Effect of aeration and method of addition of glucose sugar to culture medium on growth and sporulation of some Bacillus thuringiensis isolates from Sudan soils

Abdulwahab A. Ahmed, Hamid A. Dirar

Abstract


An experiment was conducted in the microbiology laboratory at the Faculty of Agriculture, University of Khartoum in the year 2003 to study the effect of aeration and method of addition of glucose sugar on growth and sporulation of three selected B. thuringiensis isolates (BR12, N10 and EA3) derived from Sudan soils. The isolates responded differently to air supply. Spore counts of isolate BR12 and EA3 increased with an increase in air supply. The highest count was produced at 19:1 air-to-medium ratio (v/v) and the lowest count at 3:1 ratio, whereas the highest spore count by isolate N10 was produced at 4:1 air-to-medium ratio (v/v) and any increase in aeration levels resulted in lower counts. On the other hand, method of addition of glucose sugar was found to affect both pH pattern during incubation period and spore count in the final culture for all selected isolates. Fed-batch addition of glucose resulted in survival of many growing cells which would have been killed in case of batch addition, with subsequent better sporulation. The effect of method of addition of glucose sugar on growth and sporulation of the tested isolates was found to be significant at 1% level.


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