A system-oriented strategy to enhance electron production of Synechocystis sp. PCC6803 in bio-photovoltaic devices: experimental and modeling insights

Abstract

Bio-photovoltaic devices (BPVs) harness photosynthetic organisms to produce bioelectricity in an eco-friendly way. However, their low energy efficiency is still a challenge. A comprehension of metabolic constraints can result in finding strategies for efficiency enhancement. This study presents a systemic approach based on metabolic modeling to design a regulatory defined medium, reducing the intracellular constraints in bioelectricity generation of Synechocystis sp. PCC6803 through the cellular metabolism alteration. The approach identified key reactions that played a critical role in improving electricity generation in Synechocystis sp. PCC6803 by comparing multiple optimal solutions of minimal and maximal NADH generation using two criteria. Regulatory compounds, which controlled the enzyme activity of the key reactions, were obtained from the BRENDA database. The selected compounds were subsequently added to the culture media, and their effect on bioelectricity generation was experimentally assessed. The power density curves for different culture media showed the BPV fed by Synechocystis sp. PCC6803 suspension in BG-11 supplemented with NH4Cl achieved the maximum power density of 148.27 mW m-2. This produced power density was more than 40.5-fold of what was obtained for the BPV fed with cyanobacterial suspension in BG-11. The effect of the activators on BPV performance was also evaluated by comparing their overpotential, maximum produced power density, and biofilm morphology under different conditions. These findings demonstrated the crucial role of cellular metabolism in improving bioelectricity generation in BPVs.

Investigating ethanol production using the Zymomonas mobilis crude extract

“…For example, much of the research has been working on improving bioethanol production from various substrates like lignocellulosic and agricultural waste biomass via microbial-based systems, using genetic and computational tools [6][7][8] . Furthermore, to gratify the demand to develop industrially competitive microorganisms for producing valuable metabolites, various techniques such as designing culture media, nutrient-feeding strategies, and controlling the pH of culture media; have been applied [9][10][11][12] . Although microbial-based systems are harnessing in many cases for producing many metabolites and biofuels, there are some constraints in producing metabolites in microbial-based systems.…”

Investigating ethanol production using the Zymomonas mobilis crude extract

“…For example, much research has been conducted on improving ethanol production from various substrates such as lignocellulosic and agricultural waste biomass via microbialbased systems, using genetic and computational tools [6][7][8] . Furthermore, various techniques such as designing culture media, nutrient-feeding strategies, and controlling the pH of the culture media have been applied to gratify the demand to develop industrially competitive microorganisms for producing valuable metabolites [9][10][11][12] .Although microbial-based systems are harnessing in many cases for producing many metabolites and biofuels, there are also some constraints in producing metabolites in microbial-based systems. For example, the efficiency of microorganisms' processes is often limited by the complexity of microorganism physiology.…”

“…For example, much research has been conducted on improving ethanol production from various substrates such as lignocellulosic and agricultural waste biomass via microbialbased systems, using genetic and computational tools [6][7][8] . Furthermore, various techniques such as designing culture media, nutrient-feeding strategies, and controlling the pH of the culture media have been applied to gratify the demand to develop industrially competitive microorganisms for producing valuable metabolites [9][10][11][12] .…”