Microscale advection governs microbial growth and oxygen consumption in macroporous aggregates
Microscale advection governs microbial growth and oxygen consumption in macroporous aggregates
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DOI：
10.1128/msphere.00185-24
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发表时间：
2024-03-26
期刊：
影响因子：
4.8
通讯作者：
Babbin，Andrew R.
中科院分区：
文献类型：
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作者：
Shen，Rachel;Borer，Benedict;Babbin，Andrew R.
地球上的大多数微生物生命都存在于局部微环境中，这些微环境共同在维持生态系统健康和影响全球生物地球化学循环方面发挥着至关重要的作用。在许多栖息地中，例如水生系统中的生物膜、活性污泥中的细菌絮凝物、附生生物垫或海洋中下沉的颗粒，这些微环境经历零星或连续的流动。根据其微尺度结构，微环境中的孔隙和通道允许局部流动，从而改变扩散和平流质量传输的相对重要性。这种流动如何改变营养供应、促进废物清除、推动不同微生物生态位的出现以及影响微环境的整体功能仍不清楚。在这里，我们使用微流体实验系统量化了允许流动的微环境中的孔隙如何提高对常驻细菌群落的营养供应，并从基于群体和计算流体动力学模拟的耦合中获得进一步的见解。我们发现，微尺度结构决定了平流与扩散的相对贡献，即使是通过 10 µm s−1 范围内的孔隙的适度流动也可以将微环境的承载能力提高 10%。认识到微生物热点在地球系统中发挥的基本作用，开发预测其异质形态和潜在间隙流如何改变微生物功能并共同改变全球尺度通量的框架至关重要。重要性微生物生命是全球生物地球化学循环的关键驱动因素。与地球上人类的分布类似，它们在自然界中往往不是均匀分布的，而是以类似于微生物城市的密集集群形式出现。在这些簇内部和周围，扩散通常被认为是决定养分供应和废物清除的唯一传质过程。在许多自然和工程系统中，例如水生环境中的生物膜、生物修复中的聚集体或废水处理厂中的絮凝体，这些团簇暴露在提高传质的流动中，而这一过程经常被忽视。在这项研究中，我们表明平流通量可以使单一微环境中细菌的局部生长增加高达 50%，并通过破坏局部缺氧或以不同速率提供营养来塑造细菌的新陈代谢。总的来说，平流增强的质量传输可能会调节自然和工程环境中重要的生物地球化学转变。
Most microbial life on Earth is found in localized microenvironments that collectively exert a crucial role in maintaining ecosystem health and influencing global biogeochemical cycles. In many habitats such as biofilms in aquatic systems, bacterial flocs in activated sludge, periphyton mats, or particles sinking in the ocean, these microenvironments experience sporadic or continuous flow. Depending on their microscale structure, pores and channels through the microenvironments permit localized flow that shifts the relative importance of diffusive and advective mass transport. How this flow alters nutrient supply, facilitates waste removal, drives the emergence of different microbial niches, and impacts the overall function of the microenvironments remains unclear. Here, we quantify how pores through microenvironments that permit flow can elevate nutrient supply to the resident bacterial community using a microfluidic experimental system and gain further insights from coupled population-based and computational fluid dynamics simulations. We find that the microscale structure determines the relative contribution of advection vs diffusion, and even a modest flow through a pore in the range of 10 µm s−1can increase the carrying capacity of a microenvironment by 10%. Recognizing the fundamental role that microbial hotspots play in the Earth system, developing frameworks that predict how their heterogeneous morphology and potential interstitial flows change microbial function and collectively alter global scale fluxes is critical.IMPORTANCEMicrobial life is a key driver of global biogeochemical cycles. Similar to the distribution of humans on Earth, they are often not homogeneously distributed in nature but occur in dense clusters that resemble microbial cities. Within and around these clusters, diffusion is often assumed as the sole mass-transfer process that dictates nutrient supply and waste removal. In many natural and engineered systems such as biofilms in aquatic environments, aggregates in bioremediation, or flocs in wastewater treatment plants, these clusters are exposed to flow that elevates mass transfer, a process that is often overlooked. In this study, we show that advective fluxes can increase the local growth of bacteria in a single microenvironment by up to 50% and shape their metabolism by disrupting localized anoxia or supplying nutrients at different rates. Collectively, advection-enhanced mass transport may thus regulate important biogeochemical transformations in both natural and engineered environments.