Current bioprocesses for production of value-added compounds are mainly based on pure cultures that are composed of rationally engineered strains of model organisms with versatile metabolic capacities. However, in the comparably well-defined environment of a bioreactor, metabolic flexibility provided by various highly abundant biosynthetic enzymes is much less required and results in suboptimal use of carbon and energy sources for compound production. In nature, non-model organisms have frequently evolved in communities where genome-reduced, auxotrophic strains cross-feed each other, suggesting that there must be a significant advantage compared to growth without cooperation. To prove this, we started to create and study synthetic communities of niche-optimized strains (CoNoS) that consists of two strains of the same species Corynebacterium glutamicum that are mutually dependent on one amino acid. We used both the wild-type and the genome-reduced C1* chassis for introducing selected amino acid auxotrophies, each based on complete deletion of all required biosynthetic genes. The best candidate strains were used to establish several stably growing CoNoS that were further characterized and optimized by metabolic modelling, microfluidic experiments and rational metabolic engineering to improve amino acid production and exchange. Finally, the engineered CoNoS consisting of an l-leucine and l-arginine auxotroph showed a specific growth rate equivalent to 83% of the wild type in monoculture, making it the fastest co-culture of two auxotrophic C. glutamicum strains to date. Overall, our results are a first promising step towards establishing improved biobased production of value-added compounds using the CoNoS approach.

当前用于生产增值化合物的生物过程主要基于纯培养物，这些纯培养物由具有多种代谢能力的经合理改造的模式生物菌株组成。然而，在生物反应器的相对明确的环境中，对各种高度丰富的生物合成酶提供的代谢灵活性的要求要低得多，并导致碳和能源在化合物生产中的次优使用。在自然界中，非模式生物经常在基因组减少、营养缺陷型菌株相互交叉喂养的群落中进化，这表明与没有合作的生长相比，它们必须具有显着优势。为了证明这一点，我们开始创建和研究由同一物种的两个菌株组成的生态位优化菌株 (CoNoS) 的合成群落相互依赖一种氨基酸的谷氨酸棒杆菌。我们使用野生型和基因组减少的 C1* 底盘来引入选定的氨基酸营养缺陷型，每一种都基于完全删除所有必需的生物合成基因。最佳候选菌株用于建立几个稳定生长的 CoNoS，通过代谢建模、微流体实验和合理的代谢工程进一步表征和优化，以改善氨基酸的产生和交换。最后，由l-亮氨酸和l-精氨酸营养缺陷型组成的工程化 CoNoS在单一培养中显示出相当于野生型 83% 的特定生长速率，使其成为两种营养缺陷型谷氨酸棒杆菌最快的共培养迄今为止的菌株。总体而言，我们的结果是朝着使用 CoNoS 方法建立改进的生物基增值化合物生产迈出的第一步。