Abstract
Some investigations were made on the microbiological activities of cobamides in feed upplement as a sample of fermentation products for determinating natural form of cobamides. An aqueous extract obtained by stirring the sample in water at 30℃ showed almost equal activity in Lactobacillus leichmannii assay to an extract with a boiling potassium cyanide solution. On the other hand, in Ochromonas malhamensis assay using Ford's medium containing no cyanide ion, the aqueous extract showed extremely low activity. However, addition of ascorbate or thioglycolate as stabilizing agents to the medium caused negligible loss of activity. Also, instead of autoclaving, an aseptical addition of the extract to the sterilized medium after passing through germ filter was successfully carried out. It was concluded from these results that low activity of the aqueous extract in usual Ochromonas assay was due to the existence of non-cyano type cobamides which is less stable to heat than cyano type. The non-cyano type cobamides were considered to be comparably active to cyano type and their electrophoretic and other behavior will be described elsewhere.
