Part: Bacteria Final viability
1. Using the lid of a sterile 1.7 ml microcentrifuge tube, transfer 2 lid full of soil from the treatment container into a test tube with 9mL of sterile water & appropriately labeled for each treatment Flick tube vigorously to mix. The soil will settle to the bottom. Perform a 1:10 dilution for each treatment tube. Transfer 1 ml of "dirty" water from the first test tube to a second test tube of 9 ml of sterile water (labeled "treatment letter & 1:10). Flick tube vigorously to mix.
a. Repeat for each treatment: A, B, & C
b. A sterile microcentrifuge tube should be used for each treatment
c. A total of 6 test tubes will be used
2. Spread plate 100 μl (0.1 ml) from each of your 6 tubes (A, A1:10, B, B1.10. C, C1:10) on to a labeled Enterobacteraceae enrichment agar plate.
3. Spread plate 100 μl (al ml) from each of your 6 tubes (A, A 1:10, B, B1:10, C, C1:10) on to a labeled R2A agar plate.
4. (optional) Spread plate 100 ul (0.1 ml) from each of your 6 tubes (A, A 1:10, B, B1:10, C, C1:10) on to a labeled R2A agar plate.
Questions
1) What is your hypothesis for the bacterial growth on each agar plate?
2) Why are multiple, different agars used for culturing bacteria from all the experimental treatments?
Experiment
Does the soil microbiome compete with and reduce or eliminate members of the built environment community? The built environment would be expected to have grater overlap with the human microbiome, and potentially, because human pathogens arc likely to persist longer in the built environment relative to a natural soil environment. Relative to urban environments, rural and suburban environment may have fewer reservoirs for pathogens because the natural microbial communities, such as those in soil, keep the human microbiomc members down.
Procedure - Collect "healthy" soil (unmanaged surface). Add mock bacterial pathogens (E; coil and S epidermidis) to tubes of healthy soil (autoclaved soil as control). Wait 2 weeks Extract microbiome community DNA and sequence.
Questions
1) What is a testable hypothesis for this experiment?
2) What are your control treatments?