Method for the preparation of spherical microorganism cell aggregates

A method for the production of spherically shaped bacterial cell aggregates which comprises the steps of:

• (a) providing an aqueous medium containing viable cells of an enzyme producing a microorganism;
• (b) introducing the reaction product of a long-chain, polyamine, cationic flocculating agent which is an epihalohydrin/polyamine copolymer and a cross-linking agent for said flocculating agent to the aqueous medium to flocculate the cells and form a cell/cross-linked polyamine aggregate;
• (c) removing the aggregate from the aqueous medium with sufficient filtration to form a filter cake containing 68 to 76 weight percent water;
• (d) grinding the filter cake into particles no greater than 60 mesh and adding to the ground filter cake a natural gum, a cellulose derivative or a microbial gum as binder;
• (e) mixing the combination of ground filter cake and binder to form a homogeneous mixture and extruding this mixture through an orifice, which is approximately the diameter of the spherically shaped cell aggregate to be produced, onto the rotating plate of a spheronizing device which comprises a milled friction plate as rotor situated in a cylinder such that cylinder provides a stationary side wall for the plate while allowing it freedom to rotate;
• (f) rotating the plate at a tangential velocity of 4.5 to 12 meters per second for a time sufficient to cause the extruded mixture to be disposed against the cylinder wall and be shaped into discrete spherical particles;
• and
• (g) recovering the spherical particles from the spheronizing device.