在本研究中吾人先提出正確之鏈球菌生長曲線量測方法，此量測方法與細胞型態的改變有關。根據正確的生長曲線，吾人提出一延遲之生長關聯型模式。此模式不只可成功地模擬玻尿酸醱酵，亦適用於聚麩酸醱酵生產。
本研究中也詳細探究在規模放大程序中溶氧及攪拌在玻尿酸醱酵中的角色。真正影響玻尿酸合成之主要因子為溶氧值。5%空氣飽和濃度為其臨界溶氧值，只要醱酵過程中控制溶氧值在臨界值之上，即可維持菌體在最大玻尿酸合成效率。攪拌在玻尿酸醱酵中的角色為混合以促使氧氣吸收，而非釋放玻尿酸莢膜，且過高的攪拌速率會導致玻尿酸醱酵時間延長。因此，醱酵放大設計規範為，維持溶氧值在臨界溶氧值以上，並提供均勻且溫和的攪拌。
在本研究中探究以重覆批次醱酵程序進行玻尿酸醱酵。在傳統操作下，因醱酵液中含有抑制物，導致細胞最大比生長速率及玻尿酸比產率，隨著接種體積之增加而降低。於醱酵槽中安裝不織布，在置換醱酵液時，移除含抑制物之液體，並利用不織布纖維留下細胞作為接種。在此操作方式下，長時間操作生產後會有黏附性高、無玻尿酸生產力之突變株出現於醱酵液中，並黏附生長在不織布上，導致玻尿酸醱酵生產停止。研究中提出另一重覆批次操作，利用外接過濾器，在置換醱酵液時，先排除液體並留住部份細胞，再以新鮮培養液將滯留於過濾器之細胞，逆洗接種到醱酵槽中進行重覆批次醱酵。在此操作下細胞比生長速率及玻尿酸比產率，可成功地維持在原醱酵批次水準。在相當於31%醱酵液細胞接種量之操作條件下，重覆批次醱酵之體積產率為0.59 g HA L-1 h-1，為原批次培養之2.5倍。

In this study, an accurate determination of the growth curve of the cocoid cells was first discussed, which is relevant to the change of cell morphology after entry into the stationary phase. A delayed growth-associated model was then proposed for the HA production, which is in accordance with mechanisms of HA formation reported in the literature. The proposed model was employed satisfactorily not only for HA production, but also for poly-glutamic acid production.
The role of dissolved oxygen (DO) and function of agitation in hyaluronic acid fermentation by S. zooepidemicus were also explored. The intrinsic factor affecting the efficiency of HA synthesis is DO level; and there exists a critical DO level of 5% air saturation for the HA synthesis. On the other hand, agitation functions to mix the broth, to enhance oxygen absorption, but not to release HA capsule. In addition, vigorous agitation would lengthen the operation time. It therefore suggests that the relevant criteria for scaling up the fermentor are to maintain DO level above the critical value, and to provide a mild agitation for homogeneity in the fermentor.
The production of hyaluronic acid (HA) with repeated batch fermentation has been proposed. It was found that, with conventional operation, both maximal specific growth rate and specific HA productivity decreased with increasing seed volume, suggesting that there exist some inhibitors in the broth. The removal of liquid in the seed was first attempted by installing a nonwoven fabrics (NWF) in the fermentor to retain some of the cells when draining the broth. However, this resulted in a loss of HA productivity, which in turn was attributed to the growth of a sticky, non-HA-producing mutant on the NWF. Using an external cartridge filter to partially retain the cells, followed by back-washing the filter with fresh medium for seeding, specific growth rate and specific productivity could be maintained successfully at their batch levels during the repeated cycles. In an operation that seeded 31% cell, the volumetric production rate of the repeated batch culture (0.59 g HA L-1 h-1) was found to be 2.5-fold of the batch culture (0.24 g HA L-1 h-1).

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