Exopolysaccharide production from Bacillus safensis using statistical experimental design

Microbial polysaccharide is an important biopolymer secreted either by bacteria, fungi, or yeast as natural non-toxic, biodegradable and renewable sugar monomers. It has a wide range of industrial application such as in pharmaceuticals, cosmetics, food and Microbial enhanced oil recovery. This study is aimed at a cost-effective EPS production from renewable raw material feedstock using statistical design. Six isolates WN3, WN5, WN7, WN9, WZI and WZ2 showing mucoid morphology isolated from Bonny River in Rivers State, Nigeria were examined for the Exopolysaccharide production using renewable feedstock of Sweet Potato peel and Bean Bran as carbon and nitrogen sources respectively. WN7, WZ1 and WZ2 had higher EPS yield where WN7 had EPS yield of 0.362g/l, WZ1 had EPS yield of 1.02g/l while WZ2 had EPS yield of 0.615g/l. isolate WZ1 that had the highest EPS yield was identified using the 16srRNA sequence as Bacillus safensis. Two statistical designs Plackett-Burman and Box-Behnken were used for the optimization studies where Plackett-Burman design indicated that K2HPO4, MgSO4H2O, CaSO4H2O, NaCl, Potato Peel, Bean Bran are significant (p<0.05) model terms. Box-Behnken design revealed that optimum conditions of pH 4.5, Potato Peel 15g/l, Bean Bran 3.13g/l and Incubation Time of 5 days results in maximum EPS production of 10.2g/l. After production, EPS was extracted and quantified by phenol sulphuric acid method using glucose as standard, Identified using Fourier Transform Infrared (FT-IR) and Gas Chromatography–Mass Spectroscopy (GC–MS). The presence of glycosidic linkage (C-O-C) stretching vibration, C=O, C-H and O-H stretching vibrations as revealed by the FT-IR clearly elucidated the production of EPS. This was also confirmed by the presence of Glucose, Mannose and Galactose in the GC-MS characterization of the EPS.