Production of concentrated cell suspensions: The sponge fermentor

A novel fermentor is described in which aerobic microorganisms are grown on solid medium. Cellulose sponges support a nutrient‐agar medium, resulting in a large surface area for growth within a relatively small volume. The sponges are alternately squeezed and relaxed within a piston‐and‐cylinder‐type apparatus during fermentation. Provision is made for inoculation, harvesting, and for supplying air during operation. The apparatus has been operated semicontinuously in that there are enough cells left in the sponges after harvest to inoculate fresh medium. Cell concentrations of Serratia marcescens up to 84 × 1010 per ml have been recovered. A growth curve for this micro‐organism is given and sample data on semicontinuous operation are presented.