[Study on Bacillus pumilus as a recipient strain for genetic engineering of Bacillus].

Bacillus pumilus 289 can be transformed easily by plasmid pUB110 through protoplast transformation with the frequency of 10(-5)--10(-3), similar to B. subtilis AS 1.1176, a derivative strain of B. subtilis 168. The regeneration frequency of its protoplast is only slightly lower than B. subtilis AS1.1176 (0.3-12.0% compare to 1.53--24.16%). Plasmid pUB110 can be maintained in both bacterial strains stably. The frequency of loss of the plasmid in both strains is lower than 3% after 45 generations in LB medium. But it is quite different that the hybrid plasmid (pUB110 with 3.9 kb foreign DNA fragment) can be maintained much more stably in B. pumilus 289 than in B. subtilis AS1.1176. The frequency of loss of the plasmid is lower than 5% in B. pumilus 289 and 24% in B. subtilis AS1.1176 after 25 generations when they grown in SH medium. The expression level of foreign gene in B. pumilus 289 is also much higher than that in B. subtilis AS1.1176. Therefore B. pumilus 289 is valuable to be exploited as recipient strain for genetic engineering of Bacillus in the future.