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Significance of diatom-derived polymers in carbon flow dynamics within estuarine biofilms determined through isotopic enrichment

Bellinger, BJ and Underwood, GJC and Ziegler, SE and Gretz, MR (2009) 'Significance of diatom-derived polymers in carbon flow dynamics within estuarine biofilms determined through isotopic enrichment.' Aquatic Microbial Ecology, 55 (2). pp. 169-187. ISSN 0948-3055

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Pennate diatoms are the main group of primary producers in transient microbial biofilms at the sediment surface in muddy intertidal systems. These microalgae produce a substantial quantity of extracellular polymeric substances (EPS) that contribute significantly to the cohesive properties observed in biofilms. Changes in carbohydrate content and composition and the persistence of diatom EPS were demonstrated with pulse-chase NaH13CO3 labeling and simultaneous detection of isotopic enrichment in polysaccharides and phospholipid fatty acids (PLFAs) in Colne Estuary, UK, biofilms over a 48 h period. Significant isotopic enrichment of glucan indicated that a large proportion of fixed carbon was initially sequestered into intracellular chrysolaminaran, and labeled carbon was also quickly used for production of the diatom PLFA 20:5ω3 and EPS. Saccharides in the EPS fractions were enriched rapidly, followed by labeling of distinct bacterial PLFAs through heterotrophic utilization of EPS within 4 h. Maximal isotopic enrichment of diatom and Gram-negative bacterial PLFAs and hot water- and hot bicarbonate-soluble EPS fractions occurred after 4 h, and 13C- labeling increased in Gram-positive bacterial PLFAs throughout the study period. After 48 h, PLFAs remained highly labeled relative to diatom-derived polysaccharides, indicating persistence of assimilated C in organisms within the biofilms through time and rapid turnover of polysaccharide pools within the biofilms. Coupled pulse-chase isotopic labeling and simultaneous tracking of 13C in polysaccharides and PLFAs directly demonstrated the flow of carbon between biofilm autotrophs and heterotrophic bacteria and the significance of diatom-derived carbohydrates in this exchange. © Inter-Research 2009 .

Item Type: Article
Uncontrolled Keywords: EPS; PLFA; Isotopic enrichment; Carbon pathways; Biofilms
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health
Faculty of Science and Health > Life Sciences, School of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 23 Sep 2011 15:23
Last Modified: 18 Aug 2022 11:13

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