Re-Programing Glucose Catabolism in the Microalga Chlorella sorokiniana under Light Condition

Abstract

The microalga Chlorella sorokiniana has attracted much attention for lipid production and wastewater treatment. It can perform photosynthesis and organic carbon utilization concurrently. To understand its phototrophic metabolism, a biomass compositional analysis, a 13C metabolic flux analysis, and metabolite pool size analyses were performed. Under dark condition, the oxidative pentose phosphate pathway (OPP) was the major route for glucose catabolism (88% carbon flux) and a cyclic OPP–glycolytic route for glucose catabolism was formed. Under light condition, fluxes in the glucose catabolism, tricarboxylic acid (TCA) cycle, and anaplerotic reaction (CO2 fixation via phosphoenolpyruvate carboxylase) were all suppressed. Meanwhile, the RuBisCO reaction became active and the ratio of its carbon fixation to glucose carbon utilization was determined as 7:100. Moreover, light condition significantly reduced the pool sizes of sugar phosphate metabolites (such as E4P, F6P, and S7P) and promoted biomass synthesis (which reached 0.155 h−1). In addition, light condition increased glucose consumption rates, leading to higher ATP and NADPH production and a higher protein content (43% vs. 30%) in the biomass during the exponential growth phase.

Elevated Temperature Effects on Protein Turnover Dynamics in Arabidopsis thaliana Seedlings Revealed by 15N-Stable Isotope Labeling and ProteinTurnover Algorithm

“…Employing advanced techniques such as metabolic flux analysis [ 90 , 91 , 92 ] would be key for quantifying metabolic changes and linking them to specific biochemical pathways, enhancing our understanding of plant metabolic adjustments to heat stress [ 93 , 94 , 95 ]. Finally, integrating systems biology approaches to correlate transcriptomic, proteomic, and metabolomic data could provide comprehensive insights into the regulatory networks and pathways activated during heat stress, potentially revealing critical regulatory nodes for enhancing plant heat tolerance [ 96 , 97 , 98 ].…”

The effects of photosynthetic rate on respiration in light, starch/sucrose partitioning, and other metabolic fluxes within photosynthesis

“…In this study, we used metabolic ux analysis (MFA), a powerful method for assessing intracellular metabolic uxes within living biological systems, to estimate R L and other metabolic uxes under HLHC. MFA integrates computational models with experimental isotope labeling, providing a comprehensive understanding of functional metabolism by integrating factors such as enzyme expression, activity, and network structure [41][42][43] . Recent advancements in 13 CO 2 time-course labeling and computational modeling have made isotopically nonstationary metabolic ux analysis (INST-MFA) a potent tool for studying autotrophic carbon metabolism and estimating in vivo carbon uxes 24,44 .…”

Elevated Temperature Effects on Protein Turnover Dynamics in <em>Arabidopsis thaliana</em> Seedlings Revealed by 15N-Stable Isotope Labeling and ProteinTurnover Algorithm

“…Employing advanced techniques like metabolic flux analysis [39][40][41] would be key for quantifying metabolic changes and linking them to specific biochemical pathways, enhancing our understanding of plant metabolic adjustments to heat stress. Additionally, integrating systems biology approaches to correlate transcriptomic, proteomic, and metabolomic data could provide comprehensive insights into the regulatory networks and pathways activated during heat stress, potentially revealing critical regulatory nodes for enhancing plant heat tolerance [42][43][44].…”