The acetylation degree of alginates in Azotobacter vinelandii ATCC9046 is determined by dissolved oxygen and specific growth rate: studies in glucose-limited chemostat cultivations
The acetylation degree of alginates in Azotobacter vinelandii ATCC9046 is determined by dissolved oxygen and specific growth rate: studies in glucose-limited chemostat cultivations
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DOI：
10.1007/s10295-013-1274-6
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发表时间：
2013-07-01
影响因子：
3.4
通讯作者：
Pena, Carlos F.
中科院分区：
文献类型：
--
作者：
Castillo, Tania;Galindo, Enrique;Pena, Carlos F.
藻酸盐是多糖，可用作增粘剂和凝胶或成膜剂，具有多种应用。由细菌如棕色固氮菌（Azotobacter vinelandii）产生的藻酸盐被乙酰化。在这种类型的藻酸盐中乙酰基的存在增加了其溶解度、粘度和溶胀能力。本研究的目的是评估，在葡萄糖限制恒化培养的A。vinelandii ATCC 9046的发酵液中，研究了溶解氧张力（DO）和比生长速率（mu）对该菌产藻酸盐乙酰化度的影响。在葡萄糖限制恒化器培养中，在DO（1%和9%）的两种条件下和特定生长速率（0.02-0.15 h（-1））的范围内评估藻酸盐乙酰化的程度。此外，对海藻酸盐产量和PHB产量进行了评价。培养物中的高DO导致高程度的藻酸盐乙酰化，在9%DO下达到6.88%的最大乙酰化程度。相反，μ的增加对聚合物的生产和乙酰化具有负面影响。发现在高DO（9%）和低mu下，呼吸速率降低，并且PHB积累可忽略不计，表明乙酰辅酶A（乙酰供体）的通量转向藻酸盐乙酰化。
Alginates are polysaccharides that may be used as viscosifiers and gel or film-forming agents with a great diversity of applications. The alginates produced by bacteria such as Azotobacter vinelandii are acetylated. The presence of acetyl groups in this type of alginate increases its solubility, viscosity, and swelling capability. The aim of this study was to evaluate, in glucose-limited chemostat cultivations of A. vinelandii ATCC9046, the influence of dissolved oxygen tension (DO) and specific growth rate (mu) on the degree of acetylation of alginates produced by this bacterium. In glucose-limited chemostat cultivations, the degree of alginate acetylation was evaluated under two conditions of DO (1 and 9 %) and for a range of specific growth rates (0.02-0.15 h(-1)). In addition, the alginate yields and PHB production were evaluated. High DO in the culture resulted in a high degree of alginate acetylation, reaching a maximum acetylation degree of 6.88 % at 9 % DO. In contrast, the increment of mu had a negative effect on the production and acetylation of the polymer. It was found that at high DO (9 %) and low mu, there was a reduction of the respiration rate, and the PHB accumulation was negligible, suggesting that the flux of acetyl-CoA (the acetyl donor) was diverted to alginate acetylation.