Abstract: The extracellular ribonuclease activity of Bacillus sp. was successfully improved by
optimization of nutritional and physical parameters in a set of non-statistical and statistical experiments. Plackett-
Burman and Central Composite Design in Response Surface Methodology were used to build statistical models
to screen out the significant variables and then study the effect of such variables on ribonuclease production.
Four significant variables namely malt extract, yeast extract, ammonium molybdate and fermentation broth pH
were selected via 24-factorial Central Composite Design (CCD) for ribonuclease production Bacillus sp. The
optimized values obtained by the statistical analysis showed that malt extract 1. 40 % (w/v), yeast extract 2.12 %
(w/v), ammonium molybdate 0.56 % (w/v) and pH 8.81 affected maximum ribonuclease production by Bacillus
sp. The ribonuclease production after optimization increased up to 1.83-fold with 83.52 % yield in comparison
to the conventional strategy. Analysis of variance (ANOVA) revealed high coefficient of determination (R2) of
0.9268 for the respective responses at significant level (p < 0.05).