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Maire J, Deore P, Jameson VJ, Sakkas M, Perez-Gonzalez A, Blackall LL, van Oppen MJH. Assessing the contribution of bacteria to the heat tolerance of experimentally evolved coral photosymbionts. Environ Microbiol 2023; 25:3298-3318. [PMID: 37849020 DOI: 10.1111/1462-2920.16521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 09/28/2023] [Indexed: 10/19/2023]
Abstract
Coral reefs are extremely vulnerable to ocean warming, which triggers coral bleaching-the loss of endosymbiotic microalgae (Symbiodiniaceae) from coral tissues, often leading to death. To enhance coral climate resilience, the symbiont, Cladocopium proliferum was experimentally evolved for >10 years under elevated temperatures resulting in increased heat tolerance. Bacterial 16S rRNA gene metabarcoding showed the composition of intra- and extracellular bacterial communities of heat-evolved strains was significantly different from that of wild-type strains, suggesting bacteria responded to elevated temperatures, and may even play a role in C. proliferum thermal tolerance. To assess whether microbiome transplantation could enhance heat tolerance of the sensitive wild-type C. proliferum, we transplanted bacterial communities from heat-evolved to the wild-type strain and subjected it to acute heat stress. Microbiome transplantation resulted in the incorporation of only 30 low-abundance strains into the microbiome of wild-type cultures, while the relative abundance of 14 pre-existing strains doubled in inoculated versus uninoculated samples. Inoculation with either wild-type or heat-evolved bacterial communities boosted C. proliferum growth, although no difference in heat tolerance was observed between the two inoculation treatments. This study provides evidence that Symbiodiniaceae-associated bacterial communities respond to heat selection and may contribute to coral adaptation to climate change.
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Affiliation(s)
- Justin Maire
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Pranali Deore
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Vanta J Jameson
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute of Infection and Immunity, Parkville, Victoria, Australia
- Melbourne Cytometry Platform, The University of Melbourne, Parkville, Victoria, Australia
| | - Magdaline Sakkas
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute of Infection and Immunity, Parkville, Victoria, Australia
- Melbourne Cytometry Platform, The University of Melbourne, Parkville, Victoria, Australia
| | - Alexis Perez-Gonzalez
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute of Infection and Immunity, Parkville, Victoria, Australia
- Melbourne Cytometry Platform, The University of Melbourne, Parkville, Victoria, Australia
| | - Linda L Blackall
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Madeleine J H van Oppen
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
- Australian Institute of Marine Science, Townsville, Queensland, Australia
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Brito-Bello AA, Lopez-Arredondo D. Bioactive Compounds with Pesticide Activities Derived from Aged Cultures of Green Microalgae. BIOLOGY 2023; 12:1149. [PMID: 37627033 PMCID: PMC10452921 DOI: 10.3390/biology12081149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/08/2023] [Accepted: 08/12/2023] [Indexed: 08/27/2023]
Abstract
The excessive use of synthetic pesticides has caused environmental problems and human health risks and increased the development of resistance in several organisms. Allelochemicals, secondary metabolites produced as part of the defense mechanisms in plants and microorganisms, are an attractive alternative to replace synthetic pesticides to remediate these problems. Microalgae are natural producers of a wide range of allelochemicals. Thus, they provide new opportunities to identify secondary metabolites with pesticide activities and an alternative approach to discover new modes of action and circumvent resistance. We screened 10 green microalgae strains belonging to the Chlorophyta phylum for their potential to inhibit the growth of photosynthetic and nonphotosynthetic organisms. Bioassays were established to assess microalgae extracts' effectiveness in controlling the growth of Chlorella sorokiniana, Arabidopsis thaliana, Amaranthus palmeri, and the model nematode Caenorhabditis elegans. All tested strains exhibited herbicidal, nematocidal, or algicidal activities. Importantly, methanol extracts of a Chlamydomonas strain effectively controlled the germination and growth of a glyphosate-resistant A. palmeri biotype. Likewise, some microalgae extracts effectively killed C. elegans L1 larvae. Comprehensive metabolic profiling using LC-MS of extracts with pesticide activities showed that the metabolite composition of Chlamydomonas, Chlorella, and Chloroidium extracts is diverse. Molecules such as fatty acids, isoquinoline alkaloids, aldehydes, and cinnamic acids were more abundant, suggesting their participation in the pesticide activities.
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Affiliation(s)
| | - Damar Lopez-Arredondo
- Institute of Genomics for Crop Abiotic Stress Tolerance, Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409, USA
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Life and death of Pseudokirchneriella subcapitata: physiological changes during chronological aging. Appl Microbiol Biotechnol 2022; 106:8245-8258. [PMID: 36385567 DOI: 10.1007/s00253-022-12267-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 10/20/2022] [Accepted: 10/23/2022] [Indexed: 11/18/2022]
Abstract
The green alga Pseudokirchneriella subcapitata is widely used in ecotoxicity assays and has great biotechnological potential as feedstock. This work aims to characterize the physiology of this alga associated with the aging resulting from the incubation of cells for 21 days, in the OECD medium, with continuous agitation and light exposure, in a batch mode. After inoculation, cells grow exponentially during 3 days, and the culture presents a typical green color. In this phase, "young" algal cells present, predominantly, a lunate morphology with the chloroplast occupying a large part of the cell, maximum photosynthetic activity and pigments concentration, and produce starch as a reserve material. Between the 5th and the 12th days of incubation, cells are in the stationary phase. The culture becomes less green, and the cells stop dividing (≥ 99% have one nucleus) and start to age. "Old" algal cells present chloroplast shrinkage, an abrupt decline of chlorophylls content, and photosynthetic capacity (Fv/Fm and ɸPSII), accompanied by a degradation of starch and an increase of neutral lipids content. The onset of the death phase occurs after the 12th day and is characterized by the loss of cell membrane integrity of some algae (cell death). The culture stays, progressively, yellow, and the majority of the population (~93%) is composed of live cells, chronologically "old," with a significant drop in photosynthetic activity (decay > 75% of Fv/Fm and ɸPSII) and starch content. The information here achieved can be helpful when exploring the potential of this alga in toxicity studies or in biotechnological applications. KEY POINTS: • Physiological changes of P. subcapitata with chronological aging are shown • "Young" algae exhibit a semilunar shape, high photosynthetic activity, and accumulated starch • "Old"-live algae show reduced photosynthetic capacity and accumulated lipids.
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Hoeger AL, Jehmlich N, Kipping L, Griehl C, Noll M. Associated bacterial microbiome responds opportunistic once algal host Scenedesmus vacuolatus is attacked by endoparasite Amoeboaphelidium protococcarum. Sci Rep 2022; 12:13187. [PMID: 35915148 PMCID: PMC9343445 DOI: 10.1038/s41598-022-17114-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 07/20/2022] [Indexed: 11/09/2022] Open
Abstract
The interactions of microalgae and their associated microbiomes have come to the fore of applied phycological research in recent years. However, the functional mechanisms of microalgal interactions remain largely unknown. Here, we examine functional protein patterns of the microalgae Scenedesmus vacuolatus and its associated bacterial community during algal infection by the endoparasite Amoeboaphelidium protococcarum. We performed metaproteomics analyses of non-infected (NI) and aphelid-infected (AI) S.vacuolatus cultures to investigate underlying functional and physiological changes under infectious conditions. We observed an increase in bacterial protein abundance as well as a severe shift of bacterial functional patterns throughout aphelid-infection in comparison to NI treatment. Most of the bacterial proteins (about 55%) upregulated in AI were linked to metabolism and transport of amino acids, lipids, coenzymes, nucleotides and carbohydrates and to energy production. Several proteins associated with pathogenic bacterial-plant interactions showed higher protein abundance levels in AI treatment. These functional shifts indicate that associated bacteria involved in commensalistic or mutualistic interactions in NI switch to opportunistic lifestyles and facilitate pathogenic or saprotrophic traits in AI treatment. In summary, the native bacterial microbiome adapted its metabolism to algal host die off and is able to metabolize nutrients from injured cells or decompose dead cellular material.
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Affiliation(s)
- Anna-Lena Hoeger
- Competence Center Algae Biotechnology, Anhalt University of Applied Sciences, Koethen, Germany
| | - Nico Jehmlich
- Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research - UFZ GmbH, Permoserstr. 15, 04318, Leipzig, Germany
| | - Lydia Kipping
- Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research - UFZ GmbH, Permoserstr. 15, 04318, Leipzig, Germany
| | - Carola Griehl
- Competence Center Algae Biotechnology, Anhalt University of Applied Sciences, Koethen, Germany
| | - Matthias Noll
- Institute for Bioanalysis, Coburg University of Applied Sciences and Arts, Coburg, Germany. .,Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany.
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Zamzam G, Lee CW, Milne F, Etsell J, Durnford DG. Live long and prosper: Acetate and its effects on longevity in batch culturing of Chlamydomonas reinhardtii. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Damoo DY, Durnford DG. Long-term survival of Chlamydomonas reinhardtii during conditional senescence. Arch Microbiol 2021; 203:5333-5344. [PMID: 34383108 DOI: 10.1007/s00203-021-02508-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/22/2021] [Accepted: 08/02/2021] [Indexed: 12/29/2022]
Abstract
Chlamydomonas reinhardtii undergoes conditional senescence when grown in batch culture due to nutrient limitation. Here, we explored plastid and photo-physiological adaptations in Chlamydomonas reinhardtii during a long-term ageing experiment by methodically sampling them over 22 weeks. Following exponential growth, Chlamydomonas entered an extended declining growth phase where cells continued to divide, although at a lower rate. Ultimately, this ongoing division was fueled by the recycling of macromolecules that was obvious in the rapidly declining protein and chlorophyll content in the cell during this phase. This process was sufficient to maintain a high level of cell viability as the culture entered stationary phase. Beyond that the cell viability starts to plummet. During the turnover of macromolecules after exponential growth that saw RuBisCO levels drop, the LHCII antenna was relatively stable. This, along with the upregulation of the light stress-related proteins (LHCSR), contributes to an efficient energy dissipation mechanism to protect the ageing cells from photooxidative stress during the senescence process. Ultimately, viability dropped to about 7% at 22 weeks in a batch culture. We anticipate that this research will help further understand the various acclimation strategies carried out by Chlamydomonas to maximize survival under conditional senescence.
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Affiliation(s)
- Djihane Yushrina Damoo
- Department of Biology, University of New Brunswick, Fredericton, NB, E3B 5A3, Canada.,Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Dion G Durnford
- Department of Biology, University of New Brunswick, Fredericton, NB, E3B 5A3, Canada.
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Meagher E, Rangsrikitphoti P, Faridi B, Zamzam G, Durnford DG. Photoacclimation to high-light stress in Chlamydomonas reinhardtii during conditional senescence relies on generating pH-dependent, high-quenching centres. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 158:136-145. [PMID: 33307425 DOI: 10.1016/j.plaphy.2020.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
Microalgae can respond to long-term increases in light intensity by altering the concentration of photosynthetic complexes. Under active growth, the ability of Chlamydomonas reinhardtii to acclimate to excess light is dependent on cell division to reduce the concentration of photosynthetic complexes. But, in batch culture, cells eventually reach stationary phase where their ability to divide is limited; this should impact their capacity to undergo photoacclimation. Our goal is to dissect excess-light responses as cells approach stationary phase and to determine how the strategies of photoacclimation differ compared to cells in the exponential-growth phase. In this study, cultures exited exponential growth and transitioned into a declining growth phase (DGP), where cells continued a slow rate of growth for the next seven days in both low (LL) and high-light (HL). During this period, both cultures experience a conditional senescence-related decline in chlorophyll levels. Under HL, however, the senescing cultures have a rapid decline in PSII reaction centres, maintain a stable concentration of LHCII antenna, rapidly increase LHCSR levels, and have a sustained increase in Fo/Fm. Collectively this implies that the remaining antenna act as pH-dependent, quenching centres, presumably to protect the senescing chloroplast against HL. We discovered that acclimating to HL post-exponential phase involves active degradation that is intertwined with the normal senescence process that allowed for a limited rate of cell division.
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Affiliation(s)
- Emily Meagher
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | | | - Babar Faridi
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - Ghaith Zamzam
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada
| | - Dion G Durnford
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3, Canada.
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Abstract
Damage is an inevitable consequence of life. For unicellular organisms, this leads to a trade-off between allocating resources into damage repair or into growth coupled with segregation of damage upon cell division, i.e., aging and senescence. Few studies considered repair as an alternative to senescence. None considered biofilms, where the majority of unicellular organisms live, although fitness advantages in well-mixed systems often turn into disadvantages in spatially structured systems such as biofilms. We compared the fitness consequences of aging versus an adaptive repair mechanism based on sensing damage, using an individual-based model of a generic unicellular organism growing in biofilms. We found that senescence is not beneficial provided that growth is limited by substrate availability. Instead, it is useful as a stress response to deal with damage that failed to be repaired when (i) extrinsic mortality was high; (ii) a degree of multicellularity was present; and (iii) damage segregation was effective. The extent of senescence due to damage accumulation—or aging—is evidently evolvable as it differs hugely between species and is not universal, suggesting that its fitness advantages depend on life history and environment. In contrast, repair of damage is present in all organisms studied. Despite the fundamental trade-off between investing resources into repair or into growth, repair and segregation of damage have not always been considered alternatives. For unicellular organisms, unrepaired damage could be divided asymmetrically between daughter cells, leading to senescence of one and rejuvenation of the other. Repair of “unicells” has been predicted to be advantageous in well-mixed environments such as chemostats. Most microorganisms, however, live in spatially structured systems, such as biofilms, with gradients of environmental conditions and cellular physiology as well as a clonal population structure. To investigate whether this clonal structure might favor senescence by damage segregation (a division-of-labor strategy akin to the germline-soma division in multicellular organisms), we used an individual-based computational model and developed an adaptive repair strategy where cells respond to their current intracellular damage levels by investing into repair machinery accordingly. Our simulations showed that the new adaptive repair strategy was advantageous provided that growth was limited by substrate availability, which is typical for biofilms. Thus, biofilms do not favor a germline-soma-like division of labor between daughter cells in terms of damage segregation. We suggest that damage segregation is beneficial only when extrinsic mortality is high, a degree of multicellularity is present, and an active mechanism makes segregation effective. IMPORTANCE Damage is an inevitable consequence of life. For unicellular organisms, this leads to a trade-off between allocating resources into damage repair or into growth coupled with segregation of damage upon cell division, i.e., aging and senescence. Few studies considered repair as an alternative to senescence. None considered biofilms, where the majority of unicellular organisms live, although fitness advantages in well-mixed systems often turn into disadvantages in spatially structured systems such as biofilms. We compared the fitness consequences of aging versus an adaptive repair mechanism based on sensing damage, using an individual-based model of a generic unicellular organism growing in biofilms. We found that senescence is not beneficial provided that growth is limited by substrate availability. Instead, it is useful as a stress response to deal with damage that failed to be repaired when (i) extrinsic mortality was high; (ii) a degree of multicellularity was present; and (iii) damage segregation was effective.
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Puzanskiy RK, Romanyuk DA, Kirpichnikova AA, Shishova MF. Alteration in the Expression of Genes Encoding Primary Metabolism Enzymes and Plastid Transporters during the Culture Growth of Chlamydomonas reinhardtii. Mol Biol 2020. [DOI: 10.1134/s0026893320040147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Metabolic, Physiological, and Transcriptomics Analysis of Batch Cultures of the Green Microalga Chlamydomonas Grown on Different Acetate Concentrations. Cells 2019; 8:cells8111367. [PMID: 31683711 PMCID: PMC6912441 DOI: 10.3390/cells8111367] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 10/23/2019] [Accepted: 10/30/2019] [Indexed: 01/13/2023] Open
Abstract
Acetate can be efficiently metabolized by the green microalga Chlamydomonas reinhardtii. The regular concentration is 17 mM, although higher concentrations are reported to increase starch and fatty acid content. To understand the responses to higher acetate concentrations, Chlamydomonas cells were cultivated in batch mode in the light at 17, 31, 44, and 57 mM acetate. Metabolic analyses show that cells grown at 57 mM acetate possess increased contents of all components analyzed (starch, chlorophylls, fatty acids, and proteins), with a three-fold increased volumetric biomass yield compared to cells cultivated at 17 mM acetate at the entry of stationary phase. Physiological analyses highlight the importance of photosynthesis for the low-acetate and exponential-phase samples. The stationary phase is reached when acetate is depleted, except for the cells grown at 57 mM acetate, which still divide until ammonium exhaustion. Surprisal analysis of the transcriptomics data supports the biological significance of our experiments. This allows the establishment of a model for acetate assimilation, its transcriptional regulation and the identification of candidates for genetic engineering of this metabolic pathway. Altogether, our analyses suggest that growing at high-acetate concentrations could increase biomass productivities in low-light and CO2-limiting air-bubbled medium for biotechnology.
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Florea M. Aging and immortality in unicellular species. Mech Ageing Dev 2017; 167:5-15. [PMID: 28844968 DOI: 10.1016/j.mad.2017.08.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 07/21/2017] [Accepted: 08/13/2017] [Indexed: 12/22/2022]
Abstract
It has been historically thought that in conditions that permit growth, most unicellular species do not to age. This was particularly thought to be the case for symmetrically dividing species, as such species lack a clear distinction between the soma and the germline. Despite this, studies of the symmetrically dividing species Escherichia coli and Schizosaccharomyces pombe have recently started to challenge this notion. They indicate that E. coli and S. pombe do age, but only when subjected to environmental stress. If true, this suggests that aging may be widespread among microbial species in general, and that studying aging in microbes may inform other long-standing questions in aging. This review examines the recent evidence for and against replicative aging in symmetrically dividing unicellular organisms, the mechanisms that underlie aging, why aging evolved in these species, and how microbial aging fits into the context of other questions in aging.
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Affiliation(s)
- Michael Florea
- Graduate School of Arts and Sciences, Harvard Medical School, 25 Shattuck St, Boston, MA 02115, USA.
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