[ExI] Bacterially induced megastructures
kanzure at gmail.com
Mon Apr 20 18:38:47 UTC 2009
On Mon, Apr 20, 2009 at 12:48 PM, mostromundo <mzuorski at gmail.com> wrote:
> Here's a neat little post from BLDGBLOG about using bacteria to
> solidify sand into sandstone in about a week. It sounds like a pretty
> neat use of biology, pile or pour some sand into the shape you want
> and then flood it with the right bacteria, and in a week you have a
> solid structure to live in!
That's a really beautiful post, the photographs and pictures are
fantastic as well.
"Clarifying the biochemical process through which his project could be
realized, Larsson explained in a series of emails that his "structure
is made straight from the dunescape by flushing a particular bacteria
through the loose sand... which causes a biological reaction whereby
the sand turns into sandstone; the initial reactions are finished
within 24 hours, though it would take about a week to saturate the
sand enough to make the structure habitable." The project – a kind of
bio-architectural test-landscape – would thus "go from a balloon-like
pneumatic structure filled with bacillus pasteurii, which would then
be released into the sand and allowed to solidify the same into a
"I researched different types of construction methods involving pile
systems and realised that injection piles could probably be used to
get the bacteria down into the sand – a procedure that would be
analogous to using an oversized 3D printer, solidifying parts of the
dune as needed. The piles would be pushed through the dune surface and
a first layer of bacteria spread out, solidifying an initial surface
within the dune. They would then be pulled up, creating almost any
conceivable (structurally sound) surface along their way, with the
loose sand acting as a jig before being excavated to create the
necessary voids. If we allow ourselves to dream, we could even
fantasise about ways in which the wind could do a lot of this work for
us: solidifying parts of the surface to force the grains of sand to
align in certain patterns, certain shapes, having the wind blow out
our voids, creating a structure that would change and change again
over the course of a decade, a century, a millenium."
"A vast 3D printer made of bacteria crawls undetectably through the
deserts of the world, printing new landscapes into existence over the
course of 10,000 years..."
What first came to mind when I saw this was ant and termite mounds.
When studying ridiculously large ant mounds, what researchers do is
pump some plaster throughout the entire structure and then let it sit.
They then excavate it and look at the overall pattern. But using
bacillus pasteurii might be more appropriate.
I can't help but think of selective laser sintering, a method of
printing 3D shapes. You have this giant bucket of "sand", you raster
scan a laser and the polymer or 'sand' polymerizes or whatever special
material you're using, and ultimately the result is the shape that you
wanted. So, what about photoactivation of a regulatory circuit of this
bacteria? Suppose you engineered a GRN in these bacteria such that the
lithification only occured once a certain gene is activated by laser
stimulation (chromophores?). Using a very specific wavelength of laser
that can get through the atmosphere, you could use a laser in orbit to
do selective laser sintering fabrication with deserts. You could
literally do rapid prototyping of deserts- it would require a
satellite in orbit, which is somewhat of a cost, although less costly
than running a giant 3D printer around on the desert forever (rather
than just positioning some mirrors up in orbit).
"Bacteria Could Steady Buildings Against Earthquakes"
Soil bacteria could be used to help steady buildings against
earthquakes, according to researchers at UC Davis. The microbes can
literally convert loose, sandy soil into rock. When a major earthquake
strikes, deep, sandy soils can turn to liquid, with disastrous
consequences for buildings sitting on them. Currently, civil engineers
can inject chemicals into the soil to bind loose grains together.
But these epoxy chemicals may have toxic effects on soil and water,
said Jason DeJong, an assistant professor of civil and environmental
engineering at UC Davis.
The new process, so far tested only at a laboratory scale, takes
advantage of a natural soil bacterium, Bacillus pasteurii. The microbe
causes calcite (calcium carbonate) to be deposited around sand grains,
cementing them together. By injecting bacterial cultures, additional
nutrients and oxygen, DeJong and his colleagues found that they could
turn loose, liquefiable sand into a solid cylinder.
"Starting from a sand pile, you turn it back into sandstone," DeJong
said. Similar techniques have been used on a smaller scale, for
example, to repair cracks in statues, but not to reinforce soil.
The new method has several advantages, DeJong said. There are no
toxicity problems, compared with chemical methods. The treatment could
be done after construction or on an existing building, and the
structure of the soil is not changed -- some of the void spaces
between grains are just filled in.
DeJong and his collaborators are working on scaling the method up to a
practical size, and applying for funds to test the method in the
earthquake-simulating centrifuge at UC Davis' Center for Geotechnical
Modeling. The centrifuge is part of the national Network for
Earthquake Engineering Simulation, funded by the National Science
A paper describing the work has been published in the Journal of
Geotechnical and Geoenvironmental Engineering. The other authors are
Michael Fritzges, a senior engineer at Langan Engineering,
Philadelphia; and Klaus Nusslein, associate professor of microbiology
at the University of Massachusetts, Amherst. The work was supported by
the National Science Foundation.
Microbially Induced Cementation to Control Sand Response to Undrained Shear
And from another paper-
Applications of microorganisms to geotechnical engineering for
bioclogging and biocementation of soil in situ
"Microbial Geotechnology is a new branch of geotechnical engineering
that deals with the applications of microbiological methods to
geological materials used in engineering. The aim of these
applications is to improve the mechanical properties of soil so that
it will be more suitable for construction or environmental purposes.
Two notable applications, bioclogging and biocementation, have been
explored. Bioclogging is the production of pore-filling materials
through microbial means so that the porosity and hydraulic
conductivity of soil can be reduced. Biocementation is the generation
of particle-binding materials through microbial processes in situ so
that the shear strength of soil can be increased. The most suitable
microorganisms for soil bioclogging or biocementation are facultative
anaerobic and microaerophilic bacteria, although anaerobic fermenting
bacteria, anaerobic respiring bacteria, and obligate aerobic bacteria
may also be suitable to be used in geotechnical engineering. The
majority of the studies on Microbial Geotechnology at present are at
the laboratory stage. Due to the complexity, the applications of
Microbial Geotechnology would require an integration of microbiology,
ecology, geochemistry, and geotechnical engineering knowledge."
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