Development of a Novel Cultivation Method for Molds and Its Characterization

在本研究中，我们将新开发的膜表面液体培养（简称MSLC）应用于使用霉菌生产有用物质。我们不仅打算优化培养条件，而且还澄清了MSLC中获得的较高生产率的原因，与摇瓶培养中获得的结果相比。我们研究了三种发酵系统，即，1)在不同的培养条件下，如培养基的pH和C-和N-源浓度，使用Aspergillus pilosus进行曲酸发酵，2）使用Monocluspilosus生产红色素，和3）使用重组Aspergillus pilosus生产α-葡糖苷酶。在MSLC中，我们首先考察了各种多孔膜对培养行为的影响。发现最合适的膜是具有约0.2μm的孔径和亲水性的膜。MSLC在所有三种培养系统中的生产率均高于摇瓶培养。本文通过考察不同供氧量对MSLC摇瓶培养的影响，探讨了MSLC高产的原因，发现MSLC高产的原因并不在于供氧量的增加。这表明基因表达的差异，细胞中产生的相关酶的量，以及产物通过细胞膜的渗透性可能影响MSLC的较高生产率。

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.