INDUCED RELEASE OF DIPICOLINIC ACID FROM SPORES OF BACILLUS MEGATERIUM

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Abstract
Factors inducing release of dipicolinic acid from washed clean spores of B. megaterium were studied. Spore dipicolinic acid (I) was released as free acid by mechanical breakage of the spores. Thermal release of (I) was studied in detail. Practically all of the (I) was released from intact spores by heating a few minutes at 100[degree]C; 70[degree]C was critical for the release. Loss of viability always exceeded the rate of thermal (I) release indicating that death of the cells precedes the release. Repeated freezing and thawing of normal spores did not release (I) or kill the spores, nor did exposure to X-rays at a dosage of 60,000 r for 60 min. Ultraviolet irradiation released substantial amounts of (I), but only long after the spores had lost viability. Electrodialysis of spores through a cellophane membrane resulted in substantial movement of (I) from the spores to the cathode chamber. Several organic solvents, e.g., 80% methanol, 80% ethanol, 80% acetone, released substantial amounts of (I) at 56[degree]C, whereas water extracted none under the same conditions. Of a series of chemicals tested for induction of (I) release, H2O2 (5%), phenol (5%), and a commercial surface active agent, Arquad T, were effective inducers of (I) release during exposure at various temperatures. Spores that have lost their (I) thermally in water or in solvents or in chemical reagents retained their characteristic retractility.