The yeast extract SERVABACTER is the water-soluble fraction of the yeast autolysate. SERVABACTER contains amino acids, peptides and carbohydrates and is particularly rich in B vitamins and growth factors. The powdered yeast extract serves as an additive for microbiological cell culture media such as LB-, 2x YT- or also SOB-medium for the production of transformation-competent bacteria. A 2 % aqueous solution is clear and has a pH in the range between 6.5 and 7.5. The yeast extract SERVABACTER is the water-soluble fraction of the yeast autolysate. SERVABACTER contains amino acids, peptides and carbohydrates and is particularly rich in B vitamins and growth factors. The powdered yeast extract serves as an additive for microbiological cell culture media such as LB-, 2x YT- or also SOB-medium for the production of transformation-competent bacteria. A 2 % aqueous solution is clear and has a pH in the range between 6.5 and 7.5.