GB1092634A - Improvements in or relating to supporting media for microbiological fermentation processes - Google Patents

Abstract

In microbiological fermentations, nutrient liquid and any necessary gases are passed over the surface of an inert expanded polymeric material having superficial cavities wherein the growth of micro-organisms may take place. The inert expanded polymeric material may be the cut surface of a foam material produced by generating gas in the bulk polymeric material, sintered particles of polymeric material, a mesh or grid structure formed by fusing or sticking together at their point of intersection criss-crossed filaments of polymeric material, or an expanded material formed by cutting and stretching sheets of polymeric material in a manner similar to that in which expanded metal is formed. The inert expanded polymeric material may have a roughened surface produced by mechanical treatment or by a particular foam technique. Preferably the sizes of the cavities are substantially between 0.1 and 10 mm. in width. Within the stated range larger cavities, which encourage the dislodgment of growing micro-organisms, favour reactions in which the required end product is the growing cell matter, as exemplified by yeasts, suitable for incorporation into animal feeding stuffs, obtained from waste molasses and wood pulp liquors. Smaller cavities by providing a rough surface improve adhesion of the micro-organisms thereto; this is desirable in those reactions in which the required end product is in solution in the liquor, as exemplified by the production of vinegar from alcoholic solutions and of lactic acid and other organic acids from sugar. The cavities may vary widely in size. Two or more sections of a light weight tower structure may be packed with different types of the inert expanded polymeric material, representing different stages of the fermentation of the nutrient liquor and growth of the micro-organism. Fresh nutrient liquid and different gas mixtures may be introduced at any desired level of the tower structure. The inert expanded polymeric material may consist of cubes, ovoids or spheres of longest dimension 1"-3", or rods or tubes not exceeding 12" in length. Spirals, rings, cones, pyramids, lumbriciforms, crosses and grids or meshes are also mentioned. The material may be poyurethane, polyvinyl chloride, polystyrene, polyethylene, polypropylene, a polyamide resin, and any sufficiently inert and expansible polyester resin, acrylic resin or cellulose derivative.ALSO:Lactic acid and other organic acids are produced from sugar and alcohol solutions by microbiological fermentations wherein nutrient liquid and any necessary gases are passed over the surface of an inert polymeric material having superficial cavities wherein the growth of micro-organisms may take place. The inert polymeric material may be in the form of foam material, sintered particles or a mesh or grid structure wherein the sizes of the cavities are preferably between 0.1 and 10 mm. in width. Within the stated range larger cavities, which encourage the dislodgment of growing micro-organisms, favour reactions in which the required end product is the growing cell matter. Smaller cavities, by providing a rough surface, improve adhesion of the micro-organism thereto, are desirable in those reactions in which the required end product is in solution in the liquor. The polymeric material may be polyurethane, polyvinyl chloride, polystyrene, polyethylene, polypropylene, a polyamide resin, and any sufficiently inert and expansible polyester resin, acrylic resin or cellulose derivative.