A therapeutically active bacterial preparation for the treatment of illnesses associated with unbalance of the intestinal flora comprises a culture of living non-pathogenic colon bacilli which are resistant to antibiotics, together with glutamic acid (and/or an alkali metal glutamate) and at least one pH-buffering substance which is present in such quantity as to maintain the pH of the preparation at a value between 4.0 and 9.0, preferably between 6.9 and 7.4.  The preparation may include, in addition to the colon bacilli, other aerobic and/or anaerobic micro-organisms which are normally found in the intestines of a healthy human subject (specified) in amounts up to ten times the concentration of colon bacilli, intestinal bacteriophages other than coli-bacteriophages, an aminated extract of yeast, peptones, fibrins, a thickening agent such as gelose, peptin, gum arabic or alkyl cellulose, kaolin, bismuth salts and alumina gels.  Larger survival percentages of the micro-organisms after lyophilisation is achieved by addition to the culture of mucin (mucopolysaccharides extracted from animal glands, to the extent of 2.25% by weight of the dry material of the culture.  In a preferred procedure the liquid culture of colon bacilli is centrifuged, the centrifuged substance is re-suspended in an aqueous nutritive solution containing 2-100 grams of mucin of animal origin per litre, and the dispersion obtained is frozen and then subjected to sublimation and distillation under low vacuum to give a dry powder.  Suitable buffering agents are the pairs d, l-aspartic acid and d, l-sodium aspartate, mono-sodium tartrate and disodium tartrate, mono-sodium citrate and disodium citrate, disodium citrate and trisodium citrate, acetic acid and sodium acetate, glutamic acid and sodium glutamate, disodium phosphate and mono-potassium phosphate, d, l-cystein (or d, l-tyrosine) and their hydrochlorides, and ammonia and ammonium chloride.  The bacterial preparation may be distributed in gelatine-coated pills and may be administered with lactose, sucrose and orange essence.ALSO:A therapeutically active bacterial preparation for the treatment of illnesses associated with unbalance of the intestinal flora comprises a culture of living non-pathogenic colon bacilli which are resistant to antibiotics, together with glutamic acid (and/or an alkali metal glutamate) and at least one pH-buffering substance which is present in such quantity as to maintain the pH of the preparation at a value between 4.0 and 9.0, preferably between 6.9 and 7.4.  The preparation may include, in addition to the colon bacilli, other aerobic and/or anaerobic micro-organisms which are normally found in the intestines of a healthy human subject (specified) in amounts up to ten times the concentration of colon bacilli, intestinal bacteriophages other than coli-bacteriophages, an aminated extract of yeast, peptones, fibrins, a thickening agent such as gelose, peptin, gum arabic or alkyl cellulose, kaolin, bismuth salts and alumina gels.  Larger survival percentages of the micro-organisms after lyophilisation is achieved by addition to the culture of mucin (mucopolysaccharides) extracted from animal glands, to the extent of 2.25% by weight of the dry material of the culture.  In a preferred procedure the liquid culture of colon bacilli is centrifuged, the centrifuged substance is resuspended in an aqueous nutritive solution containing 2-100 grams of mucin of animal origin per litre, and the dispersion obtained is frozen and then subjected to sublimation and distillation under low vacuum to give a dry powder.  Suitable buffering agents are the pairs d, l-aspartic acid and d, l-sodium aspartate, mono-sodium tartrate and disodium tartrate, mono-sodium citrate and disodium citrate, disodium citrate and trisodium citrate, acetic acid and sodium acetate, glutamic acid and sodium glutamate, disodium phosphate and monopotassium phosphate, d, l-cystein (or d, l-tyrosine) and their hydrochlorides, and ammonia and ammonium chloride.  The bacterial preparation may be distributed in gelatin-coated pills and may be administered with lactose, sucrose and orange essence.