs Anaerobs (do not require oxygen) Obligate anaerobs (die in the presence of O) Facultative anaerobs (E.coli) Microaerophilic bacteria

9. pH Acidophiles (grow at low pH (0-5,5) Alcaliphiles (8,5-11,5) Normal (6,5-7,2)

10. Temperature ( characteristic ranges) Psychrophiles: with optimum growth T around 20 C Mesopihles: between 15 and 45 with optimum around 37 C Thermophiles: between 30 and 75 with optimum around 55 C Hyperthermophiles: T grater than 100C

11. Techniques used to study bacteria Aseptic (sterile) techniques: Sterile media To prevent contamination (accidental intorduction of unknown bacteria) Sterilisation (autoclave, flaming) Desinfection (the removal of potentially harmful microbes : B, V,

12. Baceria are grown (cultured) Growth media: Liquid (for large numbers of bcteria) Solid (for isolation of individual bacteria) Semisolid ( for demonstration of motility) Envinronmental conditions: optimal temperature, oxygen concentration, pH, water activity

13. Growth media Defined media (synthetic)- composed form defined ingredients Complex media – composed from undefined ingredients such as proteolytic digests of meat (peptons) and meat extracts –Nutrient broth, tryptic soya broth –Nutrient agar,… –Blood- an addtive to media

14. Obtaining bacterial colonies Pure culture Isolation – using method called streaking To strake bacteria on to agar plates we are using a wire (or plastic) loop

15. Selective and differential media Selective media: for selection of particular groups of bacterial pathogens ( contain inhibitors i.e. antibiotics, bile salts, dyes, which are suppressing the growth of unwonted bacteria) Differential media: for differentiation of two species or groups (lactose +, -)

16. Agar isolated from seaweed Is not degradated by bacteria Agar is melted by boiling Liquid medium can be converted into solid medium by the adition of agar (1- 2%) or semisolid medium (0,6%)

17. Colonies Shape Size Elevation Edge Surface Opacity Consistency

18. Counting of bacteria Viable counts (according of number of colonies) Turbimetric measurements Other methods (RT PCR)