Kuhns Lisa G, Benoit Stéphane L, Bayyareddy Krishnareddy, Johnson Darryl, Orlando Ron, Evans Alexandra L, Waldrop Grover L, Maier Robert J
Department of Microbiology, University of Georgia, Athens, Georgia, USA.
Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA.
J Bacteriol. 2016 Apr 14;198(9):1423-8. doi: 10.1128/JB.00041-16. Print 2016 May.
A molecular hydrogen (H2)-stimulated, chemolithoautotrophic growth mode for the gastric pathogen Helicobacter pylori is reported. In a culture medium containing peptides and amino acids, H2-supplied cells consistently achieved 40 to 60% greater growth yield in 16 h and accumulated 3-fold more carbon from [(14)C]bicarbonate (on a per cell basis) in a 10-h period than cells without H2 Global proteomic comparisons of cells supplied with different atmospheric conditions revealed that addition of H2 led to increased amounts of hydrogenase and the biotin carboxylase subunit of acetyl coenzyme A (acetyl-CoA) carboxylase (ACC), as well as other proteins involved in various cellular functions, including amino acid metabolism, heme synthesis, or protein degradation. In agreement with this result, H2-supplied cells contained 3-fold more ACC activity than cells without H2 Other possible carbon dioxide (CO2) fixation enzymes were not up-expressed under the H2-containing atmosphere. As the gastric mucus is limited in carbon and energy sources and the bacterium lacks mucinase, this new growth mode may contribute to the persistence of the pathogen in vivo This is the first time that chemolithoautotrophic growth is described for a pathogen.
Many pathogens must survive within host areas that are poorly supplied with carbon and energy sources, and the gastric pathogen Helicobacter pylori resides almost exclusively in the nutritionally stringent mucus barrier of its host. Although this bacterium is already known to be highly adaptable to gastric niches, a new aspect of its metabolic flexibility, whereby molecular hydrogen use (energy) is coupled to carbon dioxide fixation (carbon acquisition) via a described carbon fixation enzyme, is shown here. This growth mode, which supplements heterotrophy, is termed chemolithoautotrophy and has not been previously reported for a pathogen.
报道了胃病原体幽门螺杆菌的一种分子氢（H₂）刺激的化能自养生长模式。在含有肽和氨基酸的培养基中，供应H₂的细胞在16小时内生长产量始终比未供应H₂的细胞高40%至60%，并且在10小时内从[¹⁴C]碳酸氢盐中积累的碳（按每个细胞计算）是未供应H₂细胞的3倍。对处于不同大气条件下的细胞进行的全局蛋白质组比较显示，添加H₂导致氢化酶和乙酰辅酶A（acetyl-CoA）羧化酶（ACC）的生物素羧化酶亚基以及参与各种细胞功能（包括氨基酸代谢、血红素合成或蛋白质降解）的其他蛋白质的量增加。与该结果一致，供应H₂的细胞所含的ACC活性是未供应H₂细胞的3倍。在含H₂的大气条件下，其他可能的二氧化碳固定酶未上调表达。由于胃黏液中的碳和能量来源有限，且该细菌缺乏黏蛋白酶，这种新的生长模式可能有助于病原体在体内持续存在。这是首次描述病原体的化能自养生长。
许多病原体必须在碳和能量来源供应不足的宿主区域内存活，胃病原体幽门螺杆菌几乎完全存在于其宿主营养严格的黏液屏障中。尽管已知这种细菌对胃生态位具有高度适应性，但此处展示了其代谢灵活性的一个新方面，即分子氢的利用（能量）通过一种描述的碳固定酶与二氧化碳固定（碳获取）相耦合。这种补充异养的生长模式被称为化能自养，此前尚未在病原体中报道过。
