title: Rapid Reactivation of Cyanobacterial Photosynthesis and Migration upon Rehydration of Desiccated Marine Microbial Mats.
abstract: Desiccated cyanobacterial mats are the dominant biological feature in the Earth's arid zones. While the response of desiccated cyanobacteria to rehydration is well-documented for terrestrial systems, information about the response in marine systems is lacking. We used high temporal resolution hyperspectral imaging, liquid chromatography, pulse-amplitude fluorometry, oxygen microsensors, and confocal laser microscopy to study this response in a desiccated microbial mat from Exmouth Gulf, Australia. During the initial 15 min after rehydration chlorophyll a concentrations increased 2-5 fold and cyanobacterial photosynthesis was re-established. Although the mechanism behind this rapid increase of chlorophyll a remains unknown, we hypothesize that it involves resynthesis from a precursor stored in desiccated cyanobacteria. The subsequent phase (15 min-48 h) involved migration of the reactivated cyanobacteria toward the mat surface, which led, together with a gradual increase in chlorophyll a, to a further increase in photosynthesis. We conclude that the response involving an increase in chlorophyll a and recovery of photosynthetic activity within minutes after rehydration is common for cyanobacteria from desiccated mats of both terrestrial and marine origin. However, the response of upward migration and its triggering factor appear to be mat-specific and likely linked to other factors.
authors.affiliation: Max Planck Institute for Marine Microbiology Bremen, Germany.
authors.forename: Arjun
authors.initials: A
authors.lastname: Chennu
authors.affiliation: School of Civil Engineering, The University of Queensland, St. Lucia QLD, Australia.
authors.forename: Alistair
authors.initials: A
authors.lastname: Grinham
authors.affiliation: Max Planck Institute for Marine MicrobiologyBremen, Germany; Department of Earth Sciences, Utrecht UniversityUtrecht, Netherlands.
authors.forename: Lubos
authors.initials: L
authors.lastname: Polerecky
authors.affiliation: Max Planck Institute for Marine Microbiology Bremen, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: de Beer
authors.affiliation: Max Planck Institute for Marine MicrobiologyBremen, Germany; Red Sea Research Center, King Abdullah University of Science and TechnologyJeddah, Saudi Arabia.
authors.forename: Mohammad A A
authors.initials: MA
authors.lastname: Al-Najjar
keywords: cyanobacteria; desiccation tolerance; extreme environment; photosynthesis; reactivation; rehydration