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A partially purified preparation of a water-soluble, heat-resistant, nonspecific exotoxin produced by a strain of Macrophomina phaseolina, isolated from Phaseolus mungo L. could reduce Cu++ ions and produced a red colour with 2,4-dinitrophenyl hydrazine reagent. It caused inhibition of seed germination, wilting of cult seedlings, stunted growth of young seedlings and loss of permeability of the cell membrane. Seedlings of P. mungo, grown in presence of the toxin showed a slight increase in the contents of protein and total RNA over control, but a significant increase in the specific activities of F-1, 6-BP aldolase and G-6-P isomerase.

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Summary.A temperate phage coding for constitutive hypertoxigenicity has been constructed in Vibrio cholerae strain 569B and used to lysogenise the low-toxinproducing strain MAK 757; 18% of lysogens showed 10-100-fold increase in toxin production. This property was also transmitted at low frequency to second generation lysogens. Thus temperate phage can increase toxin production in a low-toxinproducing strain.