3 ms·

(Paraphrasing because of my limited understanding of what my wife did) The biological pathway that makes them eat plastic is pretty card to keep activated. It'

(Paraphrasing because of my limited understanding of what my wife did) The biological pathway that makes them eat plastic is pretty card to keep activated. It's not a very profitable pathway, so the bugs tend to try eating other stuff if there is even a little available, or they are even a little outside the optimal range for eating plastic.

highfrequency 7y ago
Interesting stuff, would love to hear more intuition about why this is difficult. Is it just that we haven't found an economical pathway for metabolizing plastics, or is there a fundamental reason why one should not exist? Hydrocarbons have an energy density 2-3x higher than glucose, so naively it seems like there should be a profitable metabolic pathway!
- zinclozenge 7y ago
  Hydrocarbons are extremely stable, which means it requires a large energy input to break them up. The article doesn't go into a lot of detail, but my guess is that the bacteria can break up the carbamate links.
- Ductapemaster 7y ago
  As a basic analogy, think of it like human metabolism burning fat vs. carbohydrates. Fat is much more energy dense, but until you starve the body of carbohydrates, your body won't burn it. This pathway likely exists as a "backup" metabolic system so that in the absence of easy-to-digest feedstocks, the microbe can still live, but at an energetic cost.
elcritch 7y ago
Wonder if CRISPR or similar could be used to knock out regular metabolism pathways. Seems like they'd be understood enough to do so effectively.
- Supermancho 7y ago
  Once those microbes become efficient, say goodbye to specific plastics as a durable material for regular use. The microbes wouldn't know the difference between trash and in-use material.
  - GenerocUsername 7y ago
    Unless the metabolic pathway requires some super-specific and limited resource, thus garbage facilities could supply the catalyst and the microbes would begin consuming the plastics. Essentially none would survive outside designated plastic eating situations. Until ... life finds a way ...
    - elcritch 7y ago
      Given that this pathway is inefficient and plastics aren’t an inefficient food mechanism it seems likely even without a specific limiter it’d be hard for the bacteria to spread widely. Similar to the bacteria that termites host which decompose cellulose. But then again maybe plastic eating termites would co-evolve with such a bacteria. That’s creepy to think about. “My tv got eaten by plastic termites”... As you say life often finds a way.
    - TeMPOraL 7y ago
      > Until ... life finds a way ... In particular, a mutation that drops the need for catalyst turns out to be metabolically beneficial.
  - mr-ron 7y ago
    Pretty sure they alude to that in Ringworld
  - kortex 7y ago
    Plastics are very chemically difficult to degrade. The nearest biological polymer is probably lignin, and even though it's part of a very porous matrix, it still takes years to break down. I'm not too worried about PE, PET, PU, or nylon "rotting"

highfrequency 7y ago

Interesting stuff, would love to hear more intuition about why this is difficult. Is it just that we haven't found an economical pathway for metabolizing plastics, or is there a fundamental reason why one should not exist? Hydrocarbons have an energy density 2-3x higher than glucose, so naively it seems like there should be a profitable metabolic pathway!

zinclozenge 7y ago
Hydrocarbons are extremely stable, which means it requires a large energy input to break them up. The article doesn't go into a lot of detail, but my guess is that the bacteria can break up the carbamate links.
Ductapemaster 7y ago
As a basic analogy, think of it like human metabolism burning fat vs. carbohydrates. Fat is much more energy dense, but until you starve the body of carbohydrates, your body won't burn it. This pathway likely exists as a "backup" metabolic system so that in the absence of easy-to-digest feedstocks, the microbe can still live, but at an energetic cost.

elcritch 7y ago

Wonder if CRISPR or similar could be used to knock out regular metabolism pathways. Seems like they'd be understood enough to do so effectively.

Supermancho 7y ago
Once those microbes become efficient, say goodbye to specific plastics as a durable material for regular use. The microbes wouldn't know the difference between trash and in-use material.
- GenerocUsername 7y ago
  Unless the metabolic pathway requires some super-specific and limited resource, thus garbage facilities could supply the catalyst and the microbes would begin consuming the plastics. Essentially none would survive outside designated plastic eating situations. Until ... life finds a way ...
  - elcritch 7y ago
    Given that this pathway is inefficient and plastics aren’t an inefficient food mechanism it seems likely even without a specific limiter it’d be hard for the bacteria to spread widely. Similar to the bacteria that termites host which decompose cellulose. But then again maybe plastic eating termites would co-evolve with such a bacteria. That’s creepy to think about. “My tv got eaten by plastic termites”... As you say life often finds a way.
  - TeMPOraL 7y ago
    > Until ... life finds a way ... In particular, a mutation that drops the need for catalyst turns out to be metabolically beneficial.
- mr-ron 7y ago
  Pretty sure they alude to that in Ringworld
- kortex 7y ago
  Plastics are very chemically difficult to degrade. The nearest biological polymer is probably lignin, and even though it's part of a very porous matrix, it still takes years to break down. I'm not too worried about PE, PET, PU, or nylon "rotting"