In this day and age, mankind faces many challenges, such as climate change, overpopulation and resource depletion, which makes the exploration of space more and more urgent. Space, as an important area for the future development of mankind, especially Mars and other potentially migratory planets, has always been the focus of exploration. However, we have learnt that current spacesuits are inadequate in safeguarding astronauts' safety and providing long-term survival protection. For example, the Z-2 spacesuit launched by NASA in 2014 uses bionic technology to provide illumination in dim environments, but its limited luminous intensity and reliance on bulky life support systems limit astronauts' flexibility. Inspired by this, our team used synthetic biology principles to design an all-in-one life support system to ensure the safety and survival of astronauts during space exploration.
We firmly believe that space exploration can not only find new resources and living space for humankind, but also promote scientific and technological development and provide new ideas and methods for solving problems on Earth. At the same time, there are benefits to be derived both in space and on Earth, and we can both help to advance space science and solve the important problems facing the Earth. In light of today's growing global demand for maritime transport, high levels of maritime activity, and the increased frequency of maritime accidents, we are focusing our attention on rescue at sea and proposing a range of solutions.
NASA's Z-2 spacesuit creatively uses bionic technology to provide illumination in dimmer environments. However, the suit's luminous intensity is very limited, and the bulky life support system restricts the astronauts' flexibility. As a result, we considered whether we could construct an algae-bacteria Luminescence System to achieve luminescence and provide tracer functions for space work and emergency rescue. Eco-rescue smart spacesuits face the challenge of special conditions such as radiation, microgravity and extreme temperature in space environment. How to ensure the normal function of the hybrid bacterial system under these conditions, as well as how to reduce the cost and complexity of the system so that it can be widely used in practical rescue work, are the challenges we need to face.
At present, the rescue of people overboard at sea faces many difficulties. Ordinary water life jackets have poor visual signalling devices, torches have a small positioning range and short endurance, and lifeguard whistles have a very small positioning range and are physically demanding. Air search technology is highly dependent on sea visibility and weather conditions, narrow sweep width. Alarm positioning devices based on inertial guidance and other technologies have shortcomings such as high cost and poor stability. For example, the positioning accuracy of radio measurement devices is not high, the data transmission rate of wireless communication devices is low and power consumption is high, global positioning devices are greatly affected by temperature, and BeiDou navigation devices are limited in positioning in highly dynamic environments and middle and high latitude areas. How to design a stable, low energy consumption, strong signal, range accurate signal method has become a difficult problem that people need to overcome.
In view of this, we have conceived a hybrid bacterial system capable of sustainable luminescence based on marine luminescent organisms using synthetic biology technology. This system, with its blue fluorescence as a signal, is expected to help rescuers locate people in distress, offering new possibilities for space exploration and maritime search and rescue.
LuminAid is a photosynthetically autotrophic fluorescent lifesaving device that serves as an emergency rescue and sample labelling tool in extreme environmental exploration in cases of poor communication or telemetry failure.
Suitable for different usage scenarios: ocean and space.
For the marine application scenario, we designed the product as a collapsible parachute pack containing engineered bacterial powder that can be mounted on a life jacket. When the person in distress pulls on the handle to unfold the folded pack, the lyophilised powder of Cyanobacteria and Vibrio natriegens will proliferate and glow once it comes into contact with seawater, creating a large blue fluorescent area on the sea surface, thus improving the visibility of the person in distress and providing a new solution to the dilemmas of rescuing people from extreme environments and harsh spatial environments. In order to expand the scope of application, we have also designed the luminous lifejacket to serve a wider range of potential users such as commercial shipping companies, fishing vessels, government and maritime rescue organisations, recreational yacht and cruise ship passengers and water sports enthusiasts.
In space application scenarios, spacesuits need to have the ability to respond to emergencies, such as emergency oxygen supply, rapid evacuation and self-rescue devices, to ensure that astronauts can react quickly and protect themselves in unexpected situations. Our algal-bacterial symbiotic system allows the suit to glow - inside the capsule for illumination, outside the capsule for orientation, and through luminescence to help producers in the autotrophic system to generate oxygen and organic matter to supply the astronauts' life activities, providing more possibilities for survival - to satisfy the need for effective emergency response. -The requirements for an effective response to emergencies are met.
High osmotic pressure and low temperature are two characteristics of the marine environment. Vibrio natriegens is suitable for survival in high osmotic environments, but its optimal temperature for survival is 37°C, while the average temperature of the ocean is about 20°C, and in most regions the temperature is lower, studies have shown that the low temperature environment of seawater will cause the ROS content in Vibrio natriegens to rise, which is not conducive to its survival and functioning, so Vibrio natriegens needs to enhance the ability to tolerate the cold.
Based on the algal-bacterial coexistence system, we cleverly utilised sucrose synthesised and secreted by Cyanobacteria, which can firstly be used as a carbon source for the long-term survival of Vibrio natriegens. The continuous supply of sucrose activates psacB, which enables Vibrio natriegens to express downstream superoxide dismutase (SOD) and catalase to break down ROS into water and oxygen, preventing oxidative stress and conferring cold tolerance to Vibrio natriegens.
For space use scenarios, the final product will be a lyophilised powder of Cyanobacteria and Vibrio natriegens, which glows once it comes into contact with seawater. Cyanobacteria synthesise sucrose through photosynthesis, providing a persistent carbon source for the Vibrio natriegens, providing a lasting and visible sign of salvation. The freeze-dried bacterial powder can also be equipped on the outside of a space suit. When a button is pressed, the previously isolated freeze-dried bacterial powder comes into contact with seawater, triggering a glow to determine the astronaut's location.
Radiation is an important consideration for the survival of microorganisms in space, and the use of physical isolation alone is costly and detrimental to the maintenance of algal-bacterial system activity.
Inspired by Deinococcus radiodurans（Dr）, a microorganism known to have a strong ability to cope with high doses of ionising radiation, ultraviolet light, lethal chemicals, and dehydration treatment. We introduced the genes recO and recF related to resistance to ionising radiation into the chassis bacteria to protect against space ionising radiation.
The chassis bacteria in our project are Vibrio natriegens. and Synechococcus PCC7002, which are modified to rapidly emit light and proliferate in the high osmotic pressure and low temperature of seawater in order to address the problem of low visibility during nighttime sea rescue and space emergency response. The main body of the luminescent module is the aliphatic aldehyde oxidase LuxAB, which emits blue light during oxidation. LuxCDE provides substrate for LuxAB oxidation, and LuxFG increases the luminescence intensity. The Envz-OmpR two-component system senses the osmotic pressure change, so that the engineered bacteria start to accumulate luminescent substrate after entering the seawater. PumuDC can be induced by ultraviolet light, and when the daytime ultraviolet light is high PumuDC can be induced by UV light, and when UV light is strong during the daytime, it expresses downstream CI proteins to inhibit LuxAB expression, and then releases the inhibition and starts to emit light when UV light is weak at night. However, in the experimental validation of the PumuDC promoter, we found that the experimental results were unsatisfactory, and in exploring other optogenetic tools we found an optogenetic tool that has been well characterised as a far-red light-regulated transcriptional activation device: PMrka.
Cyanobacteria will constitutively express the air sac protein, so the Cyanobacteria can float on the water surface, according to this to get the inspiration in the engineered bacteria also express the appropriate amount of air sac protein, expect to increase the engineered bacterial floating area, to expand the luminescence range.
In order to better improve the luminescence efficiency, we explored the chemotactic compounds that can specifically aggregate Vibrio fischeri. We decided to use N-acetylneuraminic acid and GlcNAc2, a substance that helps Vibrio fischeri to colonise squid, as chemotactic agents to attract Vibrio fischeri specifically, and added them to the algae-bacteria symbiotic system.
We designed a sucrose dilution suicide switch. Engineered bacteria activate their sensing of sucrose only in the hypertonic environment of the ocean, and upon entering the ocean, spare sucrose in the product and sucrose produced by the algae inhibits the deterrence of Pscr by ScrR, resulting in the expression of lacI and the non-expression of MazF. When the engineered bacteria leak outside the biofilm, sucrose is diluted so that sucrose is reduced. Eventually, the leaking engineered bacteria expressed MazF, leading to suicide. The lack of a carbon source is also a factor in bacterial death, which together with the active expression of the toxin protein MazF constitutes a reliable strategy to prevent bacterial leakage. In case of leakage, not only passive killing through the reverse side of the microbial survival module, but also active killing by sensing changes in sucrose concentration formed a comprehensive passive-active anti-leakage module.
Preventing engineered bacteria from entering the environment is as important in the oceans as it is in space, and our protection strategy is equally applicable in space. We believe that this measure is effective in avoiding possible biosecurity problems.
We have designed drug-controlled termination switches to ensure that we can actively kill engineered bacteria by adding the inducer arabinose to prevent consequences such as leakage.
We also chose a temperature control system that promotes engineered bacteria toxin proteins to trigger bacterial death by controlling the temperature to kill engineered bacteria that complete the task or leak. Suicide was triggered by heating the engineered bacteria to a temperature of 37°C, inducing the expression of the toxin protein MazF.
Our bacteria will be used to increase the visibility of people in distress during night time sea rescues. In addition to sea rescue, our location-engineered bacteria can be used in scenarios such as canal search, extreme sports, sea patrol, sea fishing and rafting. It is especially useful for space work and emergency rescue tracer functions.
Luminous Bacteria Recruitment Module: Exploring the chemotaxis of engineered bacteria that secrete their own specific aggregates of Vibrio fischeri, in the future we will collect further relevant data and optimise our project.
Drug control system: arabinose is a naturally occurring simple carbohydrate that many microorganisms and aquatic organisms can utilise as a carbon source. It is usually well biodegradable and can be rapidly broken down and utilised by microorganisms. It is a natural product that does not usually cause discomfort or toxic reactions in organisms, is usually released in small amounts in the marine environment, and can be rapidly broken down by microorganisms in the water without causing long-term accumulation or pollution problems. Therefore, we believe that arabinose is a better choice. However, further experiments are still needed to prove whether the inducer is effective in killing engineering bacteria in seawater.
Temperature control system: limited by the specific heat capacity of seawater, the heating time may be longer, so the specific performance of this system needs to be further explored.
We are confident about the future and hope that our luminescent projects will play an important role in many more fields. Our Luminaid algal-bacterial system has a wide range of applications for deep space exploration, planetary surface surveys, long-duration spacewalks, deep sea exploration, shipwreck rescue, marine debris tagging, marine navigation and operations, water sports and recreation, as well as polar research and mineral extraction.
Space application products are difficult to transform, we will strive to provide insights and possibilities for the tracing of complex environments in space, and carry out regionalised design to cope with the challenges of special environments, such as Mars and the back of the moon. We will continue to learn and research to improve the performance of the algae-bacteria symbiotic system, and we believe that the luminescence project can be applied in more scenarios in the future, contributing to the development and progress of mankind. The project is based on the needs of space exploration and sea rescue, which is innovative but challenging. We are full of hope for the future, and will continue to work hard to promote the development of the project and contribute to a better future for mankind.
