{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture - Bacterial Growth

Lecture - Bacterial Growth - Goal of the bacterium is to...

Info icon This preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon
Goal of the bacterium is to become bacteria – Stan Falkow
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Growth Kinetics: Doubling time Death Kinetics: D or Z values
Image of page 2
Bacterial Growth Know your enemy: Metabolic requirements Optimum growth Inhibitory conditions Antibiotic sensitivity Mutations
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Growth Measurement Tools Direct microscopic counts Colony plate counts Turbidity Biotechnology (PCR, reporter genes, biosensors)
Image of page 4
Direct microscopic count (DMC) Hemocytometer Membrane filters Stained Cells Advantages: Fast, Simple, cheap No cultivation Disadvantages: Viability? Inaccurate: limited sample, not species-specific
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
Direct Microscopic Count (DMC) Estimate cell numbers Need > 105 CFU/ml Fluorescent dyes differentiate between live and dead cells
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Standard Plate Counts 1. Serial dilutions of sample: 1 ml into 9 ml broth/PBS 1. Spread or pour plate (100 l or 1/10 ml) 1. Count colonies (CFU=25-300) 1. Multiply by dilution factor: 45 x 105 or 4.5 x 106 1:10 10-4 1:100 10-3 10-5 10-2 10-3 10-4 10-5 10-6 6 45 750 750 45 6
Image of page 8
Turbidity Spectrophotometer: measures optical density or light scatter Dependent on wavelength (bacteria at A600) Absorbance = 1/O.D. =Proportional to cell number Pure culture or water samples (not foods) Calibrate with DMC or plate counts
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
td = Doubling time or generation time (Time required for one division) μ = specific growth rate td = ln2/ μ = 0.693/ μ μ(Δ t ) = 2.3 log10(N/ N0 ) μ=2.3 (logN - log N0) “Microbiology is the only science where multiplication and division are the same thing” – source unknown
Image of page 10
Exponential Growth: Final number of bacteria = N Initial number of bacteria = N0 Total # divisions = n N=N0 2n N=N0 e μt [ e = limit of (1+1/n)n] e μt = N/N0 [ay = x; then y= ln x] μt = ln N/N0
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 12
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern