Enhanced bacterial growth in response to photochemical transformation of dissolved organic matter

Lindell, Måns; Granéli, Wilhelm; Tranvik, Lars J.

doi:10.4319/lo.1995.40.1.0195

Cited by 318 publications

(266 citation statements)

References 11 publications

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“…Earlier, we showed that. sunlight, and especially UV-B radiation, causes DOM tcl become more available to bacteria (Lindell et al 1995), We suggest that this is due to a photolytic cleavage of high-molecular DOM into smaller moieties more available to bacteria. Thus, in addition to causing direct abiotic DIC production, light also may increase DIC production by increasing bacterial production and respiration.…”

Section: Discussionmentioning

confidence: 98%

Photo‐oxidative production of dissolved inorganic carbon in lakes of different humic content

Granéli

Lindell

Tranvik

1996

Limnology & Oceanography

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316

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Photo-oxidation of dissolved organic carbon (DOC) to inorganic carbon (DIC) in five oligotrophic south Swedish lakes of different humic content (3.9-19 mg DOC liter-r, O-140 mg Pt liter-*, Secchi depth 7.6-1.5 m) was investigated. Sterile-filtered (0.2 pm) water was incubated in UV-transparent quartz tubes and in tubes covered with aluminum foil. Samples were incubated at different depths (0,0.20,0.65, and 2.00 m) from sunrise to sunset (0400 to 2200 hours) in July. Inorganic C was measured before and after incubation. Total plankton respiration in unfiltered lake-water (production of DIC) was also measured. At the surface, photo-oxidative DIC production was 86410 mg C m-3 d-l, while plankton community respiration was 10 l-274 mg C m-3 d-l. Photo-oxidation integrated over depth was 44-l 7 1 mg C m-2 d-r, while respiration was 201-547 mg C m-2 d-r to a depth of 2 m and 398-860 mg C m-2 d-* over the depth of the epilimnion. Depth-integrated photo-oxidation was independent of water color or DOC concentration in the lakes. Photooxidation was detected deeper than the penetration of UV-B radiation, indicating that longer wavelengths (UV-A and possibly PAR) are also active. DIC production was linearly related to loss of fluorescence (excitation 355 nm, emission 455 nm) in light-incubated samples. Our study shows that photo-oxidation of DOC may be an important process causing the regularly observed supersaturation of DIC in lakes.

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Section: Discussionmentioning

confidence: 98%

Photo‐oxidative production of dissolved inorganic carbon in lakes of different humic content

Granéli

Lindell

Tranvik

1996

Limnology & Oceanography

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316

245

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“…The effective light penetration depth for production of these compounds in the open ocean was estimated to be ϳ5 m (Mopper et al 1991), close to our sampling depth of 4 m at Sta. M. Bacterial uptake of fatty acid and nitrogen-rich compounds produced from photooxidation of humic material has been observed in both freshwater and marine systems (Kieber et al 1989;Lindell et al 1995;Wetzel et al 1995;Bushaw et al 1996). Thus, given the energy constraints of the bacterial populations in the eastern North Pacific, we speculate that older, more refractory DOC may be made available for bacterial utilization and assimilation via cometabolism and/or photooxidative processes.…”

Section: Utilization Of Older Bulkmentioning

confidence: 99%

Radiocarbon in marine bacteria: Evidence for the ages of assimilated carbon

Cherrier

Bauer

Druffel

et al. 1999

Limnology & Oceanography

107

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It is generally accepted that marine bacteria utilize labile, recently produced components of bulk dissolved organic matter. This interpretation is based largely on indirect measurements using model compounds and plankton‐derived organic matter. Here, we present an assessment of the relative proportions of modern and older dissolved organic carbon (DOC) utilized by marine bacteria. Bacterial nucleic acids were collected from both estuarine (Santa Rosa Sound, FL) and open‐ocean (eastern North Pacific) sites, and the natural radiocarbon signatures of the nucleic acid carbon in both systems were determined. Bacterial nucleic acids from Santa Rosa Sound were significantly enriched in radiocarbon with respect to the bulk DOC and were similar to the radiocarbon signature of atmospheric CO2 at the time of sampling, indicating that these bacteria exclusively assimilate a modern component of the estuarine bulk DOC. In contrast, bacterial nucleic acids from the oceanic site were enriched in 14C relative to the bulk DOC but depleted in 14C with respect to modern surface dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POCsusp). This suggests that open‐ocean bacteria assimilate both modern and older components of DOC. The distinct radiocarbon signatures of the nucleic acids at these two sites (i.e., +120 ± 17‰ estuarine vs. −34 ± 24‰ oceanic) demonstrate that natural 14C abundance measurements of bacterial biomarkers are a powerful tool for investigations of carbon cycling through microbial communities in different aquatic systems.

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“…A totally different type of explanation considers cyanobacteria (mostly Prochlorococcus) as the organisms responsible for the uptake of labelled substrates in the light (Zubkov et al 2003, Church et al 2004, 2006, Michelou et al 2007). Finally, a relatively stronger negative impact of light on viruses and protistan grazers compared to bacteria (Sommaruga et al 1997, Pakulski et al 2007) and photochemical transformations of extant DOM (Lindell et al 1995, Benner & Biddanda 1998, Obernosterer et al 1999) have also been suggested. Based on the possible mechanisms governing bacterial responses to irradiance listed above, and the likely possibility that 2 or more of these mechanisms can be simultaneously operative, it becomes clear that we are still far from knowing what the relevant controls are.…”

Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 99%

Towards a better understanding of microbial carbon flux in the sea*

Gasol¹,

Pinhassi²,

Alonso‐Sáez³

et al. 2008

Aquat. Microb. Ecol.

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We now have a relatively good idea of how bulk microbial processes shape the cycling of organic matter and nutrients in the sea. The advent of the molecular biology era in microbial ecology has resulted in advanced knowledge about the diversity of marine microorganisms, suggesting that we might have reached a high level of understanding of carbon fluxes in the oceans. However, it is becoming increasingly clear that there are large gaps in the understanding of the role of bacteria in regulating carbon fluxes. These gaps may result from methodological as well as conceptual limitations. For example, should bacterial production be measured in the light? Can bacterial production conversion factors be predicted, and how are they affected by loss of tracers through respiration? Is it true that respiration is relatively constant compared to production? How can accurate measures of bacterial growth efficiency be obtained? In this paper, we discuss whether such questions could (or should) be addressed. Ongoing genome analyses are rapidly widening our understanding of possible metabolic pathways and cellular adaptations used by marine bacteria in their quest for resources and struggle for survival (e.g. utilization of light, acquisition of nutrients, predator avoidance, etc.). Further, analyses of the identity of bacteria using molecular markers (e.g. subgroups of Bacteria and Archaea) combined with activity tracers might bring knowledge to a higher level. Since bacterial growth (and thereby consumption of DOC and inorganic nutrients) is likely regulated differently in different bacteria, it will be critical to learn about the life strategies of the key bacterial species to achieve a comprehensive understanding of bacterial regulation of C fluxes. Finally, some processes known to occur in the microbial food web are hardly ever characterized and are not represented in current food web models. We discuss these issues and offer specific comments and advice for future research agendas.

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Enhanced bacterial growth in response to photochemical transformation of dissolved organic matter

Cited by 318 publications

References 11 publications

Photo‐oxidative production of dissolved inorganic carbon in lakes of different humic content

Photo‐oxidative production of dissolved inorganic carbon in lakes of different humic content

Radiocarbon in marine bacteria: Evidence for the ages of assimilated carbon

Towards a better understanding of microbial carbon flux in the sea*

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