‘Little-game’ hunters (Day 84)

Most of us are familiar and fascinated with ‘big-game’ animals like rhinos, elephants and tigers. Thankfully, they are now protected animals and their numbers have stabilised, but remain perilously low. For instance only around 3,000 tigers remain the in the wild.

By contrast, there are tens of millions of species of bacteria living in the wild. But even these are hard to capture and some are just as elusive as a Siberian Tiger.

Pandas are not the only animals difficult to breed in captivity – ‘wild’ bacteria pose similar problems.

Finding ‘wild bacteria’ is a major challenge. And it’s not just their small size that’s a problem. A bit like getting a panda to breed in a zoo, the overwhelming majority of microbes refuse to grow in the laboratory. This is despite decades of sci­en­tists’ best efforts to coax the microscopic organisms into action.

Queue the ‘little-game’ hunters like Slava Epstein, a biology professor at Northeastern University, who has dedicated his career to coming up with alternative methods for cultivating bacteria.

His favorite strategy is to take the lab bench into the wild. In nature, bac­teria are exposed to a host of nutrients and supportive chemicals that help them grow. But scientists don’t know which ones.

Rather than hunting rifles, Slava uses devices which incor­po­rate per­me­able mem­branes that allow sequestered bacteria to be exposed to the nutri­ents and mol­e­cules of their native environment.

But even this approach has limitations. Nat­ural com­pe­ti­tion between species, even in the wild, has restricted the number of species Epstein can suc­cess­fully iso­late this way. A few years ago he and his col­lab­o­rator Yoshiteru Aoi at Hiroshima Uni­ver­sity in Japan began to fan­ta­sise about a device that would permit just a single bac­te­rial cell to enter. Once inside, this cell would pro­lif­erate as in his other devices, but here it would be free of com­pe­ti­tion from other species. It would pro­vide a pure sample—just one species.

Ed Goluch
DiPietro Assistant Professor of Chemical Engineering Ed Goluch has developed a device that could allow microbiologists to isolate previously uncultivable bacteria from the wild. Photo by Brooks Canaday.

The answer to this challenge has come from a chemical engineer. Edgar Goluch, DiP­i­etro assis­tant pro­fessor in the Depart­ment of Chem­ical Engi­neering at North­eastern found the solution.

Ed’s lab is focused on cre­ating microflu­idic devices for detecting var­ious bio­log­ical enti­ties, be it a bac­te­rial cell or an enzy­matic mol­e­cule. In 2012, he and Epstein teamed up to make a series of pro­to­type devices.

Ed explains his device like this: “Think of a five lane highway going down to one lane. That’s essen­tially what this does only for bac­teria.”

The tiny device con­sists of an inner chamber con­taining a food source, to which the only access is a micro­scopic pas­sageway just slightly nar­rower than a single cell.

The pas­sageway is so small that the first cell to enter it gets stuck, blocking entry by any other cell or species. The trapped cell is still able to pro­lif­erate, how­ever, and when it does it fills up the inner chamber with a pure, single-​​species sample. Who­ever gets there first wins and gets all the stuff inside.

Slava explains how the devices can be used: “We’d like to throw these into any envi­ron­ment on the planet…the deep ocean, under the soil, into a pond… we don’t have to do any­thing, just build the devices and throw them into the envi­ron­ment. Nature does the rest.”

In order to reach that kind of range, Ed is working with a number of industry part­ners to stream­line and scale the fab­ri­ca­tion process.

Slava and his team are already testing the pro­to­types in Green­land for their first taste of real-​​world experimentation. And to quote Slava: ““Without Ed…we wouldn’t have been able to do anything.” Sound familiar to all you chemical engineers out there? Good luck with the ‘little-game’ hunting.

One thought on “‘Little-game’ hunters (Day 84)”

  1. This could be a real benefit in understanding bacteria and how we can protect human health.


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