SUMMARY: A strain of Lactobacillus plantarum has been isolated from Sauerkraut which can produce acetylcholine during growth and in washed suspensions. The conditions necessary for the production of acetylcholine are: (i) the presence of choline and (ii) the simultaneous fermentation of carbohydrate. The acetylcholine is formed inside the cells and subsequently passes into the medium. The amount formed can be about 5 μg. acetylcholine/mg. dry wt. cells/hr. The acetylcholine was identified by the usual biological tests and was also isolated and identified as the salt of hexanitrodiphenylamine. The mechanism of the acetylation has not been discovered. Cells grown in the absence of added pantothenate acetylate extremely slowly. The rate is restored by the addition of pantothenate to the cell suspension.