title: Changes in the properties of Bacillus thuringiensis after prolonged culture in a rich medium.
abstract: OBJECTIVE
  To investigate the effect of repeated culture in a rich medium on certain genetic, metabolic, pathogenic and structural characteristics of fresh isolates of Bacillus thuringiensis.
  
  
  RESULTS
  Four strains of B. thuringiensis, which had been isolated in vegetative form from leaf surfaces, were grown for 500 generations in batch culture in a rich medium. One of the strains, S4g, differed from the parent in the following respects: greater cell width; changed plasmid profile; complete loss of ability to produce delta-endotoxins; loss of ability to produce beta-exotoxin and disruption of vip3 gene; radically different fatty acid composition; and altered metabolic activity. Two of the other evolved strains (S1g and S6g) showed differences in fatty acid profiles compared with the parents. Genetic finger-printing showed that there were also mutations in the cry genes of two of the evolved strains (S1g and S2g). The delta-endotoxins of strain S6g were significantly less toxic to the larvae of Pieris brassica compared with those of the parent and it also differed in the plasmid content.
  
  
  CONCLUSIONS
  Radical and unpredictable changes can occur in fresh isolates of B. thuringiensis when subjected to growth in the laboratory.
  
  
  CONCLUSIONS
  This is the first analysis of a Gram positive and biotechnologically significant bacterium after repeated laboratory culture. It is of great relevance to the biotechnological exploitation of B. thuringiensis that prolonged growth of environmental isolates on laboratory culture media can have profound effects on their structure, genome and virulence determinants.
authors.affiliation: School of Science, University of Greenwich, Chatham Maritime, UK.
authors.forename: M F
authors.initials: MF
authors.lastname: Bizzarri
authors.forename: A H
authors.initials: AH
authors.lastname: Bishop
authors.forename: A
authors.initials: A
authors.lastname: Dinsdale
authors.forename: N A
authors.initials: NA
authors.lastname: Logan
mesh_terms: D000595:Amino Acid Sequence; D001413:Bacillus thuringiensis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001431:Bacteriological Techniques; D001483:Base Sequence; D002688:Chitinases / Q000096:biosynthesis; D003470:Culture Media; D004731:Endotoxins / Q000096:biosynthesis; D016680:Genome, Bacterial; D007218:Industrial Microbiology; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D010957:Plasmids; D012150:Polymorphism, Restriction Fragment Length; D013171:Spores, Bacterial; D013995:Time
chemical_list: D003470:Culture Media; D004731:Endotoxins; D002688:Chitinases