Charles River's mini-lab 'out of this world'

By Dr Matt Wilkinson

- Last updated on GMT

Related tags Charles river

Charles River Laboratories' portable endotoxin testing system, the
Endosafe PTS, has been successfully used to detect bacteria on the
International Space Station (ISS).

The news that Charles River's bacteria detector overcame the various problems of working in zero gravity to accurately identify the presence of bacteria around the ISS was greeted with delight by Dr Norman Wainwright, director of research and development at Charles River Laboratories.

"The ability to monitor microorganisms would be especially important on long space voyages, not only to check on the health of astronauts but also to monitor electronics and structural materials, which can be corroded or otherwise damaged by certain fungi and bacteria," he said.

The Endosafe PTS was launched into orbit on board the space shuttle Discovery to see if it could outperform the slower and more traditional method of detecting bacteria - cell culturing on Petri dishes containing different growth media.

The device is most commonly found in pharmaceutical and biotechnology facilities around the world to test that drug products and packaging are free of bacteria before shipping due to its fast analysis times and ease of use.

While this method can decisively reveal the source of an infection, whether viral or Gram-positive or Gram-negative bacteria, it takes several days before an answer is reached - often too slow for a serious infection or production line.

Pharmaceutical production facilities must be kept stringently clean and ensure that no trace of endotoxins exist in drug product containers as even small amounts can trigger the body's immune response receptors to begin the cytokine reaction that begins the infection inflammation cycle.

The device was licensed for use as a pre-release sterility test by the US Food and Drug Administration (FDA) last summer.

Depyrogenation ovens are commonly used to heat the containers to temperatures in excess of 300ºC to ensure they are germ free and that all traces of endotoxins have been sterilised away.

"In pharmaceutical systems you can imagine that on the production floor you might have several of these portable units taking measurements of inputs, whether it be the water or the raw materials that goes into the product and finding sooner rather than later sources of contamination that could effect the final release," said Wainwright.

The test for bacteria uses a capillary fluidic lab-on-a-chip to pump samples to four enzymes extracted from the blood cells of horseshoe crabs that change colour in the presence of bacteria within 15 minutes.

This assay is known as the Limulus Amebocyte Lysate assay, which can detect very low levels of the endotoxins found in the outer membrane of various Gram-negative bacteria, as well beta-glucans from yeast and mold.

According to Wainwright one of the biggest potential problems was pipetting liquids in zero gravity.

This was cleverly sidestepped by Marshall Space Flight by introducing a swab unit which included a water cartridge built into the swab that would extract the swab and dispense droplets that are pumped into the sensor in a uniform way.

Charles River also supplies a bicinchoninic acid (BCA) test that turns blue in the presence of proteins and while this is primarily aimed at the biotech field, it could also find application at determining whether proteins were present on rocks in space.

Wainwright believes that these applications are just the beginning and the company are in the process of developing more specific test cartridges.

"With each generation of cartridges, we are getting more and more specific in what we detect.

Our ultimate aim is to provide the crew with a selection of cartridges for a wide variety of target compounds, biological and chemical both inside and outside the spacecraft - something that would be especially important for long duration missions to the Moon or to Mars," he said.

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