Foto: RizaldyMusa – stock.adobe.com
Collectors for airborne germ are normally used in companies producing pharmaceuticals. Only one company worldwide produces gelatine membrane filters for these germ collection processes: Membrane filters produced by Sartorius are so outstanding that NASA even uses them for its microbiological analyses in the space station.
Membrane filters extract organisms from the air – these are usually living or inactive bacteria or fungi whose genetic material consists of DNA. For subsequent molecular genetic analysis, the sampling procedure itself must avoid introducing DNA that might falsify the result. This is possible with the airborne germ collection method, which uses gelatine membrane filters. As a result, all the germs collected can be examined reliably using molecular genetics. In the same way, the air purity in the International Space Station (ISS) can be monitored specifically by molecular genetics via polymerase chain reaction (PCR) or generally by sequencing.
The Sartorius MD8 Airscan portfolio for the continuous collection of airborne germs.
Gelatine membrane filters retain the required membrane properties for hours.
“As an alternative to molecular air monitoring, we are also investigating cultivation-based detection,” explains Kai Nesemann, Product Manager for Microbiology at Sartorius. In order to detect airborne germs, a defined amount of ambient air is sucked in with the collection device. The microbes adhere to the membrane and can then be transferred to a culture medium.
The big advantage is that this makes it possible to represent long-term and ongoing air collection. Because in order to control a low-germ environment with respect to microbiological quality, a lot of air has to be collected. Every other manufacturer uses agar plates for this process, to which the microbes adhere. However, when air flows onto agar plates, they dry out after 12 to 15 minutes. After that, the microbes no longer stick reliably to the agar and cannot therefore be detected. The necessity of frequently changing the plates in a completely clean room in turn poses the risk of contamination every time.
The germ collection process with gelatine, on the other hand, has an enormous advantage: you can turn on the “vacuum cleaner” and let the airborne germ collector with a membrane filter run for hours. It is not until eight hours later that the filter slowly loses the necessary membrane properties. The gelatine can then be dissolved in a small amount of water for examination, just as easily as in baking with gelatine, or placed directly on a nutrient agar.
It is no surprise that the cooperation between Sartorius and GELITA has been in place for such a long time, as Nesemann emphasizes: “We are the only supplier to offer these membrane filters, and are very happy to have such a reliable supplier behind us. Such a supplier is impossible to replace”.