Expression of the Chlamydomonas reinhardtii Sedoheptulose‐1,7‐bisphosphatase in Dunaliella bardawil leads to enhanced photosynthesis and increased glycerol production

Abstract

SummaryBioengineering of photoautotrophic microalgae into CO 2 scrubbers and producers of valueadded metabolites is an appealing approach in low-carbon economy. A strategy for microalgal bioengineering is to enhance the photosynthetic carbon assimilation through genetically modifying the photosynthetic pathways. The halotolerant microalgae Dunaliella posses an unique osmoregulatory mechanism, which accumulates intracellular glycerol in response to extracellular hyperosmotic stresses. In our study, the Calvin cycle enzyme sedoheptulose 1,7-bisphosphatase from Chlamydomonas reinhardtii (CrSBPase) was transformed into Dunaliella bardawil, and the transformant CrSBP showed improved photosynthetic performance along with increased total organic carbon content and the osmoticum glycerol production. The results demonstrate that the potential of photosynthetic microalgae as CO 2 removers could be enhanced through modifying the photosynthetic carbon reduction cycle, with glycerol as the carbon sink.

Metabolic engineering of Cyanobacteria and microalgae for enhanced production of biofuels and high-value products

“…The overexpression of SBPase generated more total organic carbon content and increased glycerol production by about 37% under high salinity conditions (Fang et al . ).…”

“…The overall rate of photosynthesis of the transgenic Dunaliella was superior to the wild type, where at 2 mol l À1 NaCl, the photosynthetic efficiency (nmol O 2 per cell per lmol photons per m 2 ) and rates of CrSBP were 50-100% higher. The overexpression of SBPase generated more total organic carbon content and increased glycerol production by about 37% under high salinity conditions (Fang et al 2012).…”

“…As a result, the activity of SBPase was about 80% higher in CrSBP than in the wild type. It was discovered that CrSBP growth rates at different salinities was overall slower than the wild type, yet with less variation and less sensitivity to salinity (Fang et al 2012). The overall rate of photosynthesis of the transgenic Dunaliella was superior to the wild type, where at 2 mol l À1 NaCl, the photosynthetic efficiency (nmol O 2 per cell per lmol photons per m 2 ) and rates of CrSBP were 50-100% higher.…”

Across the Board: Angela Dibenedetto

“…Fang et al [6] report the generation of transgenic Dunaliella bardawil expressing CrSBPase able to improve the photosynthetic performance alongw ith increased total organic carbonc ontent and the osmoticum glycerol production. In fact, as the name says, it catalyzes alternativelythe car-boxylation and oxygenation of ribulose, in ar ate ratio of approximately 3:1.…”

Solar-to-fuel conversion in algae and cyanobacteria

“…Heterologous overexpression of sedoheptulose-1,7-bisphosphatase (SBPase) of the Calvin-Benson cycle was reported to increase photosynthetic activity and carbon content in Dunaliella bardawil (Fang et al 2012 ), suggesting a limitation in biochemical reactions of the Calvin-Benson cycle that may be subjected to genetic improvement. SBPase has been identifi ed as a rate-limiting enzyme of the Calvin cycle, because it is important for regeneration of ribulose-1,5-bisphosphate, the substrate of RuBisCO.…”