Development of a Novel Cultivation Method for Molds and Its Characterization

在这项研究中，我们将一种新开发的膜-表面液体培养(简称MSLC)应用于利用霉菌生产有用物质。我们不仅打算优化培养条件，而且通过与摇瓶培养结果的比较，阐明了MSLC获得更高生产率的原因。研究了米曲霉发酵曲酸、红曲霉产红色素和重组米曲霉生产α-葡萄糖苷酶三种发酵条件，不同培养条件下的发酵条件不同。在MSLC中，我们首先考察了不同类型的多孔膜对培养行为的影响。结果表明，孔径在0.2μm左右且具有亲水性的膜是最合适的膜。在所考察的所有三种培养体系中，MSLC的生产率都高于摇瓶培养。我们考察了摇瓶培养中供氧量的影响，以寻找MSLC产氧量较高的原因。结果表明，基因表达、细胞内相关酶的产生量以及产物对细胞膜的通透性的差异可能影响MSLC的高产。

In this, study we applied a newly-developed membrane-surface liquid culture (abbreviated as MSLC) to production of useful substances using molds. We not only intended to optimize the cultivation conditions but also clarify the reasons for the higher productivity obtained in MSLC in comparison with the results obtained in shaking flask cultures. We studied three fermentation systems, i.e., 1) kojic acid fermentation using Aspergillus oryzae, 2) red pigment production using Monascus pilosus, and 3) production of α-glucosidase using recombinant Aspergillus oryzae under various cultivation conditions, different in factors such as pH of the medium and C-and N-source concentrations. In MSLC, we first examined the effect of kinds of porous membranes on the cultivation behaviors. The most suitable membrane was found to be such a membrane that have a pore diameter of around 0.2μm and hydrophilic property. MSLC gave a higher productivity in the all three cultivation systems examined than those with shaking flask cultures. We examined the effect of oxygen supply in the shaking flask cultures to seek the reasons for the higher productivity in MSLC.The reasons for the higher productivity in MSLC were found not to be in the higher oxygen supply. It was suggested that differences in gene expression, the amount of relating enzyme produced in the cells, and permeability of the product through the cell membrane may affect the higher productivity in MSLC.