On the 25th & 26th of March I attended the Microbes As Material workshop hosted by Rod Dillon, Jen Southern, Abandon Normal Devices and Lancaster University. I joined 5 other practitioners who responded to the open call, along with students from the University’s fine art department.
Our introduction to microbiological activities was two fold: an aerobics enactment of the ‘plating out’ colony counting protocol used for establishing the number of bacteria in a suspension, and experiments in the ‘sensor’ that is an open petri dish. I’m going to focus on recapping the former activity as this was fresh territory for me. The protocol involved diluting down a suspension of microbes which were deemed to have surpassed the ‘log phase’.
We each had 6 petri dishes to plate, corresponding to the six phases of dilution we would process: with each step in the procedure we diluted the microbes down by a magintude of 10 (200 ul to 2ml). The aim is to create a succession of dishes that show progressively less colonies. We performed this task on Wednesday afternoon and then revisted the petri dishes after they incubated overnight. We picked out the petri dish with the least amount of dots and then manually counted them. Using that number we could scale up to estimate how many were in the original solution.
I was particularly interested in this mode of counting in terms of how it related to other modes of microbial measurement, principally optical density (OD). Helena Shomar had related to me that optical density and the manual mode of colony counting can be correlated as a means of determining how many bacteria are present in a liquid suspension (though it should be noted that generic measures for OD also exist). I found this translation, from light spectra to index of a population size, an interesting one.
In the concluding workshop session we viewed Bonnie Bassler’s TED Talk on quorum sensing and were encouraged to respond to her presentation in our artistic dabbling with quorum sensing microbes. We had a “pallette” of pigmented microbes, 7 in total 1. Reviewing the ways in which the microbes could interact with one another I was struck that the palette could be understood in terms of the conditional statements which are ubiquitous in calculation and coding. This could lend itself to a form of generative art which often produces abstract art.
Though I was aware of the quorum sensing research which formed the basis of Bassler’s talk, I’d never seen it delivered in TED format before. The talk was heavy with competing metaphors, but several jumped out at me.
- “self & other”,
- “bacteria as neighbour, bacteria as communities”
These two statements formed the basis of the “painting” I wished to attempt with the microbes. With one part of my mind drawn to the fact that we would spend the final afternoon session in the gallery I decided to prototype something which might exist in that space. ‘Self & Other’ inspired this piece.
I decided to use the Chromobacterium violaceum Mutant [CV026] and the Serrtatia liquefaciens[Sl]. The latter (Sl) produces the signalling molecule C4, but remains white. CV026 will turn purple in the presence of C4. I made two dots on each petri dish, comprised of adjacent semi circles of Sl and CV026. What would result after incubation would be a half purple, half white dot.
In the middle of each semi circle I placed two antibiotic dots, S and OX. The CV026 has resistance to S, where both were resistant to OX. The dots were added to increase the visual similarities between the petri dishes. It was also the conceit of the piece – I wanted to riff on the mirror ‘self recognition’ test which is used to determine if non-human animals have a sense of self like ours. Animals are marked with a dot somewhere on their body – how they react to a reflection of themselves donning the dot is a metric of ‘sense of self’.
I’ve previously been taken with what microbial agency means for our sense of self. With this prototype I was mostly interested in playing with the apparatuses by which we judge living matter other than ourselves to be sentient. The idea was to place the petri dishes facing one another, the dots aligned as though in ‘mirror reflection’. However in this instance the dots would have a fundamental impact on the appearance of the surrounding colonies, breaking the visual symmetry between the ‘petri doubles’.
As it happened though, the Sl bacteria failed to make the CV026 transform to purple, meaning that the visual prototype couldn’t be realised. As you can see in the below photo the antibiotic dot S did effect the Sl, wiping it out
The other piece I set about creating was a reflection on the communities of bacteria, the neighbourly qualities of quorum sensing bacteria, and the fact that quorum sensing is heavily involved in microbial decision making. I decided to pay homage to Thomas Schelling’s simulations of segregation experiment, “Models of Segregation”. Schelling’s experiment was very much in the vein of Conway’s A-Life experiments, and contemporaneous with them. Retrospectively it is noteworthy for using simulation to sanitize racial segregation and for providing the basis for subsequent agent based modelling research.
I found a sample grid of Schelling’s simulation, pictured above. It shows how the system would differentiate from one iteration to the subsequent one. I decided to copy the (a) grid onto my petri dish, and simulate the black and white dots using bacteria which would change colour based on the presence of quorum sensing molecules.
As CV026 turns purple when agitated I mapped this bacteria to the black dots, and Sl to the white dots. I then repeated the mapping, keeping CV026 as the black dots but (in retrospect, counter intuitively) mapping the white dots to the purple CV0. The expected out comes were that the CV026 && Sl dish would mirror the grid (a) by the end of the incubation period, while the CV0 && CV026 would result in a total wipe out for the white dots.
Here you can see the CV026 mutant inoculated as dots on a Schelling Grid.
Side by side are the CV0 && CV026 (left) and CV026 && Sl (right) prior to being incubated. The left hand side grid is anticipated to transition from contrasting dots to a homogeneous purple swathe, where as the right hand side grid is predicted to emulate the black and white grid (a).
After 24 hours the colonies have grown but there has been a breakdown in signalling molecules. The CV0 is in the process of transfiguring its CV026 neighbourhood into a uniform purple, but the Sl hasn’t influenced its community of CV026 companions into changing colour.
In the above two close ups you can see the dots in the process of being transformed from a beige pigment to a purple pigment.
After 48 hours the change in neighbourhood is dramatic. The Sl’s refusal to communicate with its neighbours has resulted in a whitewashed neighbourhood for nobody intermixing of pigment has transpired. The CV0 has radically changed its neighbourhood, with nearly all dots now purple.
These are the last two dots of the CV0 && CV026 neighbourhood holding out against the changes sweeping their neighbourhood.
Despite the experiment not proceeding as I thought it would an interesting outcome still resulted, where the petri dishes basically became completely dichotomised in terms of pigment.
I’m pleased to say that I will return to the budding Lancaster BioArt scene in the summer for a week in order to continue the experiments begun during ‘Microbes as Material’ during a one week residency.