Free amino acids in lakes: Concentrations and assimilation rates in relation to phytoplankton and bacterial production1

Jørgensen, Niels O. G.

doi:10.4319/lo.1987.32.1.0097

Cited by 112 publications

(83 citation statements)

References 34 publications

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“…The low occurrence of arginine among free amino acids in the four lakes (arginine on average made up 3% of all free amino acids) agrees with amino-acid profiles of other lakes (Jørgensen, 1987;Simon and Rosenstock, 1992). In general, arginine is not a major amino acid in proteins of aquatic organisms (constitutes 3-8% of protein amino acids; compilation from several sources), but arginine may still be an important amino acid to bacteria owing to its high C/N ratio of 3.…”

Section: Discussionsupporting

confidence: 51%

Links between bacterial production, amino-acid utilization and community composition in productive lakes

et al. 2007

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Influence of distribution and abundance of bacterial taxa on ecosystem function are poorly understood for natural microbial communities. We related 16S rRNA-based terminal restriction fragment length polymorphism to bacterial production and arginine uptake kinetics to test if functional features of bacterioplankton in four lakes could be predicted from community composition. Maximum arginine uptake rate (arginine V max ) ranged from 10% to 100% of bacterial production. Owing to high growth efficiencies on arginine (63-77%), the bacterial community could potentially saturate its carbon demand using this single organic substrate, for example, during sudden surges of free amino acids. However, due to low in situ concentrations of arginine in these lakes (o0.9 lg l À1 ), actual uptake rates at ambient concentrations rarely exceeded 10% of V max . Bacterial production and arginine V max could be predicted from a subset of bacterial ribotypes, tentatively affiliated with several bacterial divisions (Cyanobacteria, Actinobacteria, Bacteroidetes and Proteobacteria). Multivariate statistical analysis indicates that there were both highly important and less important ribotypes for the prediction of bacterial production and arginine V max . These populations were either negatively or positively related to the respective functional feature, indicating contrasting ecological roles. Our study provides a statistically robust demonstration that, apart from environmental conditions, patterns in bacterial community composition can also be used to predict lake ecosystem function.

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Section: Discussionsupporting

confidence: 51%

Links between bacterial production, amino-acid utilization and community composition in productive lakes

et al. 2007

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“…DFAAs and protein together covered between 30% of the bacterial C demand in winter and Ͼ80% during the spring bloom with an annual mean of 60%, demonstrating their great significance as a bacterial C source. Also previously in Lake Constance, but in other environments as well, it has been shown that protein and DCAAs are relatively more important as bacterial substrates than DFAAs (Coffin 1989;Rosenstock and Simon 1993;Jørgensen et al 1994;Kroer et al 1994;Keil and Kirchman 1999). Only Keil andKirchman (1993, 1999), however, used radiolabeled protein to examine the relative significance of protein versus DFAAs as bacterial substrates.…”

Section: Discussionmentioning

confidence: 99%

“…Much is known about the turnover of dissolved free amino acids (DFAAs) and their significance for the growth of heterotrophic bacteria (e.g., Jørgensen 1987;Simon and Rosenstock 1992). Several studies found that DFAAs and ammonium are the primary N sources for bacteria (Keil and Kirchman 1991;Jørgensen et al 1993;Middelboe et al 1995a), whereas others showed that dissolved combined amino acids (DCAAs) are of similar or even higher significance for the growth of bacterioplankton (Coffin 1989;Rosenstock and Simon 1993;Kroer et al 1994). The DCAA pool is chemically complex and is composed of various types of combined amino acids, including oligo-and polypeptides, protein, and amino acids bound to humic substances (Keil and Kirchman 1993;Hubberten et al 1994).…”

Section: Acknowledgmentsmentioning

confidence: 99%

Sources and sinks of dissolved free amino acids and protein in a large and deep mesotrophic lake

Rosenstock

Simon

2001

Limnology & Oceanography

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We studied the microbial cycling of dissolved free amino acids (DFAAs) and protein in mesotrophic Lake Constance, Germany, by examining their release by phytoplankton and various heterotrophic organisms and incorporation by heterotrophic bacterioplankton. Release processes of both substrate classes, measured by an isotope dilution approach, comprised, as an annual mean, 15% of primary production and as much as 64% during the clearwater phase. DFAAs accounted for ϳ70% of total release during the spring bloom, in the early phase predominantly as photosynthetic extracellular products of rapidly growing algae and toward the end as a result of copepod grazing. Thereafter, during the clear-water phase, when daphnids were most abundant, release was dominated by protein. At this time, and again in late summer, lysis of grazing-damaged and senescent algae, including as well the hydrolytic activity of attached bacteria was one of the most important sources of protein. Rotifers, protozoans, and release processes in the fraction Ͻ1 m were minor sources of DFAA ϩ protein. Concentrations of dissolved combined amino acids (DCAAs) and protein ranged between 750-1,900 and 1-280 nM, respectively, and peaked during phytoplankton blooms in spring and summer. As an annual mean, concentrations of labile protein constituted 8% of DCAAs, and the ratio of DFAAs to DCAAs was 0.16. About 50% of the DCAAs occurred in the molecular weight fraction between DFAA and 3 kDa and 30% in that Ͼ30 kDa. Concentrations of DCAAs Ͼ3 kDa were closely correlated to chlorophyll a, suggesting their phytoplankton origin and thus a ready availability. Protein was the preferred bacterial substrate. As an annual mean, its incorporation supported 45% of bacterial biomass production, compared with 13% by DFAAs. During winter and spring, when DFAA concentrations were highest, DFAA incorporation constituted up to 40% of bacterial production. Annually, the sum of DFAA ϩ protein supported 58% and 80% of the bacterial C and N demand, respectively, indicating that they were the most important bacterial C and N sources.

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“…Many of the Biolog substrates are known to occur in lake water, especially among the carbohydrates and amino acids used (Riemann et al 1986, Jørgensen 1987, Chróst et al 1989, Münster 1993, Jørgensen & Jensen 1994, Simon 1998, Bunte & Simon 1999. A large number of other substrates whose presence has not been documented (probably because it has not been sought) are common biochemicals with many potential sources in lakes.…”

Section: Discussionmentioning

confidence: 99%

Seasonal patterns of substrate utilization by bacterioplankton: case studies in four temperate lakes of different latitudes

Grover¹,

Chrzanowski²

2000

Aquat. Microb. Ecol.

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Utilization of 95 carbon sources by bacteria in 2 Canadian Shield lakes and 2 Texan reservoirs was determined using Biolog-GN microtiter plates. Triplicate plates were inoculated and incubated for 5 d, during which color development was monitored twice daily by optical density (OD 595 ). Optical densities in plate wells containing carbon substrates were corrected for blank absorbance at each measurement time. Then, data on optical densities of all substrate wells were selected from a single measurement time, to construct a community-level physiological profile. This measurement time was chosen so that plates would be compared at similar levels of color development. This data selection also generally maximized correlations of substrate utilization patterns determined from replicate plates. Multivariate analyses (ordinations) of the community-level physiological profiles identified several amino acids, carboxylic acids, and carbohydrates associated with seasonal patterns of substrate utilization. Multivariate analyses further revealed patterns in substrate utilization common to all 4 lakes: strong relative responses to amino and carboxylic acids in cool seasons and strong relative responses to carbohydrates in warm seasons. These patterns may be driven by seasonal events among phytoplankton that influence carbohydrate supply, and appear to be dampened in an oligotrophic lake, which does not support high algal abundance.KEY WORDS: Bacterioplankton · Biolog-GN · Substrate utilization pattern · Community-level physiological profileResale or republication not permitted without written consent of the publisher

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Free amino acids in lakes: Concentrations and assimilation rates in relation to phytoplankton and bacterial production1

Cited by 112 publications

References 34 publications

Links between bacterial production, amino-acid utilization and community composition in productive lakes

Links between bacterial production, amino-acid utilization and community composition in productive lakes

Sources and sinks of dissolved free amino acids and protein in a large and deep mesotrophic lake

Seasonal patterns of substrate utilization by bacterioplankton: case studies in four temperate lakes of different latitudes

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