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Schwidetzky R, de Almeida Ribeiro I, Bothen N, Backes AT, DeVries AL, Bonn M, Fröhlich-Nowoisky J, Molinero V, Meister K. Functional aggregation of cell-free proteins enables fungal ice nucleation. Proc Natl Acad Sci U S A 2023; 120:e2303243120. [PMID: 37943838 PMCID: PMC10655213 DOI: 10.1073/pnas.2303243120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 10/06/2023] [Indexed: 11/12/2023] Open
Abstract
Biological ice nucleation plays a key role in the survival of cold-adapted organisms. Several species of bacteria, fungi, and insects produce ice nucleators (INs) that enable ice formation at temperatures above -10 °C. Bacteria and fungi produce particularly potent INs that can promote water crystallization above -5 °C. Bacterial INs consist of extended protein units that aggregate to achieve superior functionality. Despite decades of research, the nature and identity of fungal INs remain elusive. Here, we combine ice nucleation measurements, physicochemical characterization, numerical modeling, and nucleation theory to shed light on the size and nature of the INs from the fungus Fusarium acuminatum. We find ice-binding and ice-shaping activity of Fusarium IN, suggesting a potential connection between ice growth promotion and inhibition. We demonstrate that fungal INs are composed of small 5.3 kDa protein subunits that assemble into ice-nucleating complexes that can contain more than 100 subunits. Fusarium INs retain high ice-nucleation activity even when only the ~12 kDa fraction of size-excluded proteins are initially present, suggesting robust pathways for their functional aggregation in cell-free aqueous environments. We conclude that the use of small proteins to build large assemblies is a common strategy among organisms to create potent biological INs.
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Affiliation(s)
- Ralph Schwidetzky
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz55128, Germany
| | | | - Nadine Bothen
- Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz55128, Germany
| | - Anna T. Backes
- Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz55128, Germany
| | - Arthur L. DeVries
- Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL61801
| | - Mischa Bonn
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz55128, Germany
| | | | - Valeria Molinero
- Department of Chemistry, The University of Utah, Salt Lake City, UT84112
| | - Konrad Meister
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz55128, Germany
- Department of Chemistry and Biochemistry, Boise State University, Boise, ID83725
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2
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Fan C, Xie W, Hu W, Matsusaki H, Kojima T, Zhang D. Number size distribution of bacterial aerosols in terrestrial and marine airflows at a coastal site of Japan. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 865:161238. [PMID: 36586682 DOI: 10.1016/j.scitotenv.2022.161238] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
Size-differentiated concentration of bacterial aerosols is essential for investigating their dissemination via the atmosphere. In this study, the number size distribution of bacterial aerosols was measured at a coastal site in southwestern Japan (32.324°N, 129.993°E) using a size-segregated eight-stage (>11, 7.0-11, 4.7-7.0, 3.3-4.7, 2.1-3.3, 1.1-2.1, 0.65-1.1, and 0.43-0.65μm) sampler. The results showed that the distribution differed according to the source areas: terrestrial air, oceanic air, or a combination of the two. The distribution in the long-distance transported terrestrial air from the Asian continent was monomodal, with a peak of 3.3-4.7 μm. The distribution in local land breeze air was bimodal, with the peaks at 0.43-1.1 and 3.3-4.7 μm. A similar bimodal distribution was encountered when the local island air and long-distance transported terrestrial air mixed. In contrast, the size distribution did not show clear peaks in the air from either nearby or remote marine areas. According to the air mass backward trajectories, the further the distance the air moved in the 72 h before arriving at the site, the lower the concentration of total bacterial aerosols. The estimation of dry deposition fluxes of bacterial cells showed that the deposition was dominated by cells larger than 1.1 μm with a relative contribution from 70.5 % to 93.7 %, except for the local land breeze cases, where the contributions in the size ranges larger and smaller than 1.1 μm were similar. These results show the distinctive number size distributions and removal processes of bacterial aerosols in different types of air. In addition, they indicate that size-dependent characteristics of airborne bacteria should be considered when studying their activities and roles in the atmospheric environment.
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Affiliation(s)
- Chunlan Fan
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
| | - Wenwen Xie
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
| | - Wei Hu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Hiromi Matsusaki
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
| | - Tomoko Kojima
- Department Earth and Environmental Science, Faculty of Advanced Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan
| | - Daizhou Zhang
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan.
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3
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Zhang Y, Du R, Chen H, Du P, Zhang S, Ren W. Different characteristics of microbial diversity and special functional microbes in rainwater and topsoil before and after 2019 new coronavirus epidemic in Inner Mongolia Grassland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 809:151088. [PMID: 34687707 PMCID: PMC8527739 DOI: 10.1016/j.scitotenv.2021.151088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/03/2021] [Accepted: 10/15/2021] [Indexed: 05/05/2023]
Abstract
Grassland ecosystems are vital terrestrial ecosystems. As areas sensitive to climate change, they are critical for assessing the effects of global climate change. In China, grasslands account for over 40% of the land area. There is currently limited information on microbial diversity evolution in different grassland areas, particularly microorganisms with ice nucleation activity (INA) and their potential resources with potential influence to regulate regional precipitation and climate. We used Illumina MiSeq to sequence the 16S rRNA V3-V4 hypervariable region and performed a simple droplet freezing experiment to determine the variation in the grassland microbial community species composition and community structure. Rainwater and topsoil samples from the Hulunbuir Grassland in Inner Mongolia collected over three years were characterized. The dominant bacterial genus in the rainwater was Massilia, and the dominant fungus was Cladosporium. Additionally, the dominant bacteria in the soil were Sphingomonas, and the dominant fungus was Gibberella. There were differences in the microbial communities before and after the coronavirus disease epidemic. Pathogenic microorganisms exhibited inconsistent responses to environmental changes. The low relative abundance of known high-INA microorganisms and the higher freezing temperature indicated that unknown high-efficiency biological ice nucleating particles may be present. We found significant differences in species diversity and richness between the rainwater and soil populations in grassland areas by analyzing the sample community structures. Our research results revealed the species composition and structure of the microbiota in grassland ecosystems in China, indicating that environmental media and human activities may affect the microbiota in the grassland area and indicating underlying microorganisms with high INA.
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Affiliation(s)
- Yongtao Zhang
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rui Du
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Hanlin Chen
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Pengrui Du
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sujian Zhang
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weishan Ren
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
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4
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Huang S, Hu W, Chen J, Wu Z, Zhang D, Fu P. Overview of biological ice nucleating particles in the atmosphere. ENVIRONMENT INTERNATIONAL 2021; 146:106197. [PMID: 33271442 DOI: 10.1016/j.envint.2020.106197] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 10/01/2020] [Accepted: 10/05/2020] [Indexed: 05/14/2023]
Abstract
Biological particles in the Earth's atmosphere are a distinctive category of ice nucleating particles (INPs) due to their capability of facilitating ice crystal formation in clouds at relatively warm temperatures. Field observations and model simulations have shown that biological INPs affect cloud and precipitation formation and regulate regional or even global climate, although there are considerable uncertainties in modeling and large gaps between observed and model simulated contribution of biological particles to atmospheric INPs. This paper overviews the latest researches about biological INPs in the atmosphere. Firstly, we describe the primary ice nucleation mechanisms, and measurements and model simulations of atmospheric biological INPs. Secondly, we summarize the ice nucleating properties of biological INPs from diverse sources such as soils or dust, vegetation (e.g., leaves and pollen grains), sea spray, and fresh waters, and controlling factors of biological INPs in the atmosphere. Then we review the abundance and distribution of atmospheric biological INPs in diverse ecosystems. Finally, we discuss the open questions in further studies on atmospheric biological INPs, including the requirements for developing novel detection techniques and simulation models, as well as the comprehensive investigation of characteristics and influencing factors of atmospheric biological INPs.
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Affiliation(s)
- Shu Huang
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Wei Hu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
| | - Jie Chen
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Zhijun Wu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Daizhou Zhang
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
| | - Pingqing Fu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
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Elmassry MM, Ray N, Sorge S, Webster J, Merry K, Caserio A, Vecellio DJ, Kruczek C, Dowd S, Ardon-Dryer K, Vanos J, San Francisco MJ. Investigating the culturable atmospheric fungal and bacterial microbiome in West Texas: implication of dust storms and origins of the air parcels. FEMS MICROBES 2020; 1:xtaa009. [PMID: 37333960 PMCID: PMC10117434 DOI: 10.1093/femsmc/xtaa009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/21/2020] [Indexed: 11/10/2023] Open
Abstract
Individuals often experience ailments such as allergies, asthma and respiratory tract infections throughout the year. Weather reports often include estimations of common allergens that can affect these individuals. To describe the local 'atmospheric microbiome' in Lubbock, Texas, USA, we examined the culturable fungal and bacterial microbiome present in the air on calm and dust storm days using internal transcribed spacer (ITS)-1 and 16S rRNA amplicon sequencing, respectively. While some types of airborne fungi were frequently present throughout the year, distinct differences were also observed between calm and dust storm days. We also observed the influence of the origin of air parcels and wind elevation of the air trajectory. The most abundant genera of fungi identified during the study period were Cryptococcus, Aureobasidium, Alternaria, Cladosporium and Filobasidium. This observation was not surprising considering the agricultural intensive environment of West Texas. Interestingly, Cladosporium, a common allergenic mold, was increased during days with dust storm events. The predominant bacterial genera observed were Bacillus, Pseudomonas, Psychrobacter, Massilia and Exiguobacterium. The relative abundance of the psychrophiles, Psychrobacter and Exiguobacterium, was surprising, given the semi-aridity of West Texas. Coupling our observations with back trajectories of the wind (Hybrid Single-Particle Lagrangian Integrated Trajectory models) demonstrated that dust storms, regional anthropogenic activity and origin of air parcels are important influences on the diversity and temporal presence of the atmospheric microbiome.
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Affiliation(s)
- Moamen M Elmassry
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Nandini Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Sara Sorge
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Jennifer Webster
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Kyle Merry
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Angelica Caserio
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Daniel J Vecellio
- Department of Geography, Texas A&M University, College Station, TX 77843, USA
| | - Cassandra Kruczek
- Department of Medical Education, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Scot Dowd
- Molecular Research LP, Clovis Road, Shallowater, TX 79363, USA
| | - Karin Ardon-Dryer
- Department of Geosciences, Atmospheric Science Group, Texas Tech University, Lubbock, TX 79409, USA
| | - Jennifer Vanos
- School of Sustainability, Arizona State University, Tempe, AZ 85281, USA
| | - Michael J San Francisco
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
- Honors College, Texas Tech University, Lubbock, TX 79410, USA
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6
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Tarn MD, Sikora SNF, Porter GCE, Wyld BV, Alayof M, Reicher N, Harrison AD, Rudich Y, Shim JU, Murray BJ. On-chip analysis of atmospheric ice-nucleating particles in continuous flow. LAB ON A CHIP 2020; 20:2889-2910. [PMID: 32661539 DOI: 10.1039/d0lc00251h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ice-nucleating particles (INPs) are of atmospheric importance because they catalyse the freezing of supercooled cloud droplets, strongly affecting the lifetime and radiative properties of clouds. There is a need to improve our knowledge of the global distribution of INPs, their seasonal cycles and long-term trends, but our capability to make these measurements is limited. Atmospheric INP concentrations are often determined using assays involving arrays of droplets on a cold stage, but such assays are frequently limited by the number of droplets that can be analysed per experiment, often involve manual processing (e.g. pipetting of droplets), and can be susceptible to contamination. Here, we present a microfluidic platform, the LOC-NIPI (Lab-on-a-Chip Nucleation by Immersed Particle Instrument), for the generation of water-in-oil droplets and their freezing in continuous flow as they pass over a cold plate for atmospheric INP analysis. LOC-NIPI allows the user to define the number of droplets analysed by simply running the platform for as long as required. The use of small (∼100 μm diameter) droplets minimises the probability of contamination in any one droplet and therefore allows supercooling all the way down to homogeneous freezing (around -36 °C), while a temperature probe in a proxy channel provides an accurate measure of temperature without the need for temperature modelling. The platform was validated using samples of pollen extract and Snomax®, with hundreds of droplets analysed per temperature step and thousands of droplets being measured per experiment. Homogeneous freezing of purified water was studied using >10 000 droplets with temperature increments of 0.1 °C. The results were reproducible, independent of flow rate in the ranges tested, and the data compared well to conventional instrumentation and literature data. The LOC-NIPI was further benchmarked in a field campaign in the Eastern Mediterranean against other well-characterised instrumentation. The continuous flow nature of the system provides a route, with future development, to the automated monitoring of atmospheric INP at field sites around the globe.
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Affiliation(s)
- Mark D Tarn
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK. and School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
| | | | - Grace C E Porter
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK. and School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
| | - Bethany V Wyld
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK.
| | - Matan Alayof
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Reicher
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Yinon Rudich
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jung-Uk Shim
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
| | - Benjamin J Murray
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK.
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7
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Heterogeneous Freezing of Liquid Suspensions Including Juices and Extracts from Berries and Leaves from Perennial Plants. ATMOSPHERE 2019. [DOI: 10.3390/atmos10010037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Heterogeneous ice nucleation in the atmosphere is not fully understood. In particular, our knowledge of biological materials and their atmospheric ice nucleation properties remains scarce. Here, we present the results from systematic investigations of the ice nucleation activity of plant materials using cryo-microscopy. We examined berry juices, frozen berries, as well as extracts of leaves and dried berries of plants native to boreal regions. All of our samples possess reasonable ice nucleation activity. Their ice nucleating particle concentrations per unit of water volume vary between 9.7 × 105 and 9.2 × 109 cm−3 when examined within temperatures of −12 to −34 °C. Mean freezing temperatures ranged from −18.5 to −45.6 °C. We show that all samples contained ice nuclei in a size range below 0.2 µm and remain active if separated from coarse plant tissue. The results of examining ice nucleation properties of leaves and dry berry extracts suggests that their ice-nucleating components can be easily suspended in water. Sea buckthorn and black currant were analyzed using subtilisin (a protease) and urea. Results suggest proteinaceous compounds to play an important role in their ice nucleation activity. These results show that separation between ice nucleation particles stemming from microorganisms and those stemming from plants cannot be differentiated solely on proteinaceous features. Further oxidation experiments with ozone showed that black currant is highly stable towards ozone oxidation, indicating a long atmospheric life time.
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8
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Tarn MD, Sikora SNF, Porter GCE, O’Sullivan D, Adams M, Whale TF, Harrison AD, Vergara-Temprado J, Wilson TW, Shim JU, Murray BJ. The study of atmospheric ice-nucleating particles via microfluidically generated droplets. MICROFLUIDICS AND NANOFLUIDICS 2018; 22:52. [PMID: 29720926 PMCID: PMC5915516 DOI: 10.1007/s10404-018-2069-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 04/05/2018] [Indexed: 05/10/2023]
Abstract
Ice-nucleating particles (INPs) play a significant role in the climate and hydrological cycle by triggering ice formation in supercooled clouds, thereby causing precipitation and affecting cloud lifetimes and their radiative properties. However, despite their importance, INP often comprise only 1 in 103-106 ambient particles, making it difficult to ascertain and predict their type, source, and concentration. The typical techniques for quantifying INP concentrations tend to be highly labour-intensive, suffer from poor time resolution, or are limited in sensitivity to low concentrations. Here, we present the application of microfluidic devices to the study of atmospheric INPs via the simple and rapid production of monodisperse droplets and their subsequent freezing on a cold stage. This device offers the potential for the testing of INP concentrations in aqueous samples with high sensitivity and high counting statistics. Various INPs were tested for validation of the platform, including mineral dust and biological species, with results compared to literature values. We also describe a methodology for sampling atmospheric aerosol in a manner that minimises sampling biases and which is compatible with the microfluidic device. We present results for INP concentrations in air sampled during two field campaigns: (1) from a rural location in the UK and (2) during the UK's annual Bonfire Night festival. These initial results will provide a route for deployment of the microfluidic platform for the study and quantification of INPs in upcoming field campaigns around the globe, while providing a benchmark for future lab-on-a-chip-based INP studies.
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Affiliation(s)
- Mark D. Tarn
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT UK
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT UK
| | | | - Grace C. E. Porter
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT UK
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT UK
| | - Daniel O’Sullivan
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT UK
| | - Mike Adams
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT UK
| | - Thomas F. Whale
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT UK
| | | | - Jesús Vergara-Temprado
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT UK
- Present Address: Institute for Atmospheric and Climate Science, ETH Zürich, Universitätstrasse 16, 8092 Zurich, Switzerland
| | - Theodore W. Wilson
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT UK
- Present Address: Owlstone Medical Ltd., 127 Science Park, Cambridge, CB4 0GD UK
| | - Jung-uk Shim
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT UK
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Failor KC, Schmale DG, Vinatzer BA, Monteil CL. Ice nucleation active bacteria in precipitation are genetically diverse and nucleate ice by employing different mechanisms. ISME JOURNAL 2017; 11:2740-2753. [PMID: 28753208 DOI: 10.1038/ismej.2017.124] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 06/02/2017] [Accepted: 06/15/2017] [Indexed: 11/09/2022]
Abstract
A growing body of circumstantial evidence suggests that ice nucleation active (Ice+) bacteria contribute to the initiation of precipitation by heterologous freezing of super-cooled water in clouds. However, little is known about the concentration of Ice+ bacteria in precipitation, their genetic and phenotypic diversity, and their relationship to air mass trajectories and precipitation chemistry. In this study, 23 precipitation events were collected over 15 months in Virginia, USA. Air mass trajectories and water chemistry were determined and 33 134 isolates were screened for ice nucleation activity (INA) at -8 °C. Of 1144 isolates that tested positive during initial screening, 593 had confirmed INA at -8 °C in repeated tests. Concentrations of Ice+ strains in precipitation were found to range from 0 to 13 219 colony forming units per liter, with a mean of 384±147. Most Ice+ bacteria were identified as members of known and unknown Ice+ species in the Pseudomonadaceae, Enterobacteriaceae and Xanthomonadaceae families, which nucleate ice employing the well-characterized membrane-bound INA protein. Two Ice+ strains, however, were identified as Lysinibacillus, a Gram-positive genus not previously known to include Ice+ bacteria. INA of the Lysinibacillus strains is due to a nanometer-sized molecule that is heat resistant, lysozyme and proteinase resistant, and secreted. Ice+ bacteria and the INA mechanisms they employ are thus more diverse than expected. We discuss to what extent the concentration of culturable Ice+ bacteria in precipitation and the identification of a new heat-resistant biological INA mechanism support a role for Ice+ bacteria in the initiation of precipitation.
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Affiliation(s)
- K C Failor
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, USA
| | - D G Schmale
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, USA
| | - B A Vinatzer
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, USA
| | - C L Monteil
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, USA.,CNRS/CEA/Aix-Marseille Université, UMR7265 Institut de biosciences et biotechnologies, Laboratoire de Bioénergétique Cellulaire, Saint-Paul-lès-Durance, France.,INRA, UR0407 Pathologie Végétale, Montfavet cedex, France
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