A Search Into The Nitrate And Nitrite Content Of Witte's "Peptone," With Special Reference To Its Influence On The Demonstration Of The Indol And Cholera Red Reactions

Abstract

In a previous publication1 I concluded, by rather rough experimental methods and deductions, that the cholera spirillum is not a nitrifying organism and that the successful demonstration of the cholera red reaction in a culture grown in a solution of Witte's peptone depends upon the reduction of a trace of nitrates. I was unaware at the time my experiments were performed that Petri2 and Bleisch3 had already performed quite extensive and conclusive experiments upon this point. The latter worker also pointed out that the presence of an excess of nitrates or nitrites in the medium interfered with the reaction, and that the nitrate content of ordinary broth is so inconstant as to make it valueless for diagnostic purposes. Some peculiar results in testing for indol, during the study of some bacteria from a case of irregular fever, emphasized for me the urgent necessity of adopting methods of preparing and testing media which would indicate the presence or absence of certain chemical constituents influencing such a biochemical test. This led to an investigation into the manner in which nitrates and nitrites may gain an entrance to media, and the influence of such variations on the demonstration of the indol and cholera red reactions. It does not seem to me that the distinct difference between