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Interspecific bacterial outcompetition under ocean acidification scenarios
Poster Title: Interspecific bacterial outcompetition under ocean acidification scenarios
Submitted on 13 Jun 2016
Author(s): Guilhem BANC-PRANDI, Kim B. Ritchie
Affiliations: Ecole Normale Supérieure of Lyon - More Marine laboratory
Poster Views: 877
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Poster Information
Abstract: Coral microbes have been hypothesized to promote coral health and protect the host against pathogens. Recent outbreaks of coral diseases have been correlated with higher sea-surface temperatures and ocean acidification but few studies focus on the effect of these stresses on coral commensals' physiology. This study examined the impact of ocean acidification on two coral commensals' ability to prevent infection by the coral pathogen Vibrio shiloi. Beneficial bacteria Pseudoalteromonas ZJ6102 and Pseudoalteromonas euthinica were isolated from the surface of healthy Acropora cervicornis and, when challenged with V. shiloi, resulted in an antibacterial response. Competition experiments were performed by mixing equal amounts of each commensal with the pathogen in dialysis tubing maintained at high (pH=8.1) or low (pH=7.7) pH under stable temperatures (25.5°C). Colony forming units (CFUs) of each strain were calculated 24, 48 and 72 hours after inoculation. Results showed that lower pH tends to boost commensals' ability to limit the pathogen’s growth. To test commensals' ability to protect the host from bacterial infection, inoculation
experiments were performed with A. cervicornis. Coral health was estimated visually and indirectly using a PAM underwater fluorometer to assess algae deterioration by the pathogen. Results showed higher photosynthetic activity for corals treated with both the pathogen and commensal compared to controls treated with the pathogen only. Studies such as these will help our understanding of coral microbial dynamics in response to environmental changes.
Summary: Coral beneficial bacteria are known to protect their host against bacterial pathogen responsible for coral diseases. This poster gives the results of a study examining the impact of ocean acidification on the ability of coral commensals to compete with Vibrio shiloi, the causative agent of bleaching.References: Rosenberg et Ben-Haim (2002) – Microbial diseases of corals and global warming.
Thornhill et al. (2011) – A connection between Colony
Biomass and Death in Caribbean Reef-Building Corals.
Ben-Haim et al. (1999) – Inhibition of photosynthesis and bleaching of zooxanthellae by the coral pathogen Vibrio shiloi.
Krediet et al. (2013) – Coral-asspciated micro-organisms and their roles in promoting coral health and thwarting diseases. Shnit-Orland et Kushmaro (2009) – Coral mucus-associated bacteria : a possible first line of defense.
Baker et al. (2016) – Acid-adaptive mechanisms of Streptoccocus mutant.
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