Background

Halomonas boliviensis is a halophilic microorganism that accumulates poly(3-hydroxybutyrate) (PHB) using different carbons sources when nitrogen is depleted from the culture medium. This work presents an improved production of PHB using an air-lift reactor (ALR) that was fed with a concentrated solution of a carbon source, and was supplemented with an adequate airflow rate.

Results

Simple production media were used to study PHB production by H. boliviensis in an ALR. Glucose was first used as the main carbon source and was fed during the exponential phase of cell growth. The maximum CDW and PHB content were 31.7 g/L and 51 wt%, respectively, when the airflow rate entering the reactor varied between 0.5 and 1.2 L/min. Changing the air inflow to 0.5–0.9 L/min resulted in an improvement in PHB accumulation (62 wt%). A cultivation was performed by using the latter range of airflow rate and feeding glucose only when nitrogen was depleted from the medium; a considerable enhancement in PHB content (72 wt%) and CDW (27 g/L) was achieved under these conditions. Moreover, PHB was also produced using molasses as the main carbon source. Residual cell mass was about the same to that achieved with glucose, however the PHB content (52 wt%) was lower.

Conclusions

PHB production by H. boliviensis in an ALR using a simple medium is possible. CDW and PHB content in H. boliviensis can be improved with respect to batch cultivations previously reported when a carbon source is fed to the reactor. The best strategy for the production of PHB consisted of starting the cultivation in a batch mode while glutamate was present in the medium; glucose should be fed when glutamate is depleted from the medium to keep an excess of the carbon source during the synthesis of PHB.

中文翻译：

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使用简单的生产介质改进气举反应器中聚（3-羟基丁酸酯）的生产

背景

玻利莫单胞菌是一种嗜盐微生物，当培养基中的氮耗竭时，它会使用不同的碳源积累聚（3-羟基丁酸酯）（PHB）。这项工作提出了使用气举反应器（ALR）改进PHB的生产方法，该反应器装有碳源的浓溶液，并补充了足够的空气流速。

结果

使用简单的生产培养基来研究玻利维亚的PHB生产在ALR中。葡萄糖首先被用作主要的碳源，并在细胞生长的指数阶段进食。当进入反应器的气流速率在0.5至1.2 L / min之间变化时，最大CDW和PHB含量分别为31.7 g / L和51 wt％。将空气流入量更改为0.5-0.9 L / min可以改善PHB的积累（62 wt％）。通过使用后一范围的气流速率进行培养，并且仅当从培养基中耗尽氮时才供给葡萄糖。在这些条件下，PHB含量（72 wt％）和CDW（27 g / L）得到了显着提高。此外，PHB也以糖蜜为主要碳源生产。残余细胞量与葡萄糖所达到的细胞量大致相同，但是PHB含量（52 wt％）较低。

结论

使用简单的培养基，可以在ALR中通过玻利维亚杆菌生产PHB 。相对于先前报道的将碳源进料到反应器中的分批培养，可以提高玻利维亚杆菌中CDW和PHB的含量。生产PHB的最佳策略是在培养基中存在谷氨酸的情况下以分批模式开始培养。当从培养基中去除谷氨酸时，应补充葡萄糖，以在PHB合成过程中保持过量的碳源。