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Hoellrich MR, James DK, Bustos D, Darrouzet-Nardi A, Santiago LS, Pietrasiak N. Biocrust carbon exchange varies with crust type and time on Chihuahuan Desert gypsum soils. Front Microbiol 2023; 14:1128631. [PMID: 37234525 PMCID: PMC10208066 DOI: 10.3389/fmicb.2023.1128631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 03/30/2023] [Indexed: 05/28/2023] Open
Abstract
Introduction In dryland systems, biological soil crusts (biocrusts) can occupy large areas of plant interspaces, where they fix carbon following rain. Although distinct biocrust types contain different dominant photoautotrophs, few studies to date have documented carbon exchange over time from various biocrust types. This is especially true for gypsum soils. Our objective was to assess the carbon exchange of biocrust types established at the world's largest gypsum dune field at White Sands National Park. Methods We sampled five different biocrust types from a sand sheet location in three different years and seasons (summer 2020, fall 2021, and winter 2022) for carbon exchange measurements in controlled lab conditions. Biocrusts were rehydrated to full saturation and light incubated for 30 min, 2, 6, 12, 24, and 36 h. Samples were then subject to a 12-point light regime with a LI-6400XT photosynthesis system to determine carbon exchange. Results Biocrust carbon exchange values differed by biocrust type, by incubation time since wetting, and by date of field sampling. Lichens and mosses had higher gross and net carbon fixation rates than dark and light cyanobacterial crusts. High respiration rates were found after 0.5 h and 2 h incubation times as communities recovered from desiccation, leveling off after 6 h incubation. Net carbon fixation of all types increased with longer incubation time, primarily as a result of decreasing respiration, which suggests rapid recovery of biocrust photosynthesis across types. However, net carbon fixation rates varied from year to year, likely as a product of time since the last rain event and environmental conditions preceding collection, with moss crusts being most sensitive to environmental stress at our study sites. Discussion Given the complexity of patterns discovered in our study, it is especially important to consider a multitude of factors when comparing biocrust carbon exchange rates across studies. Understanding the dynamics of biocrust carbon fixation in distinct crust types will enable greater precision of carbon cycling models and improved forecasting of impacts of global climate change on dryland carbon cycling and ecosystem functioning.
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Affiliation(s)
- Mikaela R. Hoellrich
- Plant and Environmental Sciences, New Mexico State University, Las Cruces, NM, United States
| | - Darren K. James
- USDA-ARS Jornada Experimental Range, New Mexico State University, Las Cruces, NM, United States
| | - David Bustos
- US DOI White Sands National Park, Alamogordo, NM, United States
| | | | - Louis S. Santiago
- Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
| | - Nicole Pietrasiak
- Plant and Environmental Sciences, New Mexico State University, Las Cruces, NM, United States
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV, United States
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2
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Villa F, Wu YL, Zerboni A, Cappitelli F. In Living Color: Pigment-Based Microbial Ecology At the Mineral-Air Interface. Bioscience 2022; 72:1156-1175. [PMID: 36451971 PMCID: PMC9699719 DOI: 10.1093/biosci/biac091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Pigment-based color is one of the most important phenotypic traits of biofilms at the mineral-air interface (subaerial biofilms, SABs), because it reflects the physiology of the microbial community. Because color is the hallmark of all SABs, we argue that pigment-based color could convey the mechanisms that drive microbial adaptation and coexistence across different terrestrial environments and link phenotypic traits to community fitness and ecological dynamics. Within this framework, we present the most relevant microbial pigments at the mineral-air interface and discuss some of the evolutionary landscapes that necessitate pigments as adaptive strategies for resource allocation and survivability. We report several pigment features that reflect SAB communities' structure and function, as well as pigment ecology in the context of microbial life-history strategies and coexistence theory. Finally, we conclude the study of pigment-based ecology by presenting its potential application and some of the key challenges in the research.
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3
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Kratz AM, Maier S, Weber J, Kim M, Mele G, Gargiulo L, Leifke AL, Prass M, Abed RMM, Cheng Y, Su H, Pöschl U, Weber B. Reactive Nitrogen Hotspots Related to Microscale Heterogeneity in Biological Soil Crusts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:11865-11877. [PMID: 35929951 PMCID: PMC9387110 DOI: 10.1021/acs.est.2c02207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/12/2022] [Accepted: 07/12/2022] [Indexed: 06/15/2023]
Abstract
Biocrusts covering drylands account for major fractions of terrestrial biological nitrogen fixation and release large amounts of gaseous reactive nitrogen (Nr) as nitrous acid (HONO) and nitric oxide (NO). Recent investigations suggested that aerobic and anaerobic microbial nitrogen transformations occur simultaneously upon desiccation of biocrusts, but the spatio-temporal distribution of seemingly contradictory processes remained unclear. Here, we explore small-scale gradients in chemical concentrations related to structural characteristics and organism distribution. X-ray microtomography and fluorescence microscopy revealed mixed pore size structures, where photoautotrophs and cyanobacterial polysaccharides clustered irregularly in the uppermost millimeter. Microsensor measurements showed strong gradients of pH, oxygen, and nitrite, nitrate, and ammonium ion concentrations at micrometer scales in both vertical and lateral directions. Initial oxygen saturation was mostly low (∼30%) at full water holding capacity, suggesting widely anoxic conditions, and increased rapidly upon desiccation. Nitrite concentrations (∼6 to 800 μM) and pH values (∼6.5 to 9.5) were highest around 70% WHC. During further desiccation they decreased, while emissions of HONO and NO increased, reaching maximum values around 20% WHC. Our results illustrate simultaneous, spatially separated aerobic and anaerobic nitrogen transformations, which are critical for Nr emissions, but might be impacted by future global change and land management.
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Affiliation(s)
- Alexandra Maria Kratz
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
| | - Stefanie Maier
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
- Institute
of Biology, Division of Plant Sciences, University of Graz, Graz 8010, Austria
| | - Jens Weber
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
- Institute
of Biology, Division of Plant Sciences, University of Graz, Graz 8010, Austria
| | - Minsu Kim
- Institute
of Biology, Division of Plant Sciences, University of Graz, Graz 8010, Austria
| | - Giacomo Mele
- Institute
for Agriculture and Forestry in the Mediterranean, National Council of Research, 80055 Portici, Italy
| | - Laura Gargiulo
- Institute
for Agriculture and Forestry in the Mediterranean, National Council of Research, 80055 Portici, Italy
| | - Anna Lena Leifke
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
| | - Maria Prass
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
| | - Raeid M. M. Abed
- College
of Science, Biology Department, Sultan Qaboos
University, P.O. Box 36, Al Khoud, Seeb 123, Sultanate of Oman
| | - Yafang Cheng
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
| | - Hang Su
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
| | - Ulrich Pöschl
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
| | - Bettina Weber
- Multiphase
Chemistry Department, Max Planck Institute
for Chemistry, Mainz 55128, Germany
- Institute
of Biology, Division of Plant Sciences, University of Graz, Graz 8010, Austria
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4
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Water-driven microbial nitrogen transformations in biological soil crusts causing atmospheric nitrous acid and nitric oxide emissions. THE ISME JOURNAL 2022; 16:1012-1024. [PMID: 34764454 PMCID: PMC8941053 DOI: 10.1038/s41396-021-01127-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 09/16/2021] [Accepted: 09/22/2021] [Indexed: 01/12/2023]
Abstract
Biological soil crusts (biocrusts) release the reactive nitrogen gases (Nr) nitrous acid (HONO) and nitric oxide (NO) into the atmosphere, but the underlying microbial process controls have not yet been resolved. In this study, we analyzed the activity of microbial consortia relevant in Nr emissions during desiccation using transcriptome and proteome profiling and fluorescence in situ hybridization. We observed that < 30 min after wetting, genes encoding for all relevant nitrogen (N) cycling processes were expressed. The most abundant transcriptionally active N-transforming microorganisms in the investigated biocrusts were affiliated with Rhodobacteraceae, Enterobacteriaceae, and Pseudomonadaceae within the Alpha- and Gammaproteobacteria. Upon desiccation, the nitrite (NO2-) content of the biocrusts increased significantly, which was not the case when microbial activity was inhibited. Our results confirm that NO2- is the key precursor for biocrust emissions of HONO and NO. This NO2- accumulation likely involves two processes related to the transition from oxygen-limited to oxic conditions in the course of desiccation: (i) a differential regulation of the expression of denitrification genes; and (ii) a physiological response of ammonia-oxidizing organisms to changing oxygen conditions. Thus, our findings suggest that the activity of N-cycling microorganisms determines the process rates and overall quantity of Nr emissions.
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Meier DV, Greve AJ, Chennu A, van Erk MR, Muthukrishnan T, Abed RMM, Woebken D, de Beer D. Limitation of Microbial Processes at Saturation-Level Salinities in a Microbial Mat Covering a Coastal Salt Flat. Appl Environ Microbiol 2021; 87:e0069821. [PMID: 34160273 PMCID: PMC8357274 DOI: 10.1128/aem.00698-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/16/2021] [Indexed: 12/18/2022] Open
Abstract
Hypersaline microbial mats are dense microbial ecosystems capable of performing complete element cycling and are considered analogs of early Earth and hypothetical extraterrestrial ecosystems. We studied the functionality and limits of key biogeochemical processes, such as photosynthesis, aerobic respiration, and sulfur cycling, in salt crust-covered microbial mats from a tidal flat at the coast of Oman. We measured light, oxygen, and sulfide microprofiles as well as sulfate reduction rates at salt saturation and in flood conditions and determined fine-scale stratification of pigments, biomass, and microbial taxa in the resident microbial community. The salt crust did not protect the mats against irradiation or evaporation. Although some oxygen production was measurable at salinities of ≤30% (wt/vol) in situ, at saturation-level salinity (40%), oxygenic photosynthesis was completely inhibited and only resumed 2 days after reducing the porewater salinity to 12%. Aerobic respiration and active sulfur cycling occurred at low rates under salt saturation and increased strongly upon salinity reduction. Apart from high relative abundances of Chloroflexi, photoheterotrophic Alphaproteobacteria, Bacteroidetes, and Archaea, the mat contained a distinct layer harboring filamentous Cyanobacteria, which is unusual for such high salinities. Our results show that the diverse microbial community inhabiting this salt flat mat ultimately depends on periodic salt dilution to be self-sustaining and is rather adapted to merely survive salt saturation than to thrive under the salt crust. IMPORTANCE Due to their abilities to survive intense radiation and low water availability, hypersaline microbial mats are often suggested to be analogs of potential extraterrestrial life. However, even the limitations imposed on microbial processes by saturation-level salinity found on Earth have rarely been studied in situ. While abundance and diversity of microbial life in salt-saturated environments are well documented, most of our knowledge on process limitations stems from culture-based studies, few in situ studies, and theoretical calculations. In particular, oxygenic photosynthesis has barely been explored beyond 5 M NaCl (28% wt/vol). By applying a variety of biogeochemical and molecular methods, we show that despite abundance of photoautotrophic microorganisms, oxygenic photosynthesis is inhibited in salt-crust-covered microbial mats at saturation salinities, while rates of other energy generation processes are decreased several-fold. Hence, the complete element cycling required for self-sustaining microbial communities only occurs at lower salt concentrations.
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Affiliation(s)
- Dimitri V. Meier
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | | | - Arjun Chennu
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- Leibniz Centre for Tropical Marine Research, Bremen, Germany
| | | | | | - Raeid M. M. Abed
- Biology Department, College of Science, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Dagmar Woebken
- Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Dirk de Beer
- Max Planck Institute for Marine Microbiology, Bremen, Germany
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6
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Kaup M, Trull S, Hom EFY. On the move: sloths and their epibionts as model mobile ecosystems. Biol Rev Camb Philos Soc 2021; 96:2638-2660. [PMID: 34309191 PMCID: PMC9290738 DOI: 10.1111/brv.12773] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 06/18/2021] [Accepted: 06/21/2021] [Indexed: 12/20/2022]
Abstract
Sloths are unusual mobile ecosystems, containing a high diversity of epibionts living and growing in their fur as they climb slowly through the canopies of tropical forests. These epibionts include poorly studied algae, arthropods, fungi, and bacteria, making sloths likely reservoirs of unexplored biodiversity. This review aims to identify gaps and eliminate misconceptions in our knowledge of sloths and their epibionts, and to identify key questions to stimulate future research into the functions and roles of sloths within a broader ecological and evolutionary context. This review also seeks to position the sloth fur ecosystem as a model for addressing fundamental questions in metacommunity and movement ecology. The conceptual and evidence-based foundation of this review aims to serve as a guide for future hypothesis-driven research into sloths, their microbiota, sloth health and conservation, and the coevolution of symbioses in general.
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Affiliation(s)
- Maya Kaup
- Department of Biology and Center for Biodiversity and Conservation Research, University of Mississippi, University, MS, 38677-1848, U.S.A
| | - Sam Trull
- The Sloth Institute, Tulemar Gardens, Provincia de Puntarenas, Manuel Antonio, 60601, Costa Rica
| | - Erik F Y Hom
- Department of Biology and Center for Biodiversity and Conservation Research, University of Mississippi, University, MS, 38677-1848, U.S.A
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7
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Geraldes V, Pinto E. Mycosporine-Like Amino Acids (MAAs): Biology, Chemistry and Identification Features. Pharmaceuticals (Basel) 2021; 14:63. [PMID: 33466685 PMCID: PMC7828830 DOI: 10.3390/ph14010063] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 01/16/2023] Open
Abstract
Mycosporines and mycosporine-like amino acids are ultra-violet-absorbing compounds produced by several organisms such as lichens, fungi, algae and cyanobacteria, especially upon exposure to solar ultraviolet radiation. These compounds have photoprotective and antioxidant functions. Mycosporine-like amino acids have been used as a natural bioactive ingredient in cosmetic products. Several reviews have already been developed on these photoprotective compounds, but they focus on specific features. Herein, an extremely complete database on mycosporines and mycosporine-like amino acids, covering the whole class of these natural sunscreen compounds known to date, is presented. Currently, this database has 74 compounds and provides information about the chemistry, absorption maxima, protonated mass, fragments and molecular structure of these UV-absorbing compounds as well as their presence in organisms. This platform completes the previous reviews and is available online for free and in the public domain. This database is a useful tool for natural product data mining, dereplication studies, research working in the field of UV-absorbing compounds mycosporines and being integrated in mass spectrometry library software.
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Affiliation(s)
- Vanessa Geraldes
- School of Pharmaceutical Sciences, University of São Paulo, Avenida Prof. Lineu Prestes, 580, Butantã, São Paulo-SP CEP 05508-000, Brazil;
- Centre for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, Piracicaba-SP CEP 13400-970, Brazil
| | - Ernani Pinto
- Centre for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, Piracicaba-SP CEP 13400-970, Brazil
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8
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Sommer V, Mikhailyuk T, Glaser K, Karsten U. Uncovering Unique Green Algae and Cyanobacteria Isolated from Biocrusts in Highly Saline Potash Tailing Pile Habitats, Using an Integrative Approach. Microorganisms 2020; 8:E1667. [PMID: 33121104 PMCID: PMC7692164 DOI: 10.3390/microorganisms8111667] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/22/2020] [Accepted: 10/22/2020] [Indexed: 02/01/2023] Open
Abstract
Potash tailing piles caused by fertilizer production shape their surroundings because of the associated salt impact. A previous study in these environments addressed the functional community "biocrust" comprising various micro- and macro-organisms inhabiting the soil surface. In that previous study, biocrust microalgae and cyanobacteria were isolated and morphologically identified amongst an ecological discussion. However, morphological species identification maybe is difficult because of phenotypic plasticity, which might lead to misidentifications. The present study revisited the earlier species list using an integrative approach, including molecular methods. Seventy-six strains were sequenced using the markers small subunit (SSU) rRNA gene and internal transcribed spacer (ITS). Phylogenetic analyses confirmed some morphologically identified species. However, several other strains could only be identified at the genus level. This indicates a high proportion of possibly unknown taxa, underlined by the low congruence of the previous morphological identifications to our results. In general, the integrative approach resulted in more precise species identifications and should be considered as an extension of the previous morphological species list. The majority of taxa found were common in saline habitats, whereas some were more likely to occur in nonsaline environments. Consequently, biocrusts in saline environments of potash tailing piles contain unique microalgae and cyanobacteria that will possibly reveal several new taxa in more detailed future studies and, hence, provide new data on the biodiversity, as well as new candidates for applied research.
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Affiliation(s)
- Veronika Sommer
- Institute for Biological Sciences, Applied Ecology and Phycology, University of Rostock, 18059 Rostock, Germany; (V.S.); (K.G.)
- upi UmweltProjekt Ingenieursgesellschaft mbH, 39576 Stendal, Germany
| | - Tatiana Mikhailyuk
- National Academy of Sciences of Ukraine, M.G. Kholodny Institute of Botany, 01601 Kyiv, Ukraine;
| | - Karin Glaser
- Institute for Biological Sciences, Applied Ecology and Phycology, University of Rostock, 18059 Rostock, Germany; (V.S.); (K.G.)
| | - Ulf Karsten
- Institute for Biological Sciences, Applied Ecology and Phycology, University of Rostock, 18059 Rostock, Germany; (V.S.); (K.G.)
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9
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Fisher A, Wangpraseurt D, Larkum AWD, Johnson M, Kühl M, Chen M, Wong HL, Burns BP. Correlation of bio-optical properties with photosynthetic pigment and microorganism distribution in microbial mats from Hamelin Pool, Australia. FEMS Microbiol Ecol 2019; 95:5151331. [PMID: 30380056 DOI: 10.1093/femsec/fiy219] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/30/2018] [Indexed: 11/14/2022] Open
Abstract
Microbial mats and stromatolites are widespread in Hamelin Pool, Shark Bay, however the phototrophic capacity of these systems is unknown. This study has determined the optical properties and light-harvesting potential of these mats with light microsensors. These characteristics were linked via a combination of 16S rDNA sequencing, pigment analyses and hyperspectral imaging. Local scalar irradiance was elevated over the incident downwelling irradiance by 1.5-fold, suggesting light trapping and strong scattering by the mats. Visible light (400-700 nm) penetrated to a depth of 2 mm, whereas near-infrared light (700-800 nm) penetrated to at least 6 mm. Chlorophyll a and bacteriochlorophyll a (Bchl a) were found to be the dominant photosynthetic pigments present, with BChl a peaking at the subsurface (2-4 mm). Detailed 16S rDNA analyses revealed the presence of putative Chl f-containing Halomicronema sp. and photosynthetic members primarily decreased from the mat surface down to a depth of 6 mm. Data indicated high abundances of some pigments and phototrophic organisms in deeper layers of the mats (6-16 mm). It is proposed that the photosynthetic bacteria present in this system undergo unique adaptations to lower light conditions below the mat surface, and that phototrophic metabolisms are major contributors to ecosystem function.
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Affiliation(s)
- Amy Fisher
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia.,Australian Centre for Astrobiology, University of New South Wales, Sydney 2052, Australia
| | - Daniel Wangpraseurt
- Marine Biological Section, University of Copenhagen, Copenhagen 1017, Denmark.,Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.,Scripps Institution of Oceanography, University of California, San Diego 92037, CA, USA
| | - Anthony W D Larkum
- Climate Change Cluster, University of Technology, Sydney 2007, Australia
| | - Michael Johnson
- Climate Change Cluster, University of Technology, Sydney 2007, Australia
| | - Michael Kühl
- Marine Biological Section, University of Copenhagen, Copenhagen 1017, Denmark.,Climate Change Cluster, University of Technology, Sydney 2007, Australia
| | - Min Chen
- School of Life and Environmental Sciences, University of Sydney, Sydney 2006, Australia
| | - Hon Lun Wong
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia.,Australian Centre for Astrobiology, University of New South Wales, Sydney 2052, Australia
| | - Brendan P Burns
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia.,Australian Centre for Astrobiology, University of New South Wales, Sydney 2052, Australia
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10
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Steven B, Belnap J, Kuske CR. Chronic Physical Disturbance Substantially Alters the Response of Biological Soil Crusts to a Wetting Pulse, as Characterized by Metatranscriptomic Sequencing. Front Microbiol 2018; 9:2382. [PMID: 30349515 PMCID: PMC6186815 DOI: 10.3389/fmicb.2018.02382] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 09/18/2018] [Indexed: 11/13/2022] Open
Abstract
Biological soil crusts (biocrusts) are microbial communities that are a feature of arid surface soils worldwide. In drylands where precipitation is pulsed and ephemeral, the ability of biocrust microbiota to rapidly initiate metabolic activity is critical to their survival. Community gene expression was compared after a short duration (1 h) wetting pulse in both intact and soils disturbed by chronic foot trampling. Across the metatranscriptomes the majority of transcripts were cyanobacterial in origin, suggesting that cyanobacteria accounted for the bulk of the transcriptionally active cells. Chronic trampling substantially altered the functional profile of the metatranscriptomes, specifically resulting in a significant decrease in transcripts for nitrogen fixation. Soil depth (biocrust and below crust) was a relatively small factor in differentiating the metatranscriptomes, suggesting that the metabolically active bacteria were similar between shallow soil horizons. The dry samples were consistently enriched for hydrogenase genes, indicating that molecular hydrogen may serve as an energy source for the desiccated soil communities. The water pulse was associated with a restructuring of the metatranscriptome, particularly for the biocrusts. Biocrusts increased transcripts for photosynthesis and carbon fixation, suggesting a rapid resuscitation upon wetting. In contrast, the trampled surface soils showed a much smaller response to wetting, indicating that trampling altered the metabolic response of the community. Finally, several biogeochemical cycling genes in carbon and nitrogen cycling were assessed for their change in abundance due to wetting in the biocrusts. Different transcripts encoding the same gene product did not show a consensus response, with some more abundant in dry or wet biocrusts, highlighting the challenges in relating transcript abundance to biogeochemical cycling rates. These observations demonstrate that metatranscriptome sequencing was able to distinguish alterations in the function of arid soil microbial communities at two varying temporal scales, a long-term ecosystems disturbance through foot trampling, and a short term wetting pulse. Thus, community metatranscriptomes have the potential to inform studies on the response and resilience of biocrusts to various environmental perturbations.
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Affiliation(s)
- Blaire Steven
- Department of Environmental Sciences, Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Jayne Belnap
- Southwest Biological Science Center, United States Geological Survey, Moab, UT, United States
| | - Cheryl R Kuske
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM, United States
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11
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Estimating Net Photosynthesis of Biological Soil Crusts in the Atacama Using Hyperspectral Remote Sensing. REMOTE SENSING 2018. [DOI: 10.3390/rs10060891] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Effect of UV-B Radiation and Desiccation Stress on Photoprotective Compounds Accumulation in Marine Leptolyngbya sp. Appl Biochem Biotechnol 2017; 184:35-47. [PMID: 28584967 DOI: 10.1007/s12010-017-2523-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 05/19/2017] [Indexed: 01/03/2023]
Abstract
Increased awareness regarding the harmful effects of ultraviolet (UV)-B radiation has led to the search for new sources of natural UV-B protecting compounds. Mycosporine-like amino acids are one of such promising compounds found in several organisms. Cyanobacteria are ideal organisms for isolation of these compounds due to their compatibility and adaptability to thrive under harsh environmental conditions. In the following investigation, we report the production of shinorine in Leptolyngbya sp. isolated from the intertidal region. Based on the spectral characteristics and liquid chromatography-mass spectrometry analysis, the UV-absorbing compound was identified as shinorine. To the best of our knowledge, this is the first report on the occurrence of shinorine in Leptolyngbya sp. We also investigated the effect of artificial UV-B radiation and periodic desiccation on chlorophyll-a, total carotenoids, and mycosporine-like amino acids (MAAs) production. The UV-B radiation had a negative effect on growth and chlorophyll concentration, whereas it showed an inductive effect on the production of total carotenoids and MAAs. Desiccation along with UV-B radiation led to an increase in the concentration of photoprotective compounds. These results indicate that carotenoids and MAAs thus facilitate cyanobacteria to avoid and protect themselves from the deleterious effects of UV-B and desiccation.
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13
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Schmidt O, Dyckmans J, Schrader S. Photoautotrophic microorganisms as a carbon source for temperate soil invertebrates. Biol Lett 2017; 12:20150646. [PMID: 26740559 DOI: 10.1098/rsbl.2015.0646] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We tested experimentally if photoautotrophic microorganisms are a carbon source for invertebrates in temperate soils. We exposed forest or arable soils to a (13)CO2-enriched atmosphere and quantified (13)C assimilation by three common animal groups: earthworms (Oligochaeta), springtails (Hexapoda) and slugs (Gastropoda). Endogeic earthworms (Allolobophora chlorotica) and hemiedaphic springtails (Ceratophysella denticulata) were highly (13)C enriched when incubated under light, deriving up to 3.0 and 17.0%, respectively, of their body carbon from the microbial source in 7 days. Earthworms assimilated more (13)C in undisturbed soil than when the microbial material was mixed into the soil, presumably reflecting selective surface grazing. By contrast, neither adult nor newly hatched terrestrial slugs (Deroceras reticulatum) grazed on algal mats. Non-photosynthetic (13)CO2 fixation in the dark was negligible. We conclude from these preliminary laboratory experiments that, in addition to litter and root-derived carbon from vascular plants, photoautotrophic soil surface microorganisms (cyanobacteria, algae) may be an ecologically important carbon input route for temperate soil animals that are traditionally assigned to the decomposer channel in soil food web models and carbon cycling studies.
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Affiliation(s)
- Olaf Schmidt
- UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Republic of Ireland
| | - Jens Dyckmans
- Centre for Stable Isotope Research and Analysis, Büsgen-Institute, University of Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
| | - Stefan Schrader
- Johann Heinrich von Thünen-Institute-Federal Research Institute for Rural Areas, Forestry and Fisheries, Institute of Biodiversity, Bundesallee 50, 38116 Braunschweig, Germany
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14
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Murik O, Oren N, Shotland Y, Raanan H, Treves H, Kedem I, Keren N, Hagemann M, Pade N, Kaplan A. What distinguishes cyanobacteria able to revive after desiccation from those that cannot: the genome aspect. Environ Microbiol 2016; 19:535-550. [PMID: 27501380 DOI: 10.1111/1462-2920.13486] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/04/2016] [Indexed: 01/15/2023]
Abstract
Filamentous cyanobacteria are the main founders and primary producers in biological desert soil crusts (BSCs) and are likely equipped to cope with one of the harshest environmental conditions on earth including daily hydration/dehydration cycles, high irradiance and extreme temperatures. Here, we resolved and report on the genome sequence of Leptolyngbya ohadii, an important constituent of the BSC. Comparative genomics identified a set of genes present in desiccation-tolerant but not in dehydration-sensitive cyanobacteria. RT qPCR analyses showed that the transcript abundance of many of them is upregulated during desiccation in L. ohadii. In addition, we identified genes where the orthologs detected in desiccation-tolerant cyanobacteria differs substantially from that found in desiccation-sensitive cells. We present two examples, treS and fbpA (encoding trehalose synthase and fructose 1,6-bisphosphate aldolase respectively) where, in addition to the orthologs present in the desiccation-sensitive strains, the resistant cyanobacteria also possess genes with different predicted structures. We show that in both cases the two orthologs are transcribed during controlled dehydration of L. ohadii and discuss the genetic basis for the acclimation of cyanobacteria to the desiccation conditions in desert BSC.
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Affiliation(s)
- Omer Murik
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
| | - Nadav Oren
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
| | - Yoram Shotland
- Department of Chemical Engineering, Shamoon College of Engineering, Beer Sheva, 84100, Israel
| | - Hagai Raanan
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
| | - Haim Treves
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
| | - Isaac Kedem
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
| | - Nir Keren
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
| | - Martin Hagemann
- Institut für Biowissenschaften, Abteilung Pflanzenphysiologie, Universität Rostock, A.-Einstein-Str. 3, Rostock, D-18059, Germany
| | - Nadin Pade
- Institut für Biowissenschaften, Abteilung Pflanzenphysiologie, Universität Rostock, A.-Einstein-Str. 3, Rostock, D-18059, Germany
| | - Aaron Kaplan
- Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 9190401, Israel
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15
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Aslam SN, Dumbrell AJ, Sabir JS, Mutwakil MHZ, Baeshen MMN, Abo-Aba SEM, Clark DR, Yates SA, Baeshen NA, Underwood GJC, McGenity TJ. Soil compartment is a major determinant of the impact of simulated rainfall on desert microbiota. Environ Microbiol 2016; 18:5048-5062. [PMID: 27459511 DOI: 10.1111/1462-2920.13474] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 07/25/2016] [Indexed: 12/11/2022]
Abstract
Although desert soils support functionally important microbial communities that affect plant growth and influence many biogeochemical processes, the impact of future changes in precipitation patterns on the microbiota and their activities is largely unknown. We performed in-situ experiments to investigate the effect of simulated rainfall on bacterial communities associated with the widespread perennial shrub, Rhazya stricta in Arabian desert soils. The bacterial community composition was distinct between three different soil compartments: surface biological crust, root-attached, and the broader rhizosphere. Simulated rainfall had no significant effect on the overall bacterial community composition, but some population-level responses were observed, especially in soil crusts where Betaproteobacteria, Sphingobacteria, and Bacilli became more abundant. Bacterial biomass in the nutrient-rich crust increased three-fold one week after watering, whereas it did not change in the rhizosphere, despite its much higher water retention. These findings indicate that between rainfall events, desert-soil microbial communities enter into stasis, with limited species turnover, and reactivate rapidly and relatively uniformly when water becomes available. However, microbiota in the crust, which was relatively enriched in nutrients and organic matter, were primarily water-limited, compared with the rhizosphere microbiota that were co-limited by nutrients and water.
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Affiliation(s)
- Shazia N Aslam
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
| | - Alex J Dumbrell
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
| | - Jamal S Sabir
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Mohammed H Z Mutwakil
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Mohammed M N Baeshen
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Salah E M Abo-Aba
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Dave R Clark
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
| | - Steven A Yates
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
| | - Nabih A Baeshen
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Graham J C Underwood
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
| | - Terry J McGenity
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
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16
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Chennu A, Grinham A, Polerecky L, de Beer D, Al-Najjar MAA. Rapid Reactivation of Cyanobacterial Photosynthesis and Migration upon Rehydration of Desiccated Marine Microbial Mats. Front Microbiol 2015; 6:1472. [PMID: 26733996 PMCID: PMC4689872 DOI: 10.3389/fmicb.2015.01472] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/07/2015] [Indexed: 01/24/2023] Open
Abstract
Desiccated cyanobacterial mats are the dominant biological feature in the Earth's arid zones. While the response of desiccated cyanobacteria to rehydration is well-documented for terrestrial systems, information about the response in marine systems is lacking. We used high temporal resolution hyperspectral imaging, liquid chromatography, pulse-amplitude fluorometry, oxygen microsensors, and confocal laser microscopy to study this response in a desiccated microbial mat from Exmouth Gulf, Australia. During the initial 15 min after rehydration chlorophyll a concentrations increased 2-5 fold and cyanobacterial photosynthesis was re-established. Although the mechanism behind this rapid increase of chlorophyll a remains unknown, we hypothesize that it involves resynthesis from a precursor stored in desiccated cyanobacteria. The subsequent phase (15 min-48 h) involved migration of the reactivated cyanobacteria toward the mat surface, which led, together with a gradual increase in chlorophyll a, to a further increase in photosynthesis. We conclude that the response involving an increase in chlorophyll a and recovery of photosynthetic activity within minutes after rehydration is common for cyanobacteria from desiccated mats of both terrestrial and marine origin. However, the response of upward migration and its triggering factor appear to be mat-specific and likely linked to other factors.
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Affiliation(s)
- Arjun Chennu
- Max Planck Institute for Marine MicrobiologyBremen, Germany
| | - Alistair Grinham
- School of Civil Engineering, The University of Queensland, St. LuciaQLD, Australia
| | - Lubos Polerecky
- Max Planck Institute for Marine MicrobiologyBremen, Germany
- Department of Earth Sciences, Utrecht UniversityUtrecht, Netherlands
| | - Dirk de Beer
- Max Planck Institute for Marine MicrobiologyBremen, Germany
| | - Mohammad A. A. Al-Najjar
- Max Planck Institute for Marine MicrobiologyBremen, Germany
- Red Sea Research Center, King Abdullah University of Science and TechnologyJeddah, Saudi Arabia
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17
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Villa F, Pitts B, Lauchnor E, Cappitelli F, Stewart PS. Development of a Laboratory Model of a Phototroph-Heterotroph Mixed-Species Biofilm at the Stone/Air Interface. Front Microbiol 2015; 6:1251. [PMID: 26635736 PMCID: PMC4646968 DOI: 10.3389/fmicb.2015.01251] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/27/2015] [Indexed: 12/19/2022] Open
Abstract
Recent scientific investigations have shed light on the ecological importance and physiological complexity of subaerial biofilms (SABs) inhabiting lithic surfaces. In the field of sustainable cultural heritage (CH) preservation, mechanistic approaches aimed at investigation of the spatiotemporal patterns of interactions between the biofilm, the stone, and the atmosphere are of outstanding importance. However, these interactions have proven difficult to explore with field experiments due to the inaccessibility of samples, the complexity of the ecosystem under investigation and the temporal resolution of the experiments. To overcome these limitations, we aimed at developing a unifying methodology to reproduce a fast-growing, phototroph-heterotroph mixed species biofilm at the stone/air interface. Our experiments underscore the ability of the dual-species SAB model to capture functional traits characteristic of biofilms inhabiting lithic substrate such as: (i) microcolonies of aggregated bacteria; (ii) network like structure following surface topography; (iii) cooperation between phototrophs and heterotrophs and cross feeding processes; (iv) ability to change the chemical parameters that characterize the microhabitats; (v) survival under desiccation and (vi) biocide tolerance. With its advantages in control, replication, range of different experimental scenarios and matches with the real ecosystem, the developed model system is a powerful tool to advance our mechanistic understanding of the stone-biofilm-atmosphere interplay in different environments.
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Affiliation(s)
- Federica Villa
- Center for Biofilm Engineering, Montana State University, Bozeman MT, USA ; Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano Milano, Italy
| | - Betsey Pitts
- Center for Biofilm Engineering, Montana State University, Bozeman MT, USA
| | - Ellen Lauchnor
- Center for Biofilm Engineering, Montana State University, Bozeman MT, USA
| | - Francesca Cappitelli
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano Milano, Italy
| | - Philip S Stewart
- Center for Biofilm Engineering, Montana State University, Bozeman MT, USA
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