plackett-burman design and response surface optimization of medium trace nutrients for glycolipopeptide biosurfactant production

background: a glycolipopeptide biosurfactant produced by pseudomonas aeruginosa strain ikw1 reduced the surface tension of fermentation broth from 71.31 to 24.62 dynes/cm at a critical micelle concentration of 20.80 mg/l. the compound proved suitable for applications in emulsion stabilization in food, as well as in cosmetic and pharmaceutical formulations. methods: in the present study, plackett-burman design (pbd) and response surface method (rsm) were employed to screen and optimize concentrations of trace nutrients in the fermentation medium, to increase surfactant yield. results: the pbd selected 5 out of the 12 screened significant trace nutrients. the rsm, on the other hand, resulted in the production of 84.44 g glycolipopeptide/l in the optimized medium containing 1.25 mg/l nickel, 0.125 mg/l zinc, 0.075 mg/l iron, 0.0104 mg/l boron, and 0.025 mg/l copper. conclusion: significant second-order quadratic models for biomass (p<0.05; adjusted r2=94.29%) and biosurfactant (r2=99.44%) responses suggest excellent goodness-of-fit of the models. however, their respective non-significant lack-of-fit (biomass: f=1.28; p=0.418; biosurfactant: f=1.20; p=0.446) test results indicate their adequacy to explain data variations in the experimental region. the glycolipopeptide is recommended for the formulation of inexpensive pharmaceutical products that require surface-active compounds