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Berlino M, Mangano MC, Di Bona G, Lucchese M, Terzo SMC, De Vittor C, D'Alessandro M, Esposito V, Gambi MC, Del Negro P, Sarà G. Functional diversity and metabolic response in benthic communities along an ocean acidification gradient. MARINE ENVIRONMENTAL RESEARCH 2024:106520. [PMID: 38685145 DOI: 10.1016/j.marenvres.2024.106520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 04/14/2024] [Accepted: 04/15/2024] [Indexed: 05/02/2024]
Abstract
Altered ocean chemistry caused by ocean acidification (OA) is expected to have negative repercussions at different levels of the ecological hierarchy, starting from the individual and scaling up to the community and ultimately to the ecosystem level. Understanding the effects of OA on benthic organisms is of primary importance given their relevant ecological role in maintaining marine ecosystem functioning. The use of functional traits represents an effective technique to investigate how species adapt to altered environmental conditions and can be used to predict changes in the resilience of communities faced with stresses associated with climate change. Artificial supports were deployed for 1-y along a natural pH gradient in the shallow hydrothermal systems of the Bottaro crater near Panarea (Aeolian Archipelago, southern Tyrrhenian Sea), to explore changes in functional traits and metabolic rates of benthic communities and the repercussions in terms of functional diversity. Changes in community composition due to OA were accompanied by modifications in functional diversity. Altered conditions led to higher oxygen consumption in the acidified site and the selection of species with the functional traits needed to withstand OA. Calcification rate and reproduction were found to be the traits most affected by pH variations. A reduction in a community's functional evenness could potentially reduce its resilience to further environmental or anthropogenic stressors. These findings highlight the ability of the ecosystem to respond to climate change and provide insights into the modifications that can be expected given the predicted future pCO2 scenarios. Understanding the impact of climate change on functional diversity and thus on community functioning and stability is crucial if we are to predict changes in ecosystem vulnerability, especially in a context where OA occurs in combination with other environmental changes and anthropogenic stressors.
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Affiliation(s)
- M Berlino
- Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology (EMI), Sicily Marine Centre, Lungomare Cristoforo Colombo (complesso Roosevelt), 90149, Palermo, Italy; Dipartimento di Scienze della Terra e del Mare, DiSTeM, Università degli Studi di Palermo Ed. 16, 90128, Palermo, Italy; NBFC, National Biodiversity Future Center, Palermo Viale delle Scienze Ed. 16, 90128, Palermo, Italy.
| | - M C Mangano
- Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology (EMI), Sicily Marine Centre, Lungomare Cristoforo Colombo (complesso Roosevelt), 90149, Palermo, Italy; NBFC, National Biodiversity Future Center, Palermo Viale delle Scienze Ed. 16, 90128, Palermo, Italy
| | - G Di Bona
- Dipartimento di Scienze della Terra e del Mare, DiSTeM, Università degli Studi di Palermo Ed. 16, 90128, Palermo, Italy; NBFC, National Biodiversity Future Center, Palermo Viale delle Scienze Ed. 16, 90128, Palermo, Italy
| | - M Lucchese
- Dipartimento di Scienze della Terra e del Mare, DiSTeM, Università degli Studi di Palermo Ed. 16, 90128, Palermo, Italy; NBFC, National Biodiversity Future Center, Palermo Viale delle Scienze Ed. 16, 90128, Palermo, Italy; National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - S M C Terzo
- Dipartimento di Scienze della Terra e del Mare, DiSTeM, Università degli Studi di Palermo Ed. 16, 90128, Palermo, Italy; NBFC, National Biodiversity Future Center, Palermo Viale delle Scienze Ed. 16, 90128, Palermo, Italy; Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, Viale Fernando Stagno d'Alcontres 3, University of Messina, Messina, Italy; Department of Ecosustainable Marine Biotechnology, Stazione Zoologica Anton Dohrn, Via A.F. Acton, Molosiglio, Napoli, 80133, Italy
| | - C De Vittor
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - M D'Alessandro
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - V Esposito
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy; Stazione Zoologica Anton Dohrn, Research Infrastructures for Marine Biological Resources Department, Via Po 25, 00198, Roma, Italy
| | - M C Gambi
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy; Previous at the Stazione Zoologica Anton Dohrn, Department of Marine Integrative Ecology (EMI), Ischia Marine Center, Ischia Napoli, Italy
| | - P Del Negro
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - G Sarà
- Dipartimento di Scienze della Terra e del Mare, DiSTeM, Università degli Studi di Palermo Ed. 16, 90128, Palermo, Italy; NBFC, National Biodiversity Future Center, Palermo Viale delle Scienze Ed. 16, 90128, Palermo, Italy
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Ravaglioli C, De Marchi L, Anselmi S, Dattolo E, Fontanini D, Pretti C, Procaccini G, Rilov G, Renzi M, Silverman J, Bulleri F. Ocean acidification impairs seagrass performance under thermal stress in shallow and deep water. ENVIRONMENTAL RESEARCH 2024; 241:117629. [PMID: 37967703 DOI: 10.1016/j.envres.2023.117629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/21/2023] [Accepted: 11/07/2023] [Indexed: 11/17/2023]
Abstract
Despite the effects of ocean acidification (OA) on seagrasses have been widely investigated, predictions of seagrass performance under future climates need to consider multiple environmental factors. Here, we performed a mesocosm study to assess the effects of OA on shallow and deep Posidonia oceanica plants. The experiment was run in 2021 and repeated in 2022, a year characterized by a prolonged warm water event, to test how the effects of OA on plants are modulated by thermal stress. The response of P. oceanica to experimental conditions was investigated at different levels of biological organization. Under average seawater temperature, there were no effects of OA in both shallow and deep plants, indicating that P. oceanica is not limited by current inorganic carbon concentration, regardless of light availability. In contrast, under thermal stress, exposure of plants to OA increased lipid peroxidation and decreased photosynthetic performance, with deep plants displaying higher levels of heat stress, as indicated by the over-expression of stress-related genes and the activation of antioxidant systems. In addition, warming reduced plant growth, regardless of seawater CO2 and light levels, suggesting that thermal stress may play a fundamental role in the future development of seagrass meadows. Our results suggest that OA may exacerbate the negative effects of future warming on seagrasses.
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Affiliation(s)
- Chiara Ravaglioli
- Dipartimento di Biologia, Università di Pisa, CoNISMa, Via Derna 1, 56126, Pisa, Italy.
| | - Lucia De Marchi
- Dipartimento di Scienze Veterinarie, Università of Pisa, Via Livornese (lato monte), 56122, San Piero a Grado, Pisa, Italy.
| | - Serena Anselmi
- Bioscience Research Center, Via Aurelia Vecchia, 32, 58015, Orbetello, GR, Italy.
| | - Emanuela Dattolo
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy; National Biodiversity Future Centre (NBFC), Palermo, Italy.
| | - Debora Fontanini
- Dipartimento di Biologia, Università di Pisa, CoNISMa, Via Derna 1, 56126, Pisa, Italy.
| | - Carlo Pretti
- Dipartimento di Scienze Veterinarie, Università of Pisa, Via Livornese (lato monte), 56122, San Piero a Grado, Pisa, Italy; Interuniversity Consortium of Marine Biology and Applied Ecology "G. Bacci" (CIBM), Viale N.Sauro 4, 57128, Livorno, Italy.
| | - Gabriele Procaccini
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy; National Biodiversity Future Centre (NBFC), Palermo, Italy.
| | - Gil Rilov
- National Institute of Oceanography, Israel Oceanographic and Limnological Research, Haifa, Israel.
| | - Monia Renzi
- Dipartimento di Scienze Della Vita, Università di Trieste, Via Giorgieri, 10, 34127, Trieste, Italy.
| | - Jacob Silverman
- National Institute of Oceanography, Israel Oceanographic and Limnological Research, Haifa, Israel.
| | - Fabio Bulleri
- Dipartimento di Biologia, Università di Pisa, CoNISMa, Via Derna 1, 56126, Pisa, Italy; Centro Interdipartimentale di Ricerca per Lo Studio Degli Effetti Del Cambiamento Climatico (CIRSEC), Università di Pisa, Italy.
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3
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Viana IG, Artika SR, Moreira-Saporiti A, Teichberg M. Limited trait responses of a tropical seagrass to the combination of increasing pCO2 and warming. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:472-488. [PMID: 36272111 DOI: 10.1093/jxb/erac425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 10/20/2022] [Indexed: 06/16/2023]
Abstract
Understanding species-specific trait responses under future global change scenarios is of importance for conservation efforts and to make informed decisions within management projects. The combined and single effects of seawater acidification and warmer average temperature were investigated by means of the trait responses of Cymodocea serrulata, a tropical seagrass, under experimental conditions. After a 35 d exposure period, biochemical, morphological, and photo-physiological trait responses were measured. Overall, biochemical traits mildly responded under the individual exposure to high temperature and increasing pCO2 values. The response of C. serrulata was limited to a decrease in %C and an increase in the sucrose content in the rhizome under the high temperature treatment, 32 °C. This suggests that this temperature was lower than the maximum tolerance limit for this species. Increasing pCO2 levels increased %C in the rhizome, and also showed a significant increase in leaf δ13C values. The effects of all treatments were sublethal; however, small changes in their traits could affect the ecosystem services they provide. In particular, changes in tissue carbon concentrations may affect carbon storage capacity, one key ecosystem service. The simultaneous study of different types of trait responses contributes to establish a holistic framework of seagrass ecosystem health under climate change.
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Affiliation(s)
- Inés G Viana
- Department of Ecology and Animal Biology, University of Vigo, 36310 Vigo, Spain
- Department of Ecology, Leibniz Centre for Tropical Marine Research, Bremen, Germany
- Instituto Español de Oceanografía (IEO-CSIC), Centro Oceanográfico de A Coruña, 15001, A Coruña, Spain
| | - Suci Rahmadani Artika
- Department of Ecology, Leibniz Centre for Tropical Marine Research, Bremen, Germany
- Department of Marine Sciences, Faculty of Marine Sciences and Fisheries, Hasanuddin University, Indonesia
- Department of Marine Sciences, Faculty of Fisheries and Marine Sciences, Halu Oleo University, Indonesia
| | - Agustín Moreira-Saporiti
- Department of Ecology, Leibniz Centre for Tropical Marine Research, Bremen, Germany
- University of Bremen, Bremen, Germany
- The Ecosystems Center, Marine Biological Laboratory (MBL), Woods Hole, MA, USA
| | - Mirta Teichberg
- Department of Ecology, Leibniz Centre for Tropical Marine Research, Bremen, Germany
- The Ecosystems Center, Marine Biological Laboratory (MBL), Woods Hole, MA, USA
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Lee J, Gambi MC, Kroeker KJ, Munari M, Peay K, Micheli F. Resilient consumers accelerate the plant decomposition in a naturally acidified seagrass ecosystem. GLOBAL CHANGE BIOLOGY 2022; 28:4558-4576. [PMID: 35583009 DOI: 10.1111/gcb.16265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/15/2022] [Accepted: 03/22/2022] [Indexed: 06/15/2023]
Abstract
Anthropogenic stressors are predicted to alter biodiversity and ecosystem functioning worldwide. However, scaling up from species to ecosystem responses poses a challenge, as species and functional groups can exhibit different capacities to adapt, acclimate, and compensate under changing environments. We used a naturally acidified seagrass ecosystem (the endemic Mediterranean Posidonia oceanica) as a model system to examine how ocean acidification (OA) modifies the community structure and functioning of plant detritivores, which play vital roles in the coastal nutrient cycling and food web dynamics. In seagrass beds associated with volcanic CO2 vents (Ischia, Italy), we quantified the effects of OA on seagrass decomposition by deploying litterbags in three distinct pH zones (i.e., ambient, low, extreme low pH), which differed in the mean and variability of seawater pH. We replicated the study in two discrete vents for 117 days (litterbags sampled on day 5, 10, 28, 55, and 117). Acidification reduced seagrass detritivore richness and diversity through the loss of less abundant, pH-sensitive species but increased the abundance of the dominant detritivore (amphipod Gammarella fucicola). Such compensatory shifts in species abundance caused more than a threefold increase in the total detritivore abundance in lower pH zones. These community changes were associated with increased consumption (52%-112%) and decay of seagrass detritus (up to 67% faster decomposition rate for the slow-decaying, refractory detrital pool) under acidification. Seagrass detritus deployed in acidified zones showed increased N content and decreased C:N ratio, indicating that altered microbial activities under OA may have affected the decay process. The findings suggest that OA could restructure consumer assemblages and modify plant decomposition in blue carbon ecosystems, which may have important implications for carbon sequestration, nutrient recycling, and trophic transfer. Our study highlights the importance of within-community response variability and compensatory processes in modulating ecosystem functions under extreme global change scenarios.
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Affiliation(s)
- Juhyung Lee
- Hopkins Marine Station of Stanford University, Pacific Grove, California, USA
- Department of Biology, Stanford University, Stanford, California, USA
| | | | - Kristy J Kroeker
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, USA
| | - Marco Munari
- Department of Integrative Marine Ecology, Ischia Marine Centre, Stazione Zoologica Anton Dohrn, Ischia, Naples, Italy
| | - Kabir Peay
- Department of Biology, Stanford University, Stanford, California, USA
| | - Fiorenza Micheli
- Hopkins Marine Station of Stanford University, Pacific Grove, California, USA
- Department of Biology, Stanford University, Stanford, California, USA
- Stanford Center for Ocean Solutions, Pacific Grove, California, USA
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Ecological and Biotechnological Relevance of Mediterranean Hydrothermal Vent Systems. MINERALS 2022. [DOI: 10.3390/min12020251] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Marine hydrothermal systems are a special kind of extreme environments associated with submarine volcanic activity and characterized by harsh chemo-physical conditions, in terms of hot temperature, high concentrations of CO2 and H2S, and low pH. Such conditions strongly impact the living organisms, which have to develop adaptation strategies to survive. Hydrothermal systems have attracted the interest of researchers due to their enormous ecological and biotechnological relevance. From ecological perspective, these acidified habitats are useful natural laboratories to predict the effects of global environmental changes, such as ocean acidification at ecosystem level, through the observation of the marine organism responses to environmental extremes. In addition, hydrothermal vents are known as optimal sources for isolation of thermophilic and hyperthermophilic microbes, with biotechnological potential. This double aspect is the focus of this review, which aims at providing a picture of the ecological features of the main Mediterranean hydrothermal vents. The physiological responses, abundance, and distribution of biotic components are elucidated, by focusing on the necto-benthic fauna and prokaryotic communities recognized to possess pivotal role in the marine ecosystem dynamics and as indicator species. The scientific interest in hydrothermal vents will be also reviewed by pointing out their relevance as source of bioactive molecules.
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Petit‐Marty N, Nagelkerken I, Connell SD, Schunter C. Natural CO 2 seeps reveal adaptive potential to ocean acidification in fish. Evol Appl 2021; 14:1794-1806. [PMID: 34295364 PMCID: PMC8288007 DOI: 10.1111/eva.13239] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/29/2021] [Accepted: 03/29/2021] [Indexed: 01/01/2023] Open
Abstract
Volcanic CO2 seeps are natural laboratories that can provide insights into the adaptation of species to ocean acidification. While many species are challenged by reduced-pH levels, some species benefit from the altered environment and thrive. Here, we explore the molecular mechanisms of adaptation to ocean acidification in a population of a temperate fish species that experiences increased population sizes under elevated CO2. Fish from CO2 seeps exhibited an overall increased gene expression in gonad tissue compared with those from ambient CO2 sites. Up-regulated genes at CO2 seeps are possible targets of adaptive selection as they can directly influence the physiological performance of fishes exposed to ocean acidification. Most of the up-regulated genes at seeps were functionally involved in the maintenance of pH homeostasis and increased metabolism, and presented a deviation from neutral evolution expectations in their patterns of DNA polymorphisms, providing evidence for adaptive selection to ocean acidification. The targets of this adaptive selection are likely regulatory sequences responsible for the increased expression of these genes, which would allow a fine-tuned physiological regulation to maintain homeostasis and thrive at CO2 seeps. Our findings reveal that standing genetic variation in DNA sequences regulating the expression of genes in response to a reduced-pH environment could provide for adaptive potential to near-future ocean acidification in fishes. Moreover, with this study we provide a forthright methodology combining transcriptomics and genomics, which can be applied to infer the adaptive potential to different environmental conditions in wild marine populations.
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Affiliation(s)
- Natalia Petit‐Marty
- Swire Institute of Marine ScienceSchool of Biological SciencesThe University of Hong KongHong KongHong Kong SAR
| | - Ivan Nagelkerken
- Southern Seas Ecology LaboratoriesSchool of Biological Sciences and the Environment InstituteDX 650 418The University of AdelaideAdelaideSAAustralia
| | - Sean D. Connell
- Southern Seas Ecology LaboratoriesSchool of Biological Sciences and the Environment InstituteDX 650 418The University of AdelaideAdelaideSAAustralia
| | - Celia Schunter
- Swire Institute of Marine ScienceSchool of Biological SciencesThe University of Hong KongHong KongHong Kong SAR
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Mirasole A, Badalamenti F, Di Franco A, Gambi MC, Teixidó N. Boosted fish abundance associated with Posidonia oceanica meadows in temperate shallow CO 2 vents. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 771:145438. [PMID: 33548697 DOI: 10.1016/j.scitotenv.2021.145438] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/17/2021] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
Ocean acidification (OA) may induce major shifts in the structure and function of coastal marine ecosystems. Studies in volcanic CO2 vents, where seawater is naturally acidified, have reported an overall simplification of fish assemblages structure, while some primary producers are likely to increase their biomass under elevated concentration of CO2. Here we used temperate shallow CO2 vents located around the coast of Ischia island (Italy) to assess the effects of OA on necto-benthic fish assemblages associated with the foundation seagrass species Posidonia oceanica in the Mediterranean Sea. We compared P. oceanica meadow structure, its epiphytic community and the associated fish assemblage structure and diversity at vents with low pH sites and reference sites with ambient pH using underwater visual census strip transects, in two seasons (fall 2018 and summer 2019). Data were analysed using both univariate and multivariate statistical techniques. Results showed greater P. oceanica habitat complexity (i.e. shoot density) and lower abundance of epiphytic calcareous species (e.g. coralline algae) at the vents than reference sites. Total abundance of adult and juvenile fish was higher at vents than reference sites, while no differences were found for species richness and composition. Overall, the herbivore Sarpa salpa stands out among the species contributing the most to dissimilarity between vents and reference sites, showing higher abundances under OA conditions. This pattern could be explained by the combined effect of a positive response to the higher structural meadows complexity and the greater seagrasses palatability/nutritional value occurring at the vents, which may help herbivores to withstand the higher energetic cost to live under high pCO2/low pH conditions. Our results indicate that necto-benthic fish assemblages associated with the Mediterranean P. oceanica ecosystem may cope with OA under the CO2 emission scenarios forecasted for the end of this century.
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Affiliation(s)
- Alice Mirasole
- Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology, Ischia Marine Centre, Punta San Pietro, 80077 Ischia, Naples, Italy.
| | - Fabio Badalamenti
- CNR-IAS, Lungomare Cristoforo Colombo 4521, 90149 Palermo, Italy; Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology, Lungomare Cristoforo Colombo (complesso Roosevelt), 90149 Palermo, Italy
| | - Antonio Di Franco
- Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology, Lungomare Cristoforo Colombo (complesso Roosevelt), 90149 Palermo, Italy
| | - Maria Cristina Gambi
- Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology, Ischia Marine Centre, Punta San Pietro, 80077 Ischia, Naples, Italy
| | - Nuria Teixidó
- Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology, Ischia Marine Centre, Punta San Pietro, 80077 Ischia, Naples, Italy; Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, 181 chemin du Lazaret, Villefranche-sur-mer 06230, France
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Diverse Horizontally-Acquired Gene Clusters Confer Sucrose Utilization to Different Lineages of the Marine Pathogen Photobacterium damselae subsp. damselae. Genes (Basel) 2020; 11:genes11111244. [PMID: 33105683 PMCID: PMC7690375 DOI: 10.3390/genes11111244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 10/19/2020] [Indexed: 12/31/2022] Open
Abstract
The ability to metabolize sucrose is a variable trait within the family Vibrionaceae. The marine bacterium Photobacterium damselae subsp. damselae (Pdd), pathogenic for marine animals and humans, is generally described as negative for sucrose utilization (Scr−). Previous studies have reported sucrose-utilizing isolates (Scr+), but the genetic basis of this variable phenotype remains uncharacterized. Here, we carried out the genome sequencing of five Scr+ and two Scr−Pdd isolates and conducted a comparative genomics analysis with sixteen additional Pdd genomes sequenced in previous studies. We identified two different versions of a four-gene cluster (scr cluster) exclusive of Scr+ isolates encoding a PTS system sucrose-specific IIBC component (scrA), a fructokinase (scrK), a sucrose-6-phosphate hydrolase (scrB), and a sucrose operon repressor (scrR). A scrA deletion mutant did not ferment sucrose and was impaired for growth with sucrose as carbon source. Comparative genomics analyses suggested that scr clusters were acquired by horizontal transfer by different lineages of Pdd and were inserted into a recombination hot-spot in the Pdd genome. The incongruence of phylogenies based on housekeeping genes and on scr genes revealed that phylogenetically diverse gene clusters for sucrose utilization have undergone extensive horizontal transfer among species of Vibrio and Photobacterium.
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