期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：33
DOI：10.1073/pnas.2101691118
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Energy limitation is a widespread phenomenon that governs microbial processes ranging from the metabolism of individual cells to the functioning of the biosphere. By tracking the population dynamics of diverse bacterial taxa under prolonged starvation, we identified common strategies that sustain life. Although bacteria have the capacity to reproduce on timescales of minutes to hours, we predict that populations can persist for hundreds to thousands of years, placing upper bounds on microbial lifespans. While the dynamics observed in our long-term experiment were driven by a reduction in death rates, cryptic birth events generated mutations that fueled evolution. Our findings shed light on cellular longevity with implications for biodiversity in extreme environments that dominate vast expanses of Earth.
Microorganisms commonly inhabit energy-limited ecosystems where cellular maintenance and reproduction is highly constrained. To gain insight into how individuals persist under such conditions, we derived demographic parameters from a collection of 21 heterotrophic bacterial taxa by censusing 100 populations in an effectively closed system for 1,000 d. All but one taxon survived prolonged resource scarcity, yielding estimated times to extinction ranging over four orders of magnitude from 10
0 to 10
5 y. Our findings corroborate reports of long-lived bacteria recovered from ancient environmental samples, while providing insight into mechanisms of persistence. As death rates declined over time, lifespan was extended through the scavenging of dead cells. Although reproduction was suppressed in the absence of exogenous resources, populations continued to evolve. Hundreds of mutations were acquired, contributing to genome-wide signatures of purifying selection as well as molecular signals of adaptation. Consistent ecological and evolutionary dynamics indicate that distantly related bacteria respond to energy limitation in a similar and predictable manner, which likely contributes to the stability and robustness of microbial life.
