Abstract: According to the codon bias of Pichia pastoris, the insect-specific neurotoxin gene BjαIT was synthesized based on its amino acid sequence and was cloned to vectors of PET-30a (+) and pPIC9K respectively. The fusion protein of BjαIT expressed in Escherichia coli was induced with IPTG and was purified with Ni-NTA His Bind Column. The purified fusion protein was used to prepare antiserum and conduct bioactivity test. Dot blotting was used to screen the high-level expressed transformants of P. pastoris. The results showed that the highest expression of recombinant BjαIT in P. pastoris was about 20 mg/L in baffled flasks, and the BjαIT fusion protein expressed in E. coli was not toxic to locust Locusta migratoria manilensis and cockroach Blattela germanica, but that expressed in P. pastoris had insecticidal activity against locust and cockroach through injection.

Key words: Insect-specific neurotoxin, BjαIT, Escherichia coli, Pichia pastoris, fusion expression, Locusta migratoria manilensis, Blattela germanica, insecticidal activity