Abstract View
Application of DNA-Stable Isotope Probing to Study Airborne Methanotrophs
KEVIN DILLON, Valdis Krumins, Aishwarya Deshpande, Lee Kerkhof, Gediminas Mainelis, Donna Fennell, Rutgers, The State University of New Jersey
Abstract Number: 225
Working Group: Bioaerosols
Abstract
The growth and activity of bacteria have been heavily studied in nearly every environment on Earth, but there have been limited studies focusing on the air. Bacteria can be suspended in the air for a long enough time such that substrate metabolism and growth could occur. Previous studies have noted the presence of active bacteria in the air. This activity suggests the potential for microbes to grow in the air outside of water droplets on volatile compounds such as CH4. To examine airborne microbial communities, we aerosolized enrichment cultures of methane-oxidizing bacteria (methanotrophs) into 320 L rotating gas-phase bioreactors and assessed the half-lives and distributions of the particles. We investigated the ability of airborne methanotrophs to grow on CH4 using DNA-stable isotope probing (DNA-SIP). The cultures were aerosolized into gas-phase bioreactors and amended with 1500 ppmv 13CH4 or 12CH4. The cells were suspended in the air for five days, harvested, and analyzed for 13C incorporation into DNA by gradient fractionation/qPCR methods. Based on our data, low biomass is the main limitation for utilizing the DNA-SIP method for detecting activity of airborne methanotrophs. However, some results demonstrated 13C incorporation into DNA, indicating growth in air, while other experimental replicates did not. Specifically, one replicate demonstrated that members of the family Methylococcaceae metabolized and grew on CH4 while in the airborne state. We conclude that methanotrophs outside of water droplets in the air can potentially grow under certain conditions. Future work will further investigate the metabolic potential of bacteria outside of water droplets in the air.