A comparison of sodium sulfate, sodium phosphate, and boric acid for preparation of immobilized Pseudomonas putida F1 in poly(vinyl alcohol) beads

Poly(vinyl alcohol) (PVA) gel beads crosslinked with sodium phosphate or boric acid have been widely utilized for microorganism immobilization. We previously utilized sodium sulfate to induce crosslinking of PVA for preparing immobilized yeast cells in PVA beads. In this study, we compared the toxicities of sodium sulfate and conventional crosslinkers (sodium phosphate and boric acid) toward Pseudomonas putida F1 (PpF1) and the performance of the corresponding immobilized PpF1 in PVA beads. The toxicity of sodium sulfate to PpF1 was lower than those of the conventional crosslinkers. PVA-sodium sulfate beads showed a higher gel fraction of PVA and a lower swelling ratio in water than PVA-sodium phosphate beads, which indicates that the former had higher stability. PpF1 immobilized in the PVA-sodium sulfate beads completely degraded the pollutant trichloroethylene (TCE) with an initial concentration (0.42 mg/l) within the most common range of TCE concentration found in contaminated field sites.