Adaptations to extreme conditions: the strategy of the Antarctic cyanobacterium ULC007

(1)

FNRS Contact Group of Astrobiology Meeting, Liège, December 18th 2018

Antarctic mat-forming cyanobacteria: Diversity and

Function

Yannick Lara

1,2*

_{, Benoit Durieu}

2

_{, Igor S. Pessi, Emmanuelle J. Javaux}

1

_{, Annick}

Wilmotte

2,4

1_{Early Life Traces & Evolution – Astrobiology, Geology Department, University of Liège, Liège,}

Belgium.

2_{InBioS-Centre for Protein Engineering, University of Liège, Belgium.} 4_{BCCM/ULC, University of Liège, Belgium.}

(*)

_{[email protected]}

ABSTRACT

Extreme seasonality led by rapid changes in day length and harsh environmental conditions make Antarctica a unique habitat. Freshwater ecosystems range from cryoecosystems and ice shelf meltwater ponds to perennially ice-covered lakes where conspicuous benthic microbial mat communities constitute most of the biomass. In these mats, cyanobacteria form the matrix in which other microorganisms can live, and where they are the key primary producers and main drivers of the carbon and food webs [1]. Narrow filamentous cyanobacteria belonging to the order Pseudanabaenales are especially abundant in polar microbial mats [2].

Here we investigate the genome of a widely distributed Antarctic cyanobacterium,

Phormidium priestleyi ULC007. To provide a better understanding of the survival strategies

of this taxon, we used high-throughput sequencing technologies to investigate its geographic distribution and genome evolution. More precisely, we investigated the abundance of genes in targeted functional categories based on the RAST subsystems technology, so as to provide a better overview of the genetic mechanisms involved in cold adaptation and circadian oscillation [3].

In Polar regions, low temperatures lead to the success of particular organisms featuring adaptations to molecular and cellular disturbances such as rigidity of membranes, reduction of enzyme-catalyzed reactions, and solute transport. Our main results underline the importance of functional categories of genes involved in the production of key molecules for the survival of polar P. priestleyi (e.g. exopolysaccharides, chaperone proteins, fatty acids and phospholipids).

[1] Vincent WF Cyanobacterial dominance in the polar regions. In: Whitton A, Potts M, eds.

The Ecology of Cyanobacteria. Kluwer Academic Publishers; 2000:321-340.

[2] Pessi I, Lara Y, Durieu B, De Carvalho Maalouf P, Verleyen E, Wilmotte A Community structure and distribution of benthic cyanobacteria in Antarctic lacustrine microbial mats. FEMS Microbiol Ecol. 2018 Mar 14.

[3] Aziz RK, Bartels D, Best A, et al. The RAST Server: Rapid Annotations using Subsystems Technology. BMC Genomics.2008;9(1):75.