title: Experimental design and Bayesian networks for enhancement of delta-endotoxin production by Bacillus thuringiensis.
abstract: Bacillus thuringiensis (Bt) is a Gram-positive bacterium. The entomopathogenic activity of Bt is related to the existence of the crystal consisting of protoxins, also called delta-endotoxins. In order to optimize and explain the production of delta-endotoxins of Bacillus thuringiensis kurstaki, we studied seven medium components: soybean meal, starch, KH₂PO₄, K₂HPO₄, FeSO₄, MnSO₄, and MgSO₄and their relationships with the concentration of delta-endotoxins using an experimental design (Plackett-Burman design) and Bayesian networks modelling. The effects of the ingredients of the culture medium on delta-endotoxins production were estimated. The developed model showed that different medium components are important for the Bacillus thuringiensis fermentation. The most important factors influenced the production of delta-endotoxins are FeSO₄, K2HPO₄, starch and soybean meal. Indeed, it was found that soybean meal, K₂HPO₄, KH₂PO₄and starch also showed positive effect on the delta-endotoxins production. However, FeSO4 and MnSO4 expressed opposite effect. The developed model, based on Bayesian techniques, can automatically learn emerging models in data to serve in the prediction of delta-endotoxins concentrations. The constructed model in the present study implies that experimental design (Plackett-Burman design) joined with Bayesian networks method could be used for identification of effect variables on delta-endotoxins variation.
authors.affiliation: Laboratory of Probability and Statistics, Faculty of Sciences of Sfax , Sfax , Tunisia.|Centre of Biotechnology of Sfax , Sfax , Tunisia.
authors.forename: Karim
authors.initials: K
authors.lastname: Ennouri
authors.affiliation: Laboratory of Probability and Statistics, Faculty of Sciences of Sfax , Sfax , Tunisia.|Centre of Biotechnology of Sfax , Sfax , Tunisia.
authors.forename: Rayda Ben
authors.initials: RB
authors.lastname: Ayed
authors.affiliation: Physics-Mathematics and Applications, Faculty of Sciences of Sfax , Sfax , Tunisia.
authors.forename: Hanen Ben
authors.initials: HB
authors.lastname: Hassen
authors.affiliation: On AIR s.r.l., , Genova , Italy.
authors.forename: Maura
authors.initials: M
authors.lastname: Mazzarello
authors.affiliation: On AIR s.r.l., , Genova , Italy.
authors.forename: Ennio
authors.initials: E
authors.lastname: Ottaviani
mesh_terms: D001413:Bacillus thuringiensis / Q000235:genetics / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis*; D001499:Bayes Theorem; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism; D004731:Endotoxins / Q000096:biosynthesis*; D005285:Fermentation; D006460:Hemolysin Proteins / Q000096:biosynthesis*; D012107:Research Design
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D003470:Culture Media; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bacillus thuringiensis; Bayesian networks; Plackett—Burman; delta-endotoxins