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Bacterial culture in laboratory

Bacterial culture in laboratory. Bacterial culture in laboratory. Introduction : bacterial growth. Bacterial growth. Multiplication by binary fission: the bacteria grows and divides into two identical daughter cells .

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Bacterial culture in laboratory

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  1. Bacterialculture in laboratory

  2. Bacterialculture in laboratory Introduction : bacterial growth

  3. Bacterial growth • Multiplication by binary fission: the bacteriagrows and dividesintotwoidenticaldaughtercells. • Characterized by a generation time (G) variable depending on the species 20 minutes for Escherichia coli, Lactobacillus acidophilus for 100 minutes, 1000 minutes to Mycobacteriumtuberculosis

  4. Bacterial growth

  5. Bacterial growth After n cycles : 2n bactéria

  6. Bacterial growth For example, Escherichia coli G= 20 minutes • After 1 hour: 3 cycles : n = 23 = 8 bacteria • After 2 hours: 6 cycles : n = 26 = 64 bacteria • After 3 hours : 9 cycles : n = 29 = 512 bacteria • After 4 hours : 12 cycles: n = 212 = 4096 bacteria • After 5 hours : 15 cycles: n = 215 = 32768 bacteria • … • After 10 hours : 30 cycles : n = 230 = 1073741824 bacteria More than a billion bacteria after 10 hours of culture!

  7. Bacterialculture in laboratory Culture media and inoculation technique

  8. Culture media • Solid by adding a gelling agent (agar) to a liquid media • Liquid

  9. Bacteria Increasing the cell density during the growth After 16h of culture = turbid media Culture in liquid media Clear media

  10. After 16 - 24h : 1 bacteria  1 visible bacterial colony Bacteria Accumulation of cells during the growth Culture in solid media

  11. Inoculation technique In liquid media : In solid media (usually with Agar Petri dish) : Inoculation with pipette Spreading with a rake Ridges with a loop Inoculation with loop Ridges with a swab

  12. Bacterialculture in laboratory Aseptic conditions in lab

  13. Aseptic conditions in lab Problem 2 : Bacteria can contaminate the technician Problem 1 : Bacteria from environment can contaminate the preparation Bacteria to study… Problem 3 : Technician can contaminate the preparation Need a sterile zone around the preparation !!

  14. Aseptic conditions in lab Equipment to create a sterile area to work… Microbiological Safety Cabinet : System which uses an HEPA filter (High Efficiency Particulate Air) to generate a flow of sterile air  Protection for the preparation and the technician

  15. Aseptic conditions in lab Equipment to create a sterile area to work… Bunsen Burner : Gas burner which delivers a flame at 1300°C  provides a sterile air zone near

  16. Aseptic conditions in lab Working with a Bunsen Burner : • Sterile air area : • Approximately 40 cm diameteraround the burner • This area is use to open tube or agar Petridishwithbacteria Convection air movement

  17. Aseptic conditions in lab Organization of the workspace Bunsen Burner is place in the center of the workspace and all instruments are distributed around (aerial view) : Rack tubes Bunsen Burner Box with instruments (pipettes, inoculation loops…) Trash for contaminated instruments Agar Petri dish

  18. Aseptic conditions in lab Organization of the workspace

  19. Aseptic conditions in lab Consumables materials Most microbiology labs use steriledisposable equipment : Inoculation needles and loops Volumetric pipettes Spreading rake Pipettes

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