Development of multiplication medium for Bacillus thuringiensis H-14 using groundnut meal

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Bacillus thuringiensis H-14 strain IPS-18 obtain from W.H.O. was microscopically studied to confirm its identity. Local groundnut seeds were defatted using mechanized, solvent, water and roasting methods. The press cakes obtained were chemically analysed and formulate into maintenance solid media. Growth rates of the bacterium on a number of pressed cake media composed differently were compared with those on standard nutrient agar medium. A formulated medium containing groundnut cake obtained from local edible oil factory and enriched with 0.25% glutamic acid was found to be very suitable for the propagation of the bacterium. The maintenance medium of the new formulation yielded better results than the standard agar medium by 1.2 times. The comparative mass production studies of the bacterium in the proposed medium and in the standard nutrient broth medium were carried out 500 ml Erlenmeyer shaker-flasks. The bacterial growth in the new medium at 24 and 48 hours was 2.6 and 1.3 times respectively greater than that in the standard nutrient broth medium. The total cell count of the bacterium in the new medium and the standard medium at 48 hours were 4.00 x 1021 cell/ml and 6.00 x 1017 cell/ml respectively. The total cell count and LC50 value of the bacterium on Aedes aegypti larvae in the new medium at 24 hours were 7.41 x 1013 cells/ml and 10-5 dilution respectively whereas those in nutrient broth were 8.60 x 107 cells/ml and 10-3.5 dilution respectively. The potency of the formulation was found to be 32,707 ITU/mg as compared with 4,000 ITU/mg for the standard medium. The cost of one litre of the maintenance and cultivation from the now medium were $0.18 (¢16.09) and $0.04 (¢3.45) respectively as compared to $1.45 (¢131.00) and $0.51 (¢45.00) respectively for the standard medium as at June 30, 1986
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of the Degree of Master of Philosophy in Biological Sciences, 1986