Expert: Walter Hintz - 2/23/2011

Question
QUESTION: To Mr. Hintz
    My school is having a science fair in about five weeks, (deja vu). I have two options for experiments, but I need help with "ironing out some kinks", for one of them.
    The experiment is something like micro-evolution, probably closer to "survival of the fittest", but i could get a good reaction if it can be represented as some form of evolution. My idea is to take a specific strain of bacteria (I could get it from wardsci.com) and culture it in a process that I believe is called a "cocktail". (culture it in plain nutrient agar, take a sample from that, hope there is a genetic mutation and culture it in acidic agar...). What I need help with is, How do I change the acidity, or other factors, of the agar? (I could not find much online, and I have a slim budget, so I cant buy many varieties of agar.) Another problem is, what other factors should I change? Also will I be able to do this without a sterile laboratory/facility? My school does not have a laboratory, and I can't use the community college due to time restraints.(Even though it is right around the corner.) Also if you could advise me as to which strain of bacteria I should get, that would be helpful.(Although, I should probably do my own research for that, so,never mind).
    If you think this project will not be feasible (even though I want a really tough challenge) the other project I had in mind (I plan on doing it regardless) is to research how and why the chemical composition of water is so important/the basis for life. (High specific heat capacity, due to hydrogen bonds between molecules, (O from one to H of the other), helps maintain homeostasis, and water is a component in the production of glucose, which produces energy. ATP.) The thing is, my teacher loves the project, but the principal is far from thrilled.
    My first choice would be project number one, but I would be overjoyed with project number two as well.
    I would have developed and started the project weeks, maybe months ago, however when we asked about a science fair we were told that this year there would not be one, needless to say about a week ago they changed their minds. I apologize for the time restraint.
    Thank you for your time and patience.
    
P.S. Last year I tested your idea, whether soap are hand sanitizer work better. My results were that, if used properly, soap works better. I tested it five times, each time had four parts. Petri dish #1 had tap water, #2 had dirty hand and tap water, #3 had soaped hand and tap water, #4 had purelled hand and tap water. #1 and #3 looked very similar, and #2 and #4 resembled each other. Thank you for your help.

ANSWER: Hello again Zvi
I remember the soap study
Here is what I think
 Project # 1
   Evolution comes about through mutation and natural selection. Growing bacteria and "hoping" a mutation would occur in unrealistic. An experimental design whereby you hope for a certain occurrence is not a good one. Mutations are not common occurrences so
 Project # 2  This is rather vague. The Problem "Why is the chemical composition of water so important"  What hypothesis can you draw from this and what kind of an experimental design can you come up with.  

   So I am afraid I do not know what to tell you.
   You can modify Project # 1 to test the growth of bacteria at different ph levels

---------- FOLLOW-UP ----------

QUESTION: How about if I test "What factors are x strain of bacteria resistant to?" Again, I still need help with changing the properties of the agar. And what factors to test.
    What the principal is looking for is not an experiment, he is looking for a show. If my question is something like "Will natural selection keep this strain from dieing out under abnormal conditions?" and my hypothesis is "Most of the bacteria will die but some will remain" even if it is not the proper way to start an experiment (based on a specific hope) I can still answer the question, and give him his show.
(I can also ask the other judges for permission to misuse the word "(micro-)evolution" just to annoy the principal, they will probably let.)

Answer
 Outside of putting a weak acid on a Nutrient agar plate I do not see how you can alter the pH. You would have to get the agar in powder form and change it. This would get expensive.
You can get agars with lower pH levels like Sabaurauds. It is used mainly for Fungi because it inhibits most bacteria. You might try a spore former like Bacillus subtilis which you can culture off of any surface to see if any can grow on it.
 Are you in some kind of school that teaches creationism or something. What is with this principal?
 Again I do not think you can test evolution by growing bacteria unless you involve antibiotics and then you would need to fool around with pathogens.
 Try B subtilis on Sabauraurds agar