BIODESIGN RESEARCH PROJECT
LIVING COLOUR / Laura Luchtman / Ilfa Siebenhaar
TABLE OF CONTENTS
Plan of Action
Meet our Superheroes
The Lab Journal
References & Further Reading
WELCOME For 16 weeks we took part in the class Textile Academy at Waag Society in Amsterdam. Each week we learned new tools, software and skills to investigate how the textile and fashion industry can benefit from new technologies, processes, and business models. The
to develop our own in depth research project in the TextileLab. Living
Laura Luchtman & Ilfa Siebenhaar
LIVING COLOUR IS A BIODESIGN RESEARCH PROJECT EXPLORING THE POSSIBILITIES OF NATURAL DYEING WITH LIVING MICRO-ORGANISMS: BACTERIA.
Biodesign is the cross-pollination
Imagine a world where biological
of nature, science and design,
where living organisms form an
manufacturing. Until the middle
integral part of the design process.
of the 19th century, all dyes used
in textiles were naturally derived. We
Ever since the textile industry uses
growth conditions for bacterial
synthetic and toxic colourants
almost exclusively. These dyes are
mostly made from non-renewable
possibilities of growing bacteria
resources such as fossil oil, in
in patterns by subjecting them to
spite of its hazardous effect to the
sound frequencies. Asking “What
environment, animals and humans.
have on the growth of bacterial
As an alternative to synthetic
pigments?” and “Can we control
the process of growing bacterial
immense potential to produce bio
pigments?” This way we hope to
pigments. Growing bacteria as
exclude random growth in order to
a dye factory can lead to a more
upscale the bacterial dye process.
sustainable way to colour the world.
Close-up of Janthinobacterium lividum on a Nutrient Agar plate
TEXTILE DYES THE GLOBAL TEXTILE INDUSTRY DISCHARGES 40,000 â&#x20AC;&#x201C; 50,000 TONS OF DYE INTO THE WATER SYSTEM
Plants and micro-organisms are the two major sources of natural pigments. Plant pigments have limitations such as instability against light, heat, limited colour palette, low water solubility and require large amounts of water and chemical fixing agents. Because of these disadvantages and the limited availability of resources, which were also expensive, synthetic dyes were developed. Synthetic
their production process requires hazardous chemicals, creating worker safety concerns, they generate hazardous waste and are not environmentally friendly. Demand for new natural pigments is increasing day by day, because of its environmental safety as well as beneficial effects on human health. As new safe and effective natural colourants are discovered, they can hopefully replace the harmful synthetic dyes.
BACTERIAL PIGMENTS BACTERIAL PIGMENTS HAVE BIOLOGICAL ADVANTAGES SUCH AS ANTIOXIDANTS AND ANTI-CANCER AGENTS.
Some bacteria produce colourful molecules: pigments, like carotenoids and violacein. These colours are biodegradable and environmentally friendly. They also have numerous clinical characteristics like anti-oxidant, anti-cancer, anti-biotic, anti-viral and anti-bacterial. This could be beneficial to our skin, our largest organ, which now absorbs “safe” amounts of toxic chemicals. The bacterial pigments produced can be water soluble or insoluble, but oxygen is necessary for pigmentation so only aerobic bacteria are pigmented. However, pigment production also depends on factors like light, pH, temperature, and nutritional growth medium.
WHY SOUND CAN WE PROMOTE THE GROWTH OF OUR PIGMENTED BACTERIA WITH SOUND AND PERHAPS EVEN GROW THEM IN PATTERNS?
Sound can move through air, liquids and solids. These sound waves create visible and invisible patterns. Vibration of sound frequencies cause so called Faraday 1 waves that
resonating surfaces these sound waves can be made visible by the use of particles and powders; the so called Chladni 2 figures. Sound is also believed to have healing qualities, cause crop circles and earthquake roses. These sound patterns fascinate us. We want to see if we can grow bacteria in these sound waves, hopefully leaving visible patterns on fabric. A scientific study 3 also found that frequencies were able to promote the growth of E. coli bacteria. In particular, the tonal sound of 5 kHz gave significant increase in cell number of E. coli.
CYMATICS RESEARCH CYMATICS: THE STUDY OF THE WAVE PHENOMENA WHICH CAUSES MATTER TO TAKE FORM IN GEOMETRICAL PATTERNS WHEN SUBJECTED TO SOUND.
experimenting with sound by making sound visible. Laura used the bass speaker of an old 3-way speaker to see what frequencies cause matter to move and form patterns. The 1st experiment was with rice, poured straight into the speaker cone. Depending on volume and frequency, the rice started to dance. The next step was to work with smaller particles and liquids. A plastic membrane was placed over the speaker to protect it. The membrane was filled with a small layer of water. Later cornstarch, ink and turmeric (a spice and natural dye) were added. The membrane was also covered with unbleached cotton to see how liquids would interact with the textile. Not only tones but also music was used to create movement; sounds of bass, drums and strings worked best.
PLAN OF ACTION WITHIN LIMITED TIME FRAME, MEANS AND KNOWLEDGE YOU CAN USE ALL THE EXPERT HELP YOU CAN GET.
This project started right before
We needed expert advice on sound
along with the audio gear to build
our installation. Sound engineer
Eduard van Dommelen was so nice
to help us out with the audio part.
We asked him anything we could
think of and felt like little sound These micro pets had to stay warm
and survive the holidays. Luckily
Together we made an audio plan.
Christmas dinner and a scented
He lent us speakers, an amplifier, a
candle masked the smell of these
laptop, audio card, cables and wires
and made sure everything worked
beforehand. He also programmed The day before Christmas Eve we
had an appointment with Jan de
control 4 speakers with different
Jong, Biologist from Rotterdam
frequencies and volumes at the
University. He thought our project
same time. He advised us to secure
was very interesting and was
the petri dishes with the bacteria
willing to help us out by making
and fabric directly on top of the
the lab plus staff member Esther
speakers, so we wouldn’t need a
Jongste available to us for 2 weeks.
high volume, to create vibration.
MEET OUR SUPERHEROES
PURPLE Janthinobacterium lividum Janthinobacterium lividum is a soil-dwelling bacterium which produces various shades of purple pigments called violacein. Violacein has anti-bacterial, anti-viral and antifungal properties. The optimum growth temperature is a comfortable 25 ̊C.
RED Arthrobacter agilis Arthrobacter agilis is also a soil-dwelling bacterium. The pink to red pigment is called carotenoid. It can fight hexavalent chromium, which is ironically used in textile dyes and can cause severe irritation to humans. It can also reverse the effect of agricultural pesticides in the ground. This hero prefers temperatures between 25 ̊C and 30 ̊C.
YELLOW Micrococcus luteus Micrococcus luteus can be found in many places such as the human skin, water, dust, and soil. The yellow pigment is also called carotenoid. This bacteria’s pigment has the ability to absorb UV radiation that no current sunscreen can block. That’s probably why this hero adores 37 ̊C.
AUDIO INSTALLATION Humans can hear sound waves with frequencies between about 20 Hz and 20 kHz. Sound above 20 kHz is ultrasound and below 20 Hz is infrasound. Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. Animals have different hearing ranges. In general, we can feel low frequencies as vibration, depending on the volume of the sound. We need vibration to create patterns but possible high frequencies to generate growth. Therefore our audio installation consists of 4 speakers with different frequencies, from low to high.
THE LAB JOURNAL WE WERE LUCKY TO WORK IN THE RESEARCH LABORATORY OF THE BIOMEDICAL FACULTY OF ROTTERDAM UNIVERSITY.
DAY 1 - 12 JANUARY 2017 Audio experiment 1 We started by inoculating our 3-weeks old Janthinobacterium lividum (JL) cultures, obtained at Waag Society, on a new plate containing Nutrient Agar (NA) medium. On the old plates the bacteria eventually stopped growing, due to lack of leftover nutrients and moisture. We made 5 new plates, hoping there were still some cultures left alive to cultivate. Then we made some Nutrient Broth (NB) for our first audio experiment. We took 5 little pieces of untreated pure silk and sterilised them for 5 minutes under a UV light. The pieces of silk were then divided between 5 petri dishes, poured with NB medium and inoculated with the JL culture from the old plates with an inoculation loop. Next we had to build the audio installation in the climate chamber (a room where the temperature is set to a certain temperature, hot or cold). The 4 speakers were set to different frequencies: •
A: bass speaker = 100 Hz
B: mid speaker = 1000 Hz
C: mid speaker = 2500 Hz
D: tweeter = 5000 Hz
E: no sound, control experiment
The volume was kept relatively low, but high enough to feel the vibration of the bass speaker and hear tones of the other speakers. The door of the climate chamber was sound proof to these volumes. We placed 4 petri dishes direct on the speaker, keeping them levelled. The 5th petri dish was placed on a shelf, without being exposed directly to frequencies, as a control experiment. The climate chamber is set to 27 ̊-30 ̊C, although the optimum growth temperature of JL is 25 ̊C. Unfortunately the temperature could not be changed. We hoped to see the first results the next day.
DAY 2 - 13 JANUARY 2017 Analysis 1 It was time to analyse the first results after 19 hours had passed. The NA plates showed light colouration and the NB plates showed very little, pixel like, colouration. It was too early to come to any conclusions. We did find out that we forgot to add glycerol to both the NA and NB medium. The Janthinobacterium lividum bacteria need glycerol to make their purple pigments. Rookie mistake! As a back up we made some new NB medium, added 2% glycerol (87%) and poured 15 ml of the NB medium in 5 Erlenmeyer flasks. The 6th Erlenmeyer flask was filled with NB without glycerol, as a control experiment. Each flask was then inoculated with a toothpick with JL bacteria from our old NA plates. This way the bacteria could already adjust to the NB medium, and start making their pigments in the liquid, in hopes to speed up the growth process. All the flasks were placed in the climate chamber in a shaker at 27 Ě&#x160;-30 Ě&#x160;C. Now we had to wait all weekend before we could see results.
DAY 5 - 16 JANUARY 2017 Analysis 2 & Audio experiment 2 Even after a weekend had passed, 4 days since cultivation, the silks from our 1st audio experiment still hadn’t coloured. The bacteria had grown, but didn’t make pigment. So (some of) the bacteria from the old plate were still alive. The control experiment didn’t show any pigmentation either. Thus sound neither helps nor harms in this case. The NA plates do show minor colouration. Conclusion: Janthinobacterium lividum needs glycerol in a NB medium in order to make pigments. We lost some valuable time, which we hoped we could make up for by using the incubated NB medium with JL culture in our next audio experiment. Our 6 flasks turned beautifully purple over the weekend, except for flask 5 and 6. Flask 6 didn’t have glycerol in it, so that was expected, but we didn’t expect to see a flask with white/no pigment instead of purple. Also flask 4 had a lighter colour purple pigment than the 3 others. We had read in a study4 that “When the isolated bacteria were cultured at temperatures higher than 20°C, particularly in the range of 27°-30°C a mutant of light purple or white colour bacteria often appeared.” Could this also be the case for flask 4 and 5? We had to find out. We did a mutation test, inoculating bacteria from every flask on to NA plates. We hoped to see either purple, light purple, white colonies or a mixture of all of them. We placed them in the climate chamber at 27°-30°C and had to wait for a couple of days to see results. We prepared 6 new flasks of NB medium; the first 4 got 1 ml of purple culture medium from the old flasks, because they turned out so well. The 5th and 6th we gave a toothpick with some bacterial culture from our old NA plates, which we kept as a backup. Each flask was filled with NB medium up to 15 ml and put in the shaker at 27°-30°C. Then we repeated the audio test from day 1, this time with glycerol in the NB medium. The medium had already turned purple and we poured 14 ml of each flask over the silk fabric in each petri dish. Dishes A-C had purple medium and dish D had the light purple medium. The white medium we didn’t use, other than for the mutation test. Since we didn’t have a 5th purple medium left, we couldn’t do a control experiment unfortunately. •
A: bass speaker = 100 Hz
B: mid speaker = 1000 Hz
C: mid speaker = 2500 Hz
D: tweeter = 5000 Hz
The frequency was kept at the same level as day 1, but we turned up the volume a bit, still not causing any inconvenience to other people in the lab.
DAY 6 - 17 JANUARY 2017 Analysis 3 & Audio experiment 3 The results of audio experiment 2 were evident even after only 24 hours. Because we used the purple-pigmented NB medium for this experiment, we didn’t have to wait 2-3 days for the bacteria to produce their pigments. The silk fabric turned purple in all 4 dishes. We didn’t see any patterns; the fabric was completely plain and dyed evenly throughout. Silk D was a little bit lighter colour because of the lighter colour medium we used on this piece. Conclusion: When soaking small pieces of untreated silk fabric in a purple stained liquid NB culture for 24 hours while exposing them to sound frequencies, the fabric turns plain and bright purple. We can’t conclude at this stage if sound vibrations had direct influence on the way the pieces of silk were coloured, since we didn’t have a control experiment. The pieces of silk had to be put in the autoclave at 121°C for 5-10 minutes to kill the bacteria, but leave the colour. We were wondering if the bacteria would survive a normal cleaning in the washing machine at 40°C. Therefore we did a new test to see if they would continue to grow at 40°C. We cut off 2 tiny squares of silk D before autoclaving and placed them on 2 NA plates. One was stored at 27°-30°C, the other at 40°C. For audio experiment 3 we repeated the steps of audio experiment 2, but this time we added less bacteria culture to the silk fabric. We ‘injected’ 5 drops of 5 ml liquid purple culture each on the silk with a pipette in the shape of the 5 points on a dice. We hoped this would result in patterns instead of plain dyed fabric. The 4 Erlenmeyer flasks with the NB medium and 1 ml of purple stained NB culture also turned bright purple overnight. The 2 flasks with the toothpicks with NA culture take a little longer. Conclusion: Janthinobacterium lividum produces faster and more pigment in a liquid Nutrient Broth, when the broth is inoculated with a culture straight from a NB medium than from a NA medium. The bacteria respond better being transported to the same nutrient medium, than to a different medium. We also did a test to see how the bacterial pigment would adhere to different kinds of fabric. So far we had only tested untreated silk with a light and open structure. We divided 10 pieces of sterilised organic, unbleached cotton (jersey, terry, French terry, fleece, velour, sweater) between 2 petri dishes of 20cm each. We filled them with 22,5 ml of purple NB culture. Next we took a little piece of self-tanned sterilised salmon leather and placed it in a small petri dish with 7 ml of purple NB culture. Both the fabrics as the salmon leather were sterilised under a UV light for 5 minutes before placing in the dishes. The last experiment of the day was with our yellow Micrococcus luteus (ML) and red Arthrobacter agilis (Aag) bacteria that we had just received from Waag Society. We made 3 Erlenmeyer flasks of each colour bacteria; 15 ml NB medium containing 2% glycerol inoculated by a toothpick with bacterial colonies from the NA plates in each flask. We placed the red ones in the climate chamber shaker at 27°-30°C and the yellow ones in the shaker at 37°C.
DAY 9 - 20 JANUARY 2017 Analysis 4 & Audio experiment 4 Three days later we came back to the lab. We started by checking our mutation test results. Plate 1 showed purple pigments, plates 2, 3, 4 showed lighter purple pigments and plate 5 solely showed off-white pigments. Plate 6, which didn’t contain glycerol, showed nice loose colonies (dots) whereas the other plates showed more of a pigmented haze (biofilm; caused by too many, clinging bacteria, inoculated too thick). It seemed that plates 2, 3, 4 turned from normal purple pigments to lighter purple pigments. The bacteria on plate 4 had already been lighter and stayed that way. Plate 5 was inoculated with the white bacteria and also stayed that way. On Plate 6 the bacteria had grown, but hadn’t produced pigments. Conclusion: We found some mutants! Light purple ones and white ones. It seems that the mutation is so strong that no other pigments get the chance to form. Otherwise we would see a mixture of purple, lighter purple and white colonies on the same plate. It looks like we may have found some patterns in the silk fabric of audio experiment 3. Before rinsing and sterilising the coloured fabrics in the autoclave, silk A from the low-frequency bass speaker seemed to show some irregularities in coloration. Silks C and D were darker purple than A and B, but this is probably due to different kinds of silks that were used by accident. A and B were the same silk and C and D were the same silk. When the silks were taken out of the autoclave, they all seamed evenly dyed, no visible patterns. The ‘leftover’ pigments in the fluid or biofilm fixed to the fabric could have caused this. Thus far no final conclusion can be drawn. Time for audio experiment number 4. We repeated experiment number 3, but we changed the 5 drops of 5 ml purple culture to no more than 2 drops per petri dish. The bacteria are growing so fast and we have to leave them over weekend. We hope to see clearer patterns with fewer drops. We also cut a bigger piece of silk to fill the entire petri dish. So less bacteria and more fabric than the experiments before. We also lowered the high frequencies, as lower frequencies seem to create some kind of pattern: •
A: bass speaker = 100 Hz (was 100 Hz)
B: mid speaker = 200 Hz (was 1000 Hz)
C: mid speaker = 400 Hz (was 2500 Hz)
D: tweeter = 2000 Hz (was 5000 Hz)
E: no sound, control experiment
The test on different materials showed good results. All cotton fabrics were dyed purple. The colour was lighter than on the silk fabric and also showed uneven results. Some fabrics were stained and not dyed evenly. There was no direct exposure to sound frequencies in this case. The bacteria had grown so rapidly that a thick, almost black biofilm had formed on top. Perhaps this causes the fabrics to stain. The salmon leather has started to mould, but did take colour. Unfortunately there was no way we could rinse of keep the skin, because it was contaminated. Conclusion: The JL bacteria adhere to most cotton fabrics, but not as good as to silk. The live pigments love thin and open structures, were oxygen could flow freely. Salmon leather is not suitable for live bacteria dyeing, possibly because it cannot be sterilised properly.
The liquid cultures of the ML and Aag bacteria haven’t formed obvious pigments, but have grown in the liquid. There probably was no optimum condition for the bacteria to produce pigments, although we don’t know why. The new experiment of this day was to try and dye a large piece of fabric. We brought or own plastic containers, used for storage and used these as giant petri dishes. We sterilised them with disinfecting alcohol and made 6 litres (!) of Nutrient Broth. We poured 3 litres per container. In container 1 we placed a large piece of organic cotton/bamboo fabric. The fabric was folded 3 times to fit in the container. We knew there was a chance the bacteria wouldn’t adhere to the lower layers due to lack of oxygen. We randomly inoculated the fabric with a pipette containing 1,5 ml liquid JL culture. We also added the ML and Aag cultures from the NA plates. Container 2 we filled with several different pieces of fabric: cottons and silks. Here we only used the JL and Aag cultures. We hoped the colours would mix and form nice patterns. We placed the containers in the climate chamber at 27°-30°C.
DAY 12 - 23 JANUARY 2017 Analysis 5 The silk fabric from audio experiment 4 had all weekend to gain colour. Whereas the previous audio experiments showed plain fabric as a result, this time some “patterns” seem to show. In this experiment we used far less pigmented liquid culture than in the previous experiments. This seems to affect the way the fabric is dyed. Whether the sound waves created these patterns is hard to know for sure. The control experiment showed less of a pattern, but the fabric piece was a different shape and a little smaller. Conclusion: When using less pigmented liquid culture, the fabric is not dyed plain, but shows stains/patterns. Whether the sound waves created these patterns is hard to tell. The bacteria in the 2 big containers have grown over the weekend as well. The 1st container, with the cotton/bamboo blended fabric, doesn’t show red/pink or yellow colouration. The purple bacteria only made pigment on the spots where we injected the liquid culture into the fabric. The fabric is not dyed at all. The 2nd container with the different pieces of fabric and a combination of purple and red bacteria, only shows purple bacteria. The red ones didn’t have the chance to make pigments. The fabrics in the container have all dyed/stained purple. Conclusion: None of the bacteria respond well to the bamboo fabric, this fabric is not able to dye with live bacteria. The purple JL bacteria are dominant and make more pigment and/or prevent the other bacteria from growing/making pigments when inoculated at the same time. Lastly we made some new liquid cultures with the ML and Aag bacteria from the NA plates. We made 4x10 ml NB inoculated with a toothpick with 2xML and 2xAag culture. We hoped we could do a last audio and dye experiment tomorrow to make yellow and red dyed fabric.
DAY 13 - 24 JANUARY 2017 Analysis 6 & audio experiment 5 The liquid cultures of the ML have turned yellow overnight. The Aag culture didn’t grow red or pink. It seems the Aag bacteria need a longer time to make their pigments or need some other form of growth medium to turn red. Conclusion: The Aag bacteria do not produce pigments in the NB medium within a couple of days. They need a longer time to grow or some other growth medium to optimise their pigmentation. The yellow NB cultures we were able use for our 5th and last audio experiment. We sterilised 5 pieces of silk with the UV light. We divided them between 5 petri dishes. We poured in 15 ml of NB medium and inoculated each piece of fabric with 0,5 ml liquid yellow ML culture with a pipette. Then we placed them on the speakers at the same frequencies and volume as audio experiment 4: •
A: bass speaker = 100 Hz
B: mid speaker = 200 Hz
C: mid speaker = 400 Hz
D: tweeter = 2000 Hz
E: no sound, control experiment
DAY 14 - 25 JANUARY 2017 Analysis 7 After almost 24 hours had passed it was time to see the results of the yellow ML bacteria. It was too short of a time to see actual colouration. Only petri dish C, showed yellow colour on the outer edge. This was interesting, because the rest of the fabrics didn’t show any yellow colour and also because we injected the fabric in the middle, not at the edge. Whether it was the frequency of 400Hz that made the ML perform better than the other frequencies is hard to tell. Conclusion: The ML bacteria do produce a small amount of pigments in the NB medium within a day. After seeing the results it was time to pack up our things and leave the lab. We would have loved to have more time, to dive deeper in to this project, but unfortunately the exhibition is in 2 days already, so we had to end it here.
AUDIO EXPERIMENT 1
AUDIO EXPERIMENT 2
AUDIO EXPERIMENT 3
AUDIO EXPERIMENT 4
AUDIO EXPERIMENT 5
Janthinobacterium lividum is an excellent bacterium for use of textile dyeing. It grows fast, even in not so optimal conditions and produces saturated pigments. Arthrobacter agilis and Micrococcus luteus are a bit more difficult to grow for pigments. They need optimal conditions to produce a large amount of pigment. When dyeing textiles with live bacteria, the textiles donâ&#x20AC;&#x2122;t necessarily need to be mordanted before dyeing, unlike natural dyes from plants, insects and spices. Mordanting and fixing the textiles could result in even better colour results. Growing bacteria in patterns or controlling the way they grow still seems a very hard thing to achieve. It looks like sound frequencies help produce more pigment. It dyes the textiles in an even, plain and more saturated colour than growing the bacteria without sound. More excessive research should take place to form definitive conclusions. Testing bacteria in a larger petri dish filled with fabric, with more different frequencies and possibly higher volumes (so the liquid would actually visibly move) could still result in creating patterns. A big challenge lies is finding optimum, vegan and cheap growth media for the bacteria to produce maximal pigments. Although dyeing with live bacteria is a very fun and rewarding process, weâ&#x20AC;&#x2122;d recommend extracting the pigments from the bacteria and making them into a textile dye in order to upscale the process. This way controlling how the textiles are dyed is made easier. It also doesnâ&#x20AC;&#x2122;t require a sterile working environment. We challenge the industry to make these bacterial pigments into dry dyes, since excessive water use is a big problem in the textile dyeing process next to the chemicals being used. Companies like ColorZen, AirDye and DyeCoo have found ways to use 90%-96% less water and 75% less energy 5.
WE COULDNâ&#x20AC;&#x2122;T HAVE REALISED THIS PROJECT WITHOUT THE HELP OF THESE PEOPLE AND INSTITUTIONS
Special thanks Cecilia
Ista Boszhard, Eduard van Dommelen, Jan de Jong, Esther Jongste, Marijn Spierings.
Living Colour is made possible by: Lab
Text, design & photography: Laura Luchtman
CONTACT We would love to extend and continue our research. Therefore we
designers, educational institutes, textile
institutes, etc. to contact us for future collaborations. Also contact us for press, images, exhibitions or more information. - Laura Luchtman & Ilfa Siebenhaar
REFERENCES & FURTHER READING 1. Farady waves https://en.wikipedia.org/wiki/Faraday_wave
2. Chladni figures https://en.wikipedia.org/wiki/Ernst_Chladni
3. Experimental Investigation on the Effects of Audible Sound to the Growth of Escherichia coli
4. Bacterial pigments and their applications https://www.researchgate.net/profile/Chidambaram_Venil/publication/241698697_Bacterial_ pigments_and_their_applications/links/00b4951e78e9c3601e000000.pdf
5. Clothing to dye for: the textile sector must confront water risks https://www.theguardian.com/sustainable-business/dyeing-textile-sector-water-risks-adidas
Cymatics Pinterest Board https://pinterest.com/kukkadesign/cymatics-musing/
The #1 Fabric to Avoid, According to Science http://www.whowhatwear.co.uk/worst-fabrics-for-skin
Isolation of Bacteria Producing Bluish-Purple Pigment and Use for Dyeing https://eurekamag.com/pdf.php?pdf=010893172
Production of sound waves by bacterial cells and the response of bacterial cells to sound http://www.qigonginstitute.org/abstract/1704/production-of-sound-waves-by-bacterial-cellsand-the-response-of-bacterial-cells-to-sound
Effect of audible sound in form of music on microbial growth and production of certain important metabolites http://link.springer.com/article/10.1134/S0026261715020125
The test on different materials showed good results. The bacteria had grown so rapidly that a thick, almost black biofilm had formed on top.