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||high school biology, independent study/science fair, introductory undergraduate microbiology, advanced college level microbiology|
|Revision Date||April 29, 2003|
This exercise describes the construction of a "stirred batch" reactor using materials that are both economical and readily available. The resulting reactor will be suitable for growing bacterial biofilms that can be subsequently analyzed, as described in other exercises.
Students should be able to define a biofilm, describe the differences between biofilm (surface-attached) and planktonic (free-floating) bacteria, and describe why bacteria tend to grow on surfaces.
Given readily accessible materials, detailed instructions and figures, and a finished reactor system, a student will be able to construct a simple reactor system that is suitable for growing biofilms on standard glass microscope slides.
|1||wide mouth polycarbonate sample jar with cap (Cole-Parmer U-06101) http://www.coleparmer.com|
|4||#6 rubber stoppers|
|4||1x3 inch microscope slides (1mm thick)|
|1||fine tooth modeling saw|
|1||magnetic stir bar (a 1 inch teflon bar works well)|
|360 ml (approx)||1/10 Nutrient Broth, liquid LB broth, or any other desired medium|
*The ports in the reactor lid can be cut with a laser engraver, drill, or drill press with 1 1/16 inch paddle-type bits.
Note: Erie Scientific Company manufactures printed microscope slides available in a large variety of formats. The ER-243 is printed to expose 10, 7mm diameter wells on the slide surface. When inserted in a biofilm producing environment, these provide 10 distinct regions for biofilm formation of known diameter. The wells are easily scraped to recover the adherent cells. If the depth of the biofilm is measured in one of these wells, the biofilm volume (π r2 h) can also be easily determined. Erie Scientific Company, 20 Post Road, Portsmouth Industrial Park, Portsmouth, New Hampshire 03801-5691.
Assessment will be made by the instructor through visual evaluation of each student's reactor system and its test operation.
This exercise results in the construction of a biofilm growth reactor system that can be used for biofilm growth experiments described in other exercises.
Effects of culture conditions and biofilm formation on the iodine susceptibility of Legionella pneumophila. Cargill KL, Pyle BH. Can J Microbiol 1992; 38:423-429
A direct viable count method for the enumeration of attached bacteria and assessment of biofilm disinfection. Yu FP, Pyle BH, McFeters GA. J Microbiol Meth 1993; 17:167-180
Supported in part by the Waksman Foundation for Microbiology
Developed in collaboration with Dr. John Lennox, Penn State University-Altoona
© 1999-2008 Center for Biofilm Engineering, http://www.cbe.montana.edu