Microbial Degradation of Phenol in the Presence of Heavy Metal Ion by Immobilized Bacterial Cells

摘要

フェノール分解微生物, Acinetobacter calcoaceticus AH株に及ぼす亜鉛イオンと銅イオンの増殖阻害と死滅の影響が回分培養において菌体光学密度, 総菌数, 生菌数と細胞1個当たりの高分子含有量を測定することによって検討された。比増殖速度や生菌数変化速度に及ぼす重金属イオン濃度の影響が明らかにされ, 銅イオンの阻害効果は亜鉛イオンよりも非常に強いことと銅イオンは菌の増殖阻害だけでなく菌の死滅も引き起こすことがわかった。菌の担体としてアルギン酸カルシウムのゲルビーズを用いた固定化培養は従来までの液体培養よりも高濃度の重金属イオン存在下のフェノールを迅速かつ高効率で分解できた。固定化菌を用いた反復回分培養は10回の回分培養の間30mg/lの亜鉛イオンを含む100mg/lのフェノールを逐次的に分解でき, 重金属イオン存在下のフェノールの効果的処理への適用を可能とした。 The growth-inhibitory and lethal effects of zinc ion and copper ion on a phenol-degrading microorganism, Acinetobacter calcoaceticus AH strain, was examined by measuring optical density of cells, total cell number, viable cell number and macromolecule contents per cell in a batch culture. The effects of heavy metal ion concentrations on the specific growth rate and the specific change rate of viable cell number were clarified, suggesting that the inhibitory effect of copper ion was stronger than that of zinc ion and the copper ion caused not only the growth-inhibition but also the death of cells. The immobilized cell culture using alginate calcium gel beads as a carrier of cells was more effective for degrading phenol in the presence of a higher concentration of heavy metal ion rather than the conventional liquid culture. The repeated batch culture using immobilized cells could degrade 100 mg/l phenol containing 30 mg/l of zinc ion for 10 batch cultures and therefore provided the attention toward the applications in the effective degradation of phenol in the presence of heavy metal ion.