The antibiotic potencies of the culture fluids of the strain of B. prausnitzii T. were observed on many kinds of media, on various conditions of culture and on the culture fluids variously treated.
The potencies of the culture fluids were observed to be distinguished in Bouillion, peptone water, yeast extract, soybean extract, milk, casein and salts media containing casein hydrolysate or such one amino acid as glutamic acid, aspartic acid, alanine, arginine and histidine.
The potency increased by the addition of any of such sugars as galactose, lactose and maltose to the media above mentioned.
The potency was not almost detected in any salt media containing mineral N-compounds or any of glycine leucine and cystine as N-source.