Although microbial transformation has been expected as a substitution technology for organic synthesis, microbial toxicity and water-insolubility of synthetic substrates prevent the practical application of the technology. For these problems, the authors have developed two types of interfacial bioprocesses, solid-liquid and liquid-liquid interface bioreactors and applied the systems to many microbial transformations. In the bioreactors, addition of substrates and accumulation of products were remarkably enhanced based on the toxicity alleviation effect on the interfaces and solubilization of substrates and/or products in an organic phase of the bioreactors. Recently, a novel tacky liquid-liquid interface bioreactor has been developed and applied to actinomycetes and yeasts. Furthermore, a novel bioconversion system with fungal spores in an organic phase has been constructed based on the combination of two facts as follows: (i) the fungal spores are never resting cells and are active ones like the vegetable cells, (ii) the fungal spores have the excellent solvent-tolerance. In this review, the tacky liquid-liquid interface bioreactor (L-L IBRtac) and the non-aqueous sporular bioconversion system with immobilized fungal spores (NASB) are mainly given outlines.
Keywords: Cell immobilization; Fungal spores; Interface bioreactor; Microbial transformation; Non-aqueous bioreactor; Solvent tolerance.