THE INFLUENCE OF MOLDS ON THE GROWTH OF LUMINOUS BACTERIA IN RELATION TO THE HYDROGEN ION CONCENTRATION, TOGETHER WITH THE DEVELOPMENT OF A SATISFACTORY CULTURE METHOD

Abstract

The influence of molds on the length of life of cultures of luminous bacteria may be simulated by the use of buffer mixtures, or by supplying fresh alkali continually. The maximum alkalinity produced in these experiments by the influence of Penicillium sp. was pH 8.6 ∓ .2. Degeneration of cultures of luminous bacteria may be caused by growth on media insufficiently alkaline, or so slightly buffered that it soon becomes acid. Diffuse growth and spreading over the surface of the slant is caused by too low salt concentration. Long life of cultures may be secured by growing on media sufficiently alkaline, and sufficiently buffered to resist rapid change by the acid production of the bacteria, which are killed by their own acid at about pH 5.6.