Biosynthesis and isolation of gellan polysaccharide to formulate microspheres for protein capture

In the present work, the biosynthesis of the gellan gum exopolysaccharide from Sphingomonas paucimobilis fermentation was improved to 24 g/L, by increasing the oxygen content (1:5). FTIR and NMR data indicated the following procedures to recover gellan from culture medium: filtration; washing with acetone and ether (200 mL each one); permeate dissolution with distilled water; precipitation with acetonitrile (1:3). Gellan microsphere formulation by water-in-oil emulsion was optimized through central composite design to minimize the diameter (≈ 300 μm), and reinforced with different counter-ions. The optimal point was reached with 1.27% gellan concentration, 750 rpm and 92.54 °C of oil temperature. Microspheres with nickel as counter-ion revealed the most satisfactory results from semi-optical microscopy, SEM and EDX analysis. The manipulation of ionic strength or pH on the binding and elution steps allowed capturing different model proteins, exploring electrostatic or affinity interactions with these microspheres.