An Improved Technic for the Voges-Proskauer Test

Voges and Proskauer (1898) described the production of an eosin-like coloration in glucose peptone cultures of certain organ-isms to which had been added a 10 per cent solution of potassium hydroxide. The reaction is generally referred to as the V-P test and serves as a valuable aid to the identification and differ-entiation of micro6rganisms. The reaction depends upon the production of acetoin (ace-tylmethyl carbinol), a non-volatile reducing substance. Ac-cording to Harden (1905) acetylmethyl carbinol is oxidized upon the addition of KOH and in the presence of peptone there is imparted an eosin-like coloration to the medium. Later Harden and Norris (1911) reported that diacetyl in the presence of strong KOH solution reacts with proteins to give a pink coloration with a green fluorescence. The coloration appears to depend on the group