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首页> 外文期刊>Industrial Biotechnology >Oxygen Transfer and Fragmentation of Aspergillus niger Pellets in Stirred Tank and Concentric-Duct Airlift Bioreactors
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Oxygen Transfer and Fragmentation of Aspergillus niger Pellets in Stirred Tank and Concentric-Duct Airlift Bioreactors

机译：搅拌罐中曲霉颗粒的氧气转移和碎裂和同心管空载生物反应器

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摘要

The hydrodynamic environment in bioreactors is an important parameter because cultivation conditions that provide satisfactory oxygen transfer rates tend to be harmful to microorganisms, due to the effect of shear on the cellular structure. Consequently, it is a challenge to find the ideal set of bioreactor operating conditions that favor production of the metabolites of interest. The present work evaluated the fragmentation of Aspergillus niger pellets in two different types of bioreactor: a conventional stirred tank bioreactor (STB) and a concentric-duct airlift (CDA) bioreactor. Both were operated under similar oxygen transfer or shear conditions. Oxygen transfer was quantified by means of the volumetric oxygen transfer coefficient (ki/z). The shear condition was determined using the average shear rate (ydW), obtained using computational fluid dynamics (CFD), together with pellet fragmentation. The findings showed that the CDA bioreactor caused less fragmentation of the pellets, compared to the STB, when both systems were operated with the same ki.a values. For similar fragmentation levels, the kj_a value for the CDA bioreactor was 38% higher than observedfor the STB. Considering the results for both bioreactor models, the fragmentation of A. niger pellets, represented by the variation of the average normalized A. niger pellet equivalent diameter (D_(eq)/D_(eq,0)) after fragmentation assays of 4h duration (Δ_(frag)), exhibited a linear relation with γ_(av) (R~2 = 0.97). The CDA bioreactor also presented advantages in terms of specific power consumption and mass transfer efficiency. These results should assist in the selection of suitable bioreactor models and operating conditions, in order to improve the efficiency of industrial production of bio-based products.
机译：生物反应器中的流体动力学环境是一个重要参数，因为由于剪切对细胞结构的影响，提供令人满意的氧气转移率的培养条件往往是有害的微生物。因此，寻找有利于利益的代谢产物的理想生物反应器操作条件是一项挑战。本作者评估了两种不同类型的生物反应器中曲霉粒子颗粒的碎片：传统的搅拌釜生物反应器（STB）和同心 - 管道空气反应器。两者都在相似的氧气转移或剪切条件下操作。通过体积氧转移系数（Ki / Z）量化氧转移。使用使用计算流体动力学（CFD）获得的平均剪切速率（YDW）测定剪切条件，以及颗粒碎片。结果表明，与STB相比，CDA生物反应器引起颗粒的碎片化，当两个系统以相同的ki.a值操作时。对于类似的碎片水平，CDA生物反应器的KJ_A值比STB观察到38％。考虑到生物反应器模型的结果，A. niger颗粒的碎片化，由平均归一化A.尼格丸颗粒等效直径（D_（EQ）/ D_（EQ，0））的变化表示为4H持续时间（ Δ_（碎片）），与γ_（AV）（R〜2 = 0.97）表现出线性关系。 CDA生物反应器还在特定功耗和传质效率方面提出了优势。这些结果应协助选择合适的生物反应器模型和操作条件，以提高生物基产品的工业生产效率。

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