pictures

here are some of the pics of the 3M Quick Swab and the bacteria colonies (cfu- colony forming unit).

Each red dot represents one cfu.

:s

ok so im rushing to do my report while doing this.. but it turns out there were no human errors (as i thought earlier with the UHT milk) because if there were then the bacteria count would be much greater than 1. btw ill be back on later to post some pictures :)

variation in results

the variation in the results of the different types of milk are to be expected as there are very different pasteurization processes involved. The average of the lite milk bacterial count and the full cream milk bacterial count are similar due to the similar pasteurization process, while the UHT milk is heated at high temperatures to kill the majority of bacteria.

also, there may have been some small, slight error while pouring the dilution onto the petri film for UHT resulting in a bacterial count higher in a dilution compared to pur UHT milk.

results

ok, so i finally finished doing the actual experiment. Here are the results:

LITE MILK- 1

Dilution No.	Dilution	Bacteria counts (CFU- colony forming unit)
1	1/3	125
2	1/9	59
3	1/27	21
4	1/81	9

LITE MILK- 2

Dilution No.	Dilution	Bacteria counts (CFU- colony forming unit)
1	1/3	48
2	1/9	29
3	1/27	4
4	1/81	9

FULL CREAM MILK- 1

Dilution No.	Dilution	Bacteria counts (CFU- colony forming unit)
1	1/3	57
2	1/9	26
3	1/27	13
4	1/81	8

FULL CREAM MILK- 2

Dilution No.	Dilution	Bacteria counts (CFU- colony forming unit)
1	1/3	59
2	1/9	31
3	1/27	14
4	1/81	4

UHT (long life) MILK- 1

Dilution No.	Dilution	Bacteria counts (CFU- colony forming unit)
1	1/3	0
2	1/9	1
3	1/27	0
4	1/81	0

UHT (long life) MILK- 2

Dilution No.	Dilution	Bacteria counts (CFU- colony forming unit)
1	1/3	1
2	1/9	0
3	1/27	1
4	1/81	0

ok so that's all. in the end i stuck with 3 types of milk :) oh yeah- btw, the UHT milk, by itself (no dilution) also had no bacteria but i didn't put that on the results table :P anyway, i'll blog again to talk about some of the results, variation etc.

gooooood nighty

srp

ok so i have actually started my srp, but it didn't go very well.. i left the petri films in the incubator for too long. i started on sunday at 9.15 pm, and its still in there. oh well. i just wanted to say that i had a look at them, and there are distinct bacteria colonies by the third dilution, like, you don't even need a microscope to see them. so i'm thinking of leaving it a 5 dilutions.

and i didn't use water to dilute the milk, i used this pre-made diluent that comes with the test tubes. its 1mL of the diluent and 0.25mL of full cream milk in the first test tube, in the second its like 1mL of diluent and 0.25mL of the first dilution and so on.

so im going to start my srp again tonight, lets hope this goes well.

climate graph

here's the climate graph that we have to post.

method&materials

ok, so here's my method & materials so far. the method has changed a little since last time because i have access to an incubator and im using petrifilms instead of agar plates.

1. Obtain all necessary equipment- 30 petrifilms, one incubator, 3 forms of milk, test tubes and a syringe.
2. Fill 10 test tubes (approx. amount) with the same amount of water (1mL)
3. Measure out 0.1mL of full cream milk with syringe and place in first test tube.
4. Shake the test tube.
5. Measure out 0.1mL of the diluted milk from the first test tube and place in the second test tube.
6. Repeat steps 4-5 until all ten test tubes have diluted milk.
7. Mark the petri films with the test tube number.
8. Carefully peel the top cover of the petri film almost all the way without touching the internal surface.
9. Place the dilution into the middle of the film.
10. Use a spreader* to give the dilution a circular shape and to ensure it is spread evenly.
11. Repeat steps 7-10 for all 10 dilutions.
12. Place all 10 petrifilms in an incubator at 36 degrees celsius.
13. Remove the ten petri films 48 hours later.
14. Make observations and record results.
15. Repeat steps 1-14 for the two other types of milk- organic and soy
16. Once all 3 milk types have been done once, repeat steps 1-15 to ensure a fair result.

There may be some slight alterations along the way; for example i may not need ten test tubes, i may not use water but some other diluent- but that should be all.

alrighty, good nighty
*a spreader is a type of 'mould' thing that helps give the liquid its shape.