1. Aerobic Respiration

2. Anaerobic Respiration

3. Chemolithotrophic respiration

4. Phototrophic metabolism

5. Binary fission of bacteria

6. E.coli genome size: 4.6 x 10 6 nucleotides Generation time at optimal conditions: 20min DNA replication rate: 1000nt/s ≈ 1.2 x 10 6 nt/20min About 25% of genome can be replicated in one generation time

7. Population growth Growth rate: change of cell number per unit time When growth is unlimited, growth rate is low at first, increases logarithmically Plotted on semi-log paper, growth is a straight line Generation time: time required for one cell to grow into two cells (varies from several minutes to months) Specific growth: instantaneous change in relative cell numbers (µ) µ = ln(2)/generation time

8. Logarithmic growth

9. Batch growth stages

10. Lag and Exponential Lag phase –Longer when inoculum conditions differed –Some inocula may require synthesis –Apparent lag caused by partial death of inoculum Exponential phase –Logarithm of cell numbers increases linearly –Specific growth rate is constant—characteristic of growth conditions –Cell physiology is constant—best source for biochemical studies is late exponential phase

11. Stationary and Death Stationary phase –Culture is eventually limited by substrate or nutrient exhaustion or product accumulation –Metabolism changes to accommodate the limitation –Lysis of some cells may lead to growth in others –Cell increase equals decrease (cryptic growth) Death phase –Death is generally logarithmic, but slower than growth –Sometimes death rate changes after hours or days

12. Calculating specific growth rate

13. Counting Chamber

14. Counting cells in a chamber

15. Quantitative plating

16. Pour plates

17. Pour-plating techniques

18. Optical density

19. Continuous culture Chemostat permits independent control of population density and growth rate Dilution rate Concentration of limiting substrate Cultures can be maintained in exponential growth rate for a long time

20. Temperature effects on growth

21. Temperature groups

22. Psychrophile –maximum < 20 C –Optimum 15 C Mesophile –maximum > 20 C –optimum < 45 C Thermophile –optimum 45 to 70 C Hyperthermophile –optimum > 80 C –highest known maximum about 113° C (Pyrolobus fumarii)

23. Growth in hot springs

24. Deep-sea hydrothermal systems

25. Effect of pH on growth

26. Effect of salinity on growth

27. Growth with low water activity Terms reflecting tolerance of low water activity –Xerotolerant –Xerophilic Terms relating to tolerance of salt –Halotolerant –Halophilic Slightly (~0.5 M) Moderately (0.5 to 1.5 M) Extremely (> 1.5 M)

28. Compatible Solutes

29. Effect of Oxygen on Growth

30. Protection from Oxygen

31. Demonstration of catalase