Spatial configuration of extracellular polymeric substances of Bacillus megaterium TF10 in aqueous solution

Configuration of extracellular polymeric substances (EPS) excreted by microorganisms is related greatly to the inherent properties of EPS, and has a significant effect on the physicochemical characteristics of microbial aggregates, such as activated sludge for wastewater treatment, as well as their interaction with other substances in aqueous systems. In this work, the spatial configuration of microbial EPS is characterized using laser light scattering (LLS) technique, with EPS extracted from Bacillus megaterium TF10 as an example. The combined utilization of static light scanning (SLS) and dynamic light scanning (DLS) offers an effective avenue to explore the EPS configuration in aqueous solution, thus enables a better understanding about the physicochemical properties of EPS. The results show that EPS exist in the form of colloids in neutral aqueous solution (pH 7.0) and that their shape is random coil with incompletely extending chains. The attraction interaction between EPS colloids is related with the high flocculability of B. megaterium TF10. The cryo-electron microscopy image further confirms the spherical shape of EPS colloids. The LLS approach offers a powerful and convenient tool for characterizing microbial EPS configuration and understanding their behaviors in biological wastewater treatment systems.