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DOE OSTI · 3363872

Investigating overflow metabolism in heterotrophic cultures of the green alga Chromochloris zofingiensis

Meagher, Michelle [Colorado School of Mines, Golden, CO (United States)] (ORCID:0000000269662403)·Camacho, Dimitrios J. [University of California, Berkeley, CA (United States)]·Gallaher, Sean D. [University of California, Berkeley, CA (United States)]·Merchant, Sabeeha S. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]·Boyle, Nanette R. [Colorado School of Mines, Golden, CO (United States)] (ORCID:0000000291030007)
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Abstract

Chromochloris zofingiensis is of interest for its ability to perform a reversible trophic switch in the presence of glucose that is characterized by a shutdown of photosynthesis and an accumulation of energy storage metabolites. Previous work has shown that this trophic switch is accompanied by overflow metabolism and the production of lactate in aerobic conditions. This trophic switch is not observed in nutrient replete media. We utilized isotopically assisted metabolic flux analysis to characterize intracellular flux distributions that are associated with different metabolic phenotypes observed in this organism in different media formulations in light and dark conditions. The results of this analysis showed that low iron cultures have no flux through carbon fixation reactions, and that the carbon flux entering the TCA cycle in these cultures is approximately 40 % lower than that in iron replete cultures grown heterotrophically. This analysis was complemented with transcriptomics data collected for C. zofingiensis grown in iron limited conditions to provide further evidence towards the negative impact of iron limitation on both photosynthetic and respiratory activity. Overflow metabolism allows this alga to compensate for the lower energy production that results from iron limitation. This work highlights how nutrient availability can lead to changes in the metabolism of C. zofingiensis.

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59 BASIC BIOLOGICAL SCIENCESAlgaeFeIron metabolismMetabolic flux analysisMetabolic modelingTranscriptome

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Meagher, Michelle [Colorado School of Mines, Golden, CO (United States)] (ORCID:0000000269662403), Camacho, Dimitrios J. [University of California, Berkeley, CA (United States)], Gallaher, Sean D. [University of California, Berkeley, CA (United States)], Merchant, Sabeeha S. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Boyle, Nanette R. [Colorado School of Mines, Golden, CO (United States)] (ORCID:0000000291030007). 2026-04-01. Investigating overflow metabolism in heterotrophic cultures of the green alga Chromochloris zofingiensis. https://doi.org/10.1016/j.ymben.2026.01.007

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