Micro-geographies of kombucha as methodology: A cross-cultural conversation

A.C. Davidson, Emma Ransom-Jones

This chapter charts a collaborative experiment between Emma (a microbiologist) and A.C. (a geographer) around how we understand kombucha, a drink which can be purchased commercially, or home brewed by fermenting tea with a starter microbial consortium, or SCOBY (Symbiotic Culture of Bacteria and Yeast).

Sales of kombucha have increased in the last decade as part of a growing market in ‘functional drinks’: non-alcoholic beverages with supposed performance or health benefits. Commercially produced kombucha has been described as a drink consumed by the more affluent (Spackman 2018) and in gentrifying neighbourhoods alongside artisanal products with local, sustainable and ethical credentials (Bond and Browder 2019). It is important, therefore, to consider Kombucha’s geographical contexts and the social, material and economic circulations it is imbricated in. As Jasarevic (2015) highlights, in post-socialist Bosnia the ‘mushroom in a jar’ circulates within informal economies and traditional understandings of food and medicine, whereas in the North American context kombucha takes on both a highly commodified form within discourses of antibiosis (ibid.) and also a post-Pasteurian valorisation of artisanal and DIY production within queer, anti-establishment economies and discourses (Maroney 2015; Katz 2012).

As the microbiome project (Rees, Bosch, and Douglas 2018) indicates, there is an increasing drive to bring disciplines together in the study of microbes. However, there is a risk within interdisciplinarity of re-discovering – and erasing – scholarship in other disciplines. In our collaboration, we wanted to avoid this, and instead of simply adding microbiological and ethnographic methods we wanted to engage in an ‘experimental entanglement’ (Callard and Fitzgerald 2015) to see what we might learn about kombucha and microbes together. In this chapter, to emphasise the dialogue between our different research approaches and paradigms we use the form of a conversation – an approach used in STS by Woolgar (1989), Hirschauer and Mol (1995) and Sariola et al. (2017).

Our collaboration raised more questions than it answered. Some are about the practices, insights and challenges of interdisciplinary work, while others are about kombucha itself. By moving ourselves, our research paradigms, methods, SCOBYs and kombucha samples between the lab, commercial production facilities and our own kitchens, we encountered different ways of producing, knowing and consuming kombucha. Below, we introduce our approach to interdisciplinarity before discussing, in conversational form, what we found: there are micro-geographical variations to the kinds of kombuchas produced, consumed and analysed in the university lab, commercial production and home kitchen. These ‘kombuchas multiple’ (Mol 2002) differ in part because of the perceptions, regulations and practices attached to where and how they were created. We could not, for example, drink anything created in the lab. Similarly, different kombucha producers held varying degrees of attachment to their kombuchas being ‘alive’, as opposed to more predictable and consistent. However, despite desires to affix a set of meanings or politics to kombuchas, the microbiology of the kombuchas was more complex and unruly. Standardised composition across batches and a complete verification of consistency would be difficult to confirm with certainty.

Displacing experiments

Kombucha offered us, as early career researchers, a low-cost way to experiment with human-microbe relations in distinctly different spaces. Our respective research methods differ, as do the disciplinary practices of writing (critically) about the research process. We settled on providing an outline of our approach below.

Fig. 10.1 A.C.’s home-brew kombucha in the kitchen (photograph by Dawn Woolley)

1. From November 2018, we held regular voice-recorded conversations around what an interdisciplinary ethnography of kombucha cultures might look like.

2. DNA extractions from ten commercially available SCOBYs were performed by Jess (a student in the microbiology lab at Huddersfield University) using the DNeasy PowerSoil Kit (Qiagen) and used for 16S rRNA gene amplification and sequencing by Novogene.

3. A.C. conducted in-depth interviews with four UK-based commercial kombucha manufacturers and two site visits to production facilities between 2018 and 2019, as well as online research and analysis of forums and marketing information.

4. Fermentation of kombucha in our kitchens was done in autumn and winter 2019 to observe our thoughts, feelings and practices around the brewing. The recipe/method is included here for readers who would like to replicate this method:

A medium-sized kombucha SCOBY was purchased online and placed in a clean two-litre glass jar with 750 ml black tea (boiled tap water with two organic black tea bags, brewed for 30 minutes and cooled) and 75 g of caster sugar. The jar was covered with kitchen roll kept in place with an elastic band. After an initial 14-day fermentation, this process was repeated with 650 ml of tea and 100 ml of liquid from the first fermentation.

5. A supervised visit to the lab during which Emma extracted DNA from one of our own SCOBYs (point 2) and A.C. observed.

Rather than writing about scientists or interdisciplinary collaboration from within an STS perspective (such as in Balmer et al. 2015), writing in conversation across disciplines was an important part of our experiment. As well as applying interdisciplinary approaches we wanted to break down some of the distinctions between the researcher and researched. Where possible, we wanted to avoid falling into the methodological and epistemological rules of either side of the interdisciplinary collaboration. Callard and Fitzgerald (2015: 4–7) suggest that very few experiments are conducted where scientists work alongside scholars in the social sciences or humanities.

This entangled method, and the conversations it enabled us to produce, were structured also by the expectations and practices within our disciplines (and the current volume). In our writing and editing, we wrangled with what constitutes appropriate structure and style and what counts as valid research for us, and our respective fields. In many respects, this volume and its form and scope was a more comfortable fit for A.C. than for Emma. Writing this as a conversation with ourselves placed within the text was a radical departure from the traditional structure and style of a scientific manuscript reporting the methods, ‘facts’ and outcomes of an experiment. We (en)countered a key disciplinary divide here in the lines we draw between ‘fact’ and ‘opinion’. Emma reflected on how, within scientific paradigms, removal of bias and a distillation into a format of ‘the results state this, therefore x’ provides a solidity of ‘fact’ which is opposed to ‘opinion’. For A.C., more accustomed to STS paradigms, the classification of ‘fact’ and ‘opinion’ is fraught (Stengers 2018) and itself political. This particular f(r)iction was reproduced also within what we came to understand about kombuchas: what kombucha can be verified to contain microbiologically, and the meanings it carries, are entangled but by no means predictably aligned.

The methodologies of kombucha – between the lab, warehouse and kitchen

A.C.: I first encountered Kombucha in 2009 in the States, where one housemate brewed it in our kitchen, and another was buying it from a health food shop in small, expensive bottles. I was interested in how these two kombuchas were made within very different economies (DIY and gifting versus a food co-operative selling high-end foods). This is also why I was interested in understanding the ethos and practices of producers at different scales. Where did you first encounter kombucha?

Emma: It was something one of our placement students was working on, and I was asking her what it was, what she was doing with it, why there was tea in the lab! In our lab, food or drink is banned for safety so I was wondering what she was doing with it. However, most of that work was focused on the actual SCOBY rather than the resulting drink, so it wasn’t until you and I started working together that I tried kombucha.

A.C.: When I joined you in the lab to extract DNA from our SCOBY I was struck by how the same stuff we had been brewing at home, bought from the shop, and encountered in the lab, was something profoundly different because of the different spaces, practices and sets of knowledge it was being understood through (Mol 2002). For me kombucha is social, cultural, political and economic, and can’t be understood outside the context and methods employed to study or produce it. For the producers I spoke to, it was a livelihood, a product, an experiment, a brand, and sometimes a calling or an embodiment of their personal philosophy and ethics.

Emma: That’s one of the things I hadn’t even considered until we started working together. My research doesn’t really involve interviewing the people behind the samples, unless it’s to answer questions about dates, times and other metadata. It doesn’t involve looking at their motivations or connection to the samples I’m working from, although I may be aware of it in an abstract sense.

A.C.: I guess for me it goes beyond the people behind the samples. Where possible, I preferred to speak to producers in their production facility, to photograph and experience the space itself. While there are some social scientists who might focus solely on what producers say about the kombucha, or how they say it, I’m especially interested in how this relates to the practices and to the ‘stuff’ of kombucha and the instruments and spaces involved.

I’m struck by how, in the lab as a microbiologist, the kombucha is a sample that needs to be separated from human variables like motivation or connection – unless they are human actions that directly affected composition. I’m curious about how the samples were labelled.

Emma: They were actually just labelled with numbers one to ten, so although we had a record of what those numbers meant, we actually forgot it fairly quickly and it was only when we were analysing the data that I then started to put those labels back in. We often use more descriptive names for other samples, which might contain identifiers such as the place of origin or the date collected, but we keep them fairly simple.

A.C.: I’m interested also in how the methods we use to understand kombucha construct what it is. How do the methods you use in microbiology matter to how kombucha is known?

Emma: They definitely matter, because depending on what methods you use you will potentially get very different results. For example, historically microbes were studied by isolating an individual species in the lab. The problem with this is that we can only grow an estimated 1% of these organisms, which means that the majority of species couldn’t be studied and you would miss a huge amount of diversity. In addition, because you have to have a pure culture of a single organism to study it this way, you also miss out on both how the microbes function in their environment (because it’s difficult to exactly replicate these conditions) and how the whole community interacts. We now have next generation sequencing where we can sequence members of a microbial community without having to grow them first, and that has led to a rise in the analysis of the whole community, rather than its individual members, but this isn’t without its own problems. We know that results can change due to using different methods for the DNA extraction, PCR,1 and sequencing analysis, as well as the risk of introducing contamination into the samples.

A.C.: In a sense, next generation sequencing seems to bring microbiology out of the lab and into the field, making it more like ethnography. You get the chance to learn from interactions between different species in very specific, ‘uncontrolled’ environments. Except, you are not looking to interact with the communities yourself, nor are you getting the live interactions. It’s a snapshot at ‘death’/dispersal, right? I was struck by the energies – the speed of the centrifuge – it took in the lab to extract the DNA.

Emma: It’s interesting that you mention moving into the field, as recently my research has involved just that. I’ve taken the DNA extraction kit into the field in places like Malawi and Patagonia to do DNA extractions as quickly as possible after sample collection. With the invention and popularity of the MinIon (a portable sequencing device), we are seeing more scientists doing sequencing in the field, which is really exciting. In terms of getting a snapshot, this is true of any sequencing, but if we continue projects over time, we can build up a picture of what is going on and how things change over time, particularly if we also collect other data that will influence changes in the microbial community such as moisture content, temperature, pH and so on. We can also use RNA rather than DNA for sequencing, which will tell us which organisms are metabolically active (or alive) at that particular moment in time and what they are doing.

A.C.: Was it necessary, then, to take multiple samples of kombucha from each producer? It strikes me as difficult to pin kombucha down in time and place when it’s constantly fermenting and interacting with its environment. One producer I spoke to said, ‘This is why I talk about it [kombucha] less as a single product and more as a methodology’.

Emma: It was a single sample, so in and of itself we can’t say every sample from x looks like this, but when we look at the samples together, we can build up a picture of the similarities and differences and compare different samples from similar environments. It’s definitely worth bearing in mind that this is a limited sample, and more data is usually better, but that requires more time and money and is more complicated to analyse. Eventually we have to draw the line somewhere, but the good thing about this work is that it can be compared to work from other scientists doing similar things and together that adds to a much bigger picture.

A.C.: Given the variations between samples, is there a single definition, microbiologically, of what kombucha is?

Emma: Personally, I would define kombucha as tea fermented by the SCOBY, regardless of how it is brewed or the exact composition or flavour. This is a fairly simple definition, but I also recognise that there’s a broad range of variables within the kombucha itself. For example, both a greyhound and a German shepherd are dogs, but they look and behave completely differently.

A.C.: To follow this species-based definition further: is there a particular community of species that need to be present for something to be a SCOBY? Among producers there was some anxiety around what ‘true’ kombucha is. Being able to claim ‘kombucha’ can make the difference between gaining consumer recognition and being able to sell or failing to sell. Although one producer was told by Trading Standards initially that they couldn’t call their product kombucha because nobody knows what that is! In microbiological terms, is a kombucha SCOBY unique or particularly different from any other symbiotic cultures of bacteria and yeast?

Emma: There are core members of the community, yes. These are organisms that are found in every SCOBY, which in terms of bacteria are Komagataeibacter spp. and Acetobacter spp., and in terms of yeasts are Zygosaccharomyces spp. and Brettanomyces spp. (Marsh et al. 2014). But we also see that there are a huge number of other species present, and these can vary between fermentations (Villarreal-Soto et al. 2018).

A.C.: There was some variation between producers about whether the final drink needs to contain live cultures at the point of sale to be called kombucha, or whether the acids produced by fermentation are what make it kombucha. I heard of producers using ‘acid banks’ to add ‘the living cultures as a powder that’s poured in’ – is that still kombucha?

Emma: While it’s fermenting, the microbes are alive and it’s the microbes that are living rather than the tea itself. In terms of what is actually in the kombucha itself afterwards, much of this depends on how the drink is processed, whether it’s been sterilised or filtered to remove any living microorganisms, or whether it’s just been bottled, at which point some microbes will remain. I’d say that as long as the tea has been fermented, it counts as kombucha. The composition of the drink can change during transport and storage, depending on the conditions – particularly the ethanol content, which can rise if there are live microorganisms present and fermentation continues. Also, the very nature of the SCOBY means that the microbes can change drastically from batch to batch and could potentially cause health issues.

A.C.: Kombucha producers I spoke to balanced ‘keeping alive’ and ‘making die’ differently. None of the producers I spoke to believed in pasteurisation, with most preferring forms of filtration. Yet they spoke with some awe and frustration about trying to ‘control something uncontrollable’. Although I would have to speak to more producers, I found a tendency towards a kind of continuum of commodification, standardisation and ‘livingness’ based on scale of production. The smaller, more artisanal producers tended towards the side of ‘aliveness’, less standardisation and no or little filtration. To them, this is what distinguished kombucha from ‘expensive pop’. Ostensibly due to the need for stability of the product over time and more stringent regulations in larger outlets such as supermarkets, producers with a wider geographical market tended to prioritise filtration, stability, ‘safety’ and shelf-life, arguing that the final product did not need to be living. Especially among larger producers, there was an adherence to only making claims about health that could be verified by ‘science’. But, as we’re seeing with COVID-19, ‘science’ isn’t monolithic: are there microbiologists who consider there are benefits to consuming living microbial content?

Emma: We’ve actually been consuming microbes for centuries, although we didn’t know it, particularly in the form of fermented foods. Even today, approximately one third of the global human diet is fermented foods and beverages, so we absolutely do consume microbes. There are studies that demonstrate the benefits of this consumption, such as those seen due to the use of probiotics, which include improving the gut barrier and excluding pathogens from this environment, short-chain fatty acid production, and even neutralising potential carcinogens (Brodmann et al. 2017).

One of the important things to realise is that probiotics have been studied for a number of years, and we usually only need to look at one or two species and their interactions at any given time, which is relatively simple. With kombucha this is much more difficult as there are hundreds and sometimes thousands of species, so understanding all of those is much harder. You also have the additional problem that not all kombuchas are the same, adding another level of complexity. A number of studies have attributed potential health benefits to drinking kombucha, including diabetic patients having improved levels of blood glucose, the prevention of liver and cardiovascular diseases, and also the prevention of certain cancers such as renal and prostate cancer (Bhattacharya et al. 2013). I think that certainly it has potential for some people, but the issue with interventions such as this is that it’s so difficult to determine that kombucha consumption is the only thing that has caused benefits. Not only that but kombucha itself is so variable, with the chemical composition varying from batch to batch (Jayabalan et al. 2014). To add even more complexity, no two individuals are the same and so even if they drink the same kombucha they may experience different effects.

A.C.: Is there any indication that there is a pattern in the variation? So, for example, did the lab research done on kombucha SCOBYs point towards any difference between the ‘aliveness’ of the kombuchas from smaller, artisanal producers or from the larger commercial producers?

Emma: We don’t yet have definitions for what we would consider smaller or larger producers, so we have split the samples simply into commercial and laboratory grown ones. In terms of ‘aliveness’, we couldn’t actually say. First, because what would that definition be? A higher diversity of different species? More species isolated? Gas production during fermentation? And second, because depending on how we define it we don’t necessarily have the data here to answer that question.

A.C.: There might be a difference here, too, when comparing SCOBY samples versus comparing the final drink, which has been filtered to varying extents. Going back to your points about potential health impacts, it’s interesting to me how industry works with labs (like at our institution) and relies upon and is limited by what can be verified scientifically. The increased consumption of kombucha and its marketing and packaging is entangled in perceptions of health and wellbeing associated with probiotics, but also consuming less alcohol, fewer sweeteners, sugars and additives. As one producer put it, however, to avoid taking risks with making health claims, they end up: ‘implying health, but not screaming it’.

There is speculation that growth of chronic diseases might be driving kombucha sales (Companies and Markets 2015). It’s troubling when ‘health’ becomes interpreted as something provided by products sold to individuals. We are encouraged to be responsible citizens (Halse 2012 in Spackman 2018), judge what is healthy and curate our lifestyles accordingly. Wider determinants of health, like food systems, poverty, working and living conditions and structural violence (e.g. racism, sexism, ableism) are lost in this narrative. I am sometimes frustrated at lab-based sciences when industry-funded research appears to incentivise an individualised and product-based understanding of health (Stengers 2018). Doing ‘science’ properly seems to be about shielding it from wider social and political questions which are either seen as ‘beyond the scope of the study’, ‘political’, or ‘biased’ (Stengers 2018: 7). This avoids recognising how power is embedded in scientific practice and knowledge and holding sciences accountable to larger questions of how we define health, and why.

Emma: In some respects, I actually agree, and I think we do need to have this dialogue. It does depend on where the research is coming from, as industrial and academic researchers will have different pressures, as well as who has funded it. Journals usually require authors to declare the source of funding and any potential conflicts of interest. One of the main issues I have with scientific publications is if the article is behind a paywall, then you automatically limit people’s access to the research, which I don’t agree with. You also have the issue that, even if a journal is open access, it is still written in a way that is not always accessible and understandable, particularly if the reader is not a specialist. There is a lot of good work being done with regards to making research more accessible and disseminating our findings to the general public, but I think we need to do more. I also think we need to teach more critical thinking so that even if people are presented with information, they have the ability to judge it for themselves rather than thinking that because a scientist states something it must be true.

Micro-geographies of kombucha

A.C.: You mentioned how variable kombucha is. I’m particularly interested in geographical variation, and visited brewing sites where I could, and asked about their location. One producer said: ‘our whole brew is unique to this geographical location’. Another mentioned their old water supply sometimes created a ‘farty brew’. After switching to a new (non-local) water supply, the kombucha ‘loved’ the water and grew at a higher rate. A third producer described place-specificity in this way:

…they’re starting with a similar culture growing in the same place. But as soon as they take that home, over a period of three days, it will have entirely changed. […] Not entirely, there will be dominant strains, but very soon all the bacteria and yeast in the air from their kitchen, and [inaudible] will start to infiltrate it. So, it becomes a different drink.

One of the producers discussed how their SCOBY may be influenced by plant-based bacteria from the tea and from the green space nearby, as well as airborne yeasts from the neighbouring brewery. The yeast was considered a threat to the kombucha and while I was on site there was work going on to install a filtration system to help protect the brews. They were planning a brewery move and there was speculation that the brew and flavour would change. Do the different spaces and practices (possibly linked to different scales and ethos) of preparing kombucha show up in measurable differences in the microbiological make-up of the drink itself?

Emma: Absolutely. The composition of the drink, both in terms of the microbial community and the chemical components is affected by the brewing process, from what tea is used, to how much liquid is added from the initial batch, how good the aseptic conditions are, how long it is brewed for and at what temperature (Jayabalan et al. 2014). The ‘livingness’ of kombucha is actually one of the things that makes it difficult to regulate and control. Kombuchas will vary in their composition, both from brewery to brewery but also between batches from the same company. The exact composition is affected by a number of factors, such as the water and tea used and the surrounding environment, as you found in the interviews, but also the vessel the fermentation takes place, in because the size and shape will affect the oxygen levels and therefore the microbes, the length and conditions of the fermentation process, and the different species of bacteria and yeast present, which will vary between SCOBYs.

A.C.: I’m fascinated that the geographies and climates at the scale of the vessel matter, too: a micro-geography! Although, some of the SCOBYs I saw in production facilities did not feel ‘micro’…they seemed to expand to fill the surface area of the large vessel available.

Kombucha is literally shaped by what it’s made to mean, how and where it is transported, advertised, made, bottled, sold and consumed. For some producers kombucha is an ‘on trade’ low-sugar non-alcoholic drink with a flavour profile reminiscent of alcohol, sold in dark brown bottles to minimise UV rays damaging the bacteria and yeast inside, and to provide the look of a premium spirit. It is introduced in a pop-up night club or a tap room as an alternative to alcohol. For others, shifting the packaging to cans or to a more gender-neutral or ‘cleaner’, minimalist style meant broadening the market from relatively-wealthy, female, health-conscious consumers. There’s a wider geography of kombucha, too. There are politics and places deemed to suit kombucha better – urban cultures of London and Manchester, Bristol, Birmingham, Brighton, Berlin or Amsterdam. As one producer put it, ‘Where people are a bit more liberal’. In our own geographical experimentation, too: No matter the actual composition of the home-, commercially-, or lab-brewed kombuchas, we treated each like fundamentally different things based on the places the drink was associated with.

Emma: I remember saying to you before we started our home-brews that I’d brewed kombucha in the lab and there was absolutely no way I was drinking that. Which seemed strange to you at the time, but our lab is a Category 2 microbiology lab, which means that we have potentially pathogenic organisms in there and you would never take the risk. I think it probably made more sense when you came into the lab and I had to give you the health and safety induction about not even being allowed mobile phones.

A.C.: The lab visit made it sink in how this was different from our kitchens or the little corner lab in the warehouse, which a producer used to test different attributes of the brew. The process of putting on a lab coat, safety glasses and having your safety briefing emphasised the difference of this space. It didn’t feel like the same kombucha. The SCOBY you were extracting DNA from, and the glass bottles in the lab filled with stages of kombucha ferment suddenly made it feel like a potentially dangerous substance. Even bringing the SCOBY from home and into the lab environment required a set of procedures to transform it into a thing fit for the lab: you had a sterile petri dish, we tried not to cross-contaminate it in various ways. ‘Do I hold it with my hands to transfer it into this petri dish’?, I remember asking you, and yet, I’d held it in my hands at home without a second thought!

Emma: For me, although they were using the same methods, brewing kombucha in a lab was very much part of an experiment, whereas at home the end goal was to be able to drink it. I think that is almost entirely due to the change in environment and my background. As a student, I was always taught to practise good aseptic technique, to ensure that samples were not contaminated, as well as the set of rules and behaviours that are required for good laboratory practice. Because I’ve been doing it for so long, the transition from ‘outside’ to the lab is almost second nature to me, despite it seeming completely foreign to other people. When I teach students, I have to write down the rules to remember to tell them everything, otherwise I run the risk of forgetting things simply because it seems obvious to me. However, there are things that, because of the work I do in the lab, I carry over to ‘outside’. Things like the way in which I wash my hands (although due to recent events people are now doing this properly!), and recording ‘experiments’, particularly things such as cooking and baking recipes, the same way I would in my laboratory notebook.

When we were talking about trying different kombuchas I was also conflicted about my ideas regarding home-brewed versus commercial kombuchas. Part of this was born of the idea that my home-brewed one should be ‘safe’. I know what I’m doing and was very careful about how I did things, but a part of me still felt the commercial brews would be safer, despite the fact that there isn’t much regulation about the exact composition of commercial kombuchas. There are standards in terms of ethanol content, but in terms of the microbial composition I don’t know of any, and as it’s such a diverse community you could never be 100% certain of the contents without testing.

A.C.: We happily drank the commercial kombucha together, but it sounds like we both had mixed feelings about drinking our own. My relationship to my home brew shifted, and I no longer have my own SCOBY. There was a point where my awe, curiosity, sense of care and pride in the multiplying layers of SCOBY was outweighed by a wary disgust: what is this slimy, hungry thing proliferating in the jar?! It turned from a potentially health-inducing wonder to something more closely aligned in my mind with decay and danger: at one point I threw my SCOBY in the bin with very mixed feelings of regret, guilt and relief.

Learning with unruly subjects

Our interdisciplinary experiment has involved containing and editing unruly conversations into a language and content that is relevant in both our subject areas. Using the form of a conversation allowed us to maintain the differences and tensions between our epistemological frameworks. Within microbiology, the knowledge of what communities of kombucha microbes are and do, is uncovered through scientific methods (a ‘naturalistic’ approach). In contrast, within a more constructivist feminist STS tradition, the microbes emerge within social practices and the instruments and structures of scientific knowledge.

Our collaboration did not shift these respective epistemological positions fundamentally. This is unsurprising, as in some respects such a shift would have needed to undo our (early) careers’ worth of training and knowledge. However, our experiments offered a significant opportunity to participate in, be exposed to, and troubled by concepts and methods outside our subject bubbles. Perhaps this serves as an apt metaphor for our interdisciplinary interactions: we have learned how kombucha’s microbiological and social processes are interacting and inextricable at different scales. The kombucha that made its way into the university microbiology lab was there because of the ideas around health and wellbeing attached to probiotics, and because fermentation of sugars by the SCOBY produces something people have a taste for. The different contexts of the lab, our home kitchens and the commercial producers produced kombuchas that we perceived and dealt with in fundamentally different ways, despite their composition not necessarily showing large or predictable variation.

Yet, it is important not to overdetermine kombucha through its social construction. It can be tempting to see kombucha as a metaphor or harbinger for a new paradigm or radical social change – for a queerer or more symbiotic model of living with other beings. It has been suggested that SCOBYs might act as ‘model systems’ to address human social questions about competition and cooperation (May et al. 2019). However, our collaboration leaves us wary of imbuing kombucha with political meaning. Perhaps our geographical and microbiological lenses mean we insist on the particularities of relations in different contexts and at different scales. Despite playing with the word ‘culture’ in the title of this piece, communities cannot be studied at the microbiological level with conclusions scaled up to human societies. And despite microbes sometimes being anthropomorphised in the lab and production facilities, microbes cannot be read as if they were human.

From our work together, it is difficult to see kombucha fermentation as a revolution bubbling up from kitchen counters. This is not only a question of scale but of how kombucha becomes through wider social, political and economic configurations of production, consumption and social reproduction. The politics of kombucha needs to be understood through its conditions of production and the effects this hybridity of human-microbe and matter-meaning has in the world. Even if culturation and fermentation were to replace global energy systems and production based on extraction and combustion of fossil fuels (kombucha cellulose, for example, is already used to make plastic alternatives), would this simply be a new frontier – a new micro spatial fix – in a system that is built on, and requires, exploitation? On a less ambitious scale, our work indicates that kombucha operates through desires and markets for meaning, creativity, identity and health, rather than representing a systemic challenge to unhealthy environments and food systems. Those who have the microbial cultural capital (Paxson 2008) have a greater capacity to curate their exposures and to take risks with not knowing precisely what it is they are ingesting.

The microbial variation was part of the difficulty of ‘fixing’ kombucha in a definition, and in space and time. While there is a core community present in every SCOBY tested in our university lab, the amounts varied. Kombucha varies from SCOBY to SCOBY in terms of its initial microbial composition, the environment in which it is brewed, and the substrates used. The lab-grown and commercially produced kombuchas showed some variation in bacterial communities, but there was more significant variation in yeast communities. Our research was too limited to conclude that there is a significant difference in microbial communities between different sizes or types of kombucha producer. Confronted with its ever-changing nature, the attempt to pin down what kombucha is seems fraught. It may be more apt to say that multiple kombuchas become with the tools, practices, meanings and micro-geographies they are entangled with in hybrid human-microbial relations. This does not mean the slippery SCOBY and kombuchas can be made to mean and do whatever we want them to. The aliveness required to ferment – and to produce the purported health benefits of kombucha – is the same unruly process that brings risk and unpredictability, requiring work and care.


1 For more information on PCR see: https://www.ncbi.nlm.nih.gov/probe/docs/techpcr/.


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