Distribution of Bacillus thuringiensis in Forest Soil of Four Nature Reserves in China

A total of 75 forest soil samples at 0~5cm depth collected from four nature reserves (Chang Bai Shan,Bai Hua Shan,Deng Hu Shan,Jiang Feng Ling) in China were examined for account of Bacillus and Bacillus thu-ringiensis,for description of the distribution of B.thuringiensis and calculation of the rate of B.thuringiensis to Bacillus in these forest soil.39 isolates of B.thuringiensis obtained from the forest soil were identified by means of the characterization of physiology-biochemistry and esterase type.It indicated that among the 39 isolates,17 belong to B.t.subsp.kurstaki (H-serotype 3a3b),6 belong to B.t.subsp.dendrolimus (H-serotype 4a4b),and 16 were different from known subspecies.These isolates were toxin-tested to insects.70% of the 39 isolates were Lepidopteran-toxin:the mortality against Clostera anachoreta and Dendrolimus punctatus were above 50%.Coleoptero-toxin were not observed.