Production and characterization of a microbial glucan, synthesized by Geobacillus tepidamans V264 isolated from Bulgarian hot spring

The thermophilic strain producing extracellular polysaccharide (EPS) was isolated from Velingrad hot spring, Bulgaria. StrainV264 showed 98% similarity in 16S rRNA gene sequence with Geobacillus tepidamans. Maltose was found to be the most appropriate carbon source for exopolysaccharide production. Maximum EPS production was reached in the early stationary phase. Highest EPS production of 111.4 mg L−1 was obtained in fermentor batch cultures at 300 rpm. The purified EPS expressed a high molecular weight and it was very stable at high temperature, showing a degradation at 280 °C. Chemical composition of the bio-polymer, determined by using a high pressure anion exchange-pulsed amperometric detector (HPAE-PAD), showed glucose as its major component. The polysaccharide was also investigated by spectroscopic methods (1H and 13C NMR) which demonstrated the structure complexity of this bio-polymer.