A method for automated fast production of
large-sized polymer beads (24 mm)

Developed by Juan-Pablo Hernandez

Environmental Microbiology Group, Northwestern Center
for Biological Research (CIBNOR), La Paz, B.C.S., Mexico

Macrobead-producing assembly

Entrapment of microorganisms in a polymer matrix was invented three decades ago by the fermentation industry to produce industrial products with microorganisms in fermentation units without losing the microorganisms when the product was harvested.

In 1986, this technology was modified in Israel to produce microbial inoculants of plant growth-promoting bacteria (PGPB) in agriculture. In the mid-1990s, this technology was further modified to entrap (immobilize) microalgae for wastewater treatment. In 2000, the technology was modified to allow co-immobilization of microalgae and beneficial bacteria for enhanced wastewater treatment. In 2002, the microbead concept for enhancing plant growth with PGPB was introduced. This is an experimental technology in all its modifications, currently used in research laboratories, worldwide. The use of beads is reported in dozens of scientific publications and is a widely accepted tool in the science community.

The main limitation of the technology is the slow rate of bead production because it involves dropping the viscous polymer solution (mostly alginate) through a small opening in a large syringe, which is a tiring procedure for lab personnel.

An automatic procedure was developed to overcome the basic problem of excessive time and effort to produce beads. This tool can produce beads (spheres) for experimental use with little effort and in any quantity. It is basically an assembly involved a peristaltic pump, tubing, syringe, and sources of monomers and microorganisms.

The advantages of the automated
macrobead-producing procedure are:

  1. Produces beads with very little effort.
  2. Beads are homogenous, all are identical.
  3. Quantity is time dependent, the more beads you need, the more time it will take, but with no additional work is involved.
  4. The apparatus is easily constructed from common laboratory materials, including a standard peristaltic laboratory pump and silicone tubing; therefore it is inexpensive.
  5. Can be cleaned with running water.
  6. Can be sterilized for axenic cultures.
  7. Requires only about 10 minutes of training of personnel.
  8. Production rates are about 10 min for 100 ml volume of beads.
  1. The beads are produced automatically without supervision and saves working time of laboratory personnel.

This website contains technical specifications and construction of the device and operational procedure, a technical diagram, a PowerPoint presentation of the procedure (1.23 MB) for rapidly producing the beads, a PDF containing instructions on how to prepare a mixture of alginate and microorganisms and photographs (in a photo gallery).

Related pages:

  1. Mass production of large polymer beads: http://bashanfoundation.org/device.html
  2. Production of polymer microbeads: http://bashanfoundation.org/bead.html