One hundred and two Bacillus thuringiensis Berliner strains isolated from six different types of Canadian soil and dust from different grain storage bins were cultured in shake flasks containing Great Northern White Bean (GNWB) protein concentrate (48.6% protein) as the main nitrogen source and dextrose as the main carbohydrate source. The resulting endotoxins were bioassayed against the bertha armyworm, Mamestra configurata Wlk. Thirty-three percent of soil and 66% of grain dust samples were positive for B. thuringiensis. The bacterium was found most frequently in organic-rich soil. The four most toxic soil isolates (which were seven to 15 times more toxic than the international standard, HD1-S-1980), and two nontoxic grain dust isolates were characterized by serological typing, biochemical analysis, carbohydrate utilization, plasmid profile analysis, protein profile analysis using sodium dodecyl sulfate – polyacrylamide gels, and polymerase chain reaction. Four isolates were determined to be subsp. kurstaki containing 130–140 and 63–65 kDa proteins, and two isolates (tested for comparison) were subsp. canadensis containing 31 and 38 kDa proteins. Nonpyramidal-crystal-producing strains did not grow well in culture media containing GNWB, degossypellized cotton seed meal (61% protein), defatted soy flour (55% protein), or peptone as nitrogen sources. Excess of GNWB protein concentrate in shake flask culture media (30 g/L) inhibited bacterial growth and reduced the toxicity of isolate A1.2/72 subsp. kurstaki, which was the most toxic soil isolate. Isolate A1.2/72, which was 15 times more toxic for bertha armyworm larvae than the international standard (HD1-S-1980), contained three cry1A genes (cry1Aa, cry1Ab, and cry1Ac), whereas HD-1 lacked the cry1Ab gene. This strain was synergistic with strain HD-551 subsp. kenyae (cry1A, cry2A, and cry1B genes) but not with HD-133 subsp. aizawai (cry1Ab, cry1B, cry1C, and cry1D genes) when the strains were cultured together in a cotton seed meal medium and fed to M. configurata. The growth rate, economic yield, and toxicity of the new isolate, A1.2/72, produced in a 14-L laboratory fermenter declined when the fermentation ingredients were tripled. We believe that the indigenous strain A1.2/72 warrants further research development for bertha armyworm control.