Cry gene and plasmid profiling of Bacillus thuringiensis isolated from Indian soils

摘要

HCry gene and plasmid profiling of indigenous Bacillus thuringiensis isolates from North East India and Andaman were carried out. A total of 29 isolates were screened and HD-1 was used as reference. Plasmid profiling showed distinct bands of differentsizes with unique patterns for each strain. Twenty one isolates had plasmids above 33500 bp and only 14 had plasmids of the same size. One isolate NBAII-TRBT17 showed presence of four plasmids having sizes of 2500bp, 7000bp, 7500bp and 33500bp.Six of them had three plasmids of different sizes. The isolates NBAII-BT5, NBAII-TRBT9, NBAII-TRBT18, NBAII-ASBT15, NBAII-ASBT11 andNBAII-AGBT5 showed similar band migration with three plasmids between 7000 to 9000 bp and 33500 megaplasmid each. Strain NBAII-BTN3showed two different plasmids but plasmid size ranged as 9000 bp and 33, 500 bp which had similar pattern with NBAII-ASBT1, but NBAII-ASBT1 also harbored plasmid above 33500 bp. The isolates NBAII-TRBT10, NBAII-TRBT16, NBAII-TRBT8, NBAII-BTAN$,NBAII-BTAN5, NBAII-ASBT20, NBAII-ASBT2, NBAII-ASBTN1, NBAII-BTEG1, NBAII-AGBT13,NBAII-AGBT6, NBAII-AGBT1 and NBAII-ASBT21 showed presence of a single plasmid above 33500bp. The isolates NBAII-ASBT24, NBAII-BT3 and NBAII-AGBT25 showed similar migration of plasmidsranging between 15000-33500 bp. The plasmids were probed for Cryl, Cry2 and Cry3 genes with universal primers and isolates showed differential expression of the genes. Six of the isolates namely NBAII-ASBT20, NBAII-ASBT24, NBAII-TRBT10, NBAII-TRBT17, NBAII-BTAN4 and NBAII-BTAN5 showed presence of Cry3 gene also apart from Cryl which could indicate that it could be active against coleopterans also. Plasmid DNA profiles and cry protein characterization provided information on diversity among the isolatesand the cry gene diversity.