School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom.
Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom.
Appl Environ Microbiol. 2023 Mar 29;89(3):e0218122. doi: 10.1128/aem.02181-22. Epub 2023 Feb 22.
In scientific studies, replicas should replicate, and identical conditions should produce very similar results which enable parameters to be tested. However, in microbial experiments which use real world mixed inocula to generate a new "adapted" community, this replication is very hard to achieve. The diversity within real-world microbial systems is huge, and when a subsample of this diversity is placed into a reactor vessel or onto a surface to create a biofilm, stochastic processes occur, meaning there is heterogeneity within these new communities. The smaller the subsample, the greater this heterogeneity is likely to be. Microbial fuel cells are typically operated at a very small laboratory scale and rely on specific communities which must include electrogenic bacteria, known to be of low abundance in most natural inocula. Microbial fuel cells (MFCs) offer a unique opportunity to investigate and quantify variability as they produce current when they metabolize, which can be measured in real time as the community develops. In this research, we built and tested 28 replica MFCs and ran them under identical conditions. The results showed high variability in terms of the rate and amount of current production. This variability perpetuated into subsequent feeding rounds, both with and without the presence of new inoculate. In an attempt to control this variability, reactors were reseeded using established "good" and "bad" reactors. However, this did not result in replica biofilms, suggesting there is a spatial as well as a compositional control over biofilm formation. The research presented, although carried out in the area of microbial fuel cells, reaches an important and broadly impacting conclusion that when using mixed inoculate in replica reactors under replicated conditions, different communities emerge capable of different levels of metabolism. To date there has been very little research focusing on this, or even reporting it, with most studies using duplicate or triplicate reactors, in which this phenomenon is not fully observed. Publishing data in which replicas do not replicate will be an important and brave first step in the research into understanding this fundamental microbial process.
在科学研究中，复制品应该能够复制，相同的条件应该产生非常相似的结果，从而能够测试参数。然而，在使用真实世界混合接种物来产生新的“适应”群落的微生物实验中，这种复制非常困难。真实世界微生物系统中的多样性是巨大的，当从这种多样性中抽取一个子样本放入反应器容器或表面形成生物膜时，随机过程就会发生，这意味着这些新群落中存在异质性。子样本越小，这种异质性就越有可能存在。微生物燃料电池通常在非常小的实验室规模下运行，依赖于必须包含已知在大多数自然接种物中丰度较低的发电细菌的特定群落。微生物燃料电池 (MFC) 提供了一个独特的机会来调查和量化变异性，因为它们在代谢时会产生电流，并且可以在群落发展过程中实时测量。在这项研究中，我们构建并测试了 28 个复制品 MFC，并在相同条件下运行它们。结果表明，电流产生的速率和数量存在高度的可变性。这种可变性在随后的进料循环中持续存在，无论是在有新接种物存在还是不存在的情况下。为了控制这种可变性，使用已建立的“好”和“坏”反应堆对反应堆进行了再接种。然而，这并没有导致复制品生物膜的形成，这表明生物膜的形成不仅受到空间控制，还受到组成控制。本研究虽然是在微生物燃料电池领域进行的，但得出了一个重要而广泛影响的结论，即在相同条件下使用混合接种物在复制品反应器中进行复制品实验时，会出现不同的群落，它们能够进行不同水平的代谢。迄今为止，很少有研究关注这一点，甚至没有报道这一点，大多数研究使用重复或三重反应器，在这种情况下，这种现象没有得到充分观察。发表复制品不能复制的数据将是理解这一基本微生物过程的研究中的一个重要而勇敢的第一步。
