Standardized microbial mock community against pandemic threats

Abstract

Microbial monitoring has become an increasing and essential research interest particularly due to the global SARS-CoV-2 pandemic. Predominantly affected was public transportation, which is a mean of transportation used by millions of people on a daily basis. Mass transit systems represent confined rooms, where transmission of infectious diseases through bioaerosols and surfaces is facilitated. To this date, no authentic, microbial enriched bioaerosol has been used and tested for aerosol distribution research. In this study, an artificial microbial mock community was developed, that consists of surrogates from human-associated bacteria that have been found in the airplane cabin (based on Weiss et al. 2019). For technically safe usage in field studies, it was inactivated by high dose X-Ray irradiation. We aimed it to be highly reproducible; for this reason it consists of commercially available bacterial type strains. Among others, low temperature shelf life and desiccation stress testing was performed as with both X-Ray irradiated and unirradiated mock communities. For analysis, 16S amplicon rRNA sequencing was performed by two independent facilities. The obtained results from amplicon sequencing conducted in two individual sequencing facilities showed that the abundances within the mock communities were similarly distributed, but did not completely match. That observation was made for almost all treatments, which proves that significant abundance shifts can be well detected by 16S rRNA sequencing. After desiccation, the mock community was still detectable with similar abundances as the control. Moreover, testing the stability of the mock community at 4°C over one week, a good shelf life was observed. The findings build a foundation for future studies in interdisciplinary aerosol research, using the developed microbial mock community as a biological tool for various studies in applied bioaerosol research as well as for technical improvement studies. It represents a realistic, yet safe and reproducible product used in bioaerosol research for pandemic research, contributing to the development of optimized ventilation systems, or as reference for the evaluation of decontamination methods.