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Title: Comprehensive characterization of an aspen ( Populus tremuloides ) leaf litter sample that maintained ice nucleation activity for 48 years
Abstract. Decaying vegetation was determined to be a potentially important source ofatmospheric ice nucleation particles (INPs) in the early 1970s. The bacteriumPseudomonas syringae was the first microorganism with ice nucleationactivity (INA) isolated from decaying leaf litter in 1974. However, the icenucleation characteristics of P. syringae are not compatible withthe characteristics of leaf litter-derived INPs since the latter were foundto be sub-micron in size, while INA of P. syringae depends on muchlarger intact bacterial cells. Here we determined the cumulative icenucleation spectrum and microbial community composition of the historic leaflitter sample 70-S-14 collected in 1970 that conserved INA for 48 years. Themajority of the leaf litter-derived INPs were confirmed to be sub-micron insize and to be sensitive to boiling. Culture-independent microbial communityanalysis only identified Pseudomonas as potential INA.Culture-dependent analysis identified one P. syringae isolate, twoisolates of the bacterial species Pantoea ananatis, and one fungalisolate of Mortierella alpina as having INA among 1170 bacterialcolonies and 277 fungal isolates, respectively. Both Pa. ananatisand M. alpina are organisms that produce heat-sensitive sub-micronINPs. They are thus both likely sources of the INPs present in sample 70-S-14and may represent important terrestrial sources of atmospheric INPs, aconclusion that is in line with other recent results obtained in regard toINPs from soil, precipitation, and the atmosphere. more »« less
Yang, Shu; Vinatzer, Boris A.
(, Microbiology Resource Announcements)
Bruno, Vincent
(Ed.)
ABSTRACT Mortierella alpina is a filamentous fungus commonly associated with soil and is one of very few fungal species known to include strains with ice nucleation activity. Here, we report the draft genome sequence of the ice nucleation-active M. alpina strain LL118, isolated from aspen leaf litter collected in Alberta, Canada.
Wolf, Martin J.; Zhang, Yue; Zawadowicz, Maria A.; Goodell, Megan; Froyd, Karl; Freney, Evelyn; Sellegri, Karine; Rösch, Michael; Cui, Tianqu; Winter, Margaux; et al
(, Nature Communications)
null
(Ed.)
Abstract Atmospheric ice nucleating particles (INPs) influence global climate by altering cloud formation, lifetime, and precipitation efficiency. The role of secondary organic aerosol (SOA) material as a source of INPs in the ambient atmosphere has not been well defined. Here, we demonstrate the potential for biogenic SOA to activate as depositional INPs in the upper troposphere by combining field measurements with laboratory experiments. Ambient INPs were measured in a remote mountaintop location at –46 °C and an ice supersaturation of 30% with concentrations ranging from 0.1 to 70 L –1 . Concentrations of depositional INPs were positively correlated with the mass fractions and loadings of isoprene-derived secondary organic aerosols. Compositional analysis of ice residuals showed that ambient particles with isoprene-derived SOA material can act as depositional ice nuclei. Laboratory experiments further demonstrated the ability of isoprene-derived SOA to nucleate ice under a range of atmospheric conditions. We further show that ambient concentrations of isoprene-derived SOA can be competitive with other INP sources. This demonstrates that isoprene and potentially other biogenically-derived SOA materials could influence cirrus formation and properties.
Renzer, Galit; Eufemio, Rosemary J; Schwidetzky, Ralph; Fröhlich-Nowoisky, Janine; Bonn, Mischa; Meister, Konrad
(, The Journal of Physical Chemistry C)
Ice-nucleating proteins (INPs) from bacteria like Pseudomonas syringae are among the most effective ice nucleators known. However, large INP aggregates with maximum ice nucleation activity (at approximately −2 °C) typically account for less than 1% of the overall ice nucleation activity in bacterial samples. This study demonstrates that polyols significantly enhance the assembly of INPs into large aggregates, dramatically improving bacterial ice nucleation efficiency. Simple compounds like polyvinyl alcohol increased the abundance of large INP aggregates by a factor of 100. This remarkable boost in ice nucleation efficiency is attributed to the stabilization of INP aggregates through membrane−polyol interactions that stabilize INP interactions and reduce structural fluctuations. The ability to regulate the abundance of large INP aggregates in bacterial ice nucleators enables fine-tuning ice nucleation processes at much lower concentrations for specific biomedical and technological purposes.
Failor, Kevin C.; Liu, Haijie; Llontop, Marco E.; LeBlanc, Sophie; Eckshtain-Levi, Noam; Sharma, Parul; Reed, Austin; Yang, Shu; Tian, Long; Lefevre, Christopher T.; et al
(, The ISME Journal)
Abstract Earth’s radiation budget and frequency and intensity of precipitation are influenced by aerosols with ice nucleation activity (INA), i.e., particles that catalyze the formation of ice. Some bacteria, fungi, and pollen are among the most efficient ice nucleators but the molecular basis of INA is poorly understood in most of them. Lysinibacillus parviboronicapiens ( Lp ) was previously identified as the first Gram-positive bacterium with INA. INA of Lp is associated with a secreted, nanometer-sized, non-proteinaceous macromolecule or particle. Here a combination of comparative genomics, transcriptomics, and a mutant screen showed that INA in Lp depends on a type I iterative polyketide synthase and a non-ribosomal peptide synthetase (PKS-NRPS). Differential filtration in combination with gradient ultracentrifugation revealed that the product of the PKS-NRPS is associated with secreted particles of a density typical of extracellular vesicles and electron microscopy showed that these particles consist in “pearl chain”-like structures not resembling any other known bacterial structures. These findings expand our knowledge of biological INA, may be a model for INA in other organisms for which the molecular basis of INA is unknown, and present another step towards unraveling the role of microbes in atmospheric processes.
Summary Microbial nitrogen (N) fixation accounts forc. 97% of natural N inputs to terrestrial ecosystems. These microbes can be free‐living in the soil and leaf litter (asymbiotic) or in symbiosis with plants. Warming is expected to increase N‐fixation rates because warmer temperatures favor the growth and activity of N‐fixing microbes.We investigated the effects of warming on asymbiotic components of N fixation at a field warming experiment in Puerto Rico. We analyzed the function and composition of bacterial communities from surface soil and leaf litter samples.Warming significantly increased asymbiotic N‐fixation rates in soil by 55% (to 0.002 kg ha−1 yr−1) and by 525% in leaf litter (to 14.518 kg ha−1 yr−1). This increase in N fixation was associated with changes in the N‐fixing bacterial community composition and soil nutrients.Our findings suggest that warming increases the natural N inputs from the atmosphere into this tropical forest due to changes in microbial function and composition, especially in the leaf litter. Given the importance of leaf litter in nutrient cycling, future research should investigate other aspects of N cycles in the leaf litter under warming conditions.
Vasebi, Yalda, Mechan Llontop, Marco E., Hanlon, Regina, Schmale III, David G., Schnell, Russell, and Vinatzer, Boris A. Comprehensive characterization of an aspen ( Populus tremuloides ) leaf litter sample that maintained ice nucleation activity for 48 years. Retrieved from https://par.nsf.gov/biblio/10140639. Biogeosciences 16.8 Web. doi:10.5194/bg-16-1675-2019.
Vasebi, Yalda, Mechan Llontop, Marco E., Hanlon, Regina, Schmale III, David G., Schnell, Russell, & Vinatzer, Boris A. Comprehensive characterization of an aspen ( Populus tremuloides ) leaf litter sample that maintained ice nucleation activity for 48 years. Biogeosciences, 16 (8). Retrieved from https://par.nsf.gov/biblio/10140639. https://doi.org/10.5194/bg-16-1675-2019
Vasebi, Yalda, Mechan Llontop, Marco E., Hanlon, Regina, Schmale III, David G., Schnell, Russell, and Vinatzer, Boris A.
"Comprehensive characterization of an aspen ( Populus tremuloides ) leaf litter sample that maintained ice nucleation activity for 48 years". Biogeosciences 16 (8). Country unknown/Code not available. https://doi.org/10.5194/bg-16-1675-2019.https://par.nsf.gov/biblio/10140639.
@article{osti_10140639,
place = {Country unknown/Code not available},
title = {Comprehensive characterization of an aspen ( Populus tremuloides ) leaf litter sample that maintained ice nucleation activity for 48 years},
url = {https://par.nsf.gov/biblio/10140639},
DOI = {10.5194/bg-16-1675-2019},
abstractNote = {Abstract. Decaying vegetation was determined to be a potentially important source ofatmospheric ice nucleation particles (INPs) in the early 1970s. The bacteriumPseudomonas syringae was the first microorganism with ice nucleationactivity (INA) isolated from decaying leaf litter in 1974. However, the icenucleation characteristics of P. syringae are not compatible withthe characteristics of leaf litter-derived INPs since the latter were foundto be sub-micron in size, while INA of P. syringae depends on muchlarger intact bacterial cells. Here we determined the cumulative icenucleation spectrum and microbial community composition of the historic leaflitter sample 70-S-14 collected in 1970 that conserved INA for 48 years. Themajority of the leaf litter-derived INPs were confirmed to be sub-micron insize and to be sensitive to boiling. Culture-independent microbial communityanalysis only identified Pseudomonas as potential INA.Culture-dependent analysis identified one P. syringae isolate, twoisolates of the bacterial species Pantoea ananatis, and one fungalisolate of Mortierella alpina as having INA among 1170 bacterialcolonies and 277 fungal isolates, respectively. Both Pa. ananatisand M. alpina are organisms that produce heat-sensitive sub-micronINPs. They are thus both likely sources of the INPs present in sample 70-S-14and may represent important terrestrial sources of atmospheric INPs, aconclusion that is in line with other recent results obtained in regard toINPs from soil, precipitation, and the atmosphere.},
journal = {Biogeosciences},
volume = {16},
number = {8},
author = {Vasebi, Yalda and Mechan Llontop, Marco E. and Hanlon, Regina and Schmale III, David G. and Schnell, Russell and Vinatzer, Boris A.},
}
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