Elucidating Electron Transfer Kinetics and Optimizing System Performance for Escherichia coli-Based Semi-Artificial H-2 Production

Uppsala universitet, Molekylär biomimetik Uppsala universitet, Institutionen för kemi - Ångström Uppsala universitet, Fysikalisk kemi Tech Univ Munich, TUM Campus Straubing Biotechnol & Sustainabil, D-94315 Straubing, Germany Tech Univ Munich, TUM Campus Straubing Biotechnol & Sustainabil, D-94315 Straubing, Germany 2023

Both photo- and biocatalysis are well-established andintensivelystudied. The combination of these two approaches is also an emergingresearch field, commonly referred to as semi-artificial photosynthesis.Semi-artificial photosynthesis aims at combining highly efficientsynthetic light harvesters with the self-healing and potent catalyticproperties of biocatalysis. In this study, a semi-artificial photocatalyticsystem featuring Escherichia coli bacteria,which heterologously express the [FeFe] hydrogenase enzyme HydA1 fromgreen algae, is employed as a hydrogen gas production catalyst. Toprobe the influence of photochemistry on overall system performance,the E. coli whole-cell catalyst iscombined with two different photosensitizers and redox mediators.The addition of a redox mediator greatly improves the rates and longevityof the photocatalytic system, as reflected in increases of both theturn-over number (0.777 vs 10.9 & mu;mol H-2 mL(-1) OD600 (-1)) and the turn-over frequency(175 vs 334 & mu;mol H-2 mL(-1) h(-1) OD600 (-1)). The redoxmediator is found to both protect from photobleaching and enable electrontransport to the hydrogenase from an extracellular photosensitizer.However, E. coli cells are stronglyaffected by the photocatalytic system, leading to a decrease in cellintegrity and cell viability, possibly due to toxic decompositionproducts formed during the photocatalytic process. We furthermoreemployed steady-state and transient absorption spectroscopy to investigatesolution potentials and the kinetics of electron transfer processesbetween the sacrificial electron donor, photosensitizer, redox mediator,and the [FeFe] hydrogenase as the final electron acceptor. These resultsallowed us to rationalize the different activities observed in photocatalyticassays and offer a better understanding of the factors that influencethe photocatalytic performance of E. coli-based whole-cell systems.

hydrogenase; whole-cell catalysis; semi-artificialphotosynthesis; hydrogen; transient absorption; redox mediator; sacrificial electron donor; Biochemistry and Molecular Biology; Biokemi och molekylärbiologi; Article in journal; info:eu-repo/semantics/article; text

10.1021.acscatal.3c01347

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English

UPE oai:DiVA.org:uu-510973
0000-0002-6647-0916
0000-0001-9225-4910
0000-0002-5303-7865
0000-0002-9933-9084
0000-0002-6717-6612
doi:10.1021/acscatal.3c01347
ISI:001021458700001
1399994077

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