Bacterial cellulose in architecture - culture comparison, composites, contamination


#1

Hello everyone,

This year I’m working on a thesis at VUB (Brussels) experimenting with bacterial cellulose, evaluating wether it could be suitable for use in tensile architecture. I will share my experiments and findings in this forum throughout the year so that everyone can follow what happens, learn from it and give me input :slight_smile:
other experiments:


The first large part is focusing on mechanical strength. I will test the tensile strength of the plain material, will look into how seams can be created and what their strength could be and I will also look at composites, combining the growth of the BC with another material in order to enhance its strength.

I will write this post as a sort of chronological logbook on what I’m doing, trying to remain concise, and see how it works out. (Input on how I could improve this post is always welcome too!)

sidenote: I work in lab environment with autoclave, laminar flow and a 30°C growing room.

(I have a recurrent struggle with a contamination. If you have had this too and think you could be of help, please continue reading! :slight_smile: )

time-based objective: have materials ready for testing by the end of december.

LOGBOOK
OCTOBER-NOVEMBER: growing

I started out just growing BC (without any real BC experience, but under supervision of Elise, also active in this forum, I thought it would work out) from the mother cultures I had from Elise, hoping to make large sheets quite quickly but it isn’t really working out at the moment.

The mothercultures of Acetobacter Xylinum were grown following this recipe from biohack academy.


motherculture

1.First growing attempt
I started two batches in large bottles which were easy to seal with Parafilm. After two days already a surface layer was developing. Unfortunately it was a contamination. Threw it away after 10 days, it grew quickly in the beginning and then stagnated.


9 days growing (contamination)

2.Second growing attempt
I tried a larger batch in an IKEA box, here also after 2 days already a contamination was visible (see pic). Unfortunately it could not be autoclaved so I had to sterilise it with Ethanol before/while going into the laminar flow. The sealing was not optimal as well, had to close it all around with Parafilm but got some holes.


3 days of growing (contamination)

after two failed growing attempts I was a bit worried and curious about what that contamination was about.
Some guesses:

  • Contamination already present in recipients - bad sterilising
  • Contamination already present in mother culture
  • Contamination from the warm growing room - bad sealing

3.Third growing attempt - mother and feedstock growing comparison
I scaled down again to see if growing a small batch would even work. I directly grew different types of 200 ml batches to be able to compare 4 methods:

  • 2 mother cultures (One original kombucha + one purified Acetobacter Xylinum mother)
  • 2 feedstock recipes (One DIY recipe from this forum + one optimised, mentioned before)
    criscrossing them gives 4 combinations, made 3 batches to have some more consistent results.

    12x 200ml batches - day 0

This gave some interesting results:


Zoom images:

12 days of growing

We can conclude:

  • The optimised recipe from biohack academy works very well, developing a homogeneous and plain sheet of BC, growth of about 5 to 8mm in 12 days

  • For some reason the DIY recipe with kombucha mother didn’t work at all

  • Only one batch was contaminated, showing also a darker colour of liquid. What does this mean…?

  • After some comments I learned that actually the optimised biohack recipe which isolates AX bacteria makes it possible to grow this very pure cellulose layer, while also making it more vulnerable for contaminations.

4.FIlter and composite test
Simultaneously with (3.) I grew 4 other batches to check wether there would be contamination in a medium recipient (larger than 200ml flask but smaller than IKEA box) with another filter type. I used two of them to do a first test on growing composites.

4a. filtertest: again both batches contaminated.


filtertest after 5 days, contaminated

4b. composite test: Semi contaminated, semi BC.
I tought this one had the least chance to work, since it was difficult to remain clean. I made a small construction to be able to tension the Hemp net in the box, so that the BC would grow on a ‘pretensioned’ net.


start: other filters + hemp net stretched at level of liquid surface

growth 3 days: contamination?

Took out after 5 days - left: both BC and contamination in hemp net - right: cleaned sheet

(14.11 update)
Dried sheets of composites: The BC is very thin and transparent, but it seems to keep all the fibers in place. Will continue trying this, maybe with a more dense fibre net (someone ideas for other materials?), also will have to look into how I can keep the material at the surface while pretensioning it + keeping everything sealed.

dried sheets of BC and hemp

(11.03 update)
haven’t updated this for a long time.
I have had multiple other attempts since november, a lot of them contaminated (looks like Kahm yeast that someone commented to me), some of them worked!

I’m adding a post on another test I did on trying to grow/create SEAMS, a subject in BC that really intruiged me: BC - creating seams between cellulose sheets

And another post on post-processing of BC sheets for mechanical purposes: BC post-processing mechanical comparison protocols

(this text is a logbook of my work, things will be added through time)

If someone is interested in spending some time reading more on what I’m doing, in this google drive link I placed a pdf of my WIP (beware, very WIP!!) writing. Also not everything I did up untill now is included yet, but comments are of course very welcome.
https://drive.google.com/open?id=1_QZPnoEDVlzX3L2gP8EKU91jyyccp4Ej

Thank you for reading me!

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
Master Thesis by Bastien Damsin, Under supervision of Elise Elsacker, Prof. Lars De Laet and Prof. Eveline Peeters / Vrije Universiteit Brussel / Department of Architectural Engineering and Bioengineering Sciences.


Hello I'm Amber, working on kombucha leather
BC post-processing mechanical comparison protocols
Introducing myself
Mechanical properties of mycelium brick
#2

Hello @bdamsin, unfortunately I cannot help you. But you, sir, sure are a hell of a documentation writer. You put the hacking in biohacking.

Keep this up and you will have a lot of help for sure!


#3

Hi, no problem, though I hope someone will recognise the contamination! I’m doubting a bit about the length of the text, this is only the beginning of my thesis… Maybe I’ll split it up in parts when it becomes too long. Thanks for the reply!


#4

Hi, thanks for the reply :slight_smile:

Actually my contaminations resemble a lot to the Kahms yeast, I will look into that.

  • Why only bacteria?
    I think only using the bacteria grows a better (more pure, homogeneous, without bubbles) cellulose layer, which I deduct out of my comparison experiment (3. in the post). But if I understand well, by making the mixture more pure, it gets more fragile for contaminations. So I should find a way to protect the bacteria while keeping the quality of the grown cellulose I think. Maybe another recipe, or Elise suggested me looking into antibiotics.

  • What tea?
    I used a japanese bulk green tea.

Thanks also for that source on AX, will check out their sources they look interesting!


#5

I wouldn’t go to antibiotics! :o There’s already enough of that in the world.

Could it be that your mother is contaminated? Leading to mixed results. And then it makes sense that the “optimized recipes” do work if they isolated the right Acetobacter bacteria (implying that the contaminations also get killed).

Ie. getting a new culture would be a good check. Given that you’re working in a lab with proper equipment it seems highly unlikely to me that contamination is coming from anywhere in that environment (unless some sloppy student did something really nasty and it wasn’t cleaned up properly.)


#6

We work in a lab with yeast-research too and our samples are grown (although closed) in the same room. So it’s likely that the contamination is within the lab or one of our mother cultures.

I would also suggest to buy a new mother culture. @bdamsin, can you look into that?

Where to find mother culture of Acetobacter bacteria? Normally you can contact the researchers of the papers you’ve read and ask them to send their culture. @winnieponcelet do you know any other “wetlab” stores?

A mother culture of Scoby can be found easily on internet.


#7

If there really is “yeast in the air” you’ll need to upgrade your sterile working techniques and be quite strict. The symbiotic element of the kombucha prevents contamination. So your cultures of just the acetobacter will contaminate way more easily than a kombucha culture.

You can order microorganisms at BCCM at UGent. There is a community member at ReaGent also working with them in one of the.labs she teaches at university. I’ll get you in touch :slight_smile:


#8

Have a look here:


#9

Two different techniques:

Biocouture, Suzanne Lee drying scoby on various types of textile.

lksmyczek growing scoby on cheesecloth
http://lksmyczek.squarespace.com/kombucha-fabric/


#10
  • What is the average life of the materials that are currently used in tensile architecture?
  • Why did you choose bacterial cellulose over mushroom leather for example?
  • Which material is cheaper in mass production?

#11

Thanks for these critical questions. Originally I was planning to do compressed and gelified mycelium too, but since I am having problems with my cellulose I am focussing on that first. Maybe later on I will do that too :slight_smile: the price and lifetime are indeed things I should include in my thesis explanation, thanks.


#12

I’m reposting this video of @amiridina here as well, since it’s relevant for your project too: https://biofabforum.org/t/3d-manufacturing-with-biomaterials/8784/15


#13

This is also nice: http://www.jannishuelsen.com/?/work/Xylinumcones/


#14

Very well documented @bdamsin. Impressive. Funny that I just came accross your post today as @loreDeBacker, who is doing an internship @ GLIMPS was mentioning yesterday that she had green molds when using the original recipe from biohack academy and a kombucha mother (also had these when trying this biohack academy recipe). So based on your results, it looks like the optimised recipe, purified mother works the best. Is this optimised recpipe mentioned in the biohack academy site? Thanks and keep up the good work!


#15

Hi,

I should update the post with some new knowledge. What I called ‘optimised recipe’ is from the Biohack academy (https://biohackacademy.github.io/bha3/annex/cultivation-media/acetobacter-medium/) and is actually the common recipe used in academic literature, referred to as ‘Hestrin-Schramm’ (or simply HS culture). Following my experiments up untill now I think that the DIY culture (based on tea) will have good yields because the kombucha mother has yeasts, which helps the bacteria break down sugars to build up cellulose (in comparison to using a pure strain of AX. It will also be more resistant to molds maybe, as long as you work sterile (this is a guess, I have only lab experience…). Replacing the DIY culture by HS/biohack academy culture gave me nicer sheets of BC (no bubbles etc), but chances exist it is more fragile (since I had a contamination in that one). I didn’t explain how I came to ‘purified mother’. It’s actually simply a kombucha mother on which I’ve used the HS recipe. This appears to feed only the AX bacteria, coming to a more pure mother culture (I’m not a biologist, I’m just assuming this). Sorry for the long explanation haha, but indeed this ‘purified mother’ with HS culture medium gave the best results for me BUT I’ve only managed to grow larger batches one month ago. I’ve had contaminations the whole time… So maybe the result is better, but it may be more fragile for contaminations. I don’t know if you guys work in a lab environment? Biologists at my lab suggested me to use glass dishes, cover them with aluminium and seal with tape, then autoclave. SInce it’s a liquid culture in general those are more likely to get contaminated, so working clean is extremely important (I dont understand how DIY’ers manage to grown this in their kitchen so easily haha, but after my thesis I will try). Okay if I didn’t really answer your question let me know haha


#16

Saw this passing on @JasperB linkedin, and thought to also share it here: https://thr34d5.org/karp/