Microbes first into the life rafts: preserving microbiomes to secure health in degrading ecosystems.

Microorganisms are responsible for environmental and organismal health, and the stewardship of microbiota has applications for human, plant, animal, and environmental health on local and global scales. The concepts described here are pertinent, in particular, to the United Nations’ Sustainable Development Goal (3) good health and well-being. Additionally, our paper is relevant to goals (6) clean water and sanitation, (9) industry, innovation, and infrastructure, (11) sustainable cities and communities, (12) responsible consumption and production, (13) climate action, (14) life below water, (15) life on land, and (17) partnerships for the goals. Historically, our understanding of, and relationship to, microorganisms has originated from the ways in which we most closely interact with them, even before we knew they existed. In this way, our concept of microorganisms/microbiota went from “a nuisance” to “a tool”: from food spoilers to fermentation chemists, from infectious agents to probiotics, from competitors for resources to partners for hosts. Environmental ecosystems, from soil to water to air, can only support complex forms of life of the chemistry that microorganisms perform (Gilbert and Neufeld ) and many host ecosystems rely on facultative or obligate symbioses with microbiota to support specific biological functions. Given our intrinsic reliance on microbial ecosystems, research communities have been discussing the need to consider microbiota as a facet of planetary health for several decades. For example, as strong modifiers of environments, arguments have been made for using microbiota for environmental remediation and reducing the impacts of climate change (Bodelier , Peixoto et al. , Rappuoli et al. ), which recently culminated in a microbial specialist group for the International Union for the Conservation of Nature (IUCN) with the goal of developing a framework for conservation of biological and environmental entities (Gilbert et al. ). In parallel, public health efforts have promoted the integration of microbial ecology into personal and public medicine (Lowry et al. , Ishaq et al. , Rook ). Biological conservation efforts have also recognized the importance of specific microorganisms or collections thereof: microbial communities, in ensuring the health and repatriation of wildlife (Trevelline et al. , Mueller et al. ). Guided by insights from our colleagues (e.g. Trevelline et al. , Poyet and Groussin , Ishaq et al. , Rappuoli et al. , ), we note a growing consensus on the importance of protecting key microbial communities, which are essential for environmental and host health. Our work on the integral nature of microbiomes to host and environmental health, and the need for policy to promote best practices in microbiome research and industries, has led to the development of the concept of microbiome stewardship to promote consideration of the role of microbial communities in public and planetary health, agriculture and food systems, and ecosystem conservation and maintenance (Choudoir et al. , O’Doherty et al. ). We define microbiome stewardship as “a set of insights, responsibilities, and practices aimed at maintaining microbial biodiversity and microbiome functioning across microbial habitats, which, in turn, supports the health and well-being of humans, animals, plants, and ecosystems” and we develop a more detailed framework for the implementation of microbiome stewardship elsewhere (Choudoir et al. , O’Doherty et al. ). Our main premise is that there is a need to attend to conservation and stewardship of microbiota based upon the reliance that higher forms of life have on fundamental biochemical processing which microorganisms provide, and based on observations that human activities are disrupting, and even extinguishing, entire microbial communities. We recognize that there are also moral arguments to support protections of microbiota (Bossert and Höll ). Here, we do not take a position on the moral status of microorganisms or a responsibility to protect any life; instead, we focus on scientific arguments for their importance in sustaining life on our planet and achieving social goals (e.g. food security, population health).