Construction Of A Hybrid System Based On Recombinant Escherichia Coli And Gold Nanoclusters And The Study Of Its Products

Solar energy is the most abundant renewable energy source on earth,and the development of solar-to-chemical energy conversion systems offers a high potential strategy for alleviating the energy crisis.The use of photocatalytic materials to capture light energy has significantly promoted the conversion rate of solar energy,but there are problems with a single product and poor specificity.In contrast,biological production can achieve product diversification and high specificity,but most organisms cannot directly utilize solar energy.Based on the hybrid system of whole cells,it innovatively combines the excellent light-harvesting ability of photocatalytic materials with the high-efficiency catalytic ability of intracellular biocatalysts,and has the advantages of both,providing a new way for the sustainable production of high-value-added products.In this experiment,gold nanoclusters were used as photocatalytic materials,designed to be introduced into recombinant Escherichia coli,and the existing catalytic pathway of recombinant Escherichia coli was used to construct a hybrid system.Utilizing the light-harvesting ability of photocatalytic materials and catalytic pathways of microorganisms.The main research content of this thesis is as follows:（1）Preparation of Au Nanoclusters:Using chloroauric acid（HAu Cl₄ 3H₂O）and L-glutathione（GSH）as raw materials,gold nanoclusters（Au NCs）were prepared by a one-step reduction method.The Au NCs were characterized and analyzed by UV-vis,PL,SEM,and TEM,and the particle size of the successfully prepared liquid material was counted using the software Nano measurer.The analysis results showed that the prepared Au NCs had good structure,morphology,and function.Verify that the preparation was successful.（2）Construction of gold nanoclusters-recombinant E.coli hybrid system（E.coli-Au NCs）:Prepare Au NCs with different concentration gradients and culture them with recombinant E.coli.After finding the optimal concentration,proceed to the next experiment,using ultraviolet-visible light spectroscopy The characteristic peaks were characterized by a photometer,and then the structure illumination microscope（SIM）was further used to clarify the position of the gold nanoclusters in the hybrid biological system by collecting the emission fluorescence of the gold nanoclusters under excitation at 560 nm,Transmission electron microscope（TEM）and other optical microscopes were used to characterize the microscopic morphology of the hybrid system to verify that the material successfully entered the bacteria and successfully constructed the hybrid system.（3）Based on the catalytic pathway of the hybrid system itself,light promotes the efficient synthesis of various products:use a xenon lamp to simulate sunlight as a bionic light source,and replace the heterotrophic medium with an autotrophic medium before exposing it to simulated sunlight to ensure that glucose is the only carbon source.Two sets of control experiments were set up,with gold nanoclusters and light as single variables,and 0.5 g/L decanoic acid as the reaction substrate for whole-cell catalysis,continuous light for 8 hours,and samples were taken every two hours to detect product changes.Finally,the qualitative and quantitative analysis of the product was carried out by GC-MS.The conversion of 10-hydroxy-decanoic acid increased by 19.8%and the conversion of succinic acid by 14%.The experimental results prove that the product consumption rate of the hybrid system is faster,and the ability to synthesize 10-hydroxy-decanoic acid and succinic acid is stronger.This study successfully constructed an efficient,stable,and sustainable semi-artificial photosynthesis system by combining photocatalytic materials with recombinant E.coli.The construction of this system is expected to provide a valuable reference for the development and industrial application of artificial photosynthesis in the future,and at the same time,the continuous light energy conversion by mimicking the natural photosynthesis of plants also provides a new feasible solution to alleviate the energy crisis and environmental problems.