Abstract
SUMMARY: Shigella dysenteriae organisms of a very young culture released neurotoxin into the medium within 1 hr after it was infected with T-phages. Two types of phage-associated enzymes were considered to be involved in this process. The first type was phage-bound enzyme, which was bound firmly with phage, worked together with phage, and depolymerized neurotoxin into smaller molecules. The second type enzyme was phage-induced lysin, so-called ‘endolysin’, which was separable from phage and had lytic activity on dead bacteria. The latter enzyme, however, had no direct effect on the amount of neurotoxin released from acetone-powder preparations of the bacteria into phosphate buffer, although endolysin lysed 25 % of the bacteria at 30° in 30 min. Young living S. dysenteriae organisms did not release neurotoxin into the medium under normal conditions, whereas the acetone-powder preparations of S. dysenteriae, i.e. dead organisms, released neurotoxin into the medium freely under the same conditions.