Continuous phenol (PhOH) decomposition experiments were carried out with PhOH-degrading bacteria immobilized in a copolymerized spherical hydrogel (ENTG-co-PSβCyD) and a mixed spherical hydrogel (ENTG-mix-βCyD/HDI). Similar to the results obtained from the batch PhOH degradation experiments, both β-CyD-containing spherical hydrogels, which feature cylindrical hydrophobic intramolecular spaces, exhibited higher activity than the ENTG spherical hydrogels lacking β-CyD. The bacterial cells were extensively distributed on the surface and inside the copolymerized carrier and throughout the entire mixed carrier, while only a small amount of bacteria were found on the surface of the ENTG carrier. Furthermore, the PhOH-degrading bacterial flora (microflora) in the copolymerized and mixed spherical gel matrices were identified. Pseudomonas putida formed a niche in the copolymerized spherical hydrogel, and Sphingomonas sp. formed a niche in the mixed hydrogel. In the continuous PhOH degradation experiment, the performance of both hydrogels was almost identical because the ability of both strains to degrade PhOH is similar. However, in the batch removal experiment using p-xylene as the substrate instead of PhOH, the rates of substrate removal by the copolymerized gel and mixed gel 2.4 times and 1.6 times greater than that of the ENTG gel, respectively. This occurred because the bacterial species in the mixed gel was Sphingomonas sp. instead of P. putida, and the high substrate removal by the copolymerized gel was a result of the high reactivity of P. putida.
- Hirohito Yamasaki
- Yasu-yuki Nagasawa
- Kimitoshi Fukunaga
