Technical specifications and construction

Material and equipment needed:

  1. Adjustable, standard peristaltic laboratory pump
  2. Laboratory stirrer
  3. Silicone tubing (we use Masterflex tube #14 (Cole-Palmer, USA))
  4. Standard syringe needle for 10 ml syringe (optional, small diameter silicone tubing)
  5. Beaker containing the monomers of alginate and cultures
  6. Receptor beaker for product (must be larger in size)
  7. 2% CaCl2 solidification solution
  8. Laminar flow hood (optional, for sterile work)


The syringe is attached to one end of the tubing and the other end of the tubing is immersed in the solution containing the alginate monomers plus the microorganism(s) to be immobilized, via a peristaltic pump. The distance between the solidifying solution and the opening of the syringe is 20 cm.


  1. Make a mixture of 2% alginate solution with the desired microorganism(s) (bacteria, microalgae, yeast, or any single-cell microorganisms) and place in a beaker), mix well by low stirring for about 60 min. Connect the beaker by silicone tubing via the peristaltic pump to the syringe.
  2. Set the speed of the pump to 5 to produce this size of beads.
  3. Start the pump. As long as there is substrate in the beaker and the pump is operating, beads are produced at a constant rate.
  4. After the curing period (see below), wash the form beads in the desired buffer or distilled water and they are ready to use.

Limitations and options

  1. To avoid formation of an alginate film on the surface of the CaCl2 solution, the distance from the syringe should be strictly kept at 20 cm when using a 10-ml syringe. Other syringe sizes will need a distance adjustment.
  2. For curing the formed bead in the CaCl2 solution, only slow stirring at a maximum 40 rpm is required. About 1 h is needed for complete curing of the beads.
  3. For production of larger size beads (>4 mm), the syringe can be replaced by small-diameter silicone tubing.
  4. The size of the bead is controlled by the diameter size of the syringe.
  5. The amount of beads produced, although theoretically unlimited, is controlled by the pace of their production; therefore, it is only suitable for experimental needs and not mass production. For mass production, visit the website:

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