A cleaner production for protein recovery from the coelomic fluid of earthworms using electrooxidation and membrane processes and synthesis of magnetite nanoparticles

Coelomic fluid (CF) secreted by earthworms during stress (electric current, heat, cold, etc.) releases of bioactive components, such as proteins, peptides, polysaccharides, enzymes, etc. In this study, the electrooxidation process (EO) and membrane process were used for protein recovery from the CF of earthworms. EO experiments used graphite electrodes as electrode pairs were applied by Box-Behnken design (BBD) for the protein recovery optimization from CF. Membrane experiments were conducted using ultrafiltration (UP150) and nanofiltration (NF270) membranes. The maximum recovery of protein (550.12 mg/L) was achieved at 25 g of earthworms quantity, 0.85 g/L of NaCl concentration, 10 V of current density, and 25 min of reaction time in the EO process. Membrane experimental results showed that NF270 membrane supplied the highest protein recovery (98%) compared to UP150 membrane (80%). These results suggested that the combined EO and membrane processes were an efficient strategy to recover and concentrate protein from the CF. The concentrated CF were used to synthesize magnetite nanoparticles (Fe3O4-NPs). The synthesized Fe3O4-NPs mediated CF- Fe3O4-NPs showed good antioxidant activity. CF-Fe3O4-NPs inhibited 56.10% and 72.80% biofilm formation of S. aureus and P. aeruginosa, respectively. Also, CF-Fe3O4-NPs showed perfect cell viability inhibition effect against E. coli with 99.99% at 500 mg/L concentration.