1. Chapter 6, part B Microbial Growth

2. Preserving Bacteria Cultures • Deep-freezing: -50°to -95°C • Lyophilization (freeze-drying): Frozen (-54° to -72°C) and dehydrated in a vacuum

3. Reproduction in Prokaryotes • Binary fission • Budding • Conidiospores (actinomycetes) • Fragmentation of filaments

4. Binary Fission Figure 6.11

5. Figure 6.12b

6. If 100 cells growing for 5 hours produced 1,720,320 cells:

7. Figure 6.13

8. Figure 6.14

9. Direct Measurements of Microbial Growth • Plate Counts: Perform serial dilutions of a sample Figure 6.15, top portion

10. Plate Count • Inoculate Petri plates from serial dilutions Figure 6.16

11. Plate Count • After incubation, count colonies on plates that have 25-250 colonies (CFUs) Figure 6.15

12. Direct Measurements of Microbial Growth • Filtration Figure 6.17a, b

13. Direct Measurements of Microbial Growth • Multiple tube MPN test • Count positive tubes and compare to statistical MPN table. Figure 6.18b

14. Direct Measurements of Microbial Growth • Direct Microscopic Count

15. Direct Measurements of Microbial Growth Figure 6.19

16. Estimating Bacterial Numbers by Indirect Methods • Turbidity Figure 620

17. Estimating Bacterial Numbers by Indirect methods • Metabolic activity • Dry weight