Determination of the Optimum Laboratory Conditions for the Production of Crystal Protein by Bacillus thuringiensis KS3 Isolated from Iraqi Soils

Khlood Abid-Alelah Alkhafaji*(1) Samera Oda Khleoy(2) Safaa Abid Alrahem Mahmoud(1) Shaemaa Rajab Farhan(1) Sabreen Abid Alhadi Saleh(2) and Mohamed Abid al- Rahem Abiallah(1)

(1). Applied Microbiology Department, Center of Biotechnology, Directorate of Agricultural Research, Ministry of Science and Technology. Iraq.

(2). Biology Control Department, Pest Integrating Management Center, Directorate of Agricultural Research. Ministry of Science and Technology. Iraq.

(*Corresponding author: Khlood Abid-Alelah Alkhafaji. E-Mail:

Received: 15/03/2018                                Accepted: 25/09/2018


This research aimed to determine the optimum conditions for the production of crystal protein produced by a local Iraqi isolate of Bacillus thuringiensis KS3. This research was conducted at the laboratories of Directorate of Agricultural Research during the period from 2016 to 2017. Growth factors such as sugar, nitrogen sources and minerals were evaluated, also pH was determined. Environmental factors such as temperature, aeration and time of production were studied separately; Laurea Bertani broth (LB) was modified for optimal production of crystal protein. Sucrose gave the best concentration of protein which reached up to 4.49 mg/ml, while peptone could be used as a substitute of a tryptone as best nitrogen source. No significant differences among tryptone, soytone, beef extract and casein. The best C:N ratio was that of 2% peptone and 1.5% sucrose which gave 5.252 mg/ml. Magnesium sulfate increased the crystal protein concentration which reached to 7.92. No significant difference was observed between magnesium sulfate and manganese chloride. Medium equilibrated to pH 7.5 was used for highest crystal protein production compared with pHs 6.5, 7, and 8. Culture of Bacillus thuringiensis KS3 incubated for 72 h at 30C with 120 rpm/min in a shaker incubator gave the best protein concentration.

Key words: Bacillus thuringiensis, delta toxin, sucrose, peptone, pH.

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