AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Release of Bioaerosol Genomic DNA Due to Membrane Damage During Aerosolization and Sampling
HUAJUN ZHEN, Taewon Han, Donna Fennell, Gediminas Mainelis, Rutgers, The State University of New Jersey
Abstract Number: 452 Working Group: Health Related Aerosols
Abstract Bioaerosol particles are exposed to great stresses during aerosolization and sampling, which results in rapid loss of viability. Here we demonstrate for the first time that the stress due to aerosolization and sampling could be so strong that it damages cell membranes of the bioaerosol particles resulting in the release of their genomic DNA.
We investigated cell membrane damage of gram-negative Escherichia coli and gram-positive Bacillus atrophaeus bacteria for different aerosolization and sampling methods. The cells with their membranes intact and the damaged cells in each sample were quantified by epifluorescence microscopy and quantitative polymerase chain reaction (qPCR), respectively. The results are reported as a ratio of the DNA quantity released due to cell damage with the DNA quantity remaining within the intact cells.
When E. coli culture suspension was aerosolized by a Collison nebulizer, the ratios were found to significantly increase over 60 minutes. The use of the Collison nebulizer with a polycarbonate jar instead of a glass jar reduced the ratio from 0.17 ± 0.080 to 0.093 ± 0.032. For E. coli collected for five-minute with Button Aerosol Sampler, Anderson Impactor and BioSampler, the ratios had ranges of 0.054-0.094, 0.19-0.58 and 0.06-0.32, respectively. Application of our new electrostatic collector is expected to yield low ratios due to low stress. B. atrophaeus had similar amount of membrane damage when sampled by Button Aerosol Sampler and BioSampler, but significantly lower than E. coli when sampled by Anderson Impactor. The magnitude of cell membrane damage to bioaerosols aerosolized by C-Flow PFA concentric nebulizer, Liquid Sparging Aerosolizer and Single-Pass Aerosolizer is under investigation.
Our results strongly suggest that quantification of microorganisms using the methods that rely on intact cells would underestimate bioaerosol concentrations. It also provides guidance for selecting optimal aerosolization and sampling methods to preserve the physiological status of microorganisms.