Disgusting Biodiversity: surprising reason your kitchen sponge is a bacterial incubator
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| Researchers have discovered that a sponge’s structure mimics that of soil to produce an environment more hospitable to microbial diversity than most laboratory equipment. |
Environmental structure affects interactions between microbial species, making the common kitchen sponge a better incubator for bacterial diversity than a laboratory Petri dish.
But it’s not just the trapped leftovers that make the
cornucopia of microbes swarming around so happy and productive, it’s the
structure of the sponge itself.
In a series of experiments, the scientists show how various microbial species can affect one another’s population dynamics depending on factors of their structural environment such as complexity and size.
Some bacteria thrive in a
diverse community while others prefer a solitary existence. And a physical
environment that allows both kinds to live their best lives leads to the
strongest levels of biodiversity.
Soil
provides this sort of optimal mixed-housing environment, and so does your
kitchen sponge.
The
Duke biomedical engineers say their results suggest that structural
environments should be taken into account by industries that use bacteria to
accomplish tasks such as cleaning up pollution or producing commercial
products.
The results were published online on February 9, 2022, in the journal Nature Chemical Biology.
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| These different species of bacteria — each engineered to glow a different color so researchers can track their growth — are thriving in harmony with one another thanks to their structured environment. Credit: Andrea Weiss, Zach Holmes and Yuanchi Ha, Duke University |
Bacteria
are just like people living through the pandemic — some find it difficult being
isolated while others thrive,” said Lingchong You, professor of biomedical
engineering at Duke. “We’ve demonstrated that in a complex community that has
both positive and negative interactions between species, there is an
intermediate amount of integration that will maximize its overall coexistence.”
Microbial
communities mix in varying degrees throughout nature. Soil provides many nooks
and crannies for different populations to grow without much interaction from
their neighbors. The same can be said for individual droplets of water on the
tops of leaves.
But when humans throw many bacterial species together into a structureless goop to produce commodities like alcohol, biofuel, and medications, it’s usually on a plate or even a big vat. In their experiments, You and his laboratory show why these industrial efforts may be wise to begin taking a structural approach to their manufacturing efforts.
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| These different species of bacteria — each engineered to glow a different color so researchers can track their growth — are thriving in harmony with one another thanks to their structured environment. Credit: Andrea Weiss, Zach Holmes and Yuanchi Ha, Duke University |
The
researchers barcoded about 80 different strains of E. coli so that they could track their population
growth. Then they mixed the bacteria in various combinations on laboratory
growth plates with a wide variety of potential living spaces ranging from six
large wells to 1,536 tiny wells. The large wells approximated environments in
which microbial species can mix freely, while the small wells mimicked spaces
where species could keep to themselves.
Regardless
of the habitat sizes, the results were the same. The small wells that began
with a handful of species wound up evolving into a community with only one or
two strains surviving. Similarly, the large wells that began with a broad range
of biodiversity also ended the experiment with only one or two species
remaining.
“The
small portioning really hurt the species that depend on interactions with other
species to survive, while the large portioning eliminated the members that
suffer from these interactions (the loners),” You said. “But the intermediate
portioning allowed a maximum diversity of survivors in the microbial
community.”
The
results, You says, create a framework for researchers working with diverse
bacterial communities to begin testing what structural environments might work
best for their pursuits. They also point toward why a kitchen sponge is such a
useful habitat for microbes. It mimics the different degrees of separation
found in healthy soil, providing different layers of separation combined with
different sizes of communal spaces.
To
prove this point, the researchers also ran their experiment with a strip of
regular household sponge. The results showed that it’s an even better incubator
of microbial diversity than any of the laboratory equipment they tested.
“As
it turns out, a sponge is a very simple way to implement multilevel portioning
to enhance the overall microbial community,” You said. “Maybe that’s why it’s a
really dirty thing — the structure of a sponge just makes a perfect home for
microbes.”
Reference:
“Modulation of microbial community dynamics by spatial partitioning” by Feilun
Wu, Yuanchi Ha, Andrea Weiss, Meidi Wang, Jeffrey Letourneau, Shangying Wang,
Nan Luo, Shuquan Huang, Charlotte T. Lee, Lawrence A. David and Lingchong You,
10 February 2022, Nature Chemical Biology.
DOI: 10.1038/s41589-021-00961-w
This
research was supported by the National Institutes of Health (R01GM098642,
R01GM110494), the National Science Foundation (MCB-1412459, MCB-1937259; DEB
1257882), the Office of Naval Research (N00014-12-1-0631) and the Army Research
Office (W911NF-14-1-0490).
