Characterizing phylogenetic diversity in airborne bacterial populations in China

ZAHRA CHAUDHRY (1), Joshua Santarpia (1), J. Vanderlei Martins (2)

(1) JHU Applied Physics Lab, Laurel, MD (2) University of Maryland, Baltimore County, MD

     Abstract Number: 717
     Last modified: May 14, 2010

Abstract
Considering the importance of its potential implications for human health, agricultural productivity, and ecosystem stability, surprisingly little is known regarding the composition or dynamics of the atmosphere’s biological aerosol community. The few studies that have examined phylogenetic diversity in China focused on a single sampling period, whereas this study spans 3 months and includes over 300 samples. Using Phylochips, a microarray designed for comprehensive identification of bacterial organisms, we examined samples collected in Xianghe, China from July-September 2008. Aerosols were collected on Nuclepore filters downstream of a PM10 impactor. Samples were scheduled for 8-hour collection windows and 48-hour back-trajectories were calculated using NOAA’s Hysplit Model. The 300+ samples were categorized by month and direction of their back-trajectory. DNA extraction was carried out on the pooled samples in a quantitative manner to allow for comparison between the amount of extracted material and the amount of initial total aerosol mass. On average, 8% of the original total aerosol sample was measured to be nucleic acid via Nanodrop, but that value ranged from 2-20%. PCR was utilized to achieve the necessary amount of 16s rRNA to hybridize to the Phylochips. Within an individual month, samples originating from similar land types and about equidistant to the sampling location exhibited similar diversity, whereas samples originating from much further distances and from different land types included phyla unique to that location. We also observed variability in the phyla from the same origin from one month to the next. The biological diversity found from the Phylochips reinforces the notion that air samples carry a biological record of their history.