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).