title: The effect of aeration conditions, characterized by the volumetric mass transfer coefficient K(L)a, on the fermentation kinetics of Bacillus thuringiensis kurstaki.
abstract: The aeration is a key factor for Bacillus thuringiensis growth, sporulation and δ-endotoxins production. The objective of our work was to study the effect of aeration on the fermentation kinetics of Bacillus thuringiensis kurstaki (Btk), cultivated in a cereal milling byproduct (CMB) mono-component medium, in order to improve the δ-endotoxins productivity. Aeration conditions were systematically characterized by the volumetric mass transfer coefficient KLa. In the 6% CMB culture medium, different values of the maximal specific oxygen uptake rate were obtained at different values of KLa. For KLa of 7.2 h(-1), the growth was inhibited and the sporulation was defective. There was a linear increase of the average specific growth rate and faster sporulation and liberation of spores and δ-endotoxins crystals when KLa was increased between 13.3 h(-1) and 65.5 h(-1). Similar kinetic was observed in cultures performed at KLa equal to 65.5 h(-1) and 106.2 h(-1). The highest toxins productivity of 96.1 mg L(-1) (h)-1 was obtained in the 9% CMB culture medium for KLa of 102 h(-1). It was possible to track the evolution of the bacterial cells between vegetative growth, sporulation and liberation of mature spores by following the variation of the CO2 percent in the effluent gas.
authors.affiliation: Université de Toulouse, INPT, UPS, Laboratoire de Génie Chimique, 4 Allée Emile Monso, F-31030 Toulouse, France; CNRS, Laboratoire de Génie Chimique, F-31030 Toulouse, France; Université Saint Joseph de Beyrouth, Centre d'Analyse et de Recherche, Unité de Technologie et Valorisation Alimentaire B.P. 11-514 Riad El Solh, Beyrouth 11072050, Lebanon. Electronic address: gihane.rahbany@net.usj.edu.lb.
authors.forename: Jihane Rahbani
authors.initials: JR
authors.lastname: Mounsef
authors.affiliation: Université Saint Joseph de Beyrouth, Centre d'Analyse et de Recherche, Unité de Technologie et Valorisation Alimentaire B.P. 11-514 Riad El Solh, Beyrouth 11072050, Lebanon. Electronic address: dominique.salameh@usj.edu.lb.
authors.forename: Dominique
authors.initials: D
authors.lastname: Salameh
authors.affiliation: Université Saint Joseph de Beyrouth, Centre d'Analyse et de Recherche, Unité de Technologie et Valorisation Alimentaire B.P. 11-514 Riad El Solh, Beyrouth 11072050, Lebanon. Electronic address: nicolas.louka@usj.edu.lb.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Louka
authors.affiliation: Université de Toulouse, INPT, UPS, Laboratoire de Génie Chimique, 4 Allée Emile Monso, F-31030 Toulouse, France; CNRS, Laboratoire de Génie Chimique, F-31030 Toulouse, France. Electronic address: cedric.brandam@ensiacet.fr.
authors.forename: Cedric
authors.initials: C
authors.lastname: Brandam
authors.affiliation: Université Saint Joseph de Beyrouth, Centre d'Analyse et de Recherche, Unité de Technologie et Valorisation Alimentaire B.P. 11-514 Riad El Solh, Beyrouth 11072050, Lebanon. Electronic address: roger.lteif@usj.edu.lb.
authors.forename: Roger
authors.initials: R
authors.lastname: Lteif
mesh_terms: D000332:Aerobiosis; D001413:Bacillus thuringiensis / Q000254:growth & development* / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism*; D061249:Batch Cell Culture Techniques; D003470:Culture Media; D004731:Endotoxins / Q000378:metabolism*; D005285:Fermentation; D006460:Hemolysin Proteins / Q000378:metabolism*; D007700:Kinetics; D013171:Spores, Bacterial / Q000254:growth & development
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D003470:Culture Media; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Aeration; Bacillus thuringiensis; K(L)a; Kinetics