Fluorescent pseudomonads isolated from Hebridean cloud and rain water produce biosurfactants but do not cause ice nucleation
By H. Ahern, K. Walsh, T. Hill, B. Moffett. 2007
87 citations recorded by the source corpus.
Abstract. Microorganisms were discovered in clouds over 100 years ago but information on bacterial community structure and function is limited. Clouds may not only be a niche within which bacteria could thrive but they might also influence dynamic processes using ice nucleating and cloud condensing abilities. Cloud and rain samples were collected from two mountains in the Outer Hebrides, NW Scotland, UK. Community composition was determined using a combination of amplified 16S ribosomal DNA restriction analysis and sequencing. 256 clones yielded 100 operational taxonomic units (OTUs) of which half were related to bacteria from terrestrial psychrophilic environments. Cloud samples were dominated by a mixture of fluorescent Pseudomonas spp., some of which have been reported to be ice nucleators. It was therefore possible that these bacteria were using the ice nucleation (IN) gene to trigger the Bergeron-Findeisen process of raindrop formation as a mechanism for dispersal. In this study the IN gene was not detected in any of the isolates using both polymerase chain reaction (PCR) and differential scanning calorimetry (DSC). Instead 55% of the total isolates from both cloud and rain samples displayed significant biosurfactant activity when analyzed using the drop-collapse technique. All isolates were characterised as fluorescent pseudomonads. Surfactants have been found to be very important in lowering atmospheric critical supersaturations required for the activation of aerosols into cloud condensation nuclei (CCN). It is also known that surfactants influence cloud droplet size and increase cloud lifetime and albedo. Some bacteria are known to act as CCN and so it is conceivable that these fluorescent pseudomonads are using surfactants to facilitate their activation from aerosols into CCN. This would allow water scavenging,~countering desiccation, and assist in their widespread dispersal.
Subfields: Atmospheric Science, Ecology, Ecology, Evolution, Behavior and Systematics
View Paper: https://www.semanticscholar.org/paper/f8016f852f92b606ed0fc9117f6ec62f7594dc68
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Citations in the corpus
- Long-term features of cloud microbiology at the puy de Dôme (France) (2012, background): “So far, the Pseudomonad species isolated from clouds were shown to produce biosurfactant, which could involve them also in the formation of cloud droplets (Ahern et al., 2007).”
- Characterization of primary biogenic aerosol particles in urban, rural, and high-alpine air by DNA sequence and restriction fragment analysis of ribosomal RNA genes (2007, background): “…like pollen, bacteria, spores, viruses, plant and animal fragments (e.g., dandruffs, skin fragments), are all within this size range (Simoneit and Mazurek, 1982; Matthias-Maser and Jaenicke, 1994; Artaxo, 1995; Bauer et al., 2005; Ahern et al., 2007; Elster et al., 2007; Zhang et al., 2007).”