The purification and properties of the L-threonine deaminase of the rumen micro-organism LC1.

The micro-organism LC, isolated from the sheep rumen by Elsden, Volcani, Gilchrist & Lewis (1956), ferments a variety of substrates to yield volatile fatty acids (Elsden & Lewis, 1953). Washed cells of the organism fermented L-threonine and L-serine. Hydrogen, carbon dioxide and ammonia were produced from both substrates and, in addition, propionate was formed from threonine and acetate from serine (Lewis & Elsden, 1955). Acetone-dried powders converted L-threonine into a keto acid, identified as 2-oxobutyrate, as well as the above end products. When 2-oxobutyrate was used as substrate, hydrogen, carbon dioxide and propionate were the principal products. These experiments suggested that a threonine deaminase is involved and that 2-oxobutyrate is an intermediate in threonine fermentation.