When it comes to sustainable and environmentally friendly products, bacteria may not be the first thing that comes to mind. However, scientists have made significant progress in recent years by creating microbe-semiconductor biohybrids that harness the power of living systems and the capabilities of semiconductors to convert solar energy into valuable chemical products. This merging of biology and technology has the potential to revolutionize the production of bioplastics and biofuels. However, there is still much to learn about the complex energy transport processes in these tiny biohybrids and how they can be optimized for greater efficiency.
A team of researchers from Cornell University has developed a multimodal platform for imaging these biohybrids at the single-cell level. By being able to visualize and understand how these biohybrids function, the researchers hope to uncover new insights and improve the energy conversion process. The study, titled “Single-Cell Multimodal Imaging Uncovers Energy Conversion Pathways in Biohybrids,” was published in Nature Chemistry and is a collaborative effort between the College of Arts and Sciences, the Smith School of Chemical and Biomolecular Engineering, and the College of Agriculture and Life Sciences.
Traditionally, biohybrid research has been conducted with bacteria in bulk, focusing on the overall yield of value-added chemicals and the collective behaviors of the cells. However, this approach overlooks the heterogeneity of individual cells and the underlying mechanisms that drive complex chemical transformations. To address this, the researchers developed a platform that provides quantitative assessments of protein behaviors and a mechanistic understanding of electron transport from semiconductors to bacteria cells.
Using the new imaging platform, the researchers studied the bacterium Ralstonia eutropha and successfully differentiated the functional roles of two types of hydrogenases. These hydrogenases, one bound to the cell’s membrane and the other soluble in the cytoplasm, are crucial for metabolizing hydrogen and driving CO2 fixation. While the soluble hydrogenase was known to be critical, the researchers discovered that the membrane-bound hydrogenase actually facilitates the process and increases its efficiency.
Furthermore, the researchers obtained experimental evidence that bacteria can take in a large amount of electrons from semiconductor photocatalysts. The measured electron current was three orders of magnitude larger than previously thought, suggesting that future bacteria strains can be engineered to enhance energy conversion efficiency. The team also found that both membrane-bound and soluble hydrogenases play important roles in mediating electron transport from the semiconductor into the cell. Additionally, the bacteria demonstrated the ability to release electrons in the opposite direction without the aid of hydrogenases.
The multimodal imaging platform developed by the researchers is not limited to studying biohybrids and can be applied to other biological-inorganic systems, such as yeast. It also has the potential to investigate other processes like nitrogen fixation and pollutant removal. However, the platform does have its limitations, as it cannot analyze small molecule compositions. Further integration with techniques like nanoscale mass spectrometry could enhance its capabilities and provide a more comprehensive understanding of these systems.
The study conducted by Cornell researchers sheds light on the energy conversion pathways in bacteria-semiconductor biohybrids. By utilizing a multimodal imaging platform, the team gained insights into the roles of specific proteins and electron transport within these biohybrids. The findings open up possibilities for optimizing energy conversion efficiency and engineering bacteria strains to improve sustainable product generation. With further advancements in imaging techniques and interdisciplinary collaborations, biohybrids have the potential to play a significant role in a more sustainable future.