Cogo Carolina, Pérez-Giménez Julieta, Rajeswari Chandrasekar B, Luna María F, Lodeiro Aníbal R
Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas-UNLP y CCT La Plata-CONICET, La Plata, Argentina.
Departamento de Ciencias Básicas, Facultad de Ingeniería-UNLP, La Plata, Argentina.
Front Microbiol. 2018 Jun 5;9:1189. doi: 10.3389/fmicb.2018.01189. eCollection 2018.
, a soybean N-fixing symbiont, constitutes the basic input in one of the most prominent inoculant industries worldwide. This bacterium may be cultured with D-mannitol or L-arabinose as carbon-plus-energy source (C-source) with similar specific growth rates, but with higher biomass production with D-mannitol. To better understand the bacterium's carbon metabolism, we analyzed, by liquid chromatography and tandem mass spectrometry (MS), the whole set of proteins obtained from cells grown on each C-source. Among 3,334 proteins identified, 266 were overproduced in D-mannitol and 237 in L-arabinose, but among these, only 22% from D-mannitol cultures and 35% from L-arabinose cultures were annotated with well defined functions. In the D-mannitol-differential pool we found 19 enzymes of the pentose-phosphate and Calvin-Benson-Bassham pathways and accordingly observed increased extracellular-polysaccharide production by D-mannitol grown bacteria in a CO-enriched atmosphere. Moreover, poly-3-hydroxybutyrate biosynthesis was increased, suggesting a surplus of reducing power. In contrast, the L-arabinose-differential pool contained 11 enzymes of the L-2-keto-3-deoxyarabonate pathway, 4 enzymes for the synthesis of nicotinamide-adenine dinucleotide from aspartate, with those cultures having a threefold higher O-consumption rate than the D-mannitol cultures. The stoichiometric balances deduced from the modeled pathways, however, resulted in similar O consumptions and ATP productions per C-mole of substrate. These results suggested higher maintenance-energy demands in L-arabinose, which energy may be used partly for flagella-driven motility. Since produces the lateral-flagella system in only L-arabinose, we calculated the O-consumption rates of a ::Km mutant devoid of lateral flagella cultured in L-arabinose or D-mannitol. Contrary to that of the wild-type, the O-consumption rate of this mutant was similar on both C-sources, and accordingly outcompeted the wild-type in coculture, suggesting that the lateral flagella behaved as parasitic structures under these conditions. Proteomic data are available via ProteomeXchange with identifier PXD008263.
作为一种大豆固氮共生菌，是全球最著名的接种剂产业之一的基本投入物。这种细菌可以用D - 甘露醇或L - 阿拉伯糖作为碳源和能源（C源）进行培养，其比生长速率相似，但用D - 甘露醇培养时生物量产量更高。为了更好地理解该细菌的碳代谢，我们通过液相色谱和串联质谱（MS）分析了从在每种C源上生长的细胞中获得的全套蛋白质。在鉴定出的3334种蛋白质中，有266种在D - 甘露醇中过量产生，237种在L - 阿拉伯糖中过量产生，但其中只有22%来自D - 甘露醇培养物的蛋白质和35%来自L - 阿拉伯糖培养物的蛋白质具有明确的功能注释。在D - 甘露醇差异库中，我们发现了戊糖磷酸途径和卡尔文 - 本森 - 巴斯姆途径的19种酶，并相应地观察到在富含CO的气氛中，用D - 甘露醇培养的细菌胞外多糖产量增加。此外，聚 - 3 - 羟基丁酸酯的生物合成增加，表明还原力过剩。相比之下，L - 阿拉伯糖差异库包含L - 2 - 酮 - 3 - 脱氧阿拉伯糖酸途径的11种酶、4种从天冬氨酸合成烟酰胺腺嘌呤二核苷酸的酶，这些培养物的耗氧率比D - 甘露醇培养物高三倍。然而，从建模途径推导的化学计量平衡导致每摩尔底物的耗氧量和ATP产量相似。这些结果表明L - 阿拉伯糖中维持能量的需求更高，这些能量可能部分用于鞭毛驱动的运动。由于仅在L - 阿拉伯糖中产生侧鞭毛系统，我们计算了在L - 阿拉伯糖或D - 甘露醇中培养的缺乏侧鞭毛的::Km突变体的耗氧率。与野生型相反，该突变体在两种C源上的耗氧率相似，因此在共培养中胜过野生型，这表明在这些条件下侧鞭毛表现为寄生结构。蛋白质组学数据可通过ProteomeXchange获得，标识符为PXD008263。
