Ritva Landén

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Bacillus thuringiensis strains were found to be naturally present in the soils of southern Sweden, being isolated from nine out of 12 sites examined. Forest soil samples were more rich in B. thuringiensis strains than soil samples collected from cultivated areas. A wide diversity of B. thuringiensis strains, representing different biochemical groups, was(More)
Flagellin from Bacillus thuringiensis subspecies alesti strain Bt75 was isolated both from the culture medium and from flagella. Two protein forms with molecular masses close to 32 kDa were obtained from flagella; one form was identical to the flagellin purified from the culture medium. The N-terminal amino acid sequences were identical for both forms. Two(More)
Plasmid DNA-mediated transformation of vegetative cells of Bacillus thuringiensis was studied with the following two plasmids: pBC16 coding for tetracycline resistance and pC194 expressing chloramphenicol resistance. A key step was the induction of competence by treatment of the bacteria with 50 mM Tris hydrochloride buffer (pH 8.9) containing 30% sucrose.(More)
The gene for the secreted neutral metalloprotease, immune inhibitor A (InA), from Bacillus thuringiensis var. alesti has been cloned and sequenced. The deduced amino acid sequence has been confirmed by partial amino acid sequencing. The central part of the amino acid sequence showed similarity to the active site in thermolysin. Southern and Western blots(More)
An avirulent pleiotropic mutant of the insect pathogen Bacillus thuringiensis subsp. gelechiae, isolated by Heierson et al. (A. Heierson, I. Sidén, A. Kivaisi, and H. G. Boman, J. Bacteriol. 167:18-24, 1986) as a spontaneous phage-resistant mutant, was further characterized and found to lack the expression of phosphatidylcholine- and(More)
At moderate concentration, 23 of 40 strains of Bacillus thuringiensis isolated from Sweden were toxic to Trichoplusia ni and five were toxic to Aedes aegypti. Five of the strains were toxic to Diabrotica undecimpunctata at high concentration, two were toxic to Heliothis virescens at low concentration and five produced thuringiensin (formerly called(More)
Two Bacillus thuringiensis strains were tested for the ability to adhere to cultured Spodoptera and Drosophila insect cells. The wild-type strain is virulent and motile and readily adheres to and kills both types of insect cells. The avirulent mutant strain, which lacks flagella and several other of the proposed virulence factors, does not adhere to the(More)
We have previously described a phage (ϕ63) for generalized transduction in Bacillus thuringiensis and used it for mapping of four chromosomal antibiotic resistance markers, namely nalA-rifA-strA-spcA (Landén et al. 1981). From ϕ63 we have now isolated a host range mutant called ϕ64 which contains 52–56 megadalton of DNA. Phage ϕ64 was found to be a more(More)
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