Sarah Vitalk: This is the 60-second science of Scientific American. This is Sarah Vitalk.
Modern medicine and bacterial pathogens are in an arms race. We use antibiotics to stop them. Then they adapt to immunity to these antibiotics and evolve into super bacteria.
This battle is an asymmetrical battle-we just don’t have so many choices in the battle. Most of our antibiotics come from bacteria-most of them come from a single genus: Streptomyces. Most antibiotics use the same few strategies to attack bacteria.
But there is a reason why we only use a small part of the antibiotic chemicals that exist in nature.
Miriam Rosenbaum: In the past 30 years, this kind of exploration of new materials has not been successful. But it is difficult to be sure that we have found an antibiotic-a substance produced by microorganisms that is toxic to other microorganisms but not to humans.
Vitac: Miriam Rosenbaum He is a professor of synthetic biotechnology at the Hansnell Institute in Germany.
But if they are hard to find, how do scientists know that we only found one Very small part Antibiotic substances in nature?
Rosenbaum: We do know this because we have been in the midst of this biological revolution in sequencing for the past 20 years.
Vitac: Researchers like Rosenbaum have taken this revolution underground-literally-like deep into the earth.
Rosenbaum: Therefore, through these environmental sequencing activities, we found that in fact, the microbial world is much larger than we thought. This is how we know that there is only 5% in the laboratory, because we only see the DNA in the soil sample-we see that there is 95%. But where are they? We have no cells. We can know more than their names—or not just their existence. Let’s see what genes they have.
Vitac: They have no cells, because currently only about 1% to 15% of natural bacteria can grow in the laboratory. It’s like swiping your fingerprints in a room, and it turns out that this place is completely covered-and in places where you don’t have an ID card. Moreover, the party is still going on around you, but you cannot see the guests.
What Rosenbaum were able As can be seen from the sequence, these invisible bacteria Do Make more different kinds of antibiotics.
So which bacteria are making them? Is it possible to keep them alive long enough to make IDs? Rosenbaum’s answer: Microscopic bacteria pool party.
Rosenbaum: Slowly, for a long time, our scale has become smaller and smaller. We are now in picoliter-sized droplets, much smaller than the milliliters you can still see or the microliters that you can barely see. It is a million times smaller than a microliter. So these, these picoliter droplets, are now the home of these microorganisms.
Vitalk: Such a microscopic water house.
Rosenbaum: We put a cell into one of the droplets, so each cell has its own house. Then, because they are so small, we can breed millions of such small water drop houses in one experiment. So we took a sample of a few grams of soil-we got millions of bacterial cells, and we put them all in our respective houses. Then we see what growth.
Vitac: The work was published in the journal Electronic life. [Lisa Mahler et al., Highly parallelized droplet cultivation and prioritization of antibiotic producers from natural microbial communities]
They found that they were able to cultivate a completely different set of bacteria compared to bacteria that grow normally using traditional cell culture techniques.
Rosenbaum: So under normal circumstances, we either put them in a shaker bottle, as big as a hand, and then we have some microbial cells, and they basically disappear in the ocean. Or, when they don’t normally grow in this type of environment, we put them on agar plates on solid medium.
Vitac: Giving them their own private space to grow up alone may also help…
Rosenbaum: Let them withdraw from the competition, give them a chance to truly grow, grow without competition, no one will produce antibiotics and fight against them, etc.
Vitalk: Facts have proved that the micro water house is a very flexible incubator. They are small, so you can grow millions together in one test tube, and you can manipulate them. So they can be placed on an agar plate separately to allow bacteria to grow better there. Or they can be used to perform experiments with different conditions in each individual drop.
But the goal has always been to turn them into small antibiotic factories.
Rosenbaum: So we took out all the droplets growing in it, and then we added a light-labeled, fluorescent-labeled indicator bacteria. If these indicator bacteria can grow when added to the droplet, then we will get a light signal-the green or red signal of the droplet.
Vitalk: so Red or green Light From the droplet means that wild bacteria will not produce antibiotics-this will kill the indicator bacteria in the droplet. The color of the light can easily tell them what type of bacteria are still alive.
But one dark The droplet-so no light comes from it-means whether wild bacteria are killing the indicator bacteria Stop it From growing and preventing it from producing light. So it must be producing antibiotics.
Rosenbaum: So we can select all the dark droplets and deposit them. Now we want to acquire these cultures; we want to find people who produce antibiotics. Now we want to remove them from the droplets.
Vitalk: This means they can quickly and easily screen millions of bacteria for antibiotic properties.
In these microscopic bacteria pool parties, humans may have the upper hand in the arms race with super bacteria.
thanks for listening. For the 60-second science of Scientific American, my name is Sarah Vitak.
[The above text is a transcript of this podcast.]