Statistical analysis using a response surfaces design method (RSM)
A statistical analysis utilizing the response surface design method, referred to as RSM, is DD (%) of chitosan extraction, with the ultimate goal of obtaining a highly pure chitosan product. The selected RSM employs a central composite design (CCD), employing a second-degree mathematical model featuring two-way interactions (Ben Seghir and Benhamza, 2017). The experimental design comprises thirty-two factorial points, each with three coded levels (-1, 0, and +1), and three axial points to establish a central point (refer to Table 1).
Here, A, B, C, D and E correspond to the independent variables outlined in Table 1. The response surface methodology (RMS) implementation employed the Design Expert 12 statistics software and features quadratic terms, as presented in Table 2.
Pseudomonas aeruginosa ATCC 10145 was obtained from the microbiology section of the Institut Pasteur in Tehran, Iran. The microorganism was preserved as a stock culture in a 50% glycerol solution (Pars Azma, Iran) at -70°C. Prior to each experiment, the cryopreserved culture was cultured in liquid LB medium (Sigma, UK) at 37°C and 150 rpm for 24 hours until it reached 0.5 OD at 595 nm (1 × 107CFU ml−1).