This laboratory contamination study was conducted in the United Kingdom. The client in this contamination study is an international, UK headquartered company, developing, manufacturing and marketing a wide range of specialized bio-research reagents that simplify, accelerate and improve life sciences research. The Genano 310 unit is used in one of their UK based laboratories, to keep the air quality acceptable for use in their quality control laboratory.
An experiment was set up to test for the laboratory’s’ contamination of commonly used DNA fragments. A technique known as qPCR (quantitative Polymerase Chain Reaction) was used to test the samples for the presence of any contaminating DNA fragments. Samples were collected from the outlet of Genano 310 air purifier to determine the unit’s ability to clean the air to keep the air quality level acceptable for the quality control laboratory.
qPCR (quantitative Polymerase Chain Reaction), also known as a real-time polymerase chain reaction (Real-Time PCR) technique is used to amplify and measure very specific fragments of DNA. It monitors the amplification of a targeted DNA molecule during the PCR, i.e. in real-time, and not at its end, as in conventional PCR. Real-time PCR can be used quantitatively (quantitative real-time PCR), and semi-quantitatively (semi quantitative real-time PCR). (Pfaffl et. al., 2004)
qPCR can also be applied to the detection and quantification of DNA in samples to determine the presence and abundance of a particular DNA sequence in these samples (Watson et. al., 2004). The samples of this study were tested for the presence of any contaminating DNA fragments. After the amplification, the assay performed a melt curve analysis of any amplified DNA product. This melt curve analysis is used to determine if any contaminating DNA is present. When testing the samples, the samples were run against positive and negative controls to show evidence of potential contamination.
Figure 1: Melt curve analysis of 3 primer sets.
A: Primer set 1 with positive (black) and negative (light blue) samples only. B: Primer set 1 with positive and negative samples overlaid with test samples.
C: Primer set 2 with positive (black) and negative (light blue) samples only. D: Primer set 2 with positive and negative samples overlaid with test samples.
E: Primer set 3 with positive (black) and negative (light blue) samples only. F: Primer set 3 with positive and negative samples overlaid with test samples.
The melt curve is a particular use of the qPCR assay designed to look at the melting point of the product formed during amplification. The positive controls in each primer set show a specific peak at the melting temperature of the correct product. The negative controls in each primer set show how the melt peak looks when no target DNA is present. Any peaks in the negative control will be expected to differ from the peaks in the positive control and show up any non-specific amplification products.
In all cases, the samples did not produce any specific product when overlaid onto the positive controls. This is a very strong indication that contaminants were not detected in the laboratory environment after processing the air through Genano 310.
For this study the company had an Genano 310 air purifier for a 6 months rental period. Based on the successful results of the study, the company has now purchased Genano 310 for their permanent use.
Pfaffl, M.W., Tichopad, A., Prgomet, C. et al. Biotechnology Letters (2004) 26: 509. https://doi.org/10.1023/B:BILE.0000019559.84305.47
Watson, J D; Baker, T A; Bell, S P; Gann, A; Levine, M; Losick, R (2004). Molecular Biology of the Gene (Fifth ed.). San Francisco: Benjamin Cummings. ISBN 0-321-22368-3.