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Scientists Cram 1,200 Fungal Colonies Onto a Single Microscope Slide

New tech might lead to faster drug testing.
Soon, growing bacteria in petri dishes might become a thing of the past. Photo via USDA

Say so-long to Petri dishes. Scientists at the University of Texas at San Antonio have found a way to grow more than 1,000 individual microbe cultures on one microscope slide, which could vastly improve the speed and ease at which new drugs are tested.

The method uses a commercially-available robot to place 1,200 individual dots of a microbe culture—each less than 100 microliters in volume, which is thousands of times smaller than the cultures generally grown in today's labs—onto a "microarray" that can be studied under a single microscope. The team published their research in mBio.

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The upshot to this? Speed and efficiency: While it takes about 24 hours to grow fungus or bacterial cultures in a test tube or Petri dish, using this method, researchers are shooting to grow them in just six hours. Instead of growing 1,200 copies of the same microbe, they can grow different sets of strains or even combine colonies to test drugs for what are known as polymicrobial infections, or diseases caused by more than one bacteria or fungus.

"In principle, each dot is an individual colony so you can test as many number of drugs as you want to test," Anand Ramasubramanian, one of the researchers, said. "We can do it with bacteria and combos of fungi and bacteria, we can test new antibiotics and antifungals and antimicrobials, we can test on multiple species and strains of an organism. It allows us to do a lot."

The above image shows how the dots of cultures grow over time on nanofilm. For complete caption, visit mBio.

To test whether their method worked, the team grew cultures of Candida albicans, a fungus that is commonly treated with topical antifungals without problem. But when the fungus gets into the bloodstream, which can happen in patients who need catheters, can be deadly. Using three common antifungals, the team found that Candida albicans grown in their microarray were just as scientifically useful as those grown using common methods.

For now, the drawback to the process is cost: Though Ramasubramanian says the technique will eventually save labs money because the prep work and culture growth time is vastly cut using a microarray, the robot needed to set this up costs about $50,000. Typically, microbe colonies are grown by hand, meaning there's low equipment costs. So big pharma companies might spring for the tools needed to do this, but smaller labs almost certainly won't.

With the dismal speed at which we're developing new antibiotics to fight increasingly resistant bugs, lets hope this leads to some new discoveries.