Nutrient requirements for growth of the extreme oligotroph 'Candidatus Pelagibacter ubique' HTCC1062 on a defined medium
Nutrient requirements for growth of the extreme oligotroph 'Candidatus Pelagibacter ubique' HTCC1062 on a defined medium
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DOI：
10.1038/ismej.2012.122
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发表时间：
2013-03-01
期刊：
影响因子：
11
通讯作者：
Giovannoni, Stephen J.
中科院分区：
文献类型：
--
作者：
Carini, Paul;Steindler, Laura;Giovannoni, Stephen J.
SAR 11分支的化能异养海洋细菌是地球上最丰富的生物。在SAR 11细菌的第一次培养之后，“遍在披碱草属”菌株HTCC 1062（Ca.在2002年，确定了对还原硫化合物和甘氨酸或丝氨酸的不寻常的营养需求。这些要求与基因组精简有关，基因组精简是在营养有限的海洋生境中选择有效利用资源而产生的。在这里，我们报告的第一个成功的种植钙。在确定的人工海水培养基（AMS 1）上的泛假单胞菌，以及对丙酮酸盐或丙酮酸盐前体的额外要求。最佳的增长与无机宏量和微量营养素，维生素，蛋氨酸，甘氨酸和丙酮酸盐的集体添加观察。蛋氨酸作为唯一的硫源，但蛋氨酸和甘氨酸不足以支持生长。当甘氨酸和丙酮酸之间的化学计量比为1：4时，获得最佳的细胞产量，并且在丙酮酸饥饿的培养物中观察到不完全的细胞分裂。葡萄糖和草酰乙酸可以完全取代丙酮酸，但不能取代乙酸、牛磺酸或多种三羧酸循环中间产物。此外，甜菜碱和丝氨酸都可以替代甘氨酸。有趣的是，在没有甘氨酸的情况下，乙醇酸盐部分恢复了生长。我们认为，这是使用乙醇酸，浮游植物代谢的产物，作为呼吸的碳源和作为甘氨酸的前体的结果。这些发现很重要，因为它们为以下假设提供了支持：由于简化选择和基因丢失导致的不寻常的营养需求，一些微生物难以培养。我们的研究结果还说明了不寻常的代谢重排，使这些细胞适应极端寡养，并强调了在具有非典型代谢途径的生物体中从基因组序列重建代谢的挑战。The ISME Journal（2013）7，592-602; doi：10.1038/ismej.2012.122; 2012年10月25日在线发表
Chemoheterotrophic marine bacteria of the SAR11 clade are Earth's most abundant organisms. Following the first cultivation of a SAR11 bacterium, 'Candidatus Pelagibacter ubique' strain HTCC1062 (Ca. P. ubique) in 2002, unusual nutritional requirements were identified for reduced sulfur compounds and glycine or serine. These requirements were linked to genome streamlining resulting from selection for efficient resource utilization in nutrient-limited ocean habitats. Here we report the first successful cultivation of Ca. P. ubique on a defined artificial seawater medium (AMS1), and an additional requirement for pyruvate or pyruvate precursors. Optimal growth was observed with the collective addition of inorganic macro-and micronutrients, vitamins, methionine, glycine and pyruvate. Methionine served as the sole sulfur source but methionine and glycine were not sufficient to support growth. Optimal cell yields were obtained when the stoichiometry between glycine and pyruvate was 1: 4, and incomplete cell division was observed in cultures starved for pyruvate. Glucose and oxaloacetate could fully replace pyruvate, but not acetate, taurine or a variety of tricarboxylic acid cycle intermediates. Moreover, both glycine betaine and serine could substitute for glycine. Interestingly, glycolate partially restored growth in the absence of glycine. We propose that this is the result of the use of glycolate, a product of phytoplankton metabolism, as both a carbon source for respiration and as a precursor to glycine. These findings are important because they provide support for the hypothesis that some micro-organisms are challenging to cultivate because of unusual nutrient requirements caused by streamlining selection and gene loss. Our findings also illustrate unusual metabolic rearrangements that adapt these cells to extreme oligotrophy, and underscore the challenge of reconstructing metabolism from genome sequences in organisms that have non-canonical metabolic pathways. The ISME Journal (2013) 7, 592-602; doi:10.1038/ismej.2012.122; published online 25 October 2012