Directed Evolution of 4-Hydroxyphenylpyruvate Biosensors Based on a Dual Selection System.

Biosensors based on allosteric transcription factors have been widely used in synthetic biology. In this study, we utilized the Acinetobacter ADP1 transcription factor PobR to develop a biosensor activating the PpobA promoter when bound to its natural ligand, 4-hydroxybenzoic acid (4HB). To screen for PobR mutants responsive to 4-hydroxyphenylpyruvate(HPP), we developed a dual selection system in E. coli. The positive selection of this system was used to enrich PobR mutants that identified the required ligands. The following negative selection eliminated or weakened PobR mutants that still responded to 4HB. Directed evolution of the PobR library resulted in a variant where PobRW177R was 5.1 times more reactive to 4-hydroxyphenylpyruvate than PobRWT. Overall, we developed an efficient dual selection system for directed evolution of biosensors.

Analysis of research trends on hydrogen explosion by bibliometric approach.

As a carbon-free clean energy source and energy carrier, the risk of hydrogen explosion is one of the major problems in industrial production processes and has attracted a lot of attention from research scholars. According to the records in the Web of Science Core Collection database, a total of 1043 articles or reviews related to hydrogen explosion were published from 2001 to 2021. In this study, the collected literature information was visually analyzed using VOSviewer and CiteSpace. The results show that China, USA, Germany, and Japan are major contributors to hydrogen explosion research; the International Journal of Hydrogen Energy has the highest publications among all source journals. The research theme of hydrogen explosion has developed into two main directions: hydrogen mixture explosion characteristics and suppression methods, hydrogen explosion characteristics and suppression methods. Compared to traditional suppression methods, fine water mist is more efficient and environmentally friendly for the explosion of hydrogen and its mixtures. New research hotspots have appeared related to hydrogen fuel cells, the mechanism and prediction method of hydrogen VCE and DDT, explosive suppressants with engineering practicality and economy, and numerical methods that can accurately simulate the turbulence of hydrogen combustion. The results of the study can be used to help researchers quickly understand the current status and research frontiers of hydrogen explosion research and contribute to further research in the field.