Mutator: a unique radiation detecting BioInk

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Bacteria are essentially haploid, that is they only contain one copy of their genome. Consequently, unlike higher organisms which are usually diploid, and which containing two copies of the genome, changes in the DNA sequence of the genome (mutations) usually result directly in measurable phenotypes. There is no blending or filtering of the genome’s informational content as is the case with higher organisms and mutations or glitches in the genetic code can become readily visible.

The bacterium Serratia marcescens usually grows as a distinctive and red pigmented colony. However, if it is exposed to agents which cause DNA mutation, and these genetic changes occur in pathway that gives rise to the red pigment, then the bacterium will become white.

In this process here, I have dramatically increased the natural mutation rate of the genome of this bacterium by exposing it to radiation. The damage to its DNA can clearly been seen in the emergence of many non-pigmented white mutants, amongst the red-pigment parent strain.

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It strikes me that this system could be used as a living biological ink which would record exposure to radiation, and perhaps form the basis of a biological radiation detector. Maybe it’s already sniffing out and detecting the legacies of Chernobyl and Fukushima.

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Resistant Materials: an aesthetic exploration of antibiotics and antimicrobial resistance

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The disc diffusion test is a commonly used, and important, method for determining antibiotic sensitivity of bacteria in the clinical and research laboratory.  In this test, paper discs impregnated with different antibiotics  are placed onto an agar plate in which bacteria have been spread all over the surface, and the culture is then incubated. If an antibiotic is effective against a particular antibiotic, it will prevent the bacteria from growing, or kill them, so that there will be an area around the disc  where the bacteria have not grown. This is called a zone of inhibition, and its appearance indicates sensitivity of the bacterium to the antibiotic. When a zone of inhibition does not appear, or is very small, then the bacterium is resistant to the antibiotic.

To make this aesthetic interpretation of the disc diffusion assay, I chose to use two naturally pigmented bacteria, Serratia marcescens (Sm), red,  and Chromobacterium violaceum (Cv), purple and to test their sensitivity to three antibiotics, namely Cloxacillin (C), Kanamycin (K) and Trimethoprim (T). Moreover, instead of using the conventional circular discs for the assay and chose to use antibiotic impregnated papers that had been cut into letters.

In the first run of this process,  the sensitivity of Sm and Cv to C and were investigated. After 12 hours incubation it became apparent that CV was resistant C, as it grew right up to the antibiotic impregnated paper, and in fact,  even grew though it.  On the other hand Sm was sensitive to C, as evidenced by the large and clear zone of inhibition (see below).

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Sm left and Cv right. The reversed L shape on the lefthand side of the agar plates is impregnated with K, and the L on the right with C.

 

After 16 hours of incubation, mutant  colonies of Sm that were resistant to C had begun to emerge. A direct visualisation of evolution and the emergence of  antimicrobial resistance (see below).

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A close up photograph of the zone inhibition in Sm caused by C reveals small red C resistant mutants.

 

After 24 hours incubation the C resistant mutants of Sm are clearly visible but neither bacterial strain, Sm or Cv, displays any resistance to K (see below).

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Sm left and Cv right. The reversed L shape on the lefthand side of the agar plates is impregnated with K, and the L on the right with C.

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A close up image of the C resistant mutants of Sm

 

In the second run of this process, the same bacteria were used, but the antibiotic Trimethoprim (T) replaced C and K. In the image below is the first run of this process (top) and run with T (bottom) but before incubation.

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Top, first run of the process. Bottom, second run, left Sm with T, and bottom right Cv with T.

After 12 hours of incubation both Sm and Cv exhibit sensitivity to T, as evidenced by large and clear zones of inhibition(see below).

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Top, first run of the process. Bottom, second run, left Sm with T, and bottom right Cv with T. Note also how the fungal colonies top left are resistant to both C and  K. 

 

In a very unexpected development, after 24 hours of incubation Sm, but not Cv, had become resistant to T. However, Sm in doing so,  had lost its ability to produce its red pigment and thus become white in the process (see below).

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Left Sm with T, and right Cv with T. The T resistant form of Sm is white. There might also be a white T resistant form of Cv emerging at the bottom of the T.

The Animalcule Drawings I: Black Carbon (BC)

” Unique conflicting BioArt made with life and Anthropogenic Materials”

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Antonie van Leeuwenhoek is widely regarded as one of the founding father’s of microbiology, as he was one of the first individuals to observe protozoa (1674) using a microscope that he had made himself. In a letter written in September, 1674, Leeuwenhoek describes a spiral microorganism, possibly what we know of today as Spirogyra, in his observations on lake water,

“Passing just lately over this lake, . . . and examining this water next day, I found floating therein divers earthy particles, and some green streaks, spirally wound serpent-wise, and orderly arranged, after the manner of the copper or tin worms, which distillers use to cool their liquors as they distil over”

Van Leeuwenhoek originally referred to these microscopic creatures as Animalcules (from the Latin animalculum, meaning tiny animal). Such microscopic life forms are also called  Infusoria from the Latin infundere (infuse) and so named because they were originally found in infusions of decaying organic matter. Today, these micro-organisms referred to as unicellular organisms or Protozoa (meaning first animals). As the principal hunters and grazers of the microbial world, protozoa play a key role in maintaining the balance of bacterial, algal, and other microbial life in natural and urban ecosystems. They also are themselves, an important food source for larger creatures and form the basis of many food chains. Protozoa have been found in almost every kind of soil environment, from peat bogs to arid desert sands, and vast numbers microscopically animate, the deep seas,  near the surface waters, form the tropic to  frigid Arctic and Antarctic waters.

Protozoa, have evolved many different strategies for feeding some are sessile and acquire nutrition through filter-feeding,  whilst others are motile and actively seek out their prey. In both, cases these activities are powered by organelles called cilia or flagella which beat  wave, allowing which allow the protozoa to move and to generate powerful micro-currents, to filter feed.

Humans pollute the environment with huge quantities of soot every year and it is believed  to be the second most important human-made agent of climate change. It is generated by burning of forests and savannah, by diesel engines, and coal burning. A major constituent of soot, is Black Carbon (BC) which can absorb one million times more energy than CO2. BC is the second largest contributor to climate change after CO2. However, unlike CO2, which can stay in the atmosphere for thousands of years, BC, because it is particulate, remains in the atmosphere only for days to weeks before it returns to earth with rain or snow. When it falls to earth with this precipitation, not only does it damage ecosystems and reduce agricultural productivity, but BC also darkens the surface of snow and ice, reducing their albedos (the reflecting power of a surface), warming the ice, and hastening melting.

Air pollution also  causes millions of premature deaths each year, these being mainly caused by the inhalation of microscopic particulate matter. BC is especially dangerous to human health because of its tiny size. In fact, the WHO reported in 2012,  that there was sufficient evidence to link exposure to BC to cardiopulmonary morbidity and mortality.  The review of the toxicological studies suggested that BC may not be a major directly toxic component of fine particulate matter, but that it may operate as a universal carrier for a wide variety of toxic chemicals into the human body.

India ink, commonly used in drawing and in art, has an intriguing link with Black Carbon (BC) in that a form of BC called Lampblack is its main constituent, other than water.  Usually no binder material is necessary in order to stabilise the ink as the BC particles are in colloidal suspension, and they form a waterproof layer after drying. Lampblack is made from burning oily or resinous materials and collecting the resulting soot containing the BC.

To make the Animalcule Drawings, I mixed various animalcules with India Ink and observed them under a Differential Interference Contrast microscope at 200x magnification. This  processes simultaneously reveals the complexity of these lifeforms and the complex fluid dynamics that their activity generates, and also the insidious nature through which a widespread and anthropogenically generated pollutant, Black Carbon,  infiltrates living organisms, and the enters into the bottom of the food chain.

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Blepharisma

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Unidentified fast moving animalcules

 

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