Fig 1. Sampling duration experiments for microorganisms collected on filters.

(a)–Comparison of 1×24 hour versus 3×8 hour parallel sampling. Two sets of sampling trains collected air at the same time and location for 24 hours. The first set sampled the air continuously for 24 hours on a single filter, while the other set’s filter was replaced every 8 hours. DNA extracted from the three 8-h filters was then pooled and the result is compared with the first set which was extracted alone. (b)–Testing loss of GFP-tagged bacteria during sampling. A set of filters sampled air at the same time and location for a total duration of 20 hours. Known quanta of GFP-tagged S. oneidensis cells were spiked onto the filters at staggered timepoints, exposing them to different durations of air sampling.