Coculture is an important model system in microbial ecology studies. As a key experimental parameter, the initial inoculation ratio has a crucial impact on the results of the coculture system. However, such an effect has never been investigated under multiple niche conditions. In this study, we established a simple coculture system with two model bacteria in various carbon sources and investigated the influence of initial inoculum ratios of 1:1000 to 1000:1 on community structure, function, and bacterial interaction. We found that the final ratio of the cocultures with different initial inoculum ratios differed in approximately five-sixths of the carbon sources, suggesting that the final ratio is highly dependent on the initial inoculum ratio, while the carbon source preferences of bacteria could not predict the final ratio of cocultures. Furthermore, we found that the initial ratio could regulate the metabolic capacity of the coculture, as only cocultures with initial ratios of 1:1 and 1000:1 gained high capacity on 14 specific carbon sources. The underlying reason may be that the pattern of species interaction is changed by the initial ratio. In conclusion, we showed that the initial ratio can induce emergent properties in coculture. These findings suggest that the initial ratio not only impacts the reproducibility of coculture experiments but also can influence our understanding of generic microbial ecology.

共培养是微生物生态学研究中的一个重要模型系统。作为关键的实验参数，初始接种率对共培养系统的结果具有至关重要的影响。然而，从未在多个生态位条件下研究过这种效应。在本研究中，我们在不同碳源中建立了两种模型细菌的简单共培养系统，并研究了 1:1000 至 1000:1 的初始接种比例对群落结构、功能和细菌相互作用的影响。我们发现不同初始接种比的共培养最终比例在大约六分之五的碳源中存在差异，表明最终比例高度依赖于初始接种比例，而细菌的碳源偏好无法预测共培养的最终比例。此外，我们发现初始比例可以调节共培养的代谢能力，因为只有初始比例为 1:1 和 1000:1 的共培养才能获得对 14 种特定碳源的高容量。根本原因可能是物种相互作用的模式因初始比率而改变。总之，我们表明初始比率可以诱导共培养中的突现特性。这些发现表明，初始比率不仅会影响共培养实验的可重复性，还会影响我们对一般微生物生态学的理解。根本原因可能是物种相互作用的模式因初始比率而改变。总之，我们表明初始比率可以诱导共培养中的突现特性。这些发现表明，初始比率不仅会影响共培养实验的可重复性，还会影响我们对一般微生物生态学的理解。根本原因可能是物种相互作用的模式因初始比率而改变。总之，我们表明初始比率可以诱导共培养中的突现特性。这些发现表明，初始比率不仅会影响共培养实验的可重复性，还会影响我们对一般微生物生态学的理解。