Faust R M, Abe K, Held G A, Iizuka T, Bulla L A, Meyers C L
Plasmid. 1983 Jan;9(1):98-103. doi: 10.1016/0147-619x(83)90034-3.
Three crystalliferous (Cry+) strains of Bacillus thuringiensis subsp. israelensis (serotype 14) that produce parasporal protein crystals toxic to dipteran larvae and several acrystalliferous (Cry-) mutants, either induced or spontaneously derived from a single Cry+ parent, were examined for the presence of covalently closed circular (CCC) DNA in attempts to correlate toxin production with the presence of a specific plasmid. The plasmid profiles of both Cry+ and Cry- variants were analyzed by both a cleared lysate- and a modified Eckhardt lysate-electrophoresis technique. All of the Cry- mutants derived from the Cry+ parental strain had lost a 4.0- to 4.4-megadalton (Mdal) plasmid. Bioassay data confirmed loss of toxin production by the Cry- variants. All three Cry+ strains, including the parent of the Cry- strains, contained CCC plasmids DNAs of the following approximate molecular weights: 4.0 to 4.4, 5.2 to 6.0, and 11.4 to 13.0 Mdal. One Cry+ strain contained an additional CCC plasmid of 6.7 to 7.2 Mdal. The plasmid patterns for several Cry- derivatives differed in other respects from the pattern for their parent strain. The various Cry+ and Cry- strains could be distinguished either by phenotypical differences in antibiotic sensitivity, crystal production, and toxicity, or by differences in their plasmid profiles.
苏云金芽孢杆菌以色列亚种（血清型14）的三株产晶体（Cry+）菌株，可产生对双翅目幼虫有毒的伴孢晶体蛋白，以及几株无晶体（Cry-）突变体，这些突变体要么是由单个Cry+亲本诱导产生，要么是自发产生的。研究人员检测了它们是否存在共价闭合环状（CCC）DNA，试图将毒素产生与特定质粒的存在联系起来。通过清亮裂解物电泳技术和改良的埃克哈特裂解物电泳技术，分析了Cry+和Cry-变体的质粒图谱。所有从Cry+亲本菌株衍生而来的Cry-突变体都丢失了一个4.0至4.4兆道尔顿（Mdal）的质粒。生物测定数据证实了Cry-变体毒素产生能力的丧失。所有三株Cry+菌株，包括Cry-菌株的亲本，都含有以下近似分子量的CCC质粒DNA：4.0至4.4、5.2至6.0和11.4至13.0 Mdal。一株Cry+菌株还含有一个6.7至7.2 Mdal的额外CCC质粒。几种Cry-衍生物的质粒图谱在其他方面与其亲本菌株的图谱不同。各种Cry+和Cry-菌株可以通过抗生素敏感性、晶体产生和毒性方面的表型差异，或通过其质粒图谱的差异来区分。
