title: Endospore degradation in an oligosporogenic, crystalliferous mutant of Bacillus thuringiensis.
abstract: We isolated a new oligosporogenic mutant from Bacillus thuringiensis var. kurstaki HD73 that retains the ability to produce insecticidal crystal inclusions. Sporulation in this mutant initiates in a manner similar to the wild-type strain, and under the electron microscope endospores are seen, but these do not reach maturity (except for 0.2% of them). At a late stage, the coat surrounding the forespore seems to lack shape and to be empty. Most mutant cells exhibit a well-formed bipyramidal crystal but are completely devoid of the forespore. The mutant has a functional SigK holoenzyme, which is required for the expression of genes involved in the formation of spore coat and cortex and for cry1A transcription from the BtII promoter. Defective maturation of spores could be due to an inadequate forespore coat or cortex structure resulting in the arrest of sporulation at late stage III or early stage IV.
authors.affiliation: Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Gto. 36500, Mexico.
authors.forename: Pável
authors.initials: P
authors.lastname: Sierra-Martínez
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Ibarra
authors.forename: Mayra
authors.initials: M
authors.lastname: de la Torre
authors.forename: Gabriela
authors.initials: G
authors.lastname: Olmedo
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000166:cytology / Q000235:genetics* / Q000502:physiology* / Q000648:ultrastructure; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology / Q000633:toxicity; D001427:Bacterial Toxins / Q000096:biosynthesis / Q000633:toxicity; D004731:Endotoxins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology / Q000633:toxicity; D017930:Genes, Reporter; D006460:Hemolysin Proteins; D007763:Lac Operon; D018402:Manduca / Q000254:growth & development / Q000382:microbiology; D008853:Microscopy; D008854:Microscopy, Electron; D008858:Microscopy, Phase-Contrast; D009154:Mutation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000502:physiology; D013171:Spores, Bacterial / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D014157:Transcription Factors / Q000502:physiology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C030956:insecticidal crystal protein, Bacillus Thuringiensis; C084190:sigma K