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This is bacteria growing after being frozen. Photo: University of Warwick

Researchers at the University of Warwick have found that synthetic reproductions of antifreeze proteins found in polar fish can be used to cryopreserve, or 'freeze' bacteria. This revolutionary approach was found to be more effective than the current industry standard.

The findings could radically improve storage and transportation of human organs, food and medicine, and advance laboratory research.

Researchers from the Department of Chemistry and Warwick Medical School established a way to cryopreserve (or 'freeze') a broad range of bacteria using synthetic reproductions of the natural antifreeze proteins found in polar organisms.

The team found that adding the protein mimics slows ice crystal growth, and stops them destroying the bacteria cells.

Bacteria are used in a vast range of processes including food technology (e.g. in yogurt and probiotics), pharmaceutical manufacturing (e.g. insulin) and enzyme production (e.g. for washing powders), and they are routinely used in research labs to study infection and the fundamentals of living processes.

The traditional approach to preserve bacteria, used in nearly every laboratory worldwide, is to add glycerol to the bacteria to reduce cold-induced damage during freezing. However, not all the bacteria recover after thawing and the glycerol needs to be removed from the bacteria to enable their growth and usefulness.

The Warwick team, led by Matthew Gibson, from Warwick's Department of Chemistry and Warwick Medical School, have developed a new method for cryopreservation, inspired by the process that organisms, known as extremophiles, use to survive in some of the coldest regions on Earth.

The group have a particular interest in the polar fish species that produce antifreeze proteins. The research team demonstrated that synthetic polymers that mimic the protein from these fish are effective in doing the same job.

By combining two polymers to slow ice growth during cryopreservation, the researchers were able to recover more bacteria after freezing than using conventional methods.

They also used less total additives, in some cases using just 1 percent of weight (compared to the 20 percent used in traditional methods).

The team believes this will transform how micro-organisms are cryopreserved, and will build on their previous research into storing human cells.

"Bacteria underpin a vast amount of basic biosciences and health research, but their storage and transport is based on an old method," Gibson said. "Our bio-inspired solutions, which we have also used for mammalian cell storage, provide a new platform to hopefully improve the availability and quality of bacteria, but with an easy-to-use approach which does not involve researchers or industries significantly adjusting their laboratory procedures."

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