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A culture medium for production of bacterial alkaline protease was developed following preliminary
studies by means of response surface method. Central composite design was applied to optimize the
medium constituents and explain the combined effects of three medium constituents, viz., molasses,
potassium nitrate and inoculum size. The optimum values for the tested variables were molasses
(1%), potassium nitrate (0.75%) and inoculum size (1%). A second-order model equation was
suggested and then validated experimentally. The model adequacy was very satisfactory. The B.
cereus strain S8 produced 205±0.35U/ml protease under experimental optimized culture conditions
with these three significant variables over the basal medium (165±0.28 U/ml).
Key words: Alkaline protease; Bacillus cereus strain S8; Medium optimization; Response surface methodology, central composite design.