Salinity Lab

Purpose:

To find out how well Halo grows in solutions with different salt concentrations. To discover the "ideal salinity" at which halo grows.

Procedure:

Day 1:

Concentrations of Complete Media (CM): 2.3 M, 2.8 M, 3.3 M, 3.8 M, 4.3 M

1. For each concentration, add 5 mL to 4 falcon tubes using a beral pipet. (20 falcon tubes total, 5 will be controls)

2. Add 100.0 μL of Halobacterium (OD between .6 and .8) to each Falcon tube EXCEPT THE CONTROLS using a micropipet. 

3.Place inoculated, labeled Falcon tubes in incubating rack. The samples will incubate for 48 hours at 37° C & 220 rpm. (Record the date and time the samples are placed in the incubator.)

Day 2:

1. Obtain samples from the incubator.

2.Gently agitate and pour each sample from the Falcon tube into a clean, empty cuvette.

3. Measure the cell density of each sample using the spectrophotometer.

a. Set spectrophotometer reading to absorbance and the wavelength to 600 nm.

b. Use Kim wipes when handling cuvettes.

c. To zero spectrophotometer insert provided blank, press blank button and wait for zero to appear.

d. Insert cuvette with sample, record absorbance reading.

e. Repeat steps a – d for each sample.  (Run blank before each sample.)

Results:

As seen in the graph, halo had the most growth in 3.3 M Complete Media (CM); however, in the lab halo is grown in a higher salinity to prevent other organisms from growing in the CM and contaminating it.