Bacillus thuringiensis and related insect pathogens.

The recently discovered high-frequency transfer of plasmids between strains of Bacillus thuringiensis was used to study the genetic relationship between plasmids and production of the insecticidal delta-endotoxin crystal. Three strains of B. thuringiensis transmitted the Cry+ (crystal-producing) phenotype to Cry- (acrystalliferous) B. thuringiensis recipients. Agarose gel electrophoresis showed that one specific plasmid from each donor strain was always present in Cry+ "transcipients." The size of the transmissible crystal-coding plasmid varied with the donor strain, being 75 MDal (megadaltons) in size in HD-2, 50 MDal in HD-73, and 44 MDal in HD-263. Immunological analysis showed the Cry+ transcipients to be hybrid strains, having flagella of the recipient serotype and crystals of the donor serotype. These results demonstrate that the structural genes for the delta-endotoxin are plasmid borne. Crystal-coding plasmids also transferred into two strains of the related species Bacillus cereus and yielded transcipients that produced crystals of the same antigenicity as the donor strain.

https://www.pnas.org/content/pnas/79/22/6951.full.pdf

Transfer of Bacillus thuringiensis plasmids coding for delta-endotoxin among strains of B. thuringiensis and B. cereus

The location of crystal protein genes in 22 crystalliferous Bacillus thuringiensis strains representing 14 subspecies was investigated by hybridization of an intragenic restriction fragment from a cloned crystal protein gene to whole plasmid preparations. Hybridization was found to a single plasmid in eight strains, to more than one plasmid in seven strains, and to one or both of two large, unresolved plasmids in two strains. The sizes of the hybridized plasmids ranged from 33 to over 150 megadaltons. In one additional subspecies, hybridization was only to linear DNA fragments, suggesting a chromosomal crystal protein gene, and for four other subspecies, not reported to be toxic to lepidopteran insects, no hybridization was found to either plasmids or to total cell DNA. Hybridization to restriction digests of plasmids and total cell DNA of several strains of subspecies thuringiensis and kurstaki revealed that all homology to the cloned crystal protein gene was plasmid associated and that several of these strains contained multiple regions of homology, implying the presence of multiple crystal protein genes.

Diversity of locations for Bacillus thuringiensis crystal protein genes.

Correlation between specific plasmids and delta-endotoxin production in Bacillus thuringiensis.

This review article starts with the discovery of Bacillus thuringiensis Berliner in Japan at the turn of the century and notes that the observations of the early Japanese workers clearly show that they were aware of the toxin-mediated nature of the activity of B. thuringiensis toward insect larvae. The early work in Europe with B. thuringiensis against Ostrinia nubilalis (Hubner) showed that the bacterium had promise as a microbial control agent. The commercial development of B. thuringiensis in France in the late 1930s, and in Eastern Europe and the United States in the 1950s, is traced.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0008347X00023427

Janina Krywienczyk

Papers

Occurrence of two serologically distinct groups within Bacillus thuringiensis serotype 3 ab var. kurstaki

Serological investigations of insect viruses I. Comparison of three highly purified cytoplasmic-polyhedrosis viruses

Cerato-ulmin, a Wilting Toxin of Ceratocystis ulmi

Electrophoretic fractionation of cytoplasmic polyhedrosis virus genome

A serological comparison of several crystalliferous insect pathogens