关键词: 苏云金芽孢杆菌, δ—内毒素, 毒性多肽, 鞘翅目

Abstract: Noctuids-sensitive parasporal crystals were dissolved and protoxins were activated with trypsin or gut juice of larva of Prodenia litura and Bomhyx mori. Toxic polypeptide produced by digestion of B. mori gut juice or trypsin was toxic only to B. mori, whereas toxic polypeptide pro duced by gut juice of P. litura was toxic to both P. limra and B. mori. Coleoptera-sensitlve δ-endotoxins of 70 Kd and 50kD could not be degraded completely by trypsin or gut juice of Mythimna separata. SDS-PAGE and chromatography showed that the 130 Kd protoxin was degraded to P. litura- specific toxins of 70 Kd and 75 Kd by P. litura gut juice, B. mori-specific toxins of 62 Kd and 65 Kd by B. mori gut juice and B. mori-specific toxins of 65 Kd and 68 Kd by trypsin. WhenP. litura-specific polypeptides of 70-75 Kd were subsequently treated with B. mori gut juice,the resulting polypeptides of 62-64 Kd were no longer toxic to P. litura but acquired B. moritoxicity. Reversely, protoxin treated first with B. mori gut juice or trypsin and then with P.Litura gut juice, resulting 62-65 Kd polypeptides were toxic only to B. mori. It was shown that the action of proteases of B. mori gut juice was similar to trypsin but different from proteases of P. litura gut juice.

Key words: Bacillus thuringiensis——δ-endotoxin——toxic polypetide——Coleoptera