Characterization of Bacillus thuringiensis ser. balearica (Serotype H48) and ser. navarrensis (Serotype H50): Two Novel Serovars Isolated in Spain

Abstract

The novel strains of Bacillus thuringiensis PM9 and NA69, isolated from soil samples in Spain, were classified and characterized in terms of their crystal proteins, plasmid profile, cry genes content, and their toxicological properties against several species of Lepidoptera, Coleoptera, and Diptera. Both strains share morphological and biochemical characteristics with previously described B. thuringiensis strains, although their unique H antigens identify them as two new serotypes. Two new serovar names, B. thuringiensis serovar balearica (H serotype 48) and B. thuringiensis serovar navarrensis (H serotype 50) are proposed for the type strains PM9 and NA69, respectively.

Contents of cry genes and insecticidal toxicity of Bacillus thuringiensis strains from terrestrial and aquatic habitats

“…The crystal protein composition of the strains serovar thuringiensis was previously analysed by SDS‐PAGE gel electrophoresis (Iriarte et al. 1998, 2000), and it was shown that cry2 was only expressed in the seven strains of aquatic habitats that were toxic against T. oleracea .…”

“…The strains analysed in this work were isolated from a national screening programme carried out in terrestrial environments of Spain (Iriarte et al. 1998), and from a sampling of aquatic environments of the Spanish province of Navarre (Iriarte et al. 2000).…”

“…The strains analysed in this work were isolated from a national screening programme carried out in terrestrial environments of Spain (Iriarte et al 1998), and from a sampling of aquatic environments of the Spanish province of Navarre (Iriarte et al 2000). A group of 38 strains from the former collection and 24 isolates from aquatic habitats were randomly selected for further analysis by means of PCR, as well as by serology and insect toxicity.…”

“…The number of strains lacking all the genes tested was 11 and only two strains were toxic, one of them being active against both lepidopteran species and the other against H. armigera. The crystal protein composition of the strains serovar thuringiensis was previously analysed by SDS-PAGE gel electrophoresis (Iriarte et al 1998(Iriarte et al , 2000, and it was shown that cry2 was only expressed in the seven strains of aquatic habitats that were toxic against T. oleracea.…”

Screening of the Insecticidal Activity of <I>Bacillus thuringiensis</I> Strains Against <I>Lygus hesperus</I> (Hemiptera: Miridae) Nymphal Population

“…Among the 50,000 B. thuringiensis strains kept in various collections worldwide (Sanchis et al 1996), only a limited number of strains belonging to a small number of serovars have been developed for the control of insect pests . B. thuringiensis serovars that synthesize parasporal inclusion bodies with unknown insect toxicity or function is a frequent occurrence (Lee et al 1994, Porcar et al 1999, Iriarte et al 2000. Before concluding that L. hesperus is not amenable to biocontrol with B. thuringiensis ␦-endotoxins, it would be worthwhile to try other proteolytic enzymes on the B. thuringiensis strains tested here, in hopes of generating an active fragment.…”