Deep space exploration is not an easy endeavour. The challenge to keep astronauts alive and healthy long enough to reach other planets or solar systems has kept scientists busy for decades. Earth is where we have enough sunlight, water, soil, and raw materials on which we rely to build the tools that we need. Far from Earth, all resources are limited, and everything must be recycled as much as possible. Waste disposal and food production methods continue to be researched [1], but food production by algae and plants is limited by light and soil availability. Moreover, astronauts should have readily available treatments and materials in case of injury and sickness. The need for reliable methods of material and food production on board are crucial for the success of a mission.
These challenges made us think that synthetic biodegradable material produced from waste could be versatile enough to solve many of these problems. Based on previously published literature, bacterial cellulose (BC) produced by K.xylinus can be functionalized with chitin by using genes from C.albicans [4]. Thus, we decided to expand on the idea by using bioinformatic analysis to identify and clone homologous genes from S.cerevisiae that should produce a similar end product with broader applications. K.xylinus is a gram-negative bacterium [2] that can synthesize BC [3]. We propose to use components from degraded organic waste so bacteria can use it to synthesize this co-polymer. The process is light independent, and its BC could have a wide range of novel applications in space[5, 6]. For example, it could be used as an additional source of food as BC can be a form of dietary fiber[7, 8]. Additionally, it could be used as a polymer with varying biodegradability with pharmaceutical and biotechnological applications [9] like wound dressing, tissue engineering and sustained drug delivery[10]. Finally, it could function as a biodegradable membrane used [10] post-surgery that protects and delivers treatment locally, thus avoiding the need of multiple medical procedures that require repeated wound cleansing and treatment (e.g. cancer lump removal)[11].
According to literature evidence, human enzymes such as lysozymes and chitinases are capable of breaking down chitin hydrogels [12] (a polymer found in yeast, crustaceans, arthropods, etc.). The introduction of chitin monomers acetylglucosamine within the cellulose structure, would allow our body to break it down and remove it once it has served its medical purpose[2]. The biodegradability could be controlled by altering the nutrients of the media, as the rate of the addition of chitin monomers [13], which is essential for biodegradability, would theoretically depend on the nitrogen source [glutamine concentration][12].
Space Exploration offers unique research opportunities and has inspired scientists to develop some of the technologies we use every day on Earth (e.g. solar cells, LEDs, fire detection, memory foams, etc.). Our aim is to create more trust in GMO products, and we also believe our modified BC can be a source of medical raw materials and a complement in nutrition for countries with scarce arable land or even in emergency situations like war or drought[10]. High scale production of BC depends on the availability of the growth medium. Ethylene has been known [14] to enhance the yield in BC production and it is found abundantly in sources of nitrogen and sugar like ripe and overripe fruits. Perhaps, then, this modified bacterium can be of even more use in places rich in ethylene rich bio-waste yet economically challenged. At the same time, developed countries can use organic waste [15] to grow BC locally, lowering their carbon footprint by producing more raw materials locally.
