Use of free and immobilized Pseudomonas putida cells for the reduction of a thiophene derivative in organic media

An organic-aqueous two-liquid phase system was developed in order to perform the reduction of 3-thiophenecarboxaldeyde (3-TC) to 3-thiophenemethanol (3-TM), two intermediate log P compounds, using Pseudomonas putida S 12 cells. Although, high bioconversion yields were observed in a bioconversion medium composed by Tris-HCl pH 8.5 buffer and n-octanol, adverse phase toxicity effects were observed following incubation periods in excess of 24 h. Furthermore, a stable emulsion was formed in two-liquid phase system in the presence of free cells. This prevented effective separation of the biocatalyst and of the two-liquid phases. Whole cells were effectively entrapped in Ca-alginate beads, thus enhancing biocatalyst recovery. No shifts in the pH versus activity profile resulted from the immobilization. Successive batches were carried out with the immobilized biocatalyst, but a decrease in the specific activity was observed. (C) 2002 Elsevier Science B.V. All rights reserved.