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.

D;

the past 3 days has just been test after test after test, and there are still 2 more to go :( oh well, i just wanted to say that i'll be starting my srp after the science rotation test, so everything should be fine. i'm trying to cut down my experiment so that it takes 2 and a half weeks to finish instead of a month because i don't have enough time otherwise.

different milk dilutions

sorry i havent blogged for 2 or 3 weeks, but i've found out something about milk dilutions.. on http://answers.yahoo.com/question/index?qid=20080529154304AAFr7ru :)
the 'best answer' is really helpful, but i don't know what it means fully. i'll have to call up dadio and ask to explain.
also, daddy said he's got everything ready for the srp except for milk- the agar plates, cotton buds etc.

okok its time to go to bed here, good nightie. i might blog more next week.

toodle oooo

im just letting you know that i might not post on this blog as often as i may not have internet access in some of the places i go.

im also getting prepared to start my srp as soon as i get back. anyway.. that's all folks.

alrighty fellow srp bloggers.

i believe this is how i shall conduct the experiment:
Soy, full cream and organic milk shall be used.
the different types of milks will be swabbed.
the swabs will be placed in the agar plates.
the bacteria will be allowed to grow for exactly 24x3 hours. that's... 72 hours.
it will be counted and results recorded.
the steps will be repeated 3 or 4 times with one or two day gaps in between the repitition. this is so that i use 2 weeks at least to conduct the experiment. or, maybe just repeat it 3 times and let the bacteria grow for 4 or 5 days?

must research some more >:[

the bacteria in milk pt. 2

• as i have not fully thought about how i will coduct this experiment, i cannot say whether it is 100% reliable. however, what i have thought about now seems to be pretty good. the milks will be swabbed at the same time, twice to make sure that the temperature at which they are swabbed in is the same for both the first and second trials. i don't know whether i should leave them at room temperature or whether i need an incubator.
  
• as mentioned before, the milks will be swabbed twice at the same time (for one type of milk two serial dilutions will be done) to ensure the experiment is fair.
• Yessum, it certainly can be conducted within the time frame. at the very least it will take 2 weeks, to get everything ready and to wait for the bacteria to grow. even if it does take 3 days to grow bacteria, i think i can leave the dilutions in the agar plates for a day or two more :) all together it shold take 3-5 weeks (that's a very rough approximation)
• everything can be conducted at home, home equipment can be used and im not sure about whether to get an incubator or not, still need to think about that. if i do need one i think my parents can get me one :D
• can i give a valid and conclusive result? oh, now there's a question. i haven't done the experiment so i cannot answer that question properly. but i believe that a valid and conclusive response can be drawn from the results of the experiment. Organic milk should have different bacteria quantity to soy milk and skim milk, full cream milk may be similar to skim milk etc.
  

i think im done now.. ok i'll go through everything once more to make sure i have evrything.

bacteria counting

im attempting to watch LOST now, so i'll be brief:
i need different dilutions of my milk samples. this site says that they should be in the quantities of 1:10, 1:100, 1:1000 etc. each dilution is grown in different petri dishes and agar plates.
after 2 or 3 days, the bacteria grows in colonies which appear as small spots on the agar plates. To find out how much bacteria is there i need to count the colonies & by doing this i will know the original amount of bacteria in the milk. so this involves some maths, but i have to research if there are easier ways of doing this or if this is the only one.

blog due tomorrow :/

i'm just checking that i've done everything for tomorrow's blog thing.

• You need to have shown (in your blogs) some ideas which you have researched. At this point, you need to have an initial idea about your experiment and a brief plan as to how you are planning to complete the experimentation. Done.
• 2 marks out of the 15 will be allocated to whether you have sent me a blog URL and whether this was on time. If you were sending it to the wrong address, or something happened with your email, as long as you have shown me the proof that you sent it before it was due, it will not be deemed as late. URL sent :)
• 3 marks of the 15 will be allocated to whether you have been active on your blog. i.e. how much work have you put into posting information onto the blog. oh.. well i hope i have. what can i do now?
• 5 marks will then be allocated to whether you have thought through several different project designs and whether you have listed the independent variable and the dependent variable. i went through around 4 different topics on my blog. i think that's enough. i can't help it if i can't think of original ideas :L
• The last 5 marks will be for whether the experiment:
  1. is reliable
  2. will be conducted fairly
  3. can be completed within the time frame
  4. can be conducted at home using normal household equipment
  5. can give you a VALID and conclusive result. gahhh. not finished. i'll post another blog with this information :)

ok, i guess i better hop to it then. and i have some more research on the milk bacteria counting.

lightbulb

i have new information.

apparently the bacteria in skim milk and full cream milk isnt significantly different, so maybe i should replace one with organic milk? or should i just add organic milk to the list of milks im testing?

and if i don't repeat the experiment at a different time, can i do it twice in one go? like a repetition the same time i do the first one? and do i need an incubator for this or should i leave it at room temperature?

arrgh. so many questions, i'll research this tomorrow.
my shoulders hurt, im off to bed now.
toodle-ooo.

...

i haven't thought much about the srp in the past 24 hours, with the rotation test coming up.. but i think im going to stick with the soy, skim, full cream and long life milk to do my experiment.
im not sure whether to start my experiment now. or when i get back. or maybe i should do one trial of all the milks now and another one when i come back.
my dad (i think) printed this article about the easiest way of counting bacteria, although i haven't gotten around to reading it yet. it looks very helpful, though. i hope they're easy to count. maybe i should read the article. or i'll go to bed and read it in the morning.
yes, i'll go to bed.
good night everyone :]

i've decided not to do any of my srp in India, because there are alot of variables and its not going to be easy. oh, and i have to study for maths and geography as well :( Further investigation shows that it takes way less than 3 weeks for bacteria to grow (thanks ms zhang) and i thought that since it only takes around 3 days, not 3 weeks, i might as well do 3 or 4 different types of milk. so far i've thought about using:

• soy milk
• skim milk
• full cream milk
• long life milk

any other suggestions? or should i stick with these 4?
also, i don't know whether i should actually start doing the experiment now or when i come back. (i come back on april 30th) or should i do half of it before i go and the other half when i get back?
i thought this srp would be so much easier, but there's alot of thought in it... >:[
ok, im going now, i have this science prac report due and man vs wild is on :)

serial dilution

i researched serial dilution, and it basically means diluting a liquid in water or any other solution. That seems to be what i have planned to do for my srp (see previous blog).
I'm still unsure on how to manage the experiment (Ms Zhang- do all the dilutions have to be done at the same time to make it a fair test?) & i still need to work out the variables; so far this is what i have:

• independent variable- the different types of milk
• dependent variable- the amount of different colonies of bacteria
• controlled variable- times that the milk is diluted; no. of days that diluted milk is kept in agar plates.

I also found the 'recipe' or method for making agar plates, it looks really long, though.. i found another site that doesn't involve getting nutrients, but instead using an agar tablet to make it. and i have to make sure i use the EXACT amount of everything when i repeat the experiment. This SRP may take a little longer than i thought to plan.

Ms Zhang- if i make the agar plates myself, would i have to include that in the time of doing my experiment (2wks-6wks)? And the sites, are they the correct methods?

the bacteria in milk

came across an idea to investigate the bacteria in different types of milk.

ok, so maybe around 4 or 5 test tubes/glasses (depending on what i have access to) are gonna be filled with the same amount of water. a swab thing is supposed to be dipped in milk e.g. full cream milk; and then placed in the first glass of water. same thing done with another tube, except after it's dipped in the milk, it gets dipped in the first glass again and then in the second. the third time, the swab gets dipped in the milk, then the first glass, then the second, and finally in the third. same thing for the furth and fifth ones.

Then the swabs are placed on petri dishes (or another alternative) with this nutrient agar thing (google nutrient agar plates, they have a good definition of it). now, im not sure how to do this next part, but somehow the bacteria is counted? i still have to work on that.

The experiment is repeated for skim milk and soy milk. what do you think, good idea? or should i think of another one?

NOTE: my dad said this experiment may take up to 2 weeks, and im going overseas in the holidays, so i was thinking maybe compare soy milk from here and soy milk from india, and skim milk from here and skim milk from india and so on. should i do this or is it too much?

EDIT- it may take up to 3 weeks.

ideas

it's the second week after I signed up for this, and now that the science test is over i can think about ideas for this. So far I've thought of one or two ideas:
1) which egg tastes better: battery cage or free rang or organic eggs?
(I'm not quite sure how to conduct this experiment, but it's an alright idea)
2) how different soils affect the growth of plants- with this experiment i was thinking about planing the same type of plant in different things such as plain mud, soil, sand, soil with fertilizer etc.
3) again with the plant idea, how the pH of soils affects the growth of plants
4) the effect of sunlight on plants- maybe have two leaves from the same plant of approx. the same size and put one in the sun and the other completely covered from sunlight.

so those area few ideas for the research project, hope i come up with some more soon :)

hello world

finally, finished signing up for this :)