Microbial Fishing

Using a device like that shown, microscope slides can be anchored in natural aquatic environments where biofilms might form.
Several slides can be sited together in a device made from the plastic spine usually used to hold student reports in plastic binders.
  1. The spine section can be cut in half and about six cleaned microscope slides can be inserted into the two halves thus formed.
  2. The halves of the binder are held together by rubber bands.
  3. Thus six slides can be sited as a unit.
  4. Individual slides can be removed at intervals and examined for biofilm production.

Erie scientific Company (20 Post Road, Portsmouth, NH) produces microscope slides with multiple clear wells separated by a highly hydrophobic masking material. The number of wells can vary from 1 to 12 and the size of the wells range from 4 to 14 mm.
A multiple well slide can be used in a microbial fishing exercise by masking all but one of the wells with transparent tape or Parafilm prior to placing the slide at its site. Then each day or other selected interval, one additional well can be exposed. At the end of the sampling period each student has a sequence representing the growth of a biofilm over a period of time all on one slide.

  The results, with a little luck, appear somewhat like the image shown here which is from the ASM Biofilm collection. This image entitled Biofilm Accumulation on a Glass Surface is of a mixed biofilm of Pseudomonas aeruginosa, P, fluorescenns and Klebsialla phneumoniaeand was photographed under confocal microscopy (Paul Stoodley and Zbigniew Lewandowski,1995). The various panels illustrate the accumulation of a mixed biofilm on a glass surface at 72, 98, 122, 144, 165, 191, 220. 268 and 309 hours (reading from top left to bottom right). Note the complex structure of biofilm clusters (dark patches) and water channels and the sloughing event that occurred between 268 and 309 hours.

 

Further Notes:

 The Micro-Fishing instructions available with the Microcosmos Curriculum Guide to Exploring Microbial Space (Zook, 1992).

 An aquarium, a hay infusion, an illuminated pond water sample, or one of the River Tanks distributed by Carolina Biological Supply Company makes an excellent classroom location for siting Micro-Fishing slides.

 References:

 Lewandowski, Z. and Stoodley, P. 1995. Flow induced vibrations, drag force, and pressure drop in conduits covered with biofilm. International IAWQ Conference Workshop on Biofilm Structure, Growth, and Dynamics. 30 Aug. to 1 Sept. Noordwijkerhout, The Neth erlands.

 Zook, Douglas, 1992, The Microcosmos Curriculum Guide to Exploring Microbial Space, Kendall Hunt Publishing Company, Dubuque.