Fig. 3

Individual parameter effects on melanin production by Curvularia soli AS 21 ON076460 a normal plot and b Pareto chart for un-irradiated control, c normal plot and d Pareto chart for 1.0 kGy. The positive effect was represented by orange columns, while the negative effect was represented by blue columns. The extremely optimistic factors on the optimizing conditions for melanin production with the un-irradiated control are heavy metals, C-source, N-source, temperature, pH, incubation time, and L-tyrosine. With gamma irradiation at 1.0 kGy, shaking and medium type have positive effect on the melanin productivity