Production, optimization and characterization of exopolysaccharide from various mesophilic and thermophilic bacteria

In this study, the growth levels of the strains in the medium was investigated by using thermophilic bacteria such as Bacillus licheniformis 3CA2, Geobacillus vulcani 2Cx, Bacillus zhangzhounesis 2CA, Bacillus licheniformis 3CA, Bacillus licheniformis 2CS and mesophilic bacteria such as Acinobacter calcoaceticus E2, Pseudomonas aeruginosa D7, Enterobacter ludwigi D8, Pseudomonas putida D10, Acinetobacter pittii D11, Pseudomonas rhodesiae D12 in the Molecular Genetics, Microbial Biotechnology and Immunology Research Laboratory of the Dicle University, in different media (M1, M2 and M3), different carbon sources (fructose, galactose, glucose, xylose, lactose, maltose, sucrose) and different ratios of yeast extract (0.05%, 0.1%, 0.15% and 0.2%). Thermophilic bacteria were found to grow in M3 medium compared to other media. B.licheniformis 2CS was grown by 7.06 times in the presence of sucrose, B.zhangzhounesis 2CA by 4.09 times in the presence of sucrose, while B.licheniformis 3CA2 was by 1.86 times in the presence of sucrose, and 2.61 in glucose containing medium. Considering the EPS amounts produced by thermophilic bacteria, the best total EPS dryweight was obtained as 121 mg from B.licheniformis 2CS containing %0.2 yeast extract and %1 sucrose in M3 medium. Both carbohydrate amount and protein amount in EPS was determined by using the phenol-sulfuric acid method and the Lowry method, respectively. The amount of carbohydrate in EPS produced by this bacterium was determined as 333.28 µg/mL, while the amount of protein was determined as 0.19 µg/mL. B.zhangzhounesis 2CA was found to be the bacterium with the highest carbohydrate content (1087.03 µg/mL). The antibacterial activities of EPS from B.licheniformis 2CS, B.zhangzhounesis 2CA and B.licheniformis 3CA2 were investigated against pathogenic E.coli, S.aureus, K.pneumoniae and P.aeruginosa. The best effect was seen in EPS produced by B.licheniformis 2CS bacteria from medium containing %0.2 yeast extract and %1 sucrose. The antibacterial activity against E.coli was determined to be a zone diameter of 16 mm. Keywords: Exopolysaccharide production, Thermophilic, Phenol-sulfuric acid, Lowry, Antibacterial effect