Location of 43 kD mosquito-larvicidal toxin gene of highly toxic Bacillus sphaericus 10

The direct evidence of the location of the mosquito-larvicidal gene of Bacillus sphaericus 10 (isolated from Jiangsu Province of China) on megaplasmid pFW1 was given by molecular cloning. The clone (pFL109) containing the 1.4 kb HindIII DNA fragment from pFW1 expressed the mosquito-larvicidal toxin protein (43 kD). The location of the gene coding for the 43 kD toxin protein within the XhoI B fragment on the restriction map of pFW1 was confirmed by Southern blotting using the 1.4 kb HindIII DNA fragment as a probe. The non-toxic strains of Bacillus sphaericus were revealed to be 43 kD toxin gene deletion mutants by Southern and Western analyses. The 1.4 kb HindIII fragment of pFL109 can be used as a probe for differentiating the non-toxic strains of Bacillus sphaericus from the toxic ones.