Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2147, 4059, Casilla, Valparaíso, Chile.
Facultad de Ciencias Tecnológicas, Universidad Nacional de Agricultura, Carretera a Dulce Nombre de Culmí, km 212, Barrio El Espino, Catacamas, Honduras.
Bioprocess Biosyst Eng. 2021 Jun;44(6):1275-1287. doi: 10.1007/s00449-021-02532-8. Epub 2021 Feb 26.
Alginates can be used to elaborate hydrogels, and their properties depend on the molecular weight (MW) and the guluronic (G) and mannuronic (M) composition. In this study, the MW and G/M ratio were evaluated in cultures of Azotobacter vinelandii to 3 and 30 L scales at different oxygen transfer rates (OTRs) under diazotrophic conditions. An increase in the maximum OTR (OTR) improved the alginate production, reaching 3.3 ± 0.2 g L. In the cultures conducted to an OTR of 10.4 mmol L h (500 rpm), the G/M increased during the cell growth phase and decreased during the stationary phase; whereas, in the cultures at 19.2 mmol L h was constant throughout the cultivation. A higher alginate MW (520 ± 43 kDa) and G/M ratio (0.86 ± 0.01) were obtained in the cultures conducted at 10.4 mmol L h. The OTR as a criterion to scale up alginate production allowed to replicate the concentration and the alginate production rate; however, it was not possible reproduce the MW and G/M ratio. Under a similar specific oxygen uptake rate (qO) (approximately 65 mmol g h) the alginate MW was similar (approximately 365 kDa) in both scales. The evidences revealed that the qO can be a parameter adequate to produce alginate MW similar in two bioreactor scales. Overall, the results have shown that the alginate composition could be affected by cellular respiration, and from a technological perspective the evidences contribute to the design process based on oxygen consumption to produce alginates defined.
海藻酸盐可以用来制备水凝胶，其性质取决于分子量 (MW) 以及古洛糖醛酸 (G) 和甘露糖醛酸 (M) 的组成。在这项研究中，在固氮条件下，不同氧传递速率 (OTR) 下，在 3 升至 30 升规模下，评估了固氮菌 (Azotobacter vinelandii) 培养物中的 MW 和 G/M 比。最大 OTR (OTR) 的增加改善了海藻酸盐的生产，达到 3.3 ± 0.2 g/L。在 OTR 为 10.4 mmol/L·h（500 rpm）的培养物中，G/M 在细胞生长阶段增加，在静止阶段减少；而在 OTR 为 19.2 mmol/L·h 的培养物中则在整个培养过程中保持不变。在 OTR 为 10.4 mmol/L·h 的培养物中获得了更高的海藻酸盐 MW（520 ± 43 kDa）和 G/M 比（0.86 ± 0.01）。作为扩大海藻酸盐生产的标准的 OTR 允许复制浓度和海藻酸盐生产速率；然而，不可能复制 MW 和 G/M 比。在类似的特定耗氧率 (qO)（约 65 mmol/g·h）下，两种规模下的海藻酸盐 MW 相似（约 365 kDa）。这些证据表明，qO 可以是产生两种生物反应器规模下相似的海藻酸盐 MW 的合适参数。总的来说，结果表明海藻酸盐的组成可能受到细胞呼吸的影响，从技术角度来看，这些证据有助于基于氧消耗的设计过程，以生产出定义明确的海藻酸盐。
