Abstract Methylomicrobium buryatense 5 GB1 has been identified as a promising biocatalyst for industrial methane conversion to produce value-added products. However, despite recent advancements in understanding the metabolism of 5 GB1, existing knowledge on the differences between oxygen-limited and methane-limited phenotypes is still limited. In this work, both batch and continuous experiments were carried out to systematically examine the strain’s oxygen-limited and methane-limited phenotypes. Total carbon balances were performed to ensure the obtained measurements of CH4 and O2 consumption rates and CO2 production rate were accurate. Our results showed that the feed gas composition alone does not dictate the strain’s growth phenotype. In order to achieve a desired phenotype, both feed gas composition and cell growth rate have to be controlled. In addition, contrary to the common belief that oxygen-limited conditions lead to increased production of organic compounds, our results suggest that it is the methane-limited condition that has higher yield for organic compounds. Knowledge of these differences could provide key understanding into how M. buryatense 5 GB1 regulate its carbon flow among different pathways under different growth conditions, which will provide the key insights for both mutant design and process design (e.g., culture conditions) for desired outcomes such as increased production of organic acids. Finally, using data collected in this work and those published in literature, we further validated a published genome-scale model under optimal growth condition. In addition, our results suggest that the current model lacks key metabolic routes to explain the surprisingly robust growth exhibited by the strain under wide substrate availability conditions.

中文翻译：

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Methylomicrobium buryatense 5GB1 限氧和限甲烷生长表型的比较研究

摘要 Methylomicrobium buryatense 5 GB1 已被确定为一种很有前途的生物催化剂，可用于工业甲烷转化以生产增值产品。然而，尽管最近在理解 5 GB1 的代谢方面取得了进展，但关于氧限制和甲烷限制表型之间差异的现有知识仍然有限。在这项工作中，进行了批量和连续实验，以系统地检查菌株的氧气限制和甲烷限制表型。进行总碳平衡以确保获得的 CH4 和 O2 消耗率以及 CO2 生成率的测量结果准确。我们的结果表明，单独的原料气组成并不能决定菌株的生长表型。为了获得所需的表型，必须控制进料气体组成和细胞生长速率。此外，与普遍认为的氧气限制条件导致有机化合物产量增加相反，我们的结果表明，甲烷限制条件具有更高的有机化合物产率。了解这些差异可以提供对 M. buryatense 5 GB1 如何在不同生长条件下调节不同途径之间的碳流动的关键理解，这将为突变体设计和工艺设计（例如培养条件）提供关键见解，以获得所需的结果，例如随着有机酸产量的增加。最后，使用在这项工作中收集的数据和文献中发表的数据，我们进一步验证了在最佳生长条件下已发表的基因组规模模型。此外，