Volume 6, number 2
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Overproduction of Mosquitocidal Toxins of Bacillus Thuringiensis Serotype 14 on Cost Effective Media

M. S. Foda, Maysa E. Moharam*, Magda A. El-Bendary and T. Kahil

Microbial Chemistry Department, National Research Centre, Dokki, Giza Egypt.   Corresponding Author E-mail: maysa12000@hotmail.com 

ABSTRACT: Bacillus thuringiensis serotype 14 (Bti) is being widely used in mosquito control programs. Large scale production of this subspecies is expensive because of the high cost of the production medium ingredients. In this study, we attempted to develop two cost effective media based on inexpensive locally available raw materials namely fodder yeast, a byproduct produced in plenty from ethanol industry in Egypt and grinded seeds of black eyed pea (cowpea; Vigna unguiculata subspecies unguiculata ) a highly protein rich legume seed. Various nutritional and cultural parameters influencing diptera-specific delta-endotoxin synthesis by Bti serotype 14 were investigated. Optimum concentration of both fodder yeast and black eye pea was about 9%(w/v) after which a notable decrease in mortality percentage was evident. Adequate concentration of inorganic phosphate (50 mM K2HPO4) was required for an effective synthesis of mosquitocidal toxin. High aeration level corresponding to 20 : 1 air : medium ratio favored toxin production. Within tested sizes of inocula, 26 ª 10 6 CFU and 13 ª 10 5 /mL were suitable for attainment of highest mortality percentage against second instar larvae of Culex pipiens for fodder yeast(65.4% at 5ppm) and black eyed pea (97.5% at 1ppm)based media after 72 hour and 48 hour incubation period respectively. Addition of 0.1% Tween 80 to fodder yeast based medium nearly doubled toxicity percentage, while Ca inhibited toxin biosynthesis. LC50 value was determined for toxin produced on the two media were 1.5 ppm and 0.37 ppm for fodder yeast and black eyed pea based media respectively. The obtained results were discussed in the light of lowering the poduction cots this important biological control bacterium .

KEYWORDS: Bacillus thuringiensis; Culex pipiens; fodder yeast; black eyed pea

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M. S. Foda. M. S, Moharam. M. E, El-Bendary. M. A, Kahil. T. Overproduction of Mosquitocidal Toxins of Bacillus Thuringiensis Serotype 14 on Cost Effective Media. Biosci Biotechnol Res Asia 2009;6(2)
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M. S. Foda. M. S, Moharam. M. E, El-Bendary. M. A, Kahil. T. Overproduction of Mosquitocidal Toxins of Bacillus Thuringiensis Serotype 14 on Cost Effective Media. Biosci Biotechnol Res Asia 2009;6(2). Available from: https://www.biotech-asia.org/?p=8633

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