Bioengineers from London’s Imperial College may have found a way of turning regular baker’s yeast into the mini medicine factories of the future.

The team have re-engineered individual yeast cells to produce a special type of the antibiotic penicillin, using natural compounds called ‘nonribosomal peptides’. Usually produced by bacteria and fungi, these natural products form the basis of most modern antibiotics. With the vast array of antibiotics on offer however, many bacteria are developing a resistance to drugs, giving rise to a host of new superbugs. In an effort to beat antimicrobial resistance, engineers must find new ways to create antibiotic drugs.

‘Cut and paste’ genetics

By snipping the DNA out of a penicillin-producing, filamentous fungus and inserting it into yeast cells, the team were able to trick the yeast into performing the same job. Not only did the yeast produce the antibiotic itself, it then expelled the penicillin out of the cell and into the solution around it. As well as saving the team the effort of extracting the antibiotic, this also meant they could easily test to see if it worked. Their initial experiments showed the now bacteria-fighting yeast successfully tackled streptococcus bacteria in the area surrounding it.

Dr Tom Ellis, a researcher in synthetic biology and synthetic genome engineering at Imperial, explained: “Humans have been experimenting with yeast for thousands of years. From brewing beer to getting our bread to rise, and more recently for making compounds like anti-malarial drugs, yeast is the microscopic workhorse behind many processes.”

Alongside its delicious applications in the kitchen, yeast is also remarkably easy to genetically engineer. Simply by cutting and pasting DNA from another organism, yeast can take on that organisms desired behaviours, including making antibiotics.

First, the yeast cells undergo a complex chemical reaction, stitching together the base, or backbone, of the peptide from naturally occurring molecules. Then fungal enzymes, produced by the transplanted fungal DNA, can turn these bases into the active antibiotic.

It’s still early days…

The team is keen, however, to note that the research is still young and so far, only small amounts of antibiotic penicillin have been produced by the yeast. Their next step will be to adapt the process to produce commercially viable quantities of the antibiotic.

Dr Ali Awan, a co-author on the study from Imperial’s Department of Bioengineering explained that fungi have the advantage of millions of years of evolution behind them. “We, scientists, have only been working with yeast in this context for a handful of years,” he said. “But now that we’ve developed the blueprint for coaxing yeast to make penicillin, we are confident we can further refine this method to create novel drugs in the future.”

“Penicillin was first discovered by Sir Alexander Fleming at St Mary’s Hospital Medical School, which is now part of Imperial,” added Dr Ellis. “He also predicted the rise of antibiotic resistance soon after making his discovery. We hope, in some small way, to build on his legacy, collaborating with industry and academia to develop the next generation of antibiotics using synthetic biology techniques.”

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