Larvicidal activities against agricultural pests of transgenic Escherichia coli expressing combinations of four genes from Bacillus thuringiensis

Vadim Khasdan, Maria Sapojnik, Arieh Zaritsky, A. Rami Horowitz, Sammy Boussiba, Mario Rippa, Robert Manasherob, Eitan Ben-Dov

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The genes cry1Ac and cry1Ca from Bacillus thuringiensis subsps. kurstaki HD-73 and aizawai 4J4, respectively, encoding δ-endotoxins against lepidopteran larvae were isolated, cloned and expressed in Escherichia coli, with and without cyt1Aa (encoding cytolytic protein) and p20 (accessory protein) from subsp. israelensis. Nine combinations of the genes under control of an early T7, PA1 inducible promoter, produced the encoding proteins. Toxicities were examined against larvae of three major agricultural pests: Pectinophora gossypiella, Helicoverpa armigera and Spodoptera littoralis. The clones expressing cyt1Aa, with or without p20, were not toxic. The clone expressing cry1Ac (pBt-1A) was the most toxic to P. gossypiella (LC50 of 0.27 × 108 cells g-1). Clone pBt-1CA expressing cry1Ca and cry1Ac displayed the highest toxicity (LC50 of 0.12 × 108 cells ml-1) against S. littoralis. Clone pBt-1CARCy expressing all four genes (cry1Ca, cry1Ac, p20, cyt1Aa) in tandem exhibited the highest toxicity to H. armigera (LC50 of 0.16 × 108 cells ml-1). Cyt1Aa failed to raise the toxicity of these Cry toxins against P. gossypiella and S. littoralis but significantly enhanced toxicity against H. armigera. Two additional clones expressing either cry1Ac or cry1Ca under tandem promoters, PA1 and PpsbA (constitutive), displayed significantly higher toxicities (7.5- to 140-fold) than their counterparts with PA1 alone, reducing the LC50 values to below 107 cells ml-1.

Original languageEnglish
Pages (from-to)643-653
Number of pages11
JournalArchives of Microbiology
Volume188
Issue number6
DOIs
StatePublished - 1 Dec 2007

Keywords

  • Agriculture pests
  • Bacillus thuringiensis
  • Transgenic Escherichia coli
  • δ-Endotoxin

ASJC Scopus subject areas

  • Microbiology
  • Biochemistry
  • Molecular Biology
  • Genetics

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