Isolation of Bacillus thuringiensis from tropical and subtropical soil samples
1994
Zelazny, B. | Welling, M.
As part of attempts to find isolates of Bacillus thuringiensis with specific toxicity to locusts, soil samples were collected from tropical and subtropical countries, particularly from arid and semi-arid areas frequented by locusts and grasshopper swarms, and examined for the presence of this bacterium. The present article deals with the isolation procedure and the prevalence of B. thuringiensis in the samples. Out of 456 soil samples 104 contained B. thuringiensis, and the estimated median concentration of colony forming units for all samples was about 4000 g soil. In some countries, where soil samples were taken at regular intervals along the roads, B. thuringiensis could be found to be a common soil bacterium over stretches of more than 100 km. Out of 176 B. thuringiensis isolates obtained, 74 were toxic to larvae of the lepidoptera Plutella xylostella and Ephestia kuehniella. The abundance of B. thuringiensis and taxonomically similar forms (Bacillus cereus-like bacteria) was not significantly related in the samples
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