(191r) Extremophilic Biopolymer-Based Films: Production, Characterization, and Application

Exopolysaccharides (EPSs) are high molecular weight carbohydrate biopolymers that are composed of sugar residues linked together through glycosidic bonds, and secreted by microorganisms into the surrounding environment with certain properties and functions. The EPSs are one of the adaptations developed by various kinds of extremophiles in order to survive in the environments with harsh conditions, such as extreme temperature, salinity, or pH. Extremophiles are considered as producers of EPSs with novel and unusual characteristics which may hardly be found in more traditional polymers. Recently some extremophilic EPSs have already been characterized, and the properties and functions of EPSs from related extremophiles were also partly elucidated. However cumulative knowledge of the structural and functional properties of extremophilic EPSs is still limited. In this research, a thermophilic strain, Geobacillus sp. (WSUCF1) which produced unique type of EPSs has been studied. WSUCF1 could utilize glucose as optimum carbon and energy source to produce significant amount of EPSs (382 mg/L). Two purified EPSs were obtained through ion-exchange and gel filtration columns, and both of them demonstrated higher degradation temperature (319.20 and 314.85 °C) than the thermophilic EPSs recently reported. Monosaccharide composition analysis showed that these two EPSs were composed of mannose and glucose with various relative molar ratios (1/0.2141 and 1/0.0270). FTIR and NMR spectrum analysis also showed several unique features of the EPSs. The EPS-based films were developed through a solvent casting technique using glycerol as plasticizer, and their characteristics, such as surface morphology, thermal stability, mechanical properties and biocompatibility are currently under investigation. EPSs from the relatively unexplored WSUCF-1 strain will likely provide a valuable resource for exploitation in novel biotechnological processes and opportunities in various industrial fields including bio-based polymeric materials and antitumor-drug carrier. Meanwhile, the research on EPSs from strain WSUCF1 will also expand the scope for microorganisms isolated from hostile life environments.