Redirecting carbon to bioproduction via a growth arrest switch in a sucrose-secreting cyanobacterium

Abramson, Bradley W.; Lensmire, Josh; Lin, Yang-Tsung; Jennings, Emily E.; Ducat, Daniel C.

doi:10.1016/j.algal.2018.05.013

Cited by 26 publications

(15 citation statements)

References 53 publications

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“…Interestingly, in other studies conducted on terpenoid production strains it is observed that the introduction of terpenoid based carbon sinks do not increase photosynthetic efficiency (Wang et al, 2016). This contrasts findings in which sucrose production in cyanobacteria is accompanied by increases in photosynthetic efficiency (Abramson et al, 2016;Abramson et al, 2018;Lin et al, 2020). It is reasonable to assume that the increase in photosynthetic efficiency in response to the addition of a sucrose carbon sink can be attributed to the fact that sucrose production does not affect intracellular ATP:NADPH equilibrium (Thiel et al, 2019).…”

Section: Resultscontrasting

confidence: 87%

Characterizing Photosynthetic Biofuel Production: Isotopically non-stationary¹³C metabolic flux analysis (INST-¹³CMFA) on limonene producingSynechococcussp. PCC 7002

Newman

Sake

Metcalf

et al. 2022

Preprint

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Synechococcus sp. PCC 7002 is a unicellular cyanobacterium capable of fast growth, even under high light intensity and high salinity. These attributes along with genetic tractability make Synechococcus sp. PCC 7002 an attractive candidate for industrial scale production of specialty and commodity chemicals. One such strain produces limonene, an energy dense diesel jet fuel drop-in additive, at a titer of 4 mg/L over a four-day incubation period. In this study, we use the state-of-the-art whole-cell characterization tool, isotopically non-stationary 13C metabolic flux analysis (INST-13CMFA) to determine intracellular fluxes through the pathways of central metabolism for the limonene producing strain and wild type strain of Synechococcus sp. PCC 7002. We find similar flux distribution in the Calvin-Benson-Bassham cycle, photorespiration, oxidative pentose phosphate pathway, and reductive tricarboxylic acid cycle. The key difference between strains is observed in the production of pyruvate. The limonene producing strain displays significantly higher flux through the amphibolic pathways of phosphoenolpyruvate carboxylase and the malic enzyme to synthesize pyruvate, while the wild type strain uses pyruvate kinase in a single step. Our findings suggest that this flux distribution is a mechanism to recover a physiologically optimal ratio of ATP to NADPH. The upregulation of this amphibolic pathway may act to restore the physiological ATP:NADPH ratio that has been disturbed by limonene biosynthesis.

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Section: Resultscontrasting

confidence: 87%

Characterizing Photosynthetic Biofuel Production: Isotopically non-stationary¹³C metabolic flux analysis (INST-¹³CMFA) on limonene producingSynechococcussp. PCC 7002

Newman

Sake

Metcalf

et al. 2022

Preprint

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“…We sought to gain deeper insight into the adaptive cellular response that results from engagement of a strong heterologous carbon sink. We first validated that the previously described CscB/SPS strain (Abramson et al, 2016; Abramson et al, 2018; Santos-Merino et al, 2021) was capable of sucrose export under our experimental setup (Fig. 1b) and exhibited the previously-described increase in photosynthetic performance upon activation of this heterologous sink via IPTG addition (Supplementary Fig.…”

Section: Resultssupporting

confidence: 78%

Multi-layer Regulation of Rubisco in Response to Altered Carbon Status in Synechococcus elongatus PCC 7942

Singh

Santos-Merino

Sakkos

et al. 2021

Preprint

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Photosynthetic organisms possess a variety of mechanisms to achieve balance between absorbed light (source) and the capacity to metabolically utilize or dissipate this energy (sink). While regulatory processes that detect changes in metabolic status/balance are relatively well-studied in plants, analogous pathways remain poorly characterized in photosynthetic microbes. Herein, we explore systemic changes that result from alterations in carbon availability in the model cyanobacterium Synechococcus elongatus PCC 7942 by taking advantage of an engineered strain where influx/efflux of a central carbon metabolite, sucrose, can be regulated experimentally. We observe that induction of a high-flux sucrose export pathway leads to depletion of internal carbon storage pools (glycogen), and concurrent increases in photosynthetic parameters. Further, a proteome-wide analysis and fluorescence reporter-based analysis revealed that upregulated factors following the activation of the metabolic sink are strongly concentrated on ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) and axillary modules involved in Rubisco maturation. Carboxysome number and Rubisco activity also increase following engagement of sucrose secretion. Conversely, reversing the flux of sucrose by feeding exogenous sucrose heterologously results in increased glycogen pools, decreased Rubisco abundance, decreased photosystem II quantum efficiency, and carboxysome reorganization. Our data suggest that Rubisco activity and organization are key outputs connected to regulatory pathways involved in metabolic balancing in cyanobacteria.

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“…This result improves most frequent concentrations around 1.5 g sucrose•L −1 from sucrose exporting Synecchococcus sp. PCC 7942 strains (Du et al, 2013;Duan et al, 2016;Ducat et al, 2012;Hays et al, 2017;Kirsch et al, 2018;Löwe et al, 2017;Niederholtmeyer et al, 2010;Smith and Francis, 2017;Song et al, 2016;Weiss et al, 2017) and also the most recent improvement after genetic manipulation of sucrose synthesis and export, and cell proliferation at 6 g sucrose•L −1 (Abramson et al, 2018). This aspect may have technological implications if this kind of cyanobacteria-based platforms are to be envisioned as a source of sugars for the production of ethanol, since a minimum of 40 g ethanol•L −1 would be needed to reduce distillation costs (Möllers et al, 2014).…”

Section: Sucrose Extraction From Anabaena Biomassmentioning

confidence: 99%

Ethanol and protein production from minimally processed biomass of a genetically-modified cyanobacterium over-accumulating sucrose

Smachetti

Cenci

Salerno

et al. 2019

Bioresource Technology Reports

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One of the main bottlenecks of a microalgal or cyanobacterial biomass biorefinery is the separation of different useful fractions using simple, low energy-consuming, cost-effective, and scalable separation processes. Although the carbohydrates-rich biomass of these microorganisms presents clear advantages over conventional terrestrial crops as feedstocks for ethanol, it still requires acid and/or enzymatic hydrolysis for efficient fermentation. Here, we show the genetic modification of carbohydrates partitioning in a filamentous cyanobacterium towards the accumulation of sucrose up to 10% (w/w) as a readily fermentable feedstock. We optimized two methods for the preparation of concentrated sucrose syrups, which were efficiently converted into ethanol by yeasts, without the need of additional pretreatments. Biomass drying and milling, followed by aqueous extraction of sugars and proteins, and the recovery of proteins by short pulses of heat, kept the value of sugars as a feedstock for ethanol and protein for feed supplements within a cost-effective biomass biorefinery.

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Redirecting carbon to bioproduction via a growth arrest switch in a sucrose-secreting cyanobacterium

Cited by 26 publications

References 53 publications

Characterizing Photosynthetic Biofuel Production: Isotopically non-stationary¹³C metabolic flux analysis (INST-¹³CMFA) on limonene producingSynechococcussp. PCC 7002

Characterizing Photosynthetic Biofuel Production: Isotopically non-stationary¹³C metabolic flux analysis (INST-¹³CMFA) on limonene producingSynechococcussp. PCC 7002

Multi-layer Regulation of Rubisco in Response to Altered Carbon Status in Synechococcus elongatus PCC 7942

Ethanol and protein production from minimally processed biomass of a genetically-modified cyanobacterium over-accumulating sucrose

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Redirecting carbon to bioproduction via a growth arrest switch in a sucrose-secreting cyanobacterium

Cited by 26 publications

References 53 publications

Characterizing Photosynthetic Biofuel Production: Isotopically non-stationary13C metabolic flux analysis (INST-13CMFA) on limonene producingSynechococcussp. PCC 7002

Characterizing Photosynthetic Biofuel Production: Isotopically non-stationary13C metabolic flux analysis (INST-13CMFA) on limonene producingSynechococcussp. PCC 7002

Multi-layer Regulation of Rubisco in Response to Altered Carbon Status in Synechococcus elongatus PCC 7942

Ethanol and protein production from minimally processed biomass of a genetically-modified cyanobacterium over-accumulating sucrose

Contact Info

Product

Resources

About

Characterizing Photosynthetic Biofuel Production: Isotopically non-stationary¹³C metabolic flux analysis (INST-¹³CMFA) on limonene producingSynechococcussp. PCC 7002

Characterizing Photosynthetic Biofuel Production: Isotopically non-stationary¹³C metabolic flux analysis (INST-¹³CMFA) on limonene producingSynechococcussp. PCC 7002