title: Recovery of Bacillus thuringiensis in vegetative form from the phylloplane of clover (Trifolium hybridum) during a growing season.
abstract: Two media were developed which specifically allow the cultivation of Bacillus thuringiensis while it is in the vegetative as opposed to the spore form. Using these media B. thuringiensis was shown conclusively for the first time to exist in an active form on the phylloplane. The profile of its appearance in vegetative and spore form was followed over a growing season on clover (Trifolium hybridum) in the field. Three simultaneous and sudden rises and declines of both spore and vegetative cell densities were observed. The most common other spore-former on these leaves was Bacillus cereus but the fluctuations in appearance of these two very closely related species were not co-incident. Using specific PCR primers a considerable diversity of cry toxin gene types was found in isolates that had been recovered in vegetative form ('vegetative isolates') with the majority possessing multiple delta-endotoxin genes while some had only one of those tested. Bioassays against a lepidopteran insect of purified delta-endotoxins showed that they were no more potent than those from a laboratory-adapted strain. PCR primers for an internal region of the vip3A gene produced amplification in 70% of the vegetative isolates compared to 25% of the laboratory-adapted strains tested.
authors.affiliation: School of Science, University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK.
authors.forename: Mariangela F
authors.initials: MF
authors.lastname: Bizzarri
authors.forename: Alistair H
authors.initials: AH
authors.lastname: Bishop
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000633:toxicity; D001427:Bacterial Toxins / Q000235:genetics / Q000633:toxicity; D001431:Bacteriological Techniques; D001681:Biological Assay; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D004731:Endotoxins / Q000235:genetics / Q000633:toxicity; D005798:Genes, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics / Q000633:toxicity; D007915:Lepidoptera / Q000187:drug effects; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012621:Seasons; D029921:Trifolium / Q000254:growth & development / Q000382:microbiology*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003470:Culture Media; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis