Amid the manifold social and ecological crises of the Anthropocene, diverse understandings of the entanglement of human life with more-than-human species and entities have emerged across and between disciplines, alongside attempts to intervene in these relations. Fields such as Earth system science and sustainability science have envisioned, charted and emphasized the interrelatedness of (socio)ecological processes and phenomena across spatial scales and geopolitical borders, while science and technology studies has explored how these global environmental knowledges are co-produced with global political orders (Miller and Edwards, 2001; Jasanoff, 2004). Posthuman and new materialist theory, often indebted to Indigenous ontologies and epistemologies (Sundberg, 2014; Giraud, 2019), has challenged Anglo-European anthropocentrism and dualisms (of nature/culture, mind/body, social/material), by considering the human to be always, relationally and mutually constituted with often agential or lively nonhumans, whether animals, technologies, energies, landscapes or elements (Haraway, 2007; Bennett, 2010; Povinelli, 2016).

In environmental, life and health sciences, the symbiotic roles of bacteria and other microbes in constituting animal lives and creating or maintaining individual, ecological and planetary health has become a key area of investigation (McFall-Ngai et al, 2013), shaping popular imaginaries of ecologies within and beyond human bodies (Turney, 2015; Yong, 2016), and producing new forms of microbiopolitics (Paxson, 2008). By the early twenty-first century, dominant scientific and popular representations of microbial life had ‘shifted from an idiom of peril to one of promise’ (Paxson and Helmreich, 2014: 165), in which microbes have come to represent both a ‘not yet tamed or fully known nature’ and model ecosystems that might prescribe the ways in which relations between organisms and humans ‘could, should or might be’ (p 168). Meanwhile, in feminist science studies and anthropology, the resurgence of life forms such as fungi in the ‘capitalist ruins’ (Tsing, 2015), and the multispecies, material relationalities in practices such as permaculture (Puig de la Bellacasa, 2017) have been taken as muchneeded symbols of hope and examples of the possibility of care and renewal.

Microbial capacities for ecological and material transformation are increasingly mobilized within what geographer Jamie Lorimer (2019, 2020) refers to as ‘the probiotic turn’, a shift occurring across a range of science and policy domains in parts of the WEIRD (Western, Educated, Industrialised, Rich, Democratic) world.