Genomic analysis of astrobiology-relevant adaptations to low light in far-red light utilising cyanobacteria

Abstract

Cyanobacteria have been utilised as astrobiology models and show a promise as tools that could support growth of life and production of materials on other planets. Recently, a small subset of cyanobacteria have been found to be capable of using far-red light for photosynthesis, as mediated by two known processes: far-red light photoacclimation (FARLIP) and low-light-photoacclimation (LOLIP). Due to its penetrative properties, cyanobacteria capable of harvesting far-red light can survive in low light conditions. Such extremophile cyanobacteria may be more suitable candidates within applications beyond Earth, or could be used as analogues to study the potential for life on planets receiving low luminosity. However, the genomics, evolution and application of these far-red utilising cyanobacteria are still unclear. Through an extensive genomics analysis with key marker genes, this study has identified 102 strains of cyanobacteria containing FARLIP and/or LOLIP genes. Comparative genomics of FARLIP clusters from five new genera not previously reported to be FARLIP-capable reveals conservation of a unique gene cluster containing 20 genes, as reported for other genera, with some minimal alterations. Likewise, comparative genomics of cyanobacteria containing LOLIP clusters revealed consistent appearance of apcD4 and apcB3 genes with variable appearance of LHCB and/or isiX genes. BLAST analysis also revealed several low light tolerant cyanobacteria exhibit genes necessary for providing bioavailable organics, hydrogen production and cold temperature survival that would be necessary in astrobiological life support systems or for use as analogue organisms. Through the expanded repertoire of low light tolerant cyanobacteria, confirmation of genetic conservations and exploration of astrobiological significance, we hope this study introduces the use of low light tolerant cyanobacteria in astrobiology.

Date of Award	6 Dec 2022
Original language	English
Awarding Institution	University of Bristol
Supervisor	Patricia Sanchez-Baracaldo (Supervisor) & Christopher J Williamson (Supervisor)