Screening, characterization, thermal analysis and emulsification potential of extracellular polymeric substances of...

Cyanobacterial extracellular polymeric substances (EPSs) are considered eco-friendly and sustainable green alternatives for several applications in the food, biotechnological and commercial sectors. However, exploration of high-value EPSs from cyanobacteria is still very limited. In the present investigation, we have screened among paddy field and hot-spring isolates to identify strain with high yield of EPSs. We have used the isolated cyanobacterium Neowestiellopsis sp. strain VKB03 from a paddy field for the extraction and functional analysis of EPSs. Alcian blue and toluidine blue staining confirm the presence of an acidic EPSs layer around the wall surface of the cyanobacterium. SEM analysis proves the porous and web-like nature of EPSs. The biochemical composition of isolated EPSs indicated the presence of high sugars, proteins, phosphate, acetyl, and uronic acids without sulphate and pyruvic acid constituents. Additionally, GC-MS analyses of EPSs reveal the presence of alditol products of sugar, lipids, ester, hydrocarbons C₁₁- C_29, and nucleosides. Moreover, FT-IR spectrum analyses speculated the presence of functional groups like carboxylate groups, phosphate groups, α-pyranose groups, and glycosidic linkage. Thermal stability has been elucidated by thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses reveal high thermal firmness of EPSs with high water (8987.5%) and oil (1729.5%) holding capacities. The emulsifying activity of EPSs exhibits positive results against tested substrates. The findings highlight the considerable potential of paddy field cyanobacterial EPSs for applications in industrial and commercial sectors for human welfare.

The online version contains supplementary material available at 10.1007/s13205-026-04717-y.