Sinorhizobium fredii CCBAU45436 is an excellent rhizobium that plays an important role in agricultural production. However, there still needs more comprehensive understanding of the metabolic system of S. fredii CCBAU45436, which hinders its application in agriculture. Therefore, based on the first-generation metabolic model iCC541 we developed a new genome-scale metabolic model iAQY970, which contains 970 genes, 1,052 reactions, 942 metabolites and is scored 89% in the MEMOTE test. Cell growth phenotype predicted by iAQY970 is 81.7% consistent with the experimental data. The results of mapping the proteome data under free-living and symbiosis conditions to the model showed that the biomass production rate in the logarithmic phase was faster than that in the stable phase, and the nitrogen fixation efficiency of rhizobia parasitized in cultivated soybean was higher than that in wild-type soybean, which was consistent with the actual situation. In the symbiotic condition, there are 184 genes that would affect growth, of which 94 are essential; In the free-living condition, there are 143 genes that influence growth, of which 78 are essential. Among them, 86 of the 94 essential genes in the symbiotic condition were consistent with the prediction of iCC541, and 44 essential genes were confirmed by literature information; meanwhile, 30 genes were identified by DEG and 33 genes were identified by Geptop. In addition, we extracted four key nitrogen fixation modules from the model and predicted that sulfite reductase (EC 1.8.7.1) and nitrogenase (EC 1.18.6.1) as the target enzymes to enhance nitrogen fixation by MOMA, which provided a potential focus for strain optimization. Through the comprehensive metabolic model, we can better understand the metabolic capabilities of S. fredii CCBAU45436 and make full use of it in the future.

中文翻译：

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重建弗氏中华根瘤菌CCBAU45436自由生活和共生状态的基因组规模代谢网络模型

弗氏中华根瘤菌CCBAU45436是一种优良的根瘤菌，在农业生产中发挥着重要作用。然而，仍需要对代谢系统进行更全面的了解。S。弗雷迪CCBAU45436，阻碍了其在农业中的应用。因此，基于第一代代谢模型我CC541我们开发了一种新的基因组规模代谢模型我AQY970包含970个基因、1,052个反应、942个代谢物，在MEMOTE测试中得分为89%。细胞生长表型预测我AQY970与实验数据的一致性为81.7%。将自由生活和共生条件下的蛋白质组数据映射到模型中的结果表明，对数期的生物量生产率高于稳定期，寄生在栽培大豆中的根瘤菌的固氮效率高于稳定期。野生型大豆的结果与实际情况相符。在共生条件下，影响生长的基因有184个，其中94个是必需的；在自由生活条件下，有143个基因影响生长，其中78个是必需的。其中，共生条件下的94个必需基因中有86个与预测一致。我CC541，44个必需基因经文献信息确认；同时，DEG鉴定出30个基因，Geptop鉴定出33个基因。此外，我们从模型中提取了四个关键的固氮模块，并预测亚硫酸还原酶（EC 1.8.7.1）和固氮酶（EC 1.18.6.1）作为MOMA增强固氮的目标酶，这为菌株提供了潜在的关注点优化。通过综合代谢模型，我们可以更好地了解人体的代谢能力S。弗雷迪CCBAU45436并在以后充分利用它。