Microbial biomanufacturing for space-exploration-what to take and when to make

Microbiology of human spaceflight: microbial responses to mechanical forces that impact health and habitat sustainability

SUMMARYUnderstanding the dynamic adaptive plasticity of microorganisms has been advanced by studying their responses to extreme environments. Spaceflight research platforms provide a unique opportunity to study microbial characteristics in new extreme adaptational modes, including sustained exposure to reduced forces of gravity and associated low fluid shear force conditions. Under these conditions, unexpected microbial responses occur, including alterations in virulence, antibiotic and stress resistance, biofilm formation, metabolism, motility, and gene expression, which are not observed using conventional experimental approaches. Here, we review biological and physical mechanisms that regulate microbial responses to spaceflight and spaceflight analog environments from both the microbe and host-microbe perspective that are relevant to human health and habitat sustainability. We highlight instrumentation and technology used in spaceflight microbiology experiments, their limitations, and advances necessary to enable next-generation research. As spaceflight experiments are relatively rare, we discuss ground-based analogs that mimic aspects of microbial responses to reduced gravity in spaceflight, including those that reduce mechanical forces of fluid flow over cell surfaces which also simulate conditions encountered by microorganisms during their terrestrial lifecycles. As spaceflight mission durations increase with traditional astronauts and commercial space programs send civilian crews with underlying health conditions, microorganisms will continue to play increasingly critical roles in health and habitat sustainability, thus defining a new dimension of occupational health. The ability of microorganisms to adapt, survive, and evolve in the spaceflight environment is important for future human space endeavors and provides opportunities for innovative biological and technological advances to benefit life on Earth.

Desiccated Cyanobacteria Serve As Efficient Plasmid DNA Carriers in Space Flight

Effective transport of biological systems as cargo during space travel is a critical requirement to use synthetic biology and biomanufacturing in outer space. Bioproduction using microbes will drive the extent to which many human needs can be met in environments with limited resources. Vast repositories of biological parts and strains are available to meet this need, but their on-site availability requires effective transport. Here, we explore an approach that allows DNA plasmids, ubiquitous synthetic biology parts, to be safely transported to the International Space Station and back to the Kennedy Space Center without low-temperature or cryogenic stowage. Our approach relied on the cyanobacterium Nostoc punctiforme PC73102, which is naturally tolerant to prolonged desiccation. Desiccated N. punctiforme was able to carry the non-native pSCR119 plasmid as intracellular cargo safely to space and back. Upon return to the laboratory, the extracted plasmid showed no DNA damage or additional mutations and could be used as intended to transform the model synbio host Escherichia coli to bestow kanamycin resistance. This proof-of-concept study provides the foundation for a ruggedized transport host for DNA to environments where there is a need to reduce equipment and infrastructure for biological parts stowage and storage.

Polyextremophile engineering: a review of organisms that push the limits of life

Nature exhibits an enormous diversity of organisms that thrive in extreme environments. From snow algae that reproduce at sub-zero temperatures to radiotrophic fungi that thrive in nuclear radiation at Chernobyl, extreme organisms raise many questions about the limits of life. Is there any environment where life could not "find a way"? Although many individual extremophilic organisms have been identified and studied, there remain outstanding questions about the limits of life and the extent to which extreme properties can be enhanced, combined or transferred to new organisms. In this review, we compile the current knowledge on the bioengineering of extremophile microbes. We summarize what is known about the basic mechanisms of extreme adaptations, compile synthetic biology's efforts to engineer extremophile organisms beyond what is found in nature, and highlight which adaptations can be combined. The basic science of extremophiles can be applied to engineered organisms tailored to specific biomanufacturing needs, such as growth in high temperatures or in the presence of unusual solvents.

Building Synthetic Cells─From the Technology Infrastructure to Cellular Entities

The de novo construction of a living organism is a compelling vision. Despite the astonishing technologies developed to modify living cells, building a functioning cell "from scratch" has yet to be accomplished. The pursuit of this goal alone has─and will─yield scientific insights affecting fields as diverse as cell biology, biotechnology, medicine, and astrobiology. Multiple approaches have aimed to create biochemical systems manifesting common characteristics of life, such as compartmentalization, metabolism, and replication and the derived features, evolution, responsiveness to stimuli, and directed movement. Significant achievements in synthesizing each of these criteria have been made, individually and in limited combinations. Here, we review these efforts, distinguish different approaches, and highlight bottlenecks in the current research. We look ahead at what work remains to be accomplished and propose a "roadmap" with key milestones to achieve the vision of building cells from molecular parts.

Green horizons: how plant synthetic biology can enable space exploration and drive on Earth sustainability

As humanity looks towards expanding activity from low Earth orbit to the Moon and beyond, resource use efficiency and self-sustainability will be critical to ensuring success in the long term. Furthermore, solutions developed for the stringent requirements of space will be equally valuable in meeting sustainability goals here on Earth. Advances in synthetic biology allow us to harness the complex metabolism of life to produce the materials we need in situ. Translating those lessons learned from microbial systems to more carbon-efficient photosynthetic organisms is an area of growing interest. Plants can be engineered to sustainably meet a range of needs, from fuels to materials and medicines.