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Re: A level Investigation - help required please!



parkstone@lds.co.uk wrote:
> 
> Hi!
> I am a sixth form student studying A level Biology. As part of the course,
> students are required to do a Longer Investigation.
> My proposed title for this investigation is:
> THE EFFECT OF TOOTHPASTE ON MICROBES.
> 
> I have thought about which species of bacteria to use, and have in the end
> decided to use two different species, Rhizopus stolonifer, and
> Penicillium. I would greatly appreciate any help, for example, suggestions
> of suitable methods, reading material, etc.
> 
> Also, I have to write the experiment up in the style of a scientific
> paper, and DESPERATELY need help here! If *anyone* can help, I would be
> eternally grateful!
> 
> Thank you very much, for taking the time and trouble to read this. I hope
> to hear from you soon!
> 

Hi Madeleine 

First thing Madeleine, you need to realise the microorganisms your
planning to use are fungi not bacteria.


I would suggest bacteria are easier to use.  You might want to try
species that live in the mouth.  You have to make a decision on which
ones to use.

Try one of the viridans streptococci and perhaps a _Staphylococcus
aureus_ (not a great mouth dweller but easy to use).

Select the brands of toothpaste and weigh them and then dilute them
serially one in two for about 10 dilutions.

Add a standard inoculum of bacteria, the easiest way to get a vague idea
to make up an arbitary turbidity standard.  If you have access to a
hospital laboratory the the microbiologists might suggest a 0.5
McFarland standard which will give you about 10^8 bacteria per mL.  A
good standard inoculum to add to the dilution tubes would be to get a
final count of 10^4 per mL.  You do this by diluting the initial
suspension by using one in ten dilutions.

This will act as a good pilot, once you have it going, repeat it a few
times and then write it up.

Use headings like

Aim

Methods and Materials

Results

Discussion

References

I'd go to your local hospital laboratory and ask to photocopy the
chapters in their relevant methods manual or text books.  A good one,
but I'm not sure whether english laboratories will always have a copy is
the 6th edition of the Manual of Clinical Microbiology, put out by the
american Society for Microbiology

Hope this helps, E-mail if you have more questions

Gary


--
******************************************************** 
Dr Gary Lum
Director of Microbiology
Royal Darwin Hospital

Microbiologists do it with culture and sensitivity 
Meet me at http://www.ozemail.com.au/~glum/index.html
E-mail me at glum@ozemail.com.au or gary.lum@nt.gov.au