Expression of parasporal crystal protein (δ-endotoxin) gene(s) of Bacillus thuringiensis var. israelensis in sporogenic and asporogenic mutant strains of Bacillus cereus.

The expression of parasporal crystal protein (δ-endotoxin) coding gene(s) of Bacillus thuringlensis var. israelensis and its association, if any, with sporulation was studied in sporogenic Bacillus cereus and its asporogenic mutant strains. Five asporogenous mutants of Bacillus cereus blocked at different stages of sporulation, were isolated from a streptomycin-resistant strain, The transconjugants isolated from the plasmid transfer experiments between Bacillus thuringiensis var. israelensis and streptomycin resistant Bacillus cereus and its asporogenous mutants, showed larvicidal activity. The crystal protein gene(s) are, therefore, expressed both in sporulating and in non-sporulating mutant strains of Bacillus cereus suggesting that the expression of crystal protein gene(s), is independent of sporulation specific functions in Bacillus cereus.

Bacillus thuringiensis crystal protein (δ-endotoxin) gene expression is independent of early sporulation specific functions.

Bacillus thuringiensis produces a parasporal insecticidal crystal protein. The correlation between sporulation and crystal protein production in Bacillus thuringiensis var. israelensis was studied. The strain was made resistant'against streptomycin (StR)- Acrystalliferous (Cry-) cured derivatives and asporogenous acrystalliferous (Spo- Cry-) mutants blocked at an early stage of sporulation were isolated. Plasmid transfer experiments were performed between Sts Spo+ Cry+ (streptomycin sensitive sporogeneous crystalliferous) and StR Spo+ Cry– and also between Sts Spo+ Cry+ and StR Spo– Cry– strains. StR colonies were selected. Insect toxicity was exhibited by the StR isolates in both the cases. The process of crystal formation is, therefore, independent of early sporulative events.

Survival of orally administered isolated intestinal Lactobacillus acidophilus in different parts of gastrointestinal tract of mice.

A strain of Lactobacillus acidophilus (Strain HF) was isolated from human faeces. A chloramphenicol resistant strain (HFCm) and a strain (HFCmSm chloramphenicol and streptomycin were developed from the isolated strain (HF). All the ) restant to both Kyd Street, Calcutta 700 016 three strains showed similar in vitro susceptibility against host defence factors like gastric acid, bile salts and volatile as well as non-volatile fatty acids. In vivo tests were done by feeding these strains to mice. When the resistant strains were orally administered along with the antibiotic(s) they were stable up to 72 h.