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Mougin J, Pavaux AS, Fanesi A, Lopez J, Pruvost E, Guihéneuf F, Sciandra A, Briandet R, Lopes F. Bacterial adhesion inhibition by microalgal EPSs from Cylindrotheca closterium and Tetraselmis suecica biofilms. Appl Microbiol Biotechnol 2024; 108:168. [PMID: 38261095 DOI: 10.1007/s00253-023-12960-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/20/2023] [Accepted: 10/24/2023] [Indexed: 01/24/2024]
Abstract
In the food industry, successful bacterial pathogen colonization and persistence begin with their adhesion to a surface, followed by the spatial development of mature biofilm of public health concerns. Compromising bacterial settlement with natural inhibitors is a promising alternative to conventional anti-fouling treatments typically based on chemical biocides that contribute to the growing burden of antimicrobial resistance. In this study, three extracellular polymeric substance (EPS) fractions extracted from microalgae biofilms of Cylindrotheca closterium (fraction C) and Tetraselmis suecica (fraction Ta rich in insoluble scale structure and fraction Tb rich in soluble EPS) were screened for their anti-adhesive properties, against eight human food-borne pathogens belonging to Escherichia coli, Staphylococcus aureus, Salmonella enterica subsp. enterica, and Listeria monocytogenes species. The results showed that the fraction Ta was the most effective inducing statistically significant reduction for three strains of E. coli, S. aureus, and L. monocytogenes. Overall, EPSs coating on polystyrene surfaces of the different fractions increased the hydrophilic character of the support. Differences in bacterial adhesion on the different coated surfaces could be explained by several dissimilarities in the structural and physicochemical EPS compositions, according to HPLC and ATR-FTIR analysis. Interestingly, while fractions Ta and Tb were extracted from the same microalgal culture, distinct adhesion patterns were observed, highlighting the importance of the extraction process. Overall, the findings showed that EPS extracted from microalgal photosynthetic biofilms can exhibit anti-adhesive effects against food-borne pathogens and could help develop sustainable and non-toxic anti-adhesive surfaces for the food industry. KEY POINTS: •EPSs from a biofilm-based culture of C. closterium/T. suecica were characterized. •Microalgal EPS extracted from T. suecica biofilms showed bacterial anti-adhesive effects. •The anti-adhesive effect is strain-specific and affects both Gram - and Gram + bacteria.
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Affiliation(s)
- Julia Mougin
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
- Laboratoire Génie Des Procédés Et Matériaux (LGPM), CentraleSupélec, Université Paris-Saclay, 91190, Gif-Sur-Yvette, France
| | - Anne-Sophie Pavaux
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
- Laboratoire Génie Des Procédés Et Matériaux (LGPM), CentraleSupélec, Université Paris-Saclay, 91190, Gif-Sur-Yvette, France
| | - Andrea Fanesi
- Laboratoire Génie Des Procédés Et Matériaux (LGPM), CentraleSupélec, Université Paris-Saclay, 91190, Gif-Sur-Yvette, France
| | - Julien Lopez
- Laboratoire d, Océanographie de Villefranche LOV, CNRS, Sorbonne Université, UMR 7093, BP 28, 06230, Villefranche-Sur-Mer, France
| | - Eric Pruvost
- Laboratoire d, Océanographie de Villefranche LOV, CNRS, Sorbonne Université, UMR 7093, BP 28, 06230, Villefranche-Sur-Mer, France
| | | | - Antoine Sciandra
- Laboratoire d, Océanographie de Villefranche LOV, CNRS, Sorbonne Université, UMR 7093, BP 28, 06230, Villefranche-Sur-Mer, France
| | - Romain Briandet
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France.
| | - Filipa Lopes
- Laboratoire Génie Des Procédés Et Matériaux (LGPM), CentraleSupélec, Université Paris-Saclay, 91190, Gif-Sur-Yvette, France.
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Duncan RJ, Nielsen D, Søreide JE, Varpe Ø, Tobin MJ, Pitusi V, Heraud P, Petrou K. Biomolecular profiles of Arctic sea-ice diatoms highlight the role of under-ice light in cellular energy allocation. ISME COMMUNICATIONS 2024; 4:ycad010. [PMID: 38328449 PMCID: PMC10848308 DOI: 10.1093/ismeco/ycad010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 12/13/2023] [Accepted: 12/14/2023] [Indexed: 02/09/2024]
Abstract
Arctic sea-ice diatoms fuel polar marine food webs as they emerge from winter darkness into spring. Through their photosynthetic activity they manufacture the nutrients and energy that underpin secondary production. Sea-ice diatom abundance and biomolecular composition vary in space and time. With climate change causing short-term extremes and long-term shifts in environmental conditions, understanding how and in what way diatoms adjust biomolecular stores with environmental perturbation is important to gain insight into future ecosystem energy production and nutrient transfer. Using synchrotron-based Fourier transform infrared microspectroscopy, we examined the biomolecular composition of five dominant sea-ice diatom taxa from landfast ice communities covering a range of under-ice light conditions during spring, in Svalbard, Norway. In all five taxa, we saw a doubling of lipid and fatty acid content when light transmitted to the ice-water interface was >5% but <15% (85%-95% attenuation through snow and ice). We determined a threshold around 15% light transmittance after which biomolecular synthesis plateaued, likely because of photoinhibitory effects, except for Navicula spp., which continued to accumulate lipids. Increasing under-ice light availability led to increased energy allocation towards carbohydrates, but this was secondary to lipid synthesis, whereas protein content remained stable. It is predicted that under-ice light availability will change in the Arctic, increasing because of sea-ice thinning and potentially decreasing with higher snowfall. Our findings show that the nutritional content of sea-ice diatoms is taxon-specific and linked to these changes, highlighting potential implications for future energy and nutrient supply for the polar marine food web.
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Affiliation(s)
- Rebecca J Duncan
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, 2007, Australia
- Department of Arctic Biology, The University Centre in Svalbard, Longyearbyen, 9170, Norway
| | - Daniel Nielsen
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, 2007, Australia
| | - Janne E Søreide
- Department of Arctic Biology, The University Centre in Svalbard, Longyearbyen, 9170, Norway
| | - Øystein Varpe
- Department of Biological Sciences, University of Bergen, Bergen, 5020, Norway
- Norwegian Institute for Nature Research, Bergen, 5006, Norway
| | - Mark J Tobin
- Australian Synchrotron—ANSTO, Clayton, Victoria, 3168, Australia
| | - Vanessa Pitusi
- Department of Arctic Biology, The University Centre in Svalbard, Longyearbyen, 9170, Norway
- Department of Arctic and Marine Biology, University in Tromsø (UiT), Tromsø, 9010, Norway
| | - Philip Heraud
- Centre for Biospectroscopy, School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia
| | - Katherina Petrou
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, 2007, Australia
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Gómez-Martínez D, Bengtson J, Nilsson AK, Clarke AK, Nilsson RH, Kristiansson E, Corcoll N. Phenotypic and transcriptomic acclimation of the green microalga Raphidocelis subcapitata to high environmental levels of the herbicide diflufenican. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 875:162604. [PMID: 36878298 DOI: 10.1016/j.scitotenv.2023.162604] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
Herbicide pollution poses a worldwide threat to plants and freshwater ecosystems. However, the understanding of how organisms develop tolerance to these chemicals and the associated trade-off expenses are largely unknown. This study aims to investigate the physiological and transcriptional mechanisms underlying the acclimation of the green microalgal model species Raphidocelis subcapitata (Selenastraceae) towards the herbicide diflufenican, and the fitness costs associated with tolerance development. Algae were exposed for 12 weeks (corresponding to 100 generations) to diflufenican at the two environmental concentrations 10 and 310 ng/L. The monitoring of growth, pigment composition, and photosynthetic performance throughout the experiment revealed an initial dose-dependent stress phase (week 1) with an EC50 of 397 ng/L, followed by a time-dependent recovery phase during weeks 2 to 4. After week 4, R. subcapitata was acclimated to diflufenican exposure with a similar growth rate, content of carotenoids, and photosynthetic performance as the unexposed control algae. This acclimation state of the algae was explored in terms of tolerance acquisition, changes in the fatty acids composition, diflufenican removal rate, cell size, and changes in mRNA gene expression profile, revealing potential fitness costs associated with acclimation, such as up-regulation of genes related to cell division, structure, morphology, and reduction of cell size. Overall, this study demonstrates that R. subcapitata can quickly acclimate to environmental but toxic levels of diflufenican; however, the acclimation is associated with trade-off expenses that result in smaller cell size.
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Affiliation(s)
- Daniela Gómez-Martínez
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
| | - Johanna Bengtson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Anders K Nilsson
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Adrian K Clarke
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Rolf Henrik Nilsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Erik Kristiansson
- Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, Gothenburg, Sweden
| | - Natàlia Corcoll
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
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Liu Y, Wei D. Enhancing carbon dioxide fixation and co-production of protein and lutein in oleaginous Coccomyxa subellipsoidea by a stepwise light intensity and nutrients feeding strategy. BIORESOURCE TECHNOLOGY 2023; 376:128885. [PMID: 36925078 DOI: 10.1016/j.biortech.2023.128885] [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: 02/15/2023] [Revised: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 06/18/2023]
Abstract
To achieve high-efficient CO2 fixation and co-production of protein and lutein, a stepwise light intensity and nutrients feeding strategy in two-phase cultivation was developed after optimization in one-phase culture of oleaginous C. subellipsoidea in this work. Results showed the incremental light intensity and CO2 feeding boosted biomass production in phase 1, then a decreased light intensity and CO2 feeding with nitrate addition enhanced protein and lutein synthesis in phase2. The highest biomass (9.40 g/L) and average CO2 fixation rate (1.4 g/L/d) were achieved with excellent content and productivity of protein (52.36% DW, 435.72 mg/L/d) and lutein (1.65 mg/g, 1.37 mg/L/d) with 40.27% of light-energy saved. While the highest contents of total amino acids (42.38% DW) and essential amino acids (17.65% DW) were obtained with an essential amino acid index (1.2) compared with FAO/WHO reference. This study provided a promising application scenario of oleaginous microalgae for carbon neutrality and multiple high-value compounds co-production.
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Affiliation(s)
- Yu Liu
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Engineering Research Center of Starch and Vegetable Protein Processing Ministry of Education, South China University of Technology, 381 Wushan Road, Guangzhou 510641, China
| | - Dong Wei
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Engineering Research Center of Starch and Vegetable Protein Processing Ministry of Education, South China University of Technology, 381 Wushan Road, Guangzhou 510641, China.
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Murison V, Hérault J, Schoefs B, Marchand J, Ulmann L. Bioinformatics-Based Screening Approach for the Identification and Characterization of Lipolytic Enzymes from the Marine Diatom Phaeodactylum tricornutum. Mar Drugs 2023; 21:md21020125. [PMID: 36827166 PMCID: PMC9964374 DOI: 10.3390/md21020125] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 02/17/2023] Open
Abstract
Oleaginous diatoms accumulate lipids of biotechnological interest when exposed to nutrient stress conditions such as nitrogen starvation. While accumulation mechanisms are well-known and have been engineered to improve lipid production, degradation mechanisms remain poorly investigated in diatoms. Identifying lipid-degrading enzymes is the initial step to understanding the catabolic processes. In this study, an in silico screening of the genome of Phaeodactylum tricornutum led to the identification of 57 putative triacylglycerol lipases (EC 3.1.1.3) grouped in 4 families. Further analysis revealed the presence of conserved domains and catalytic residues of lipases. Physico-chemical characteristics and subcellular localization predictions highlighted that a majority of these putative proteins are hydrophilic and cytosolic, suggesting they could be recruited to lipid droplets directly from the cytosol. Among the 57 identified putative proteins, three lipases were identified as possibly involved in lipophagy due to a potential vacuolar localization. The expression of the mRNA corresponding to the 57 proteins was then searched in 3 transcriptomic datasets obtained under nitrogen starvation. Nine genes were highly regulated and were considered as encoding enzymes with a probable important function in lipid catabolism. A tertiary structure prediction of these nine candidates yielded eight functional 3D models. Among those, two downregulated enzymes, Phatr3_J54974 and Phatr3_EG00720, were highlighted as good targets for future functional genomics and purification studies to investigate their role in lipid degradation.
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Affiliation(s)
- Victor Murison
- BiOSSE, Biology of Organisms: Stress, Health, Environment, Département Génie Biologique, Institut Universitaire de Technologie, Le Mans Université, F-53020 Laval, France
| | - Josiane Hérault
- BiOSSE, Biology of Organisms: Stress, Health, Environment, Département Génie Biologique, Institut Universitaire de Technologie, Le Mans Université, F-53020 Laval, France
| | - Benoît Schoefs
- BiOSSE, Biology of Organisms: Stress, Health, Environment, UFR Sciences et Techniques, Le Mans Université, F-72085 Le Mans, France
| | - Justine Marchand
- BiOSSE, Biology of Organisms: Stress, Health, Environment, UFR Sciences et Techniques, Le Mans Université, F-72085 Le Mans, France
| | - Lionel Ulmann
- BiOSSE, Biology of Organisms: Stress, Health, Environment, Département Génie Biologique, Institut Universitaire de Technologie, Le Mans Université, F-53020 Laval, France
- Correspondence:
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Duan Z, Tan X, Shi L, Zeng Q, Ali I, Zhu R, Chen H, Parajuli K. Phosphorus Accumulation in Extracellular Polymeric Substances (EPS) of Colony-Forming Cyanobacteria Challenges Imbalanced Nutrient Reduction Strategies in Eutrophic Lakes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:1600-1612. [PMID: 36642923 DOI: 10.1021/acs.est.2c04398] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Extracellular polymeric substances (EPS) are crucial for cyanobacterial proliferation; however, certain queries, including how EPS affects cellular nutrient processes and what are the implications for nutrient management in lakes, are not well documented. Here, the dynamics of cyanobacterial EPS-associated phosphorus (EPS-P) were examined both in a shallow eutrophic lake (Lake Taihu, China) and in laboratory experiments with respect to nitrogen (N) and phosphorus (P) availability. Results indicated that 40-65% of the total cyanobacterial aggregate/particulate P presented as EPS-P (mainly labile P and Fe/Al-P). Phosphorus-starved cyanobacteria rapidly replenished their EPS-P pools after the P was resupplied, and the P concentration in this pool was stable for long afterward, although the environmental P concentration decreased dramatically. A low-N treatment enhanced the EPS production alongside two-fold EPS-P accumulation (particularly labile P) higher than the control. Such patterns occurred in the lake where EPS and EPS-P contents were high under N limitation. EPS-P enrichment increased the P content in cyanobacteria; subsequently, it could hold the total P concentration higher for longer and make bloom mitigation harder. The findings outline a new insight into EPS functions in the P process of cyanobacterial aggregates and encourage consideration of both N and P reductions in nutrient management.
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Affiliation(s)
- Zhipeng Duan
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
- College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China
| | - Xiao Tan
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Lin Shi
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Qingfei Zeng
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Imran Ali
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Rui Zhu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China
| | - Huaimin Chen
- School of Environmental Engineering, Changzhou Institute of Industry Technology, Changzhou 213164, China
| | - Keshab Parajuli
- School of Population and Global Health, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, VIC 3010, Australia
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Duan Z, Tan X, Ali I, Wu X, Cao J, Xu Y, Shi L, Gao W, Ruan Y, Chen C. Comparison of organic matter (OM) pools in water, suspended particulate matter, and sediments in eutrophic Lake Taihu, China: Implication for dissolved OM tracking, assessment, and management. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 845:157257. [PMID: 35817111 DOI: 10.1016/j.scitotenv.2022.157257] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 06/13/2022] [Accepted: 07/05/2022] [Indexed: 06/15/2023]
Abstract
Suspended particulate matter (SPM) and sediments are important sources of dissolved organic matter (DOM) in lake water. However, studies on what extent and how both sources affect DOM composition are lacking, which hampers DOM management. Herein, DOM, SPM-extracted particulate organic matter (POM), and sediment-extracted organic matter (SOM) were characterized and compared in terms of absorption spectral properties and chemical composition in Lake Taihu, a large cyanobacterial bloom-affected shallow lake. A statistical method was proposed to quantify the similarity of organic matter (OM) in the different states and to evaluate the potential effects of SPM and sediments on DOM. Results showed that POM and DOM were mainly composed of small-molecular-size and low-humified organic components (i.e., 27 %-38 % tryptophan-like and ~30 % protein-like substances), and most of them were derived from autochthonous sources. While tyrosine-like (57 %) and humic-like (27 %) substances were dominant in SOM. The OM similarity between POM and DOM was approximately 1.5 times higher than that between SOM and DOM, indicating the greater effect of SPM than sediments on DOM composition. High pH and low nitrogen (e.g., nitrate and ammonia) were positively correlated to the OM similarity between POM and DOM. Further, the findings indicated that nitrogen limitation enhanced the OM exchange between POM and DOM by promoting the production of extracellular polymeric substances (EPS) in cyanobacterial aggregates. The obtained findings highlighted the importance of SPM in shaping the DOM composition relative to sediments and facilitating the DOM management in bloom-affected lakes.
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Affiliation(s)
- Zhipeng Duan
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210024, China; College of Hydrology and Water Resources, Hohai University, Nanjing, Jiangsu 210024, China
| | - Xiao Tan
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210024, China.
| | - Imran Ali
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210024, China
| | - Xiaoge Wu
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Jun Cao
- National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Hohai University, Nanjing, Jiangsu 210024, China
| | - Yangxue Xu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210024, China
| | - Lin Shi
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210024, China
| | - Wanpeng Gao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu 210024, China
| | - Yinlan Ruan
- Institute for Photonics and Advanced Sensing, The University of Adelaide, SA 5005, Australia
| | - Chen Chen
- College of Dayu, Hohai University, Nanjing, Jiangsu 210024, China
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The Dynamic Behaviors of Photosynthesis during Non-Motile Cell Germination in Haematococcus pluvialis. WATER 2022. [DOI: 10.3390/w14081280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Haematococcus pluvialis undergoes a three-phase process during the process of germination: first, repeated mitotic events; next, cytokinesis to form the zoospore; and finally, a fast release of motile cells. Physiological properties were measured using chlorophyll a fluorescence (OJIP) transient. The most obvious increase in K-value and L-value appeared at 17 h, suggesting that oxygen-evolving complex damage and lower energetic connectivity of the photosystem II units of the mother non-motile cell occurred. Compared to phase I, the values of the maximum quantum yield of PSII photochemistry (FV/FM) and PIABS increased significantly in phases II and III, suggesting that photosynthetic photochemical activity was greatly up-regulated during cytokinesis to form zoospores and the fast release of motile cells. Moreover, the significant increase in the K-band at 17 h and 22 h indicates that the PSII donor side was the limiting factor during the initial period of germination. All these results suggest that the cellular photosynthetic activity continues to strengthen during cytokinesis to form the zoospore and the fast release of motile cells, and it was postulated to meet the demands for sporangium swelling and new organelle formation.
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Abdelmageed AA, Ellah RGA, Abdel-Satar AM, Gawad SSA, Khalifa N, Zaher SS, Othman AA, Belal DM, El-Hady HHA, Salem SG, Abdo MH, Haroon AM, El-Far A, Hegab MH, Elhaddad E, El-Sherif DM, Al-Afify ADG. Evaluation of the ecological health and food chain on the shores of four River Nile Islands, Egypt. ENVIRONMENTAL MONITORING AND ASSESSMENT 2022; 194:309. [PMID: 35353284 PMCID: PMC8969041 DOI: 10.1007/s10661-022-09959-w] [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: 12/29/2021] [Accepted: 03/19/2022] [Indexed: 06/14/2023]
Abstract
This study was conducted to evaluate the impact of human activities on the ecological health and food chain at the shores of four Nile Islands in Great Cairo including El-Qeratten, El-Waraq, El-Zamalek, and El-Manial. Water quality, bacteria, phytoplankton, benthic algae, zooplankton, macrobenthic invertebrates, and bony fishes were examined at each island shore over two seasons including the lowest and the highest flow (February and July 2020, respectively). The obtained results showed that the average values of most of the chemicals in Nile Island's water were within the Egyptian water quality limits. Discriminant analysis of physicochemical factors revealed a similarity between El-Waraq and El-Qerateen and between El-Manial and El-Zamalek. El-Qeratten was the most polluted island. It has the highest total and fecal coliform bacteria count (3.155 and 3.050 Log MPN/100 mL, respectively). El-Zamalek shores have the highest phytoplankton (33,582 cells × 104 L-1) and zooplankton count (310,891 organisms × m-3) and phyto-biochemical values. Biochemical analysis of phytoplankton demonstrated the richness of the bulk by protein (> 85% of biomass), indicating that phytoplankton has a high nutritional value. Elevated zooplankton count was recorded at El-Zamalek, which coincided with the peak of phytoplankton abundance. Mollusca were the dominant macrobenthic invertebrates on most of the island's shores. Bony fishes were represented by 27 species and two crustaceans. The levels of the metals in fish samples were compared with the food safety guideline endorsed by the World Health Organization and Food and Agriculture Organization (WHO/FAO) to evaluate the toxicity level.
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Affiliation(s)
| | | | | | | | - Nehad Khalifa
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Shymaa S Zaher
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Amal A Othman
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Dalia M Belal
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | | | - Salem G Salem
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Mohamed H Abdo
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Amany M Haroon
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Alaa El-Far
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Mahmoud H Hegab
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Engy Elhaddad
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Dina M El-Sherif
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
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10
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Cheng J, Fan W, Zheng L. Development of a mixotrophic cultivation strategy for simultaneous improvement of biomass and photosynthetic efficiency in freshwater microalga Scenedesmus obliquus by adding appropriate concentration of sodium acetate. Biochem Eng J 2021. [DOI: 10.1016/j.bej.2021.108177] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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Li SF, Fanesi A, Martin T, Lopes F. Biomass production and physiology of Chlorella vulgaris during the early stages of immobilized state are affected by light intensity and inoculum cell density. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102453] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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12
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Penta WB, Fox J, Halsey KH. Rapid photoacclimation during episodic deep mixing augments the biological carbon pump. LIMNOLOGY AND OCEANOGRAPHY 2021; 66:1850-1866. [PMID: 34248203 PMCID: PMC8252461 DOI: 10.1002/lno.11728] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 09/25/2020] [Accepted: 01/18/2021] [Indexed: 05/25/2023]
Abstract
Episodic deep mixing events are one component of the biological carbon pump that physically transports organic carbon into the mesopelagic. Episodic deep mixing also disrupts summertime thermal stratification thereby changing the light field and nutrient concentrations available for phytoplankton growth. Phytoplankton survival and growth below the mixed layer following restratification depends on how rapidly cells can employ a variety of photoacclimation processes in response to the environmental changes. To compare the relative timescales of summertime episodic deep mixing events with the timescales of phytoplankton photoacclimation processes, we first analyzed autonomous float data to survey the frequency and magnitude of deep mixing events in the western North Atlantic Ocean. Next, we simulated a sustained deep mixing event in the laboratory and measured rates of acclimation processes ranging from light harvesting to growth in a model diatom and green alga. In both algae increases in chlorophyll (Chl) were coupled to growth, but growth of the green alga lagged the diatom by about a day. In float profiles, significant increases in Chl and phytoplankton carbon (C phyto) were detected below the mixed layer following episodic deep mixing events. These events pose a previously unrecognized source of new production below the mixed layer that can significantly boost the amount of carbon available for export to the deep ocean.
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Affiliation(s)
- W Bryce Penta
- Department of Microbiology Oregon State University Corvallis Oregon USA
| | - James Fox
- Department of Microbiology Oregon State University Corvallis Oregon USA
| | - Kimberly H Halsey
- Department of Microbiology Oregon State University Corvallis Oregon USA
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Glyphosate-Based Herbicide Toxicophenomics in Marine Diatoms: Impacts on Primary Production and Physiological Fitness. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10217391] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Glyphosate is the main active component of the commercial formulation Roundup®, the most widely used chemical herbicide worldwide. However, its potential high toxicity to the environment and throughout trophic webs has come under increasing scrutiny. The present study aims to investigate the application of bio-optical techniques and their correlation to physiological and biochemical processes, including primary productivity, oxidative stress, energy balance, and alterations in pigment and lipid composition in Phaeodactylum tricornutum, a representative species of marine diatoms, using the case study of its response to the herbicide glyphosate-based Roundup® formulation, at environmentally relevant concentrations. Cultures were exposed to the herbicide formulation representing effective glyphosate concentrations of 0, 10, 50, 100, 250, and 500 μg L−1. Results showed that high concentrations decreased cell density; furthermore, the inhibition of photosynthetic activity was not only caused by the impairment of electron transport in the thylakoids, but also by a decrease of antioxidant capacity and increased lipid peroxidation. Nevertheless, concentrations of one of the plastidial marker fatty acids had a positive correlation with the highest concentration as well as an increase in total protein. Cell energy allocation also increased with concentration, relative to control and the lowest concentration, although culture growth was inhibited. Pigment composition and fatty acid profiles proved to be efficient biomarkers for the highest glyphosate-based herbicide concentrations, while bio-optical data separated controls from intermediate concentrations and high concentrations.
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Genetic Impairment of Cellulose Biosynthesis Increases Cell Wall Fragility and Improves Lipid Extractability from Oleaginous Alga Nannochloropsis salina. Microorganisms 2020; 8:microorganisms8081195. [PMID: 32781613 PMCID: PMC7464416 DOI: 10.3390/microorganisms8081195] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 07/31/2020] [Accepted: 08/05/2020] [Indexed: 01/03/2023] Open
Abstract
In microalgae, photosynthesis provides energy and sugar phosphates for the biosynthesis of storage and structural carbohydrates, lipids, and nitrogenous proteins. The oleaginous alga Nannochloropsis salina does not preferentially partition photoassimilates among cellulose, chrysolaminarin, and lipids in response to nitrogenous nutrient deprivation. In the present study, we investigated whether genetic impairment of the cellulose synthase gene (CesA) expression would lead to protein accumulation without the accumulation of storage C polymers in N. salina. Three cesA mutants were generated by the CRISPR/Cas9 approach. Cell wall thickness and cellulose content were reduced in the cesA1 mutant, but not in cesA2 or cesA4 cells. CesA1 mutation resulted in a reduction of chrysolaminarin and neutral lipid contents, by 66.3% and 37.1%, respectively, but increased the soluble protein content by 1.8-fold. Further, N. salina cells with a thinned cell wall were susceptible to mechanical stress, resulting in a 1.7-fold enhancement of lipid extractability. Taken together, the previous and current studies strongly suggest the presence of a controlling mechanism that regulates photoassimilate partitioning toward C and N metabolic pathways as well as the cellulose metabolism as a potential target for cost-effective microalgal cell disruption and as a useful protein production platform.
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Mc Gee D, Archer L, Fleming GT, Gillespie E, Touzet N. The effect of nutrient and phytohormone supplementation on the growth, pigment yields and biochemical composition of newly isolated microalgae. Process Biochem 2020. [DOI: 10.1016/j.procbio.2020.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Rivera-Rondón CA, Catalan J. Diatoms as indicators of the multivariate environment of mountain lakes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 703:135517. [PMID: 31767302 DOI: 10.1016/j.scitotenv.2019.135517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 11/11/2019] [Accepted: 11/12/2019] [Indexed: 06/10/2023]
Abstract
Diatom assemblages are used widely as indicators of environmental conditions. They have been particularly useful in the assessment of some acute environmental problems such as water acidification, eutrophication and salinisation. High mountain lakes are currently a research focus as sentinels of global change, predominantly of long-distance atmospheric pollution and climate warming. The diatom assemblages in these lakes are extremely rich, and the sediment record provides short and long historical perspectives of the changes. We investigated the relative sensitivity of diatoms to the main environmental gradients found in mountain lakes and evaluated the strength and uncertainties for predicting simultaneously several environmental variables associated with these gradients based on a survey of 83 lakes in the Pyrenees. Variables related to the ionic composition and acid-base balance (calcium*, acid neutralizing capacity*, magnesium, sodium, and sulphates), trophic conditions (total phosphorus* and dissolved organic carbon) and physical factors (water temperature*, irradiance at the lake bottom*, and macrophyte cover) explained independently the variation in the diatom assemblages. However, the assemblage predictive capacity of these variables- tested by developing transfer functions (Weighted Averaging- Partial Least Squares) - was only acceptable for a subset of the variables (*). The spatial autocorrelation of the environmental variables had no influence on the performance of the transfer functions except for water temperature, which is highly dependent on altitude. Our results indicate that diatom assemblages have great potential for assessments of multiple environmental variables in mountain lakes and, consequently, in applications of global change surveillance.
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Affiliation(s)
- Carlos A Rivera-Rondón
- UNESIS, Departamento de Biología, Pontificia Universidad Javeriana, Cra. 7 No. 40-62, 110231 Bogotá, Colombia; Centre d'Estudis Avançats de Blanes, CSIC, Carrer Accés Cala St. Francesc 14, E-17300 Blanes, Spain.
| | - Jordi Catalan
- CREAF, Campus UAB, Edifici C, Cerdanyola del Vallès, E-08193, Spain; Centre d'Estudis Avançats de Blanes, CSIC, Carrer Accés Cala St. Francesc 14, E-17300 Blanes, Spain.
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McGee D, Archer L, Fleming GTA, Gillespie E, Touzet N. Influence of spectral intensity and quality of LED lighting on photoacclimation, carbon allocation and high-value pigments in microalgae. PHOTOSYNTHESIS RESEARCH 2020; 143:67-80. [PMID: 31705368 DOI: 10.1007/s11120-019-00686-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 10/21/2019] [Indexed: 05/09/2023]
Abstract
Tailoring spectral quality during microalgal cultivation can provide a means to increase productivity and enhance biomass composition for downstream biorefinery. Five microalgae strains from three distinct lineages were cultivated under varying spectral intensities and qualities to establish their effects on pigments and carbon allocation. Light intensity significantly impacted pigment yields and carbon allocation in all strains, while the effects of spectral quality were mostly species-specific. High light conditions induced chlorophyll photoacclimation and resulted in an increase in xanthophyll cycle pigments in three of the five strains. High-intensity blue LEDs increased zeaxanthin tenfold in Rhodella sp. APOT_15 relative to medium or low light conditions. White light however was optimal for phycobiliprotein content (11.2 mg mL-1) for all tested light intensities in this strain. The highest xanthophyll pigment yields for the Chlorophyceae were associated with medium-intensity blue and green lights for Brachiomonas submarina APSW_11 (5.6 mg g-1 lutein and 2.0 mg g-1 zeaxanthin) and Kirchneriella aperta DMGFW_21 (1.5 mg g-1 lutein and 1 mg g-1 zeaxanthin), respectively. The highest fucoxanthin content in both Heterokontophyceae strains (2.0 mg g-1) was associated with medium and high white light for Stauroneis sp. LACW_24 and Phaeothamnion sp. LACW_34, respectively. This research provides insights into the application of LEDs to influence microalgal physiology, highlighting the roles of low light on lipid metabolism in Rhodella sp. APOT_15, of blue and green lights for carotenogenesis in Chlorophyceae and red light-induced photoacclimation in diatoms.
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Affiliation(s)
- Dónal McGee
- Department of Environmental Science, School of Science, CERIS, Centre for Environmental Research, Innovation and Sustainability, Institute of Technology Sligo, Sligo, Ireland.
| | - Lorraine Archer
- Department of Environmental Science, School of Science, CERIS, Centre for Environmental Research, Innovation and Sustainability, Institute of Technology Sligo, Sligo, Ireland
| | - Gerard T A Fleming
- Microbiology Department, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Eoin Gillespie
- Department of Environmental Science, School of Science, CERIS, Centre for Environmental Research, Innovation and Sustainability, Institute of Technology Sligo, Sligo, Ireland
| | - Nicolas Touzet
- Department of Environmental Science, School of Science, CERIS, Centre for Environmental Research, Innovation and Sustainability, Institute of Technology Sligo, Sligo, Ireland
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Jensen EL, Yangüez K, Carrière F, Gontero B. Storage Compound Accumulation in Diatoms as Response to Elevated CO 2 Concentration. BIOLOGY 2019; 9:E5. [PMID: 31878202 PMCID: PMC7169399 DOI: 10.3390/biology9010005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/19/2019] [Accepted: 12/21/2019] [Indexed: 11/23/2022]
Abstract
Accumulation of reserve compounds (i.e., lipids and chrysolaminarin) in diatoms depends on the environmental conditions, and is often triggered by stress conditions, such as nutrient limitation. Manipulation of CO2 supply can also be used to improve both lipids and carbohydrates accumulation. Given the high diversity among diatoms, we studied the two marine model diatoms-Thalassiosira pseudonana and Phaeodactylum tricornutum, a freshwater diatom, Asterionella formosa, and Navicula pelliculosa-found in fresh- and sea-water environments. We measured the accumulation of reserve compounds and the activity of enzymes involved in carbon metabolism in these diatoms grown at high and atmospheric CO2. We observed that biomass and lipid accumulation in cells grown at high CO2 differ among the diatoms. Lipid accumulation increased only in P. tricornutum and N. pelliculosa grown in seawater in response to elevated CO2. Moreover, accumulation of lipids was also accompanied by an increased activity of the enzymes tested. However, lipid accumulation and enzyme activity decreased in N. pelliculosa cultured in fresh water. Chrysolaminarin accumulation was also affected by CO2 concentration; however, there was no clear relation with lipids accumulation. Our results are relevant to understand better the ecological role of the environment in the diatom adaptation to CO2 and the mechanisms underpinning the production of storage compounds considering diatom diversity.
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Affiliation(s)
| | | | | | - Brigitte Gontero
- CNRS, BIP, UMR 7281, IMM, FR3479, 31 Chemin J. Aiguier, Aix Marseille Univ., 13 402 Marseille CEDEX 20, France; (E.L.J.); (K.Y.); (F.C.)
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Bozzato D, Jakob T, Wilhelm C. Effects of temperature and salinity on respiratory losses and the ratio of photosynthesis to respiration in representative Antarctic phytoplankton species. PLoS One 2019; 14:e0224101. [PMID: 31634379 PMCID: PMC6802872 DOI: 10.1371/journal.pone.0224101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 10/05/2019] [Indexed: 11/18/2022] Open
Abstract
The Southern Ocean (SO) is a net sink for atmospheric CO2 whereby the photosynthetic activity of phytoplankton and sequestration of organic carbon (biological pump) plays an important role. Global climate change will tremendously influence the dynamics of environmental conditions for the phytoplankton community, and the phytoplankton will have to acclimate to a combination of changes of e.g. water temperature, salinity, pH, and nutrient supply. The efficiency of the biological pump is not only determined by the photosynthetic activity but also by the extent of respiratory carbon losses of phytoplankton cells. Thus, the present study investigated the effect of different temperature and salinity combinations on the ratio of gross photosynthesis to respiration (rGP/R) in two representative phytoplankton species of the SO. In the comparison of phytoplankton grown at 1 and 4°C the rGP/R decreased from 11.5 to 7.7 in Chaetoceros sp., from 9.1 to 3.2 in Phaeocystis antarctica strain 109, and from 12.4 to 7.0 in P. antarctica strain 764, respectively. The decrease of rGP/R was primarily dependent on temperature whereas salinity was only of minor importance. Moreover, the different rGP/R at 1 and 4°C were caused by changes of temperature-dependent respiration rates but were independent of changes of photosynthetic rates. For further interpretation, net primary production (NPP) was calculated for different seasonal conditions in the SO with specific combinations of irradiance, temperature, and salinity. Whereas, maximum photosynthetic rates significantly correlated with calculated NPP under experimental ‘Spring’, ‘Summer’, and ‘Autumn’ conditions, there was no correlation between rGP/R and the respective values of NPP. The study revealed species-specific differences in the acclimation to temperature and salinity changes that could be linked to their different original habitats.
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Affiliation(s)
- Deborah Bozzato
- University Leipzig, Institute of Biology, Plant Physiology, Leipzig, Germany
| | - Torsten Jakob
- University Leipzig, Institute of Biology, Plant Physiology, Leipzig, Germany
- * E-mail:
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20
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Wagner H, Jebsen C, Wilhelm C. Monitoring cellular C:N ratio in phytoplankton by means of FTIR-spectroscopy. JOURNAL OF PHYCOLOGY 2019; 55:543-551. [PMID: 30893470 DOI: 10.1111/jpy.12858] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 01/04/2019] [Indexed: 06/09/2023]
Abstract
Statistical growth rate modelling can be applied in a variety of ecological and biotechnological applications. Such models are frequently based on Monod or Droop equations and, especially for the latter, require reliable determination of model input parameters such as C:N quotas. Besides growth rate modelling, a C:N quota quantification can be useful for monitoring and interpretation of physiological acclimation to abiotic and biotic disturbances (e.g., nutrient limitations). However, as high throughput C:N quota determination is difficult to perform, alternatives need to be established. Fourier-transformed infrared (FTIR) spectroscopy is used to analyze a variety of biochemical, chemical, and physiological parameters in phytoplankton. Hence, a quantification of the C:N quota should also be feasible. Therefore, using FTIR spectroscopy, six phytoplankton species from among different phylogenetic groups have been analyzed to determine the effect of nutrient limitation on C:N quota patterns. The typical species-specific response to increasing nitrogen limitation was an increase in the C:N quota. Irrespective of this species specificity, we were able to develop a reliable multi-species C:N quota prediction model based on FTIR spectroscopy using the partial least square regression (PLSR) algorithm. Our data demonstrate that the PLSR approach is more robust in C:N quota quantification (R2 = 0.93) than linear correlation of C:N quota versus growth rate (R2 ranges from 0.74 to 0.86) or biochemical information based on FTIR spectra (R2 ranges from 0.82 to 0.89). This accurate prediction of C:N values may support high throughput measurements in a broad range of future approaches.
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Affiliation(s)
- Heiko Wagner
- Department of Plant Physiology, Institute of Biology, Leipzig University, Johannisallee 21-23, D-04103, Leipzig, Germany
| | - Christian Jebsen
- Department of Plant Physiology, Institute of Biology, Leipzig University, Johannisallee 21-23, D-04103, Leipzig, Germany
| | - Christian Wilhelm
- Department of Plant Physiology, Institute of Biology, Leipzig University, Johannisallee 21-23, D-04103, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, D-04103, Leipzig, Germany
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Broddrick JT, Du N, Smith SR, Tsuji Y, Jallet D, Ware MA, Peers G, Matsuda Y, Dupont CL, Mitchell BG, Palsson BO, Allen AE. Cross-compartment metabolic coupling enables flexible photoprotective mechanisms in the diatom Phaeodactylum tricornutum. THE NEW PHYTOLOGIST 2019; 222:1364-1379. [PMID: 30636322 PMCID: PMC6594073 DOI: 10.1111/nph.15685] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 12/20/2018] [Indexed: 05/07/2023]
Abstract
Photoacclimation consists of short- and long-term strategies used by photosynthetic organisms to adapt to dynamic light environments. Observable photophysiology changes resulting from these strategies have been used in coarse-grained models to predict light-dependent growth and photosynthetic rates. However, the contribution of the broader metabolic network, relevant to species-specific strategies and fitness, is not accounted for in these simple models. We incorporated photophysiology experimental data with genome-scale modeling to characterize organism-level, light-dependent metabolic changes in the model diatom Phaeodactylum tricornutum. Oxygen evolution and photon absorption rates were combined with condition-specific biomass compositions to predict metabolic pathway usage for cells acclimated to four different light intensities. Photorespiration, an ornithine-glutamine shunt, and branched-chain amino acid metabolism were hypothesized as the primary intercompartment reductant shuttles for mediating excess light energy dissipation. Additionally, simulations suggested that carbon shunted through photorespiration is recycled back to the chloroplast as pyruvate, a mechanism distinct from known strategies in photosynthetic organisms. Our results suggest a flexible metabolic network in P. tricornutum that tunes intercompartment metabolism to optimize energy transport between the organelles, consuming excess energy as needed. Characterization of these intercompartment reductant shuttles broadens our understanding of energy partitioning strategies in this clade of ecologically important primary producers.
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Affiliation(s)
- Jared T. Broddrick
- Division of Biological SciencesUC San DiegoLa JollaCA92093USA
- Department of BioengineeringUC San DiegoLa JollaCA92093USA
| | - Niu Du
- Scripps Institution of OceanographyUC San DiegoLa JollaCA92093USA
- J. Craig Venter InstituteLa JollaCA92037USA
| | | | - Yoshinori Tsuji
- Department of Environmental BioscienceKwansei Gakuin UniversitySanda669‐1337Japan
| | - Denis Jallet
- Department of BiologyColorado State UniversityFort CollinsCO80523USA
| | - Maxwell A. Ware
- Department of BiologyColorado State UniversityFort CollinsCO80523USA
| | - Graham Peers
- Department of BiologyColorado State UniversityFort CollinsCO80523USA
| | - Yusuke Matsuda
- Department of Environmental BioscienceKwansei Gakuin UniversitySanda669‐1337Japan
| | | | - B. Greg Mitchell
- Scripps Institution of OceanographyUC San DiegoLa JollaCA92093USA
| | | | - Andrew E. Allen
- Scripps Institution of OceanographyUC San DiegoLa JollaCA92093USA
- J. Craig Venter InstituteLa JollaCA92037USA
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Fanesi A, Wagner H, Birarda G, Vaccari L, Wilhelm C. Quantitative macromolecular patterns in phytoplankton communities resolved at the taxonomical level by single-cell Synchrotron FTIR-spectroscopy. BMC PLANT BIOLOGY 2019; 19:142. [PMID: 30987593 PMCID: PMC6466684 DOI: 10.1186/s12870-019-1736-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/24/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Technical limitations regarding bulk analysis of phytoplankton biomass limit our comprehension of carbon fluxes in natural populations and, therefore, of carbon, nutrients and energy cycling in aquatic ecosystems. In this study, we took advantage of Synchrotron FTIR micro-spectroscopy and the partial least square regression (PLSr) algorithm to simultaneously quantify the protein, lipid and carbohydrate content at the single-cell level in a mock phytoplankton community (composed by a cyanobacterium, a green-alga and a diatom) grown at two temperatures (15 °C and 25 °C). RESULTS The PLSr models generated to quantify cell macromolecules presented high quality fit (R2 ≥ 0.90) and low error of prediction (RMSEP 2-6% of dry weight). The regression coefficients revealed that the prediction of each macromolecule was not exclusively dependent on spectral features corresponding to that compound, but rather on all major macromolecular pools, reflecting adjustments in the overall cell carbon balance. The single-cell analysis, studied by means of Kernel density estimators, showed that the modes of density distribution of macromolecules were different at 15 °C and 25 °C. However, a substantial proportion of cells was biochemically identical at the two temperatures because of population heterogeneity. CONCLUSIONS The spectroscopic approach presented in this study allows the quantification of macromolecules in single phytoplankton cells. This method showed that population heterogeneity most likely ensures a backup of non-acclimated cells that may rapidly exploit new favourable niches. This finding may have important consequences for the ecology of phytoplankton populations and shows that the "average cell" concept might substantially limit our comprehension of population dynamics and biogeochemical cycles in aquatic ecosystems.
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Affiliation(s)
- Andrea Fanesi
- Department of Plant Physiology, Leipzig University, Institute of Biology, Johannisallee 21-23, 04103 Leipzig, Germany
| | - Heiko Wagner
- Department of Plant Physiology, Leipzig University, Institute of Biology, Johannisallee 21-23, 04103 Leipzig, Germany
| | - Giovanni Birarda
- Elettra - Sincrotrone Trieste, Synchrotron Infrared Source for Spectroscopy and Imaging – SISSI, 34149 Trieste, Basovizza Italy
| | - Lisa Vaccari
- Elettra - Sincrotrone Trieste, Synchrotron Infrared Source for Spectroscopy and Imaging – SISSI, 34149 Trieste, Basovizza Italy
| | - Christian Wilhelm
- Department of Plant Physiology, Leipzig University, Institute of Biology, Johannisallee 21-23, 04103 Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany
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Grund M, Jakob T, Wilhelm C, Bühler B, Schmid A. Electron balancing under different sink conditions reveals positive effects on photon efficiency and metabolic activity of Synechocystis sp. PCC 6803. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:43. [PMID: 30858880 PMCID: PMC6391784 DOI: 10.1186/s13068-019-1378-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 02/14/2019] [Indexed: 05/19/2023]
Abstract
BACKGROUND Cyanobacteria are ideal model organisms to exploit photosynthetically derived electrons or fixed carbon for the biotechnological synthesis of high value compounds and energy carriers. Much effort is spent on the rational design of heterologous pathways to produce value-added chemicals. Much less focus is drawn on the basic physiological responses and potentials of phototrophs to deal with natural or artificial electron and carbon sinks. However, an understanding of how electron sinks influence or regulate cellular physiology is essential for the efficient application of phototrophic organisms in an industrial setting, i.e., to achieve high productivities and product yields. RESULTS The physiological responses of the cyanobacterium Synechocystis sp. PCC 6803 to electron sink variation were investigated in a systematic and quantitative manner. A variation in electron demand was achieved by providing two N sources with different degrees of reduction. By additionally varying light and CO2 availabilities, steady state conditions with strongly differing source-sink ratios were established. Balancing absorbed photons and electrons used for different metabolic processes revealed physiological responses to sink/source ratio variation. Surprisingly, an additional electron sink under light and thus energy limitation was found not to hamper growth, but was compensated by improved photosynthetic efficiency and activity. In the absence of carbon and light limitation, an increase in electron demand even stimulated carbon assimilation and growth. CONCLUSION The metabolism of Synechocystis sp. PCC 6803 is highly flexible regarding the compensation of additional electron demands. Under light limitation, photosynthesis obviously does not necessarily run at its maximal capacity, possibly for the sake of robustness. Increased electron demands can even boost photosynthetic activity and growth.
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Affiliation(s)
- Marcel Grund
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Torsten Jakob
- Plant Physiology Group, Institute for Biology, University of Leipzig, Johannisallee 21-23, 04103 Leipzig, Germany
| | - Christian Wilhelm
- Plant Physiology Group, Institute for Biology, University of Leipzig, Johannisallee 21-23, 04103 Leipzig, Germany
| | - Bruno Bühler
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Andreas Schmid
- Department of Solar Materials, Helmholtz Center for Environmental Research GmbH–UFZ, Permoserstraße 15, 04318 Leipzig, Germany
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Yan D, Beardall J, Gao K. Variation in cell size of the diatom Coscinodiscus granii influences photosynthetic performance and growth. PHOTOSYNTHESIS RESEARCH 2018; 137:41-52. [PMID: 29322482 DOI: 10.1007/s11120-017-0476-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 12/27/2017] [Indexed: 06/07/2023]
Abstract
Cell size has implications for the package effect in photon absorption as well as for metabolic scaling of metabolism. In this study, we have avoided species-related differences by using isolates of the marine planktonic diatom Coscinodiscus granii with cells of different sizes and grown at different light intensities to investigate their energy allocation strategies. To make full use of incident light, several fold variations in cellular chlorophyll a content were employed across cell size. This modulation of pigment-related light absorbance was deemed effective as similar light absorbing capacities were found in all treatments. Unexpected low values of O2 evolution rate at the highest irradiance level of 450 μmol photons m-2 s-1 were found in medium and large cells, regardless of more photons being absorbed under these conditions, suggesting the operation of alternative electron flows acting as electron sinks. The growth rate was generally larger at higher irradiance levels except for the large cells, in which growth slowed at 450 μmol photons m-2 s-1, suggesting that larger cells achieved a balance between growth and photoprotection by sacrificing growth rate when exposed to high light. Although the ratio of carbon demand to rates of uncatalysed CO2 diffusion to the cell surface reached around 20 in large cells grown under higher irradiance, the carbon fixation rate was not lowered, due to the presence of a highly effective carbon dioxide concentrating mechanism.
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Affiliation(s)
- Dong Yan
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, China
| | - John Beardall
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, China.
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Schoefs B, Hu H, Kroth PG. The peculiar carbon metabolism in diatoms. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0405. [PMID: 28717015 DOI: 10.1098/rstb.2016.0405] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2017] [Indexed: 11/12/2022] Open
Affiliation(s)
- Benoît Schoefs
- Metabolism, bioengineering of microalgal molecules and applications, Mer Molécules Santé, UBL, IUML-FR 3473 CNRS, University of Le Mans, Le Mans, France
| | - Hanhua Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Peter G Kroth
- University of Konstanz, Fachbereich Biologie, 78457 Konstanz, Germany
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Identifying metabolic pathways for production of extracellular polymeric substances by the diatom Fragilariopsis cylindrus inhabiting sea ice. ISME JOURNAL 2018; 12:1237-1251. [PMID: 29348581 PMCID: PMC5932028 DOI: 10.1038/s41396-017-0039-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 11/08/2017] [Accepted: 12/05/2017] [Indexed: 11/09/2022]
Abstract
Diatoms are significant primary producers in sea ice, an ephemeral habitat with steep vertical gradients of temperature and salinity characterizing the ice matrix environment. To cope with the variable and challenging conditions, sea ice diatoms produce polysaccharide-rich extracellular polymeric substances (EPS) that play important roles in adhesion, cell protection, ligand binding and as organic carbon sources. Significant differences in EPS concentrations and chemical composition corresponding to temperature and salinity gradients were present in sea ice from the Weddell Sea and Eastern Antarctic regions of the Southern Ocean. To reconstruct the first metabolic pathway for EPS production in diatoms, we exposed Fragilariopsis cylindrus, a key bi-polar diatom species, to simulated sea ice formation. Transcriptome profiling under varying conditions of EPS production identified a significant number of genes and divergent alleles. Their complex differential expression patterns under simulated sea ice formation was aligned with physiological and biochemical properties of the cells, and with field measurements of sea ice EPS characteristics. Thus, the molecular complexity of the EPS pathway suggests metabolic plasticity in F. cylindrus is required to cope with the challenging conditions of the highly variable and extreme sea ice habitat.
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