Gierok Philipp, Kohler Christian, Steinmetz Ivo, Lalk Michael
Institute of Biochemistry, Ernst-Moritz-Arndt-University, Greifswald, Germany.
Friedrich Loeffler Institute of Medical Microbiology, University Medicine Greifswald, Greifswald, Germany.
PLoS Negl Trop Dis. 2016 Mar 4;10(3):e0004483. doi: 10.1371/journal.pntd.0004483. eCollection 2016 Mar.
Burkholderia pseudomallei is a water and soil bacterium and the causative agent of melioidosis. A characteristic feature of this bacterium is the formation of different colony morphologies which can be isolated from environmental samples as well as from clinical samples, but can also be induced in vitro. Previous studies indicate that morphotypes can differ in a number of characteristics such as resistance to oxidative stress, cellular adhesion and intracellular replication. Yet the metabolic features of B. pseudomallei and its different morphotypes have not been examined in detail so far. Therefore, this study aimed to characterize the exometabolome of B. pseudomallei morphotypes and the impact of acute infection on their metabolic characteristics.
We applied nuclear magnetic resonance spectroscopy (1H-NMR) in a metabolic footprint approach to compare nutrition uptake and metabolite secretion of starvation induced morphotypes of the B. pseudomallei strains K96243 and E8. We observed gluconate production and uptake in all morphotype cultures. Our study also revealed that among all morphotypes amino acids could be classified with regard to their fast and slow consumption. In addition to these shared metabolic features, the morphotypes varied highly in amino acid uptake profiles, secretion of branched chain amino acid metabolites and carbon utilization. After intracellular passage in vitro or murine acute infection in vivo, we observed a switch of the various morphotypes towards a single morphotype and a synchronization of nutrient uptake and metabolite secretion.
To our knowledge, this study provides first insights into the basic metabolism of B. pseudomallei and its colony morphotypes. Furthermore, our data suggest, that acute infection leads to the synchronization of B. pseudomallei colony morphology and metabolism through yet unknown host signals and bacterial mechanisms.
类鼻疽伯克霍尔德菌是一种存在于水和土壤中的细菌，是类鼻疽的病原体。该细菌的一个特征是形成不同的菌落形态，这些形态可从环境样本以及临床样本中分离得到，也可在体外诱导形成。先前的研究表明，不同形态型在许多特征上存在差异，如对氧化应激的抗性、细胞黏附及细胞内复制能力。然而，迄今为止，尚未对类鼻疽伯克霍尔德菌及其不同形态型的代谢特征进行详细研究。因此，本研究旨在表征类鼻疽伯克霍尔德菌形态型的胞外代谢组以及急性感染对其代谢特征的影响。
我们采用代谢足迹法，运用核磁共振波谱技术（1H-NMR）比较类鼻疽伯克霍尔德菌K96243和E8菌株饥饿诱导形态型的营养物质摄取和代谢物分泌情况。我们观察到在所有形态型培养物中均有葡萄糖酸盐的产生和摄取。我们的研究还表明，在所有形态型中，氨基酸可根据其消耗速度快慢进行分类。除了这些共同的代谢特征外，不同形态型在氨基酸摄取谱、支链氨基酸代谢物分泌及碳利用方面存在很大差异。在体外细胞内传代或体内小鼠急性感染后，我们观察到各种形态型转变为单一形态型，并使营养物质摄取和代谢物分泌同步化。
据我们所知，本研究首次深入了解了类鼻疽伯克霍尔德菌及其菌落形态型的基础代谢。此外，我们的数据表明，急性感染通过尚不清楚的宿主信号和细菌机制导致类鼻疽伯克霍尔德菌菌落形态和代谢同步化。
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