Studies on the Nutrition of Dim and Bright Variants of a Species of Luminous Bacteria

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Abstract
A brilliant variant occurred in liquid cultures of Achromobacter fisheri grown on glycerol-peptone in sea water. Suspensions of this variant showed 4-5 times increase in luminescence. The variant occurred many times and the reverse variation was also observed both in liquid and agar plate cultures. The variant produced a bright yellow-brown pigment on the ordinary agar plate culture buffered with CaCO3; the original strain did not; both strains developed pigment when the plates were buffered with phosphates at 8, neither in the acid range. Cultures of the original strain grown on glycerol-peptone became very acid, but cultures of the variant, after slight and temporary acidification, became neutral or alkaline. The sensitivity of the peptone respiration to pH was similar in both strains, but the sensitivity of the glycerine and succinic acid metabolism to acid was less for the variant. Suspensions of the variant were precipitated on the acid side of pH 6.8; the original strain was not affected at any viable pH. The bright strain may be considered a variant which adapts the species to the acid conditions unfavorable to the original strain.