Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey, USA.
Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, USA.
Microbiol Spectr. 2022 Dec 21;10(6):e0342122. doi: 10.1128/spectrum.03421-22. Epub 2022 Nov 21.
The growth and activity of bacteria have been extensively studied in nearly every environment on Earth, but there have been limited studies focusing on the air. Suspended bacteria (outside of water droplets) may stay in the atmosphere for time frames that could allow for growth on volatile compounds, including the potent greenhouse gas methane. We investigated the ability of aerosolized methanotrophic bacteria to grow on methane in the airborne state in rotating gas-phase bioreactors. The physical half-life of the aerial bacterium-sized particles was 3 days. To assess the potential for airborne growth, gas-phase bioreactors containing the aerosolized cultures were amended with 1,500 ppmv CH or CH. Three of seven experiments demonstrated C incorporation into DNA, indicating growth in air. Bacteria associated with the genera and were detected in C-DNA fractions, thus indicating that they were synthesizing new DNA, suggesting growth in air. We conclude that methanotrophs outside of water droplets in the air can potentially grow under certain conditions. Based on our data, humidity seems to be a major limitation to bacterial growth in air. Furthermore, low biomass levels can pose problems for detecting C-DNA synthesis in our experimental system. Currently, the cellular activities of bacteria in the airborne state outside of water droplets have not been heavily studied. Evidence suggests that these airborne bacteria produce ribosomes and metabolize gaseous compounds. Despite having a potentially important impact on atmospheric chemistry, the ability of bacteria in the air to metabolize substrates such as methane is not well understood. Demonstrating that bacteria in the air can metabolize and grow on substrates will expand knowledge about the potential activities and functions of the atmospheric microbiome. This study provides evidence for DNA synthesis and, ultimately, growth of airborne methanotrophs.
细菌的生长和活性在地球上几乎每一种环境中都得到了广泛的研究，但针对空气的研究却很有限。悬浮细菌（水滴之外的细菌）可能会在大气中停留一段时间，从而有可能在挥发性化合物（包括强效温室气体甲烷）上生长。我们研究了雾化甲烷氧化菌在旋转气相生物反应器中以气溶胶状态在空气中生长甲烷的能力。气载细菌大小颗粒的物理半衰期为 3 天。为了评估空气传播生长的潜力，在含有雾化培养物的气相生物反应器中添加了 1500ppmv CH 或 CH。七个实验中有三个证明了 C 掺入 DNA，表明在空气中生长。在 C-DNA 部分检测到与属 和 相关的细菌，因此表明它们在空气中合成新的 DNA，表明在空气中生长。我们得出结论，空气中水滴之外的甲烷氧化菌在某些条件下可能会生长。根据我们的数据，湿度似乎是细菌在空气中生长的主要限制因素。此外，低生物量水平会给我们的实验系统检测 C-DNA 合成带来问题。目前，尚未对空气中水滴之外的细菌的细胞活动进行大量研究。有证据表明，这些气载细菌会产生核糖体并代谢气态化合物。尽管对大气化学有潜在的重要影响，但空气中细菌代谢甲烷等底物的能力还没有得到很好的理解。证明空气中的细菌可以代谢和生长在基质上，将扩大对大气微生物组潜在活动和功能的认识。本研究为空气传播甲烷氧化菌的 DNA 合成，最终为其生长提供了证据。
