Exposure of phototrophs to 548 days in low Earth orbit: microbial selection pressures in outer space and on early earth

Abstract

An epilithic microbial community was launched into low Earth orbit, and exposed to conditions in outer space for 548 days on the European Space Agency EXPOSE-E facility outside the International Space Station. The natural phototroph biofilm was augmented with akinetes of Anabaena cylindrica and vegetative cells of Nostoc commune and Chroococcidiopsis. In space-exposed dark controls, two algae (Chlorella and Rosenvingiella spp.), a cyanobacterium (Gloeocapsa sp.) and two bacteria associated with the natural community survived. Of the augmented organisms, cells of A. cylindrica and Chroococcidiopsis survived, but no cells of N. commune. Only cells of Chroococcidiopsis were cultured from samples exposed to the unattenuated extraterrestrial ultraviolet (UV) spectrum (4110 nm or 200 nm). Raman spectroscopy and bright-field microscopy showed that under these conditions the surface cells were bleached and their carotenoids were destroyed, although cell morphology was preserved. These experiments demonstrate that outer space can act as a selection pressure on the composition of microbial communities. The results obtained from samples exposed to 4200 nm UV (simulating the putative worst-case UV exposure on the early Earth) demonstrate the potential for epilithic colonization of land masses during that time, but that UV radiation on anoxic planets can act as a strong selection pressure on surface-dwelling organisms. Finally, these experiments have yielded new phototrophic organisms of potential use in biomass and oxygen production in space exploration.

Fast, Continuous, and High-Throughput (Bio)Chemical Activity Assay forN-Acyl-l-Homoserine Lactone Quorum-Quenching Enzymes

“…GQ849010) and active-site residues (39), three homologous open reading frames were identified by a NCBI BLAST search. These belong to the two soil-and plant-associated bacteria, Paraburkholderia glathei (QqlB) (KDR41687.1; 49% amino acid identity; annotated as epoxide hydrolase) and Mesorhizobium ciceri (QqlM) (WP_013530214.1; 68% amino acid identity; annotated as ␣/␤-hydrolase), and to the salt water-associated bacterium Geminicoccus roseus (QqlG) (WP_027134646.1; 66% amino acid identity; annotated as ␣/␤-hydrolase) (41)(42)(43)(44)(45). Recombinantly expressed QqlB, QqlG, and QqlM showed QQ activity in the modified CV026 assay with crude cell lysates (see Fig.…”

Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond

“…Examples of organisms exposed in space ( (Cockell et al 2011;Jönsson et al 2008). In addition, the bacteriophages T1 and T7, the tobacco mosaic virus, and plasmid DNA (pBR322, pUC19) also have been investigated .…”

“…Microbial communities collected in extreme terrestrial environments, such as permafrost communities, desert endolithic cyanobacteria, endoevaporites (de la Torre et al 2010), antarctic cryptoendolithic communities ) and epilithic phototrophic biofilms (Cockell et al 2011;) as well as a wide selection of lichens collected from extreme environments were exposed to space conditions in low Earth orbit and upon retrieval examined on the ground (Brandt et al 2015(Brandt et al , 2016.…”

Impact shocked rocks as protective habitats on an anoxic early Earth

“…It has been used on numerous occasions to detect cyanobacterial biomarkers from extreme environments (e.g. Jorge Villar & Edwards 2006;Wang et al 2010;Vitek et al 2010;Cockell et al 2011).…”