Carbon Metabolism

Moriyama, Takashi; Mori, Natsumi; Sato, Naoki

doi:10.1007/978-981-10-6101-1_19

Cited by 1 publication

(1 citation statement)

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“…The resulting Ci scarcity likely presents an obstacle to growth of C. merolae , as this alga appears to depend on phototrophy. The only known method for heterotrophic culture of wild-type C. merolae requires supplying cells with glycerol concentrations far higher than are typical in natural or laboratory conditions, and the resulting heterotrophic growth is slow and ceases after 6–7 cell divisions (Moriyama et al 2015 , 2017 , 2018 ; Liu et al 2020 ). Accordingly, genomic data suggests that C. merolae may have a relatively limited capacity for organic carbon uptake: C. merolae ’s genome has substantially fewer putative carbohydrate transporters and glycerol permeases than the genome of a closely related facultative heterotroph (Weber et al 2004 ; Barbier et al 2005 ; Fujiwara et al 2019 ).…”

Section: Introductionmentioning

confidence: 99%

The carbon-concentrating mechanism of the extremophilic red microalga Cyanidioschyzon merolae

2023

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Cyanidioschyzonmerolae 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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