Singlet oxygen‐induced alteration of bacteria associated with phytodetritus: Effect of irradiance

• Published in: Journal of Phycology
• Main Authors: Burot, Christopher, Bonin, Patricia, Simon, Gwénola, Casalot, Laurie, Rontani, Jean‐françois
• Other Authors: Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: Arctic; attached bacteria; irradiance effect; sea ice; senescent phytoplankton; sinking particulate matter; type II photosensitized oxidation; [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology; Phytoplankton; Sea ice; ice covered areas
• Online Access: https://hal.science/hal-04286500; https://hal.science/hal-04286500/document; https://hal.science/hal-04286500/file/JPY-22-138-ART.R2_Proof_hi.pdf; https://doi.org/10.1111/jpy.13376

International audience Contrasting irradiation of senescent cells of the diatom Thalassiosira sp. in association with the bacterium Pseudomonas stutzeri showed the effect of intensity of irradiance on the transfer of singlet oxygen ( 1 O 2 ) to bacteria attached to phytoplanktonic cells. Under low irradiances, 1 O 2 is produced slowly, favors the oxidation of algal unsaturated lipids (photodynamic effect), and limits 1 O 2 transfer to attached bacteria. However, high irradiances induce a rapid and intense production of 1 O 2 , which diffuses out of the chloroplasts and easily reaches the attached bacteria, where it efficiently oxidizes their unsaturated membrane components. Analysis of numerous sinking particle samples collected in different regions of the Canadian Arctic showed that the photooxidation state of attached bacteria increased from ice‐covered areas to open water, in agreement with in vitro results. Photooxidation of bacteria appeared to be particularly intense in sea ice, where the sympagic algae–bacteria association is maintained at relatively high irradiances for long periods of time.