Fig. 3

Pareto charts of the Plackett-Burman design illustrating the effects of different factors on lipase enzyme productivity by Penicillium griseofulvum P-1707. The chart illustrates the relative significance of each factor, with bars representing the absolute values of their standardized effects. (a) Pareto chart from the first Plackett-Burman design, showing the impact of factors A (temperature), B (initial pH), C (incubation time), D (inoculum size), and E (castor oil). Positive effects are shown in orange, and negative effects are shown in blue. The Bonferroni and t-value limits indicate statistical significance, with factors E, A, and B being the most significant contributors to lipase productivity. (b) Pareto chart from the second Plackett-Burman design, evaluating factors A (temperature), B (initial pH), C (incubation time), D (inoculum size), E (frying oil), F (engine waste oil), and G (castor oil). The chart shows significant positive and negative effects, with factors B, C, D, and F represented the highest contributors to lipase productivity in the design