# Morphological Study of _Bacillus thuringiensis_ Crystals and Spores  
[PERSON]  
1 Physics Department, UR IVA, Faculty of Science, Saint Joseph University, B.P. 11-514, Riad El Soh, Beirut 1107 2050, Lebanon; [EMAIL_ADDRESS]  
[PERSON]  
2 Laboratoire OPTIMAG, IBSAM, Universite de Bretagne Occidentale, 6 Avenue Le Gorgeu, C.S. 93837, CEDEX 3, 29238 Brest, France; [EMAIL_ADDRESS] (F.P. ); [EMAIL_ADDRESS] (B.L. ); [EMAIL_ADDRESS] (G.L.B.) [PERSON]  
2 Laboratoire OPTIMAG, IBSAM, Universite de Bretagne Occidentale, 6 Avenue Le Gorgeu, C.S. 93837, CEDEX 3, 29238 Brest, France; [EMAIL_ADDRESS] (F.P. ); [EMAIL_ADDRESS] (B.L. ); [EMAIL_ADDRESS] (G.L.B.) [PERSON]  
2 Laboratoire OPTIMAG, IBSAM, Universite de Bretagne Occidentale, 6 Avenue Le Gorgeu, C.S. 93837, CEDEX 3, 29238 Brest, France; [EMAIL_ADDRESS] (F.P. ); [EMAIL_ADDRESS] (B.L. ); [EMAIL_ADDRESS] (G.L.B.) [PERSON]  
4 Laboratoire OPTIMAG, IBSAM, Universite de Bretagne Occidentale, 6 Avenue Le Gorgeu, C.S. 93837, CEDEX 3, 29238 Brest, France; [EMAIL_ADDRESS] (F.P. ); [EMAIL_ADDRESS] (B.L. ); [EMAIL_ADDRESS] (G.L.B.) [PERSON]  
4 Laboratoire OPTIMAG, IBSAM, Universite de Bretagne Occidentale, 6 Avenue Le Gorgeu, C.S. 93837, CEDEX 3, 29238 Brest, France; [EMAIL_ADDRESS] (F.P. ); [EMAIL_ADDRESS] (G.L.B.) [PERSON]  
5 Laboratoire OPTIMAG, IBSAM, Universite de Bretagne Occidentale, 6 Avenue Le Gorgeu, C.S. 93837, CEDEX 3, 29238 Brest, France; [EMAIL_ADDRESS] (F.P. ); [EMAIL_ADDRESS] (G.L.B.) [PERSON]  
3 Laboratoire OPTIMAG, IBSAM, Universite de Bretagne Occidentale, 6 Avenue Le Gorgeu, C.S. 93837, CEDEX 3, 29238 Brest, France; [EMAIL_ADDRESS] (F.P. ); [EMAIL_ADDRESS] (G.L.B. ); [EMAIL_ADDRESS] (G.L.B.) [PERSON]  
2 Laboratoire OPTIMAG, IBSAM, Universite de Bretagne Occidentale, 6 Avenue Le Gorgeu, C.S. 93837, CEDEX 3, 29238 Brest, France; [EMAIL_ADDRESS] (F.P. ); [EMAIL_ADDRESS] (G.L.B. ); [EMAIL_ADDRESS] (G.L.B.) [PERSON]  
1 Physics Department, UR IVA, Faculty of Science, Saint Joseph University, B.P. 11-514 Riad El Soh, Beirut 1107 2050, Lebanon; [EMAIL_ADDRESS]  
Dipartimento di Fisica, Universita di Fisicaof the insect midgut, whereas Cyt toxins act in a detergent-like manner on the membrane phospholipids [7]. Therefore, on the one hand, a variation in a crystal's Cry components underlines a variation in a strain's activity spectrum. So far, 73 Cry and seven Cyt families are registered in the recently updated _B. thuringiensis_ nomenclature database [8]. Each Cry family has a signature shape and activity spectrum; e.g., Cry1 family proteins form a bipyramidal crystal and are active against lepidopteran larvae [9], whereas Cry4 form a spherical crystal and are toxic to dipteran larvae [10]. On the other hand, _B. thuringiensis_ strains are classified according to their serotypes or serovars (var. ), which were once based on their respective immunological reactions caused by their flagellar H-antigen proteins, flagellin [11]. Nowadays, this classification is based on pairwise sequence comparison of the latter protein [12]. The two most studied serovars are (i) the reference for anti-dipteran activity, _B. thuringiensis_ var. _israelensis_, and (ii) the reference for anti-lepidopteran activity, _B. thuringiensis_ var. _kurstaki_. The former produces spherical crystals containing a set of proteins from the following families: Cry4, Cry10, Cry11, Cry11, and Cyt2 [13; 14; 15]. As for the latter, its crystal proteins belong to the Cry1 and Cry2 families, resulting in bipyramidal and cubic crystals, respectively [9; 16]. Other than its crystal components, each serovar is characterized by a set of plasmids, toxin-carrying, conjugative or mobilizable, providing serovar-specific peculiarities [14; 17]. An in-depth investigation of all aspects involved in _B. thuringiensis_ biopesticidal activity--be they genomic, proteomic, morphological, related to crystal and spore production kinetics and stability or otherwise--is a necessity created by the increased use of _B. thuringiensis_ spore-crystal mixtures in the environment.