Isolation and characterization of a new Bacillus thuringiensis strain Lip harboring a new cry1Aa gene highly toxic to Ephestia kuehniella (Lepidoptera: Pyralidae) larvae.

Micheline El Khouri (1, 2) , H. Azzouz (3) , A. Chavanieu (4) , N. Abdelmalak (3) , Joel Chopineau (2, 5) , M. Awad (1)

1 Biotechnology Laboratory
2 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
3 CBS - Centre de Biotechnologie de Sfax
4 IBMM - Institut des Biomolécules Max Mousseron [Pôle Chimie Balard]
5 UNIMES - Université de Nîmes

The aim of this study was to characterize new Bacillus thuringiensis strains that have a potent insecticidal activity against Ephestia kuehniella larvae. Strains harboring cry1A genes were tested for their toxicity, and the Lip strain showed a higher insecticidal activity compared to that of the reference strain HD1 (LC50 of Lip and HD1 were 33.27 and 128.61 μg toxin/g semolina, respectively). B. thuringiensis Lip harbors and expresses cry1Aa, cry1Ab, cry1Ac, cry1Ad and cry2A. DNA sequencing revealed several polymorphisms in Lip Cry1Aa and Cry1Ac compared to the corresponding proteins of HD1. The activation process using Ephestia kuehniella midgut juice showed that Lip Cry1A proteins were more stable in the presence of larval proteases. Moreover, LipCry1A proteins exhibited higher insecticidal activity against these larvae. These results indicate that Lip is an interesting strain that could be used as an alternative to the worldwide used strain HD1

Domaines: Sciences du Vivant [q-bio]; Biologie cellulaire; Biochimie, Biologie Moléculaire

Micheline El Khouri, H. Azzouz, A. Chavanieu, N. Abdelmalak, Joel Chopineau, et al.. Isolation and characterization of a new Bacillus thuringiensis strain Lip harboring a new cry1Aa gene highly toxic to Ephestia kuehniella (Lepidoptera: Pyralidae) larvae.. Archives of Microbiology, 2014, 196 (6), pp.435-44. ⟨10.1007/s00203-014-0981-3⟩. ⟨hal-01011035⟩