The role of iron in the bacterial degradation of organic matter derived from Phaeocystis antarctica
Becquevort, S.; Lancelot, C.; Schoemann, V. (2007). The role of iron in the bacterial degradation of organic matter derived from Phaeocystis antarctica. Biogeochemistry 83(1-3): 119-135. https://dx.doi.org/10.1007/s10533-007-9079-1
Van Leeuwe, M.A.; Stefels, J.; Belviso, S.; Lancelot, C.; Verity, P.G.; Gieskes, W.W.C. (Ed.) (2007). Phaeocystis, major link in the biogeochemical cycling of climate-relevant elements. Biogeochemistry, 83(1-3). Springer: Dordrecht. ISBN 978-1-4020-6213-1. 330 pp. https://dx.doi.org/10.1007/978-1-4020-6214-8, more
Bacterioplankton Chemical elements > Metals > Transition elements > Heavy metals > Iron Chemical reactions > Degradation Organic matter Phaeocystis antarctica Karsten, 1905 [WoRMS] Marine/Coastal
In high-nutrient low-chlorophyll areas, bacterial degradation of organic matter may be iron-limited. The response of heterotrophic bacteria to Fe addition may be directly controlled by Fe availability and/or indirectly controlled through the effect of enhanced phytoplankton productivity and the subsequent supply of organic matter suitable for bacteria. In the present study, the role of Fe on bacterial carbon degradation was investigated through regrowth experiments by monitoring bacterial response to organic substrates derived from Phaeocystis antarctica cultures set up in <1 nM Fe (LFe) and in Fe-amended (HFe) Antarctic seawater. Results showed an impact of Fe addition on the morphotype dominance (colonies vs. single cells) of P. antarctica and on the quality of Phaeocystis-derived organic matter. Fe addition leaded to a decrease of C/N ratio of Phaeocystis material. The bacterial community composition was modified as observed from denaturing gradient gel electrophoresis (DGGE) profiles in LFe as compared to HFe bioassays. The percentage of active bacteria as well as their specific metabolic activities (ectoenzymatic hydrolysis, growth rates and bacterial growth efficiency) were enhanced in HFe bioassays. As a consequence, the lability of Phaeocystis-derived organic matter was altered, i.e., after seven days more than 90% was degraded in HFe and only 9% (dissolved) and 55% (total) organic carbon were degraded in LFe bioassays. By inducing increased bacterial degradation and preventing the accumulation of dissolved organic carbon, the positive effect of Fe supply on the carbon biological pump may partly be counteracted.
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