Sometimes, the smallest of things have the biggest impact on our lives. Bacteria inundate every crevice of every larger crevice of our existence. They sustain us, enrich us, immunize us, and sometimes, they kill us. It’s really hard to consider yourself a “top-predator” and all-conquering master of the universe while also recognizing your utter dependence on organisms that can literally number in the millions along the edges of your fingernails.
However, these kinds of numbers also make it hard for us to study individual bacterium. The masses obfuscate the individual. We treat bacteria as a collective, discuss them as a collective and assign their traits as a collective. In fact, most non-biologists probably don’t even realize that the singular form for bacteria is bacterium. But not all bacterium are the same. In our 50-year war against bacterial disease, scientists and doctors have come to realize that some of the bacterium in a culture are different, more…resilient…persistent even.
These “persister” bacterium appear to have some sort of natural resistance to antibiotics, despite being nearly identical to the rest of the colony. But it can be devilishly hard to study persisters since they usually account for a tiny fraction of the total culture and they’re indistinguishable from the whole. This seems like a problem just begging for innovation and invention. So somebody complied.
A group from the engineering department of the University of Japan, led by Hiroyuki Noji, created a femtoliter droplet array system to study individual bacterium cells, explaining their system recently in the Frontiers of Microbiology. (Yes, femtoliter…that’s 10-15 of a liter, 1 billion times smaller than a µl (microliter)!) I can’t even begin to understand some of the engineering that went into building their amazingly tiny “plate”, but the end result was that they were able to monitor individual bacterium grow and replication, even under the selective pressure of antibiotics such as Carbenicillin.
Imagine using a system like this to develop drug treatments or programs in which you can know, statistically, the efficacy of any one treatment versus any bacterial strain. Imagine the convenience of a dose response curve that illustrates the exact limit which is necessary to kill off persisters. Imagine being able to see acquired bacterial immunity as its happening, cell by cell. There are just so many tangible benefits from a system such as this. Hats off to Dr. Noji’s group for creating this fantastic, engineering marvel! I look forward to awesome discoveries using the femtoliter droplet array in the future.
Iino, R., Matsumoto, Y., Nishino, K., Yamaguchi, A., & Noji, H. (2013). Design of a large-scale femtoliter droplet array for single-cell analysis of drug-tolerant and drug-resistant bacteria. Frontiers in microbiology, 4.
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