To explore a competitive PHB-producing fermentation process, this study evaluated the potential for Methylobacterium sp. XJLW to produce simultaneously PHB and coenzyme Q10 (CoQ10) using methanol as sole carbon and energy source. The metabolic pathways of PHB and CoQ10 biosynthesis in Methylobacterium sp. XJLW were first mined based on the genomic and comparative transcriptomics information. Then, real-time fluorescence quantitative PCR (RT-qPCR) was employed for comparing the expression level of important genes involved in PHB and CoQ10 synthesis pathways’ response to methanol and glucose. Transmission electron microscope (TEM), gas chromatography/mass spectrometry (GC-MS), nuclear magnetic resonance (NMR), Fourier transformation infrared spectrum (FT-IR), and liquid chromatography/mass spectrometry (LC-MS) methods were used to elucidate the yield and structure of PHB and CoQ10, respectively. PHB and CoQ10 productivity of Methylobacterium sp. XJLW were evaluated in Erlenmeyer flask for medium optimization, and in a 5-L bioreactor for methanol fed-batch strategy according to dissolved oxygen (DO) and pH control. Comparative genomics analysis showed that the PHB and CoQ10 biosynthesis pathways co-exist in Methylobacterium sp. XJLW. Transcriptomics analysis showed that the transcription level of key genes in both pathways responding to methanol was significantly higher than that responding to glucose. Correspondingly, strain Methylobacterium sp. XJLW can produce PHB and CoQ10 simultaneously with higher yield using cheap and abundant methanol than using glucose as sole carbon and energy source. The isolated products showed the structure characteristics same to that of standard PHB and CoQ10. The optimal medium and cultural conditions for PHB and CoQ10 co-production by Methylobacterium sp. XJLW was in M3 medium containing 7.918 g L-1 methanol, 0.5 g L-1 of ammonium sulfate, 0.1% (v/v) of Tween 80, and 1.0 g L-1 of sodium chloride, under 30 °C and pH 7.0. In a 5-L bioreactor coupled with methanol fed-batch process, a maximum DCW value (46.31 g L-1) with the highest yields of PHB and CoQ10, reaching 6.94 g L-1 and 22.28 mg L-1, respectively. Methylobacterium sp. XJLW is potential for efficiently co-producing PHB and CoQ10 employing methanol as sole carbon and energy source. However, it is still necessary to further optimize fermentation process, and genetically modify strain pathway, for enhanced production of PHB and CoQ10 simultaneously by Methylobacterium sp. XJLW. It also suggests a potential strategy to develop efficiently co-producing other high-value metabolites using methanol-based bioprocess.

中文翻译：

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通过无糖发酵共同生产聚羟基丁酸酯（PHB）和辅酶Q ₁₀（CoQ ₁₀）-甲基杆菌属（Methylobacterium sp。）J

为了探索产生PHB的竞争性发酵过程，本研究评估了甲基杆菌属菌种的潜力。XJLW使用甲醇作为唯一碳和能源，同时生产PHB和辅酶Q10（CoQ10）。甲基杆菌属中PHB和辅酶Q10生物合成的代谢途径。XJLW首先是根据基因组和比较转录组学信息进行开采的。然后，采用实时荧光定量PCR（RT-qPCR）比较PHB和辅酶Q10合成途径对甲醇和葡萄糖反应的重要基因的表达水平。透射电子显微镜（TEM），气相色谱/质谱（GC-MS），核磁共振（NMR），傅立叶变换红外光谱（FT-IR），液相色谱/质谱法（LC-MS）分别阐明了PHB和辅酶Q10的得率和结构。甲基杆菌属的PHB和CoQ10生产率。XJLW在锥形瓶中进行了培养基最优化评估，并在5升生物反应器中根据溶解氧（DO）和pH值控制在甲醇补料分批策略中进行了评估。比较基因组学分析表明，PHB和CoQ10生物合成途径共存在于甲基杆菌属中。XJLW。转录组学分析表明，在两种途径中，对甲醇有反应的关键基因的转录水平均显着高于对葡萄糖的反应。相应地，菌株甲基杆菌属。与使用葡萄糖作为唯一碳源和能源相比，XJLW使用廉价且丰富的甲醇可以同时生产PHB和CoQ10。分离出的产物显示出与标准PHB和CoQ10相同的结构特征。Methylobacterium sp。共同生产PHB和CoQ10的最佳培养基和培养条件。XJLW在30°C和pH 7.0的M3培养基中，该培养基含有7.918 g L-1甲醇，0.5 g L-1硫酸铵，0.1％（v / v）的Tween 80和1.0 g L-1氯化钠。 。在结合甲醇分批进料的5升生物反应器中，最大DCW值（46.31 g L-1），PHB和CoQ10的最高收率分别达到6.94 g L-1和22.28 mg L-1。甲基杆菌属 XJLW具有利用甲醇作为唯一碳和能源有效联产PHB和CoQ10的潜力。但是，仍然有必要进一步优化发酵过程，并通过遗传途径修改菌株途径，用于提高甲基杆菌属菌种同时提高PHB和辅酶Q10的产量。XJLW。它还提出了使用基于甲醇的生物工艺有效开发联产其他高价值代谢物的潜在策略。