Studies on the Isolation of δ-Endotoxin and Plasmids in Bacillus thuringiensis

Bacillus thuringiensis의 내독소(內毒素)와 플라스미드의 분리에 관한 연구

  • 오상수 (농촌진흥청농업기술연구소) ;
  • 이형환 (건국대학교 생물학과)
  • Received : 1985.01.31
  • Published : 1985.03.01

Abstract

Delta-endotoxin in Bacillus thuringiensis var. finitimus, HD-1, HD-9 and HD-73 strains were isolated by NaBr, CsCl and Renografin density gradients. The purity of the toxin was about 98%. The purified o-endotoxin was analyzed by SDS-PAGE, electron microscopic observation and bioassay. According to SDS-PAGE, the molecular weight of subunits of the o-endotoxin were about 66,000 and 130,000 daltons. The shapes of the crystal toxin observed by TEM except finitimus strain were bipyramidal. When the purified endotoxin was bioassayed against tobacco horn worm, the entomocidal activities ($1{\mu}g/ml$) of HD-1 and HD-73 strains were, respectively, 60% and 100% at nine days after treated. The molecular weights of the plasmids isolated from B. thuringiensis were various from 0.5 to 120 Kb. The numbers of plasmids in HD-1, HD-9 and HD-73 strains were 12, 3 and 11, respectively, but B. thuringiensis var. finitimus strain had no plasmid.

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