RESTRICTION-DEFICIENT MUTANT

摘要

PI/5-18199/A RESTRICTION-DEFICIENT MUTANT The present invention relates to a mutant of Bacillus thuringiensis and/or B. cereus that has a partial deficiency of the restriction barriers inherent in the unmutated starting strain and that may therefore be transformed significantly better than the said non-mutated starting strain when vector DNA from a heterologous intermediate host that is naturally subject to restriction in B. thuringiensis and/or B. cereus is used. Special preference is given to the partially restriction-deficient mutant B. thuringiensis var. kurstaki HD1cryB Res9, which is obtainable by means of spontaneous mutation from the B.t. strain HD1cryB and can be obtained by means of enrichment methods known per se, The invention relates also to methods of preparing the said mutants that are based on the specific enrichment of spontaneous mutants and to methods of cloning genes or other DNA sequences using the said restriction-deficient mutants of Bacillus thuringiensis and/or Bacillus cereus.