Tag: enteric bacteria
When Angelo Falcon chose his water source for the first project in BIOL 3410 Microbiology lab, he had little idea that it would bring to light an issue being discussed in Abilene City Hall. The class was charged with finding various sources of ground water and surface water to test for the numbers and types of bacteria present. Angelo sampled water from a man-made waterfall downtown, while others in the class tested streams and lakes and ponds and wells in and around Abilene. Testing included a standard MPN (most probable number) assay, followed by isolation and purification of a Gram negative bacterium, characterization of its colony morphology and staining characteristics, and biochemical testing to provide hints at its identity. The project culminated in confirming the identifications of isolates using BD-BBL Crystal(R) E/NF panels for rapid identification of enteric and non-fermenting Gram negative rods. Angelo’s isolate came back as Enterobacter cloacae, and a little snooping revealed this to be a microbe frequently associated with sewage and soil. A conversation with people associated with the waterfall revealed the water source to be a shallow well tapping into an aquifer found under much of northern Abilene.
And that is things began to add up. In early September, Abilene’s City Council dealt with the issue of shallow ground water in northern Abilene and its unsanitary condition by issuing a warning to residents with wells into this water source – do not drink the water, do not use the water for irrigating vegetables, do not allow pets or livestock to drink the water. Angelo can testify to the presence of nasty bacteria in the water. Add to Angelo’s work confirming evidence from Amanda Carter, a classmate who tested water from her father’s north-side well, and you have every reason to believe City Council made the right decision.
Its nice when what you are doing in the lab to develop basic skills has a purpose and relevance to society.
Students in Dr. Wilson’s BIOL 3410 Microbiology course are taking a look at a traditional Thanksgiving dinner from a different perspective. This week, they will be evaluating the ingredients going into the feast qualitatively and quantitatively to see what microbes are found present before and after preparation. On Tuesday, they will be taking samples from raw ingredients: turkey, stuffing “stuff”, cranberries, potatoes, green beans, and other things. The samples will be tested for the presence of bacteria including enteric bacteria and staphylococci, along with performing dilutions to determine the numbers of bacteria in the fixings before dinner is prepared. Then, on Thursday there will be a Thanksgiving feast, but not before the prepared dinner is again sampled for the presence of microbes. Through this exercise, students will see the routine presence of bacteria in wholesome foods and the impact of baking and cooking on improving the wholesomeness of foods we consume. Who says science has to be boring?
The 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!