Microfluidic chip-based long-term preservation and culture of engineering bacteria for DNA damage evaluation.

Understanding the effects of long-term exposure to space environment is paramount to maintaining the safety, health of astronauts. The physical dosimeters currently used on the space station cannot be used to assess the physiological effects of radiation. Moreover, some developed biological methods are time-consuming and passive and cannot be used for active and real-time detection of the physiological effects of radiation in space environment. Here, the SOS promoter: recA-eGFP genetic engineering bacteria was constructed and characterized, and DNA damage effects of some chemical reagents and radiation were evaluated. The results indicated the constructed engineering bacteria can distinguish DNA damage reagents from non-damage reagents and have a good dose-fluorescence effect against Co-60 radiation with the detection limit of 0.64 Gy; in order to overcome the restriction of long-term preservation of bacteria in space environment, the bacteria were freeze-dried, and the protectants were optimized, the storage time of bacteria under dry conditions was explored by accelerated storage experiment. Finally, a microfluidic chip was designed and fabricated for freeze-drying genetic engineering bacteria recovery, culture, and analysis in space environment. This study can provide support for the establishment of on-orbit radiation damage risk monitoring and early warning and can provide basic data for maintaining the health and performance of astronauts on long-term space flight missions. Moreover, the technique developed herein has a great potential to be used as a powerful tool for efficiently screening various radioactive substance, toxic chemicals, drugs, etc. KEY POINTS: • The SOS promoter: recA-eGFP genetic engineering bacteria was successfully constructed, which can distinguish DNA damage reagents from non-damage reagents and possess a good dose-effect relationship against Co-60 radiation. • The bacteria were freeze-dried to overcome the restriction of long-term preservation of bacteria in space environment, and protectants were optimized, and the survival rate of freeze-dried engineering bacteria can be predicted based on the results of accelerated storage experiment. • Microfluidic chip-based culture platform was successfully designed, fabricated, and used for freeze-drying genetic engineering bacteria recovery, culture, and analysis.