PT  - JOURNAL ARTICLE
AU  - Xu-Wen Wang
AU  - Lu Wu
AU  - Lei Dai
AU  - Xiaole Yin
AU  - Tong Zhang
AU  - Scott T. Weiss
AU  - Yang-Yu Liu
TI  - Ecological Dynamics Imposes Fundamental Challenges in Microbial Source Tracking
AID  - 10.1101/2022.05.21.492809
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.05.21.492809
4099  - http://biorxiv.org/content/early/2022/05/21/2022.05.21.492809.short
4100  - http://biorxiv.org/content/early/2022/05/21/2022.05.21.492809.full
AB  - Quantifying the contributions of possible environmental sources (“sources”) to a specific microbial community (“sink”) is a classical problem in microbiology known as microbial source tracking (MST). Solving the MST problem will not only help us understand how microbial communities were formed, but also have far-reaching applications in pollution control, public health, and forensics. Numerous computational methods, referred to as MST solvers hereafter, have been developed in the past and applied to various real datasets to demonstrate their utility across different contexts. Yet, those MST solvers do not consider microbial interactions and priority effects in microbial communities. Here, we revisit the performance of several representative MST solvers. We show compelling evidence that solving the MST problem using existing MST solvers is impractical when ecological dynamics plays a role in community assembly. In particular, we clearly demonstrate that the presence of either microbial interactions or priority effects will render the MST problem mathematically unsolvable for any MST solver. We further analyze data from fecal microbiota transplantation studies, finding that the state-of-the-art MST solvers fail to identify donors for most of the recipients. Finally, we perform community coalescence experiments to demonstrate that the state-of-the-art MST solvers fail to identify the sources for most of the sinks. Our findings suggest that ecological dynamics imposes fundamental challenges in solving the MST problem using computational approaches.Competing Interest StatementThe authors have declared no competing interest.