BACSTRESS

Study of oxic and osmotic stress in Arctic bacteria: implications for the preservation of algal material

PI MIO : Jean François Rontani

MIO Participants : J-F Rontani, P. Bonin, G. Simon, L. Casalot, S. Guasco, F. Vaultier, M. Lescot, F. Armougom et C. Burot

Description

The BACSTRESS project (2017-2019) is funded by the CNRS EC2CO-Microbial structuring initiative.

The main objective of this multidisciplinary project (microbial ecology and organic biogeochemistry) is to determine the stress state of bacteria associated with ice algae in pack ice and open water in the Arctic and to estimate its impact on the preservation of algal material.

Project progress

During the first year of the project, we were able to :

• High mortality (>60%) of bacteria attached to ice algae at the start and end of pack ice melt. It is important to note that the poor physiological state of the bacteria at the end of the melt (when the flow of algal material to the bottom is at its maximum) should therefore contribute to good preservation of the ice algae.
• Demonstrate the existence of an additional 'chemical' stress (toxicity of ice algae free fatty acids to bacteria) which we had not initially envisaged, and which will need to be taken into account in the second year of the project.
• Demonstrate that the 10S-hydroperoxyhexadec-8(trans)-enoic acid widely distributed in the Arctic resulted from the action of a bacterial 10S-DOX on ice algae, and was therefore a tracer of the latter's bacterial degradation.

Publications

• Amiraux R., Belt, S.T., Vaultier F., Galindo V., Gosselin M., Bonin P. et Rontani J-F. (2017). Monitoring of photooxidative and osmotic bacterial stresses in Arctic using specific lipid tracers. Mar. Chem. 194: 89-99.
   
• Rontani J-F., Amiraux R., Lalande C., Babin M., Kim H-R. et Belt S.T. (2018). Use of palmitoleic acid and its oxidation products for monitoring the degradation of ice algae in Arctic waters and bottom sediments. Org. Geochem. 124: 88-102.