Phoenix College Biosciences Department
This is only a brief “brainstorm” list of things that we can do together – projects can be customized or created based upon student interest!
Contact Person: Amanda Chapman, MPH, NBCT
1. Quantitative Experiments. How many bacteria are in (a kitchen sponge? a thoroughly washed hand? road sand? a gram of ground beef? etc.) This is one of the most straightforward, and yet surprisingly interesting, of experimental questions in microbiology. The basic procedures are simple: dilution series and viable count assays. One can modify these assays to even simpler, "semi-quantitative" assays for an initial screening.
Here are some possible applications:
* comparing the number of bacteria in a variety of water samples. This can be extended by looking for the presence of indicator organisms for fecal contamination: E. coli and Enterococcus faecalis .
* comparing the number of bacteria in eggs, meat, poultry, fish, or other foods. Samples are first weighed, then mixed with sufficient water to produce 1% solutions (1 gm/100 ml), and mixed thoroughly in a blender. Dilutions are assayed for total count. It is also possible to screen for the presence of certain pathogens (e.g. Salmonella) or fecal indicator organisms.
* comparing the survival of a pathogenic indicator organism (such as E. coli, an enteric bacterium that has similar survival abilities to pathogenic enterics such as Salmonella) on wood vs. plastic cutting boards. The FDA requires plastic cutting boards in food preparation, arguing that they are easier to clean. However, recent reports suggest that bacteria disappear from wood surfaces much faster.
* examining "microbiology in the home". Where are bacteria found in greatest abundance? How contaminated is a sponge that is used several times a day to clean food?
* examining the variation of numbers of bacteria in different habitats.
* examining variation over time. For example, we know that bacterial numbers on hands goes down after hand washing. But how soon does it come back up, and to what extent? A careful study, in which the same skin area was swabbed at different times and then assayed for total count, might be very revealing.
2. Population Experiments.
We tend to assume that all bacteria are alike. In fact, however, the genetic variation between a number of independent isolates of a bacterium like E. coli can be enormous, substantially larger than the genetic variation between people.
One important application of variation is to learn how much variation there is in antibiotic resistance in a population. For example, if you were to study 20 or 50 independent isolates of Staph aureus, or E. coli, and find that a substantial % were resistant to commonly used antibiotics, this would be an important finding. The student might investigate 20-50 independent isolates of E. coli for antibiotic resistance, using the Kirby-Bauer disc diffusion assay that they will learn in lab. Will all these strains show the same pattern of antibiotic sensitivity, or will there be detectable differences? We don't know, and the student could find an answer.
The student could apply the same type of antibiotic resistant survey to a population of Staph isolates. He/She could investigate what kind of variety is represented in some of these isolates: how many are endospore formers? How many are gram-positive vs. gram-negative? How do their cardinal temperatures compare: do they all show the same minimum and maximum temperatures, or are there significant variations? How many are aerobes as opposed to facultative?
3. Enrichment - Isolation - Characterization experiments. There are many microbes in nature with interesting properties, whose isolation poses interesting challenges. Here are several types of organisms you might choose to "hunt down" and study:
* Pseudomonas putida: a plant pathogen that secretes an ice-nucleating protein, responsible for the formation of ice crystals. Strains of this organism are commercially used at ski resorts to create finer crystals in snow-making machines.
* Archaea in either the extreme thermophile or halophile groups. (For technical reasons, isolating the fastidiously anaerobic methanogens is beyond our resources).
* Actinomycetes that produce antibiotics. Who knows – the student might discover some organisms that secrete antibiotics not yet known to science! Soil is loaded with actinomycetes; He/She could isolate a variety and test them to see if they inhibit other bacteria, both gram-positive and gram-negative.
* Lactic acid bacteria. This is a large group, including the Streptococci and Lactobacilli. The student could find out what microbes are present in some soured milk products (only unpasteurized products should be used).
* Bioluminescent bacteria. These organisms glow, like fireflies, in the dark. They are found at low concentrations in seawater, marine sediments, surfaces and GI tracts of marine animals such as squid, fish, or shrimp, and especially on the surfaces of decomposing fishes. Not easy to isolate, but very rewarding to work with.
4. Plant Biology - Use GPS units to locate specific plants on the Phoenix College campus.
What steps will the students take?
Locate trees, flowers, grasses.
Note coordinates. (6.2A)
Enter information in a power point presentation. (6.2C)
Collect data every three weeks to show changes as the season changes.
Graph color changes and growth data.
Construct a model of the plant to show the change over time. (6.3C)
Place the data in a power point presentation to communicate the data collected.
On a grid map of the school campus, plot the locations of the specimens.
Plot the location of the building, and place a model of it in relation to the
Predict how human activities affect your specimen’s growth.
Beneficial Microorganisms: We have a new garden that we know almost nothing about.
1) Determine which organisms are most often found in soil.
2) Determine appropriate test to detect and isolate these organisms.
This will also require research on acceptable forms of sample collection and isolation. The student would could then use those diction methods to determine That organisms are in several samples of soil on the PC campus.
3) Determine the best way to add beneficial organisms to Determine formulation for making plant fertilizer with beneficial organisms and suggestions for how often the fertilizer should be re-applied.
4) Determine appropriate methods for storing organisms for future use.
5. Environmental Monitoring - Analyze habitat characteristics and habitat suitability at the Rio Salado Habitat Restoration site or on the Phoenix College campus
· You would learn about habitat measures such as looking at types and sizes of plants, as possible food sources, shelter/cover for wildlife
· You would learn about how wildlife respond to different habitat characteristics
· You will make predictions about the ability of an area to provide habitat for particular wildlife species
· For this project you could collect your own data or you could use data gathered by previous students or both
Make observations and record wildlife (specifically birds or insects) activity at the Rio Salado Habitat Restoration site or on the Phoenix College campus.
· You would learn to identify either birds or insect species
· You would learn how to conduct population censuses looking at either birds or insects, methods for estimating numbers based on a sample.
· Look for changes with seasons or time of day or weather. Compare different habitat types within the study site.
Other Ideas for Research Projects
6. Routine tasks that may be assigned:
Garden/greenhouse work: weeding, watering, soil work
Plant work: germinating seeds, growing and monitoring plants
Tree ring lab
Garden soil microbiology
Spray down cadavers
General lab prep (making media, ordering supplies, taking inventories)