Viggiani A, Olivieri G, Siani L, Di Donato A, Marzocchella A, Salatino P, Barbieri P, Galli E
Dipartimento di Biologia Strutturale e Funzionale, Università degli Studi di Napoli, Federico II, Complesso Universitario di Monte S. Angelo, Via Cinthia, 80126 Napoli, Italy.
J Biotechnol. 2006 Jun 10;123(4):464-77. doi: 10.1016/j.jbiotec.2005.12.024. Epub 2006 Feb 20.
Phenol bioconversion by Pseudomonas stutzeri OX1 using either free or immobilized cells was investigated with the aim of searching for optimal operating conditions of a continuous bioconversion process. The study was developed by analyzing: (a) free-cell growth and products of phenol bioconversion by batch cultures of P. stutzeri; (b) growth of P. stutzeri cells immobilized on carrier particles; (c) bioconversion of phenol-bearing liquid streams and the establishment and growth of an active bacterial biofilm during continuous operation of an internal-loop airlift bioreactor. We have confirmed that free Pseudomonas cultures are able to transform phenol through the classical meta pathway for the degradation of aromatic molecules. Data indicate that bacterial growth is substrate-inhibited, with a limiting phenol concentration of about 600 mg/L. Immobilization tests revealed that a stable bacterial biofilm can be formed on various types of solid carriers (silica sand, tuff, and activated carbon), but not on alumina. Entrapment in alginate beads also proved to be effective for P. stutzeri immobilization. Continuous bioconversion of phenol-bearing liquid streams was successfully obtained in a biofilm reactor operated in the internal-circulation airlift mode. Phenol conversion exceeded 95%. Biofilm formation and growth during continuous operation of the airlift bioreactor were quantitatively and qualitatively assessed.
为了寻找连续生物转化过程的最佳操作条件，研究了施氏假单胞菌OX1使用游离细胞或固定化细胞对苯酚的生物转化。该研究通过分析以下内容展开：(a) 施氏假单胞菌分批培养中游离细胞的生长及苯酚生物转化产物；(b) 固定在载体颗粒上的施氏假单胞菌细胞的生长；(c) 在内循环气升式生物反应器连续运行期间含酚液流的生物转化以及活性细菌生物膜的形成和生长。我们已证实，游离的假单胞菌培养物能够通过经典的间位途径转化苯酚以降解芳香族分子。数据表明，细菌生长受到底物抑制，苯酚的极限浓度约为600 mg/L。固定化试验表明，可在各种类型的固体载体（硅砂、凝灰岩和活性炭）上形成稳定的细菌生物膜，但在氧化铝上则不能。包埋在海藻酸钠珠中对施氏假单胞菌的固定化也被证明是有效的。在以内部循环气升模式运行的生物膜反应器中成功实现了含酚液流的连续生物转化。苯酚转化率超过95%。对气升式生物反应器连续运行期间生物膜的形成和生长进行了定量和定性评估。
