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Steensma AK, Shachar-Hill Y, Walker BJ. The carbon-concentrating mechanism of the extremophilic red microalga Cyanidioschyzon merolae. PHOTOSYNTHESIS RESEARCH 2023; 156:247-264. [PMID: 36780115 PMCID: PMC10154280 DOI: 10.1007/s11120-023-01000-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/27/2023] [Indexed: 05/03/2023]
Abstract
Cyanidioschyzon merolae is an extremophilic red microalga which grows in low-pH, high-temperature environments. The basis of C. merolae's environmental resilience is not fully characterized, including whether this alga uses a carbon-concentrating mechanism (CCM). To determine if C. merolae uses a CCM, we measured CO2 uptake parameters using an open-path infra-red gas analyzer and compared them to values expected in the absence of a CCM. These measurements and analysis indicated that C. merolae had the gas-exchange characteristics of a CCM-operating organism: low CO2 compensation point, high affinity for external CO2, and minimized rubisco oxygenation. The biomass δ13C of C. merolae was also consistent with a CCM. The apparent presence of a CCM in C. merolae suggests the use of an unusual mechanism for carbon concentration, as C. merolae is thought to lack a pyrenoid and gas-exchange measurements indicated that C. merolae primarily takes up inorganic carbon as carbon dioxide, rather than bicarbonate. We use homology to known CCM components to propose a model of a pH-gradient-based CCM, and we discuss how this CCM can be further investigated.
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Affiliation(s)
- Anne K Steensma
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
- Michigan State University - Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
| | - Yair Shachar-Hill
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Berkley J Walker
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA.
- Michigan State University - Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA.
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Cho YL, Tzou YM, Wang CC, Lee YC, Hsu LC, Liu SL, Assakinah A, Chen YH, Thi Than NA, Liu YT, Rinklebe J. Removal and concurrent reduction of Cr(VI) by thermoacidophilic Cyanidiales: a novel extreme biomaterial enlightened for acidic and neutral conditions. JOURNAL OF HAZARDOUS MATERIALS 2023; 445:130334. [PMID: 36462243 DOI: 10.1016/j.jhazmat.2022.130334] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/26/2022] [Accepted: 11/04/2022] [Indexed: 06/17/2023]
Abstract
Thermoacidophilic Cyanidiales maintain a competitive edge in inhabiting extreme environments enriched with metals. Here, species of Cyanidioschyzon merolae (Cm), Cyanidium caldarium (Cc), and Galdieria partita (Gp) were exploited to remove hexavalent chromium [Cr(VI)]. Cm and Gp could remove 168.1 and 93.7 mg g-1 of Cr(VI) at pH 2.0 and 7.0, respectively, wherein 89% and 62% of sorbed Cr on Cm and Gp occurred as trivalent chromium [Cr(III)]. Apart from surface-sorbed Cr(VI), the in vitro Cr(III) bound with polysaccharide and in vivo chromium(III) hydroxide [Cr(OH)3] attested to the reduction capability of Cyanidiales. The distribution of Cr species varied as a function of sorbed Cr amount, yet a relatively consistent proportion of Cr(OH)3, irrespective of Cr sorption capacity, was found only on Cm and Cc at pH 2.0. In conjunction with TXM (transmission X-ray microscopy) images that showed less impaired cell integrity and possible intracellular Cr distribution on Cm and Cc at pH 2.0, the in vivo Cr(OH)3 might be the key to promoting the Cr sorption capacity (≥ 152 mg g-1). Cyanidiales are promising candidates for the green and sustainable remediation of Cr(VI) due to their great removal capacity, the spontaneous reduction under oxic conditions, and in vivo accumulation.
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Affiliation(s)
- Yen-Lin Cho
- Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yu-Min Tzou
- Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 40227, Taiwan; Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 40227, Taiwan
| | - Chun-Chieh Wang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yao-Chang Lee
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Liang-Ching Hsu
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Shao-Lun Liu
- Department of Life Science, Tunghai University, Taichung 40704, Taiwan
| | - Afifah Assakinah
- Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yu-Hsien Chen
- Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 40227, Taiwan
| | - Nhu Anh Thi Than
- Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yu-Ting Liu
- Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung 40227, Taiwan; Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 40227, Taiwan.
| | - Jörg Rinklebe
- Laboratory of Soil, and Groundwater-Management, Institute of Foundation Engineering, Water, and Waste, Management, School of Architecture and Civil Engineering, University of Wuppertal, Wuppertal 42285, Germany
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