Tag: growth curve

Micro Student Projects

by gwilson on Apr.27, 2009, under Projects

staph-bacitracin-mannitoThe end of the semester always bring forth a new crop of student research projects from the BIOL 3410 Microbiology lab.  The first portion of the course’s lab is filled with projects to teach skills and knowledge.  Then, in the last 5 weeks of the semester student groups design, conduct, analyze, and present their work. 

All of these projects were imagined and conducted by students.  They demonstrate the freedom students have in Microbiology to have some fun by using their skills to investigate more deeply an area of the course that was of particular interest to them along the way.  Here’s a synopsis of some of the projects conducted this spring.

“The inhibition of mannitol use in a Gram positive coccus by bacitracin.”  One group of students made a very curious observation when they were testing their unknown bacteria for antibiotic susceptibility.  One person’s Staphylococcus aureus was unable to use mannitol on MSA in the presence of bacitracin.  No other Gram positive cocci, including other strains of S. aureus, showed this unusual feature.  Their work investigated the phenomenon.

“Growth of bacterial cells in the presence of pomegranate and UV light.”  This group wanted to test the effectiveness of pomegranate juice as an anticancer agent by using DNA damage induced by UV light as their indicator for cell transformation.  They grew cells on media containing pomegranate extract, collected them and exposed them to UV light, and then tested their survival in comparison to controls.

“Growth and identification of bacteria isolated from raw vegetables.”  With the recent scare posed by Salmonella appearing in foods, this group decided to see whether any particular vegetables posed a greater threat in carrying those bacteria.  They found many bacteria and fungi, identified many of the bacteria, but found the vegetables tested were free from Salmonella.

“Impact of tobacco products on the growth of bacteria.”  Various tobacco products were added to growth media and growth curves were conducted to determine whether bacterial growth was retarded or enhanced.

These projects are indicative of the types routinely seen – students applying the skills learned in the course to study something of interest to them.  Are health supplements really effective?  Are my vegetables safe?  Do the chemicals in tobacco hurt cell growth?  If we accomplish in our courses the transference of knowledge to provide answers pertaining to the world at large, we have accomplished education’s greatest goal.

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Growth Curve Update

by gwilson on Apr.01, 2009, under A Day in the Life..., Projects

dscn2677We’re now 30+ hours into growth curves in BIOL 3410 Microbiology.  Students started at 8:30 am yesterday and made measurements every two hours until 8:30 last night.  We resumed this morning at 8:30 and will take a 36-hour measurement at 8:30 tonight. Our final measurement will be at 8:30 tomorrow morning.

What are my students learning from this?  First, they are learning that science doesn’t occur in convenient 2-3 hour blocks of time.  Second, they are learning that the thought and planning BEFORE beginning your work will help maximize the usefulness of the data obtained.  They are learning that the informal time spent together while collecting data can be very enjoyable.  I learned about my students and they learned something about me as we spent time together through the day.  When I returned from playing basketball, all hot and sweaty, they found I was not a sterile, stuffy professor who has no life.  Finally, I’m hoping their time spent doing this work will teach them a little microbiology.

Our experimental design has eliminated the opportunity to “cook the books” with falsified data.  Their data collection compares bacteria in their own home-made media, while their final product will be a comparison of home-made media for the growth of their own bacteria.  We’ll see how this plays out!

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Making Something from Nothing

by gwilson on Mar.28, 2009, under Projects

neg5The approach to teaching Microbiology labs at McMurry is really an exercise in making something from nothing.  This next week my BIOL 3410 students will be conducting growth curves of bacteria.  That is nothing unusual for students in a course like this.  However, my McMurry students have been challenged with creating their own broth media from scratch using kitchen items.  The competition pits groups against one another to come up with a medium that will support the growth of microbes.  We prepared on broths on Thursday, first step being to make sure their clear broths will survive autoclaving.  It is always fun to see what they come up with – this semester one group found the fluid from a can of tuna fish doesn’t make a clear broth as well as an extract from boiled spinach and potato.  SlimFast didn’t work so well, creating an opaque medium unsuitable for our study.  Another group found a protein supplement and vitamin water made a very nice medium.  Tuesday and Wednesday the games begin!

The organisms they will use are another exercise in making something from nothing, as they are the natural isolates (Staphylococci and enteric organisms) my students collected, purified, and identified earlier in the course.  Each group will try their medium with six of the cocci and six enterics, following growth spectrophotometrically.  Then the results will be pooled to see whose medium maximized the growth for the greatest number of bacteria.  All groups will report their results in the form of research posters that will adorn our walls for the remainder of the semester.  Winner gets an automatic advantage on their poster grade.

I could have given each group an organism and made their medium for them.  But what would my students have learned about the chemistry and content of media by doing that?  What would they have learned about the distribution of microbes in nature and the thought that goes into identifying them if I had given them cultures from our stock collection?  If you can get as much “bang for your buck” making something from nothing, why not make learning fun and relevant?

There is a way of teaching that brings deeper learning, the fun of competition, and the satisfaction of accomplishment in demonstrating mastery of skills and knowledge through problem-solving.  It is called discovery-based learning.  We do that through research-rich teaching.  McMurry’s BIMS program is committed to doing more to bring the science out of students – just putting science into students is not enough!

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