On the exotoxin of Bacillus thuringiensis var. thuringiensis Berliner : (1) Separation and the effect of toxin on silk worm

Insecticidal exotoxin produced from Bacillus thuringiensis var. thuringiensis Berliner was found to contain two components called F-I and F-II. Both of them had an adenine, a phosphorus and a ribose in their molecules. Molecular weight of F-I was calculated as 860 electrophotometrically. F-I was about 10 times more toxic than F-II by the lethal potency to silkworms. Toxin-injected worms were killed with elongated duration of a instar, and without ecdysis. Molting worms were less sensitive to the toxin F-I than working worms. Phenoloxidase activity in the integument of the silkworms which were injected with F-I were kept at low levels, even when the activity of normal bodies arose more higher. But the toxin scarcely inhibited the enzymatic activity in vitro.1. BTTが産生する低分子の菌体外毒素はF-I,F-IIの2種の成分からなり,その各々はリボースおよび燐を1部宛含んでおり,その毒性はF-ＩがF-IIにくらべて10倍以上強力であつた. 2. F-Iの家蚕に対する毒性は食桑蚕に対する時が眠中のそれに対する時よりも強かつた.また蚕蛹に対しては蛹化後6日以前に注射した時には羽化することなく死に至つたが,8日以降に注射すると羽化が認められ,その後斃死した. 3. 家蚕の品種による毒性の感受性には著しい差はなかつた. 4. 本毒素は蛹化前におけるフェノールオキシダーゼ活性の上昇を阻止したが,in vitroにおける酵素阻害は100倍以上の高濃度の毒素によつてわずかに認められたにすぎなかつた