Utilisation of dissolved organic carbon from different sources by pelagic bacteria in an acidic mining lake

Kamjunke, Norbert; Bohn, Christiane; Grey, Jonathan

doi:10.1127/0003-9136/2006/0165-0355

Cited by 17 publications

(23 citation statements)

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“…The high lability of algal DOC has also been traditionally equated to high nutritional quality (Thorp and Delong, 2002), and consequently to a greater potential to support growth. In contrast to this assumption, we found that the consumed algal pool was mainly diverted toward the respiratory pathway, and not to biomass production as previously suggested (Cole et al, 1988;Kamjunke et al, 2006). Although we can only speculate on the underlying mechanisms at this point, it is possible that the preferential respiration of algal compounds may in fact reflect a strategy related to growth under energy limitation in the pelagic environment of lakes (Smith and Prairie, 2004).…”

Section: Discussioncontrasting

confidence: 55%

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria

2015

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Here we explore strategies of resource utilization and allocation of algal versus terrestrially derived carbon (C) by lake bacterioplankton. We quantified the consumption of terrestrial and algal dissolved organic carbon, and the subsequent allocation of these pools to bacterial growth and respiration, based on the δ 13 C isotopic signatures of bacterial biomass and respiratory carbon dioxide (CO 2 ). Our results confirm that bacterial communities preferentially remove algal C from the terrestrially dominated organic C pool of lakes, but contrary to current assumptions, selectively allocate this autochthonous substrate to respiration, whereas terrestrial C was preferentially allocated to biosynthesis. The results provide further evidence of a mechanism whereby inputs of labile, algal-derived organic C may stimulate the incorporation of a more recalcitrant, terrestrial C pool. This mechanism resulted in a counterintuitive pattern of high and relatively constant levels of allochthony (~76%) in bacterial biomass across lakes that otherwise differ greatly in productivity and external inputs.

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Section: Discussioncontrasting

confidence: 55%

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria

2015

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“…Experimenters may intuitively assume that only simple autochthonous compounds such as glucose, if at all, may provide evidence for osmotrophy in photosynthetic organisms. Terrestrial DOC, however, was found to be converted with lower efficiency than autochthonous DOC into biomass (Kamjunke et al, 2006;Karlsson, 2007). One possible explanation why algae were more successful with more difficult substrates is that the complex and compartmented cell structure of eukaryotic organisms might help provide the specific conditions required for the consecutive degradation steps or facilitate the removal of toxic metabolites.…”

Section: Discussionmentioning

confidence: 92%

Utilisation of terrestrial carbon by osmotrophic algae

et al. 2009

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Terrestrial-derived dissolved organic carbon (DOC) contributes significantly to the energetic basis of many aquatic food webs. Although heterotrophic bacteria are generally considered to be the sole consumers of DOC, algae and cyanobacteria of various taxonomic groups are also capable of exploiting this resource. We tested the hypothesis that algae can utilise DOC in the presence of bacteria if organic resources are supplied in intervals by photolysis of recalcitrant DOC. In short-term uptake experiments, we changed irradiation in the range of minutes. As model substrates, polymers of radiolabelled coumaric acid (PCA) were used, which during photolysis are known to release aromatic compounds comparable to terrestrial-derived and refractory DOC. Three cultured freshwater algae readily assimilated PCA photoproducts equivalent to a biomass-specific uptake of 5 -60 % of the bacterial competitors present. Algal substrate acquisition did not depend on whether PCA was photolysed continuously or in intervals. However, the data show that photoproducts of terrestrial DOC can be a significant resource for osmotrophic algae. In long-term growth experiments, interval light was applied one hour per day. We allowed cultured Chlamydomonas to compete for ambient DOC of low concentration. We found higher abundances of Chlamydomonas when cultures were irradiated intermittently rather than continuously. These data suggest that photolysis of DOC supports algal heterotrophy, and potentially facilitates growth, when light fluctuations are large, as during the diurnal light cycle. We concluded that osmotrophic algae can efficiently convert terrestrial carbon into the biomass of larger organisms of aquatic food webs.

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“…This DOM has been partially degraded in terrestrial soil systems and is considered a poor substrate for bacteria because of chemical recalcitrance (Tranvik, 1998). Moreover, little of the allochthonous DOM is believed to contribute to bacterial growth because of the low community BGE (o0.1) that is observed in systems dominated by allochthonous carbon sources (del Giorgio and Cole, 1998;Kamjunke et al, 2006). Nevertheless, allochthonous DOM is an important substrate for bacteria in many unproductive lakes, evident from the fact that ambient phytoplankton production is too low to support the observed bacterial carbon demand (Jones, 1992;Karlsson et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Efficient aquatic bacterial metabolism of dissolved low-molecular-weight compounds from terrestrial sources

et al. 2009

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Carboxylic acids (CAs), amino acids (AAs) and carbohydrates (CHs) in dissolved free forms can be readily assimilated by aquatic bacteria and metabolized at high growth efficiencies. Previous studies have shown that these low-molecular-weight (LMW) substrates are released by phytoplankton but also that unidentified LMW compounds of terrestrial origin is a subsidy for bacterial metabolism in unproductive freshwater systems. We tested the hypothesis that different terrestrially derived CA, AA and CH compounds can offer substantial support for aquatic bacterial metabolism in fresh waters that are dominated by allochthonous dissolved organic matter (DOM). Drainage water from three catchments of different characters in the Krycklan experimental area in Northern Sweden were studied at the rising and falling limb of the spring flood, using a 2-week bioassay approach. A variety of CA, AA and CH compounds were significantly assimilated by bacteria, meeting 15-100% of the bacterial carbon demand and explaining most of the observed variation in bacterial growth efficiency (BGE; R 2 ¼ 0.66). Of the 29 chemical species that was detected, acetate was the most important, representing 45% of the total bacterial consumption of all LMW compounds. We suggest that LMW organic compounds in boreal spring flood drainage could potentially support all in situ bacterial production in receiving lake waters during periods of weeks to months after the spring flood.

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Utilisation of dissolved organic carbon from different sources by pelagic bacteria in an acidic mining lake

Cited by 17 publications

References 0 publications

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria

Utilisation of terrestrial carbon by osmotrophic algae

Efficient aquatic bacterial metabolism of dissolved low-molecular-weight compounds from terrestrial sources

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