Regulation of Bacterial Growth Rates by Dissolved Organic Carbon and Temperature in the Equatorial Pacific Ocean

Kirchman, David L.; Rich, James H.

doi:10.1007/s002489900003

Cited by 172 publications

(126 citation statements)

References 35 publications

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“…This fact alone proves the positive effect of Fe fertilization on bacterioplankton. Similar increases in bacterial abundance have been reported previously in Fe-amended bottle experiments (Pakulski et al 1996;Hutchins et al 1998;Kirchman et al 2000), whereas others (Church et al 2000) found that Fe alone had little effect on bacterial growth. The results of previous mesoscale Fe fertilization experiments are contradictory.…”

Section: Discussionsupporting

confidence: 88%

“…However, the current view is that, at least in some HNLC areas, bacterioplankton are not directly Fe limited, but rather carbon-limited as a consequence of the low primary productivity of Fe-limited phytoplankton (Hutchins et al 1998;Church et al 2000;Kirchman et al 2000). Primary productivity, however, did not show such a discontinuous pattern inside the patch.…”

Section: Discussionmentioning

confidence: 75%

“…Additionally, Fecontaining proteins, such as cytochrome c, a component of the electron transfer chain in the bacterial respiratory system, play a central role in bacterial metabolism. Fe-depleted bacteria exhibit slow growth and a low growth efficiency (Tortell et al 1996;Kirchman et al 2003), which ultimately determines whether bacteria will act in the trophic chain as a ''link'' (recycling and transferring significant amounts of organic material to higher trophic levels) or as a ''sink'' (mainly respiring DOM) (Williams 2000).…”

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confidence: 99%

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Response of bacterioplankton to iron fertilization in the Southern Ocean

Arrieta

Weinbauer

Lute

et al. 2004

Limnology & Oceanography

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We studied the bacterial response to Fe fertilization over 3 weeks during the second iron-enrichment experiment (EisenEx) in the Southern Ocean. Bacterial abundance in the Fe-fertilized patch increased over the first 12 d following Fe release and remained about twice as high as outside the Fe-fertilized patch until the end of the experiment. Bacterial production peaked a few days after each of the three Fe releases inside the Fe-fertilized patch, reaching rates two to three times higher than outside the patch. Besides the peaks in leucine and thymidine incorporation following Fe release, bacterial production was not significantly higher inside the patch than outside, suggesting direct limitation of bacterial growth by Fe. Bacterial aminopeptidase activity roughly followed the increase in bacterial abundance, whereas cell-specific ␣-and ␤-glucosidase were higher inside the Fe-fertilized patch. The diversity of ␤-glucosidases was determined by capillary electrophoresis zymography. The different ␤-glucosidases showed much higher activity levels inside the patch than in the surrounding waters, and three additional ␤-glucosidases constituting ϳ55% of the total ␤-glucosidase activity were present inside the Fe-fertilized patch from day 9 onward. No major changes in response to Fe fertilization were detected in the phylogenetic composition of the bacterioplankton community, as determined by 16S rDNA fingerprinting, indicating a remarkable adaptation of the bacterioplankton community to episodic iron inputs. This stability on the phylogenetic level is contrasted by the dramatic qualitative and quantitative changes in ectoenzymatic activity.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 75%

mentioning

confidence: 99%

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Response of bacterioplankton to iron fertilization in the Southern Ocean

Arrieta

Weinbauer

Lute

et al. 2004

Limnology & Oceanography

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“…In the ocean's interior, where the concentration of inorganic nutrients is relatively high, bacterial growth is presumably limited by the scarcity of degradable organic compounds. However, in the photic zone bacteria may be limited by the availability of dissolved organic carbon or of inorganic nutrients, for example, N, P or Fe (Tortell et al, 1996;Kirchman and Rich, 1997;Rivkin and Anderson, 1997;Thingstad et al, 1998;Van Wambeke et al, 2002), a situation that allows accumulation of otherwise degradable organic compounds (Williams, 1995;Thingstad et al, 1997). There are also regional differences as bacteria in some oceanic regions seem to be limited by the availability of organic carbon, whereas in others inorganic nutrient limitation seems to prevail (Rivkin and Anderson, 1997;Van Wambeke et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Mg2+ as an indicator of nutritional status in marine bacteria

et al. 2011

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Cells maintain an osmotic pressure essential for growth and division, using organic compatible solutes and inorganic ions. Mg 2 þ , which is the most abundant divalent cation in living cells, has not been considered an osmotically important solute. Here we show that under carbon limitation or dormancy native marine bacterial communities have a high cellular concentration of Mg 2 þ (370-940 mM) and a low cellular concentration of Na þ (50-170 mM). With input of organic carbon, the average cellular concentration of Mg 2 þ decreased 6-12-fold, whereas that of Na þ increased ca 3-4-fold. The concentration of chlorine, which was in the range of 330-1200 mM, and was the only inorganic counterion of quantitative significance, balanced and followed changes in the concentration of Mg 2 þ þ Na þ . In an osmotically stable environment, like seawater, any major shift in bacterial osmolyte composition should be related to shifts in growth conditions, and replacing organic compatible solutes with inorganic solutes is presumably a favorable strategy when growing in carbon-limited condition. A high concentration of Mg 2 þ in cells may also serve to protect and stabilize macromolecules during periods of non-growth and dormancy. Our results suggest that Mg 2 þ has a major role as osmolyte in marine bacteria, and that the [Mg 2 þ ]/[Na þ ] ratio is related to its physiological condition and nutritional status. Bacterial degradation is a main sink for dissolved organic carbon in the ocean, and understanding the mechanisms limiting bacterial activity is therefore essential for understanding the oceanic C-cycle. The [Mg 2 þ ]/[Na þ ]-ratio in cells may provide a physiological proxy for the transitions between C-limited and mineral nutrient-limited bacterial growth in the ocean's surface layer.

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“…Numerous studies show bacterial production is carbon limited, even though DOC concentrations are high throughout the water column (Kirchman, 1990;Carlson and Ducklow, 1995;Cherrier et al, 1996;Kirchman and Rich, 1997;Kirchman, 2000). The large reservoir of DOC that accumulates in seawater is therefore believed to be largely unavailable to meet bacterial carbon demand (Kirchman et al, 1993;Carlson and Ducklow, 1995).…”

Section: Introductionmentioning

confidence: 99%

Seqestration of dissolved organic carbon in the deep sea

Repeta¹

2006

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We used compound specific natural abundance radiocarbon analyses of neutral sugars to study carbon cycling of high molecular weight (HMW) dissolved organic carbon (DOC) at two sites in the North Pacific Ocean. Sugars released from HMWDOC by acid hydrolysis were purified by high-pressure liquid chromatography and analyzed for radiocarbon content via accelerator mass spectrometry. We find the seven most

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Regulation of Bacterial Growth Rates by Dissolved Organic Carbon and Temperature in the Equatorial Pacific Ocean

Cited by 172 publications

References 35 publications

Response of bacterioplankton to iron fertilization in the Southern Ocean

Response of bacterioplankton to iron fertilization in the Southern Ocean

Mg2+ as an indicator of nutritional status in marine bacteria

Seqestration of dissolved organic carbon in the deep sea

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