Use of qPCR Coupled With Ethidium Monoazide in Quantifying Viable Bacterial Aerosols in Different Environments

QI CHEN, Maosheng Yao

Peking University

     Abstract Number: 803
     Last modified: July 22, 2011

Abstract
Traditionally, agar culturing method is used to enumerate culturable bioaerosol particles. However, a great portion of the cells are in the state of viable but not culturable (VBNC), and thus such a method would significantly underestimate the bioaerosol load. On the other hand, DNA stain method is limited in estimating the viable fraction due to relatively lower environmental bioaerosol concentrations. Use of qPCR could detect total bioaerosols, but cannot differentiate between live and dead ones. Recent application of ethidium monoazide (EMA) in qPCR greatly broadens its capability in bioaerosol detection. Here, we collected air samples into DI water using a BioStage impactor in three different environments. Agar plates were used to enumerate those culturable bacterial cells, qPCR was used to estimate the total bacterial aerosol concentrations, and EMA-qPCR was applied to quantifying viable bacterial aerosol particles. The results from EMA-qPCR and qPCR were compared to those obtained using a Live/Dead viability assay. Freshly grown pure E. coli cells were used as positive controls for bacterial enumerations. Preliminary data indicated that EMA-qPCR is a more convenient method than those DNA stain methods in enumerating the viable bioaerosol fractions in various environments.