The Earth’s atmosphere plays a critical role in transporting and dispersing biological aerosols. Nevertheless, the amount of microbial biomass in suspension in the air is so low that it is extremely difficult to monitor the changes over time in these communities. Real-time genomic studies can provide a sensitive and rapid method for monitoring changes in the composition of bioaerosols. However, the low abundance of deoxyribose nucleic acid (DNA) and proteins in the atmosphere, which is of the order of the contamination produced by operators and instruments, poses a challenge for the sampling process and the analyte extraction. In this study, we designed an optimized, portable, closed bioaerosol sampler based on membrane filters using commercial off-the-shelf components, demonstrating its end-to-end operation. This sampler can operate autonomously outdoors for a prolonged time, capturing ambient bioaerosols and avoiding user contamination. We first performed a comparative analysis in a controlled environment to select the optimal active membrane filter based on its ability to capture and extract DNA. We have designed a bioaerosol chamber for this purpose and tested three commercial DNA extraction kits. The bioaerosol sampler was tested outdoors in a representative environment and run for 24 h at 150 L/min. Our methodology suggests that a 0.22-µm polyether sulfone (PES) membrane filter can recover up to 4 ng of DNA in this period, sufficient for genomic applications. This system, along with the robust extraction protocol, can be automated for continuous environmental monitoring to gain insights into the time evolution of microbial communities within the air.
The project was funded by the ‘Internal funding to Pump-prime Interdisciplinary Research and Impact Activities’ from the University of Aberdeen granted to T.M. J.B.R. is supported by QUADRAT NERC Doctoral Training Partnership, UKRI. M.-P.Z. was supported by grant PID2019-104205GB-C21 funded by MCIN/AEI/10.13039/501100011033.
The paper’s authors would like to acknowledge the support from the Allan and Norma Young Foundation. The paper’s authors would like to acknowledge the Microscopy and Histology Core Facility at the Institute of Medical Sciences, University of Aberdeen, for the sample preparation and training for scanning electron microscopy (SEM) images.
- active sampling
- commercial off-the shelf (COTS)
- DNA extraction