3.11: Determination of Bacterial Numbers
- Page ID
- 90988
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Plate Counts
Preparation
- sterile TSB in test tubes on hand for E. coli cultures (1 per group)
- TSA plates (4 per group)
- Sterilize:
- microcentrifuge tubes (7 per group)
- tips for pipettes (for pipettes that can dispense 990 μL and 100 μL)
- inoculate sterile TSB in test tubes with E. coli 8-16 hours before lab and incubate at 37 °C (1 per group)
Materials
- sterile microcentrifuge tubes (7 per group)
- sterile tips for pipettes (for pipettes that can dispense 990 μL and 100 μL)
- pipettes for dispensing 990 μL and 100 μL (enough for each group or for two groups to share)
- containers for used pipette tips
- 8-16 hour E. coli cultures in TSB (1 per group)
- TSA plates (4 per group)
- vortex (enough of them for groups to share)
- labeling marker (1 per group)
- spreader tools (1 per group)
- ethanol in squirt bottles
- empty petri plates (1/2 per group)
- Bunsen burners (1 per group)
- strikers (1 per group)
Absorbance Measurements
Preparation
- test tubes with 5 mL sterile TSB (4 per group)
- inoculate sterile TSB in test tubes with E. coli 8-16 hours before lab and incubate at 37 °C (1 per group) - if the plate counts are being done with the absorbance measurements, these are the same cultures used for the plate counts
Materials
- test tubes with 5 mL sterile TSB (4 per group)
- 8-16 hour E. coli cultures in TSB (1 per group)
- pipettes for transferring 5 mL (enough for each group to complete four transfers
- transfer pipettes (5 per group)
- cuvettes
- waste container for E. coli samples emptied from cuvettes
- spectrophotometer set to 600 nm (enough for two groups to share)
- labeling tape (1 per group)
- labeling marker (1 per group)
Creating a Standard Line between Plate Counts and Absorbance
Materials
- graph paper or computers with graphing software (1 per student)
- rulers (1 per student if using graph paper)