Dark CO2 fixation into phospholipid-derived fatty acids by the cold-water coral associated sponge Hymedesmia (Stylopus) coriacea (Tisler Reef, NE Skagerrak). Issue 1 (2nd January 2020)

• Record Type: Journal Article
• Authors: van Duyl, Fleur C.; Lengger, Sabine K.; Schouten, Stefan; Lundälv, Tomas; van Oevelen, Dick; Müller, Christina E.
• Is Part Of: Marine biology research. Volume 16:Issue 1(2020)
• Page Start: 1
• Page End: 17
• Publication Date: 2020-01-02
• Subjects: Marine biology -- Periodicals; Marine biology -- North Atlantic Ocean -- Periodicals; 578.7705
• DOI: 10.1080/17451000.2019.1704019
• Languages: English
• ISSNs: 1745-1000

Abstract

ABSTRACT: Many cold-water sponges harbour microorganisms of which the role in the sponge host remains enigmatic. Here, we show a transfer of fixed inorganic carbon by sponge-associated microbes to its host, the cold-water coral encrusting sponge Hymedesmia (Stylopus) coriacea . Sponge were collected at approx. 100 m depth and incubated for 1.5–2.5 days with 13 C labelled dissolved inorganic carbon (DIC) as tracer. Total DIC fixation rates ranged from 0.03–0.11 mmol C × mmol Csponge × d −1 . 13 C-tracer was recovered in bacterial-specific (i.e. short and branched) and sponge-specific (very long-chained) phospholipid-derived fatty acids (PLFA's), but was not incorporated into archaeal lipids. 13 C-incorporation in biomarkers such as C16:1w7c and C18:1w7c indicated that nitrifying and/or sulphur-oxidizing bacteria (chemoautotrophs) were likely active in the sponge. Trophic transfer of microbially-fixed carbon to the sponge host was confirmed by recovery of label in very long chain fatty acids (VLCFA's) including C26:2 and C26:3. Tracer accumulation into several VLCFA's continued after removal of 13 C-DIC, while tracer in most bacteria-specific PLFA's declined, indicating a transfer and elongation of bacterial-specific PLFA's to sponge-specific PLFA's. This implies that PLFA precursors released from chemo- as well as heterotrophic microbes in sponges contributed to the synthesis of VLCFA's, identifying sponge-associated bacteria as symbionts of the sponge.