Measurement of ectoenzyme activities as an indication of inorganic nutrient imbalance in microbial communities

Sala, M. Montserrat; Karner, M.; Arı́n, Laura; Marrasé, Cèlia

doi:10.3354/ame023301

Cited by 118 publications

(96 citation statements)

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“…However, we do not know if nutrient stress would have increased activity. In the plankton, relatively high LAP activity is often associated with low ratios of N:P, suggesting that the enzyme may be partially inducible (Sala et al 2001). However, changes in LAP activity in natural assemblages may be due to changes in species composition or activity, rather than to induction or suppression of LAP in a species.…”

Section: Discussionmentioning

confidence: 97%

“…However, the contribution of heterotrophic flagellates and cyanobacteria to proteolytic activity in the water column is usually thought to be slight (Martinez & Azam 1993a, Karner et al 1994. The contribution of eukaryotic phytoplankton to protease activity has only recently been considered (Sala et al 2001). Mulholland et al (2002) found that the 'brown tide' alga Aureococcus anophagefferens has high rates of peptide hydrolysis, ABSTRACT: We used the artificial substrate L-leucine 7-amido-4-methyl-coumarin (Leu-AMC) to measure leucine aminopeptidase (LAP) of dinoflagellates.…”

Section: Introductionmentioning

confidence: 99%

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Cell-surface proteolytic activity of photosynthetic dinoflagellates

Stoecker

Gustafson²

2003

Aquat. Microb. Ecol.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Cell-surface proteolytic activity of photosynthetic dinoflagellates

Stoecker

Gustafson²

2003

Aquat. Microb. Ecol.

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“…These enzymatic activities represent a reasonable surrogate of the transformation dynamics by the heterotrophs (Karner and Rassoulzadegan 1995). As a consequence, they may be taken as good indicators of nutrient availability (Sala et al 2001), as well as of detectors of small-scale variations of organic matter use (Romaní and Marxsen 2002).…”

Section: Discussionmentioning

confidence: 99%

The influence of substratum type and nutrient supply on biofilm organic matter utilization in streams

Romaní

Giorgi

Acuña

et al. 2004

Limnology & Oceanography

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We investigated the effect of benthic substratum type (sand and rocks) and nutrient supply (N and P) on biofilm structure and heterotrophic metabolism in a field experiment in a forested Mediterranean stream (Fuirosos). Rock and sand colonization and biofilm formation was intensively studied for 44 d at two stream reaches: control and experimental (continuous addition of phosphate, ammonia, and nitrate). Structural (C, N, and polysaccharide content and bacterial and chlorophyll density) and metabolic biofilm parameters (␤-glucosidase, peptidase, and phosphatase enzyme activities) were analyzed throughout the colonization process. The epilithic biofilm (grown on rocks) had a higher peptidase activity at the impacted reach, together with a higher algal and bacterial biomass. The positive relationship between the peptidase activity per cell and the N content of the epilithic biofilm suggested that heterotrophic utilization of proteinaceous compounds from within the biofilm was occurring. In contrast, nutrient addition caused the epipsammic biofilm (grown on sand) to exhibit lower ␤-glucosidase and phosphatase activities, without a significant increase in bacterial and algal biomass. The differential response to nutrient addition was related to different structural characteristics within each biofilm. The epipsammic biofilm had a constant and high C : N ratio (22.7) throughout the colonization. The epilithic biofilm had a higher C : N ratio at the beginning of the colonization (43.2) and evolved toward a more complex structure (high polysaccharide content and low C : N ratio) during later stages. The epipsammic biofilm was a site for the accumulation and degradation of organic matter: polysaccharides and organic phosphorus compounds had higher degradation activities.Microorganisms play a key role in the degradation of organic matter and the associated release of energy in stream ecosystems (Meyer 1994). Microbial communities feed on allochthonous (dissolved and particulate plant and animal materials) and/or autochthonous organic matter (algal detritus and exudates) and are the main factor responsible for river C cycling (Allan 1995). In low-order streams, the benthic community is the most important site for organic matter cycling. In most cases, rock, cobbles, sand, and wood coexist in a stream reach, and all of these substrata host biofilms with differing structural characteristics (Lock 1993). In association with these structural differences, there are also significant differences in photosynthetic activity, biofilm thick- AcknowledgmentsWe thank two anonymous reviewers for their helpful suggestions about the manuscript. Comments by E. Garcia Berthou and C. Freeman are very much appreciated.

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“…AMA was determined using fluorogenic substrates (Hoppe 1983(Hoppe , 1993 and followed the modifications described in Sala et al (2001). Briefly, 0.1 ml leucine 7-amido-4-methylcoumarin was added at saturating concentrations (200 µM final concentration) to 0.9 ml samples.…”

Section: Methodsmentioning

confidence: 99%

Functional diversity of bacterioplankton assemblages in western Antarctic seawaters during late spring

Sala¹,

Arı́n²,

Balagué³

et al. 2005

Mar. Ecol. Prog. Ser.

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Functional diversity and aminopeptidase activity (AMA) in bacterial assemblages were determined in western Antarctic waters during late spring 2002. Functional diversity was assayed by the patterns of sole carbon source utilization in Biolog-ECO Microplates TM and AMA with the fluorogenic substrate leucine 7-amido-4-methylcoumarin. N-acetyl-D-glucosamine and D-cellobiose were the most used carbohydrates. This suggested that used dissolved organic carbon (DOC) was mostly of either zoo-or phytoplankton origin. Principal component analysis of the sole carbon source utilization profiles separated the samples according to salinity and temperature. This separation corresponded roughly with the 3 areas of study: Bransfield Strait (BR), Gerlache Strait (GE) and Bellingshausen Sea (BE). AMA was higher in the upper 40 m, probably associated with the higher organic matter load. Phytoplankton biomass was the factor that accounted for the highest variance in AMA, but did not have a clear influence on functional diversity of bacterioplankton. Our findings indicate that differences in functional diversity of bacterioplankton populations in western Antarctic waters are not directly related to phytoplanktonic abundance. This suggests that bacteria could utilize other carbon sources than DOC freshly released by phytoplankton. KEY WORDS: Bacterial activity · Functional diversity · Biolog · Aminopeptidase · Ectoenzyme · Antarctica Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 292: [13][14][15][16][17][18][19][20][21] 2005 autotrophic production than consumption (Misic et al. 2002).Composition of the organic matter utilized by the bacterial populations is likely to be an important regulator of the metabolic activity of bacterioplankton. Biolog Microplates TM have provided an insight into the functional diversity of bacterial populations in many ecosystems (reviewed by Preston-Mafham et al. 2002). In marine environments the Biolog approach has distinguished bacterial populations according to their metabolic capabilities depending on the origin of the organic matter available in the Californian coast (Hollibaugh 1994).The distribution of bacterioplankton biomass and production in western Antarctica is relatively well known (Karl et al. 1996, and this allows studies of functional diversity of bacterioplankton that have not been investigated until now. We determined bacterial AMA and bacterial utilization of carbon sources in Biolog-ECO plates. We then proposed the following hypothesis: Since DOC in Antarctic waters derives mainly from primary production, we expect (1) a relationship between chl a concentration and AMA; and (2) a key role of phytoplankton biomass in determining functional bacterial diversity according to the sole carbon source utilization patterns in the Biolog-ECO plates. MATERIALS AND METHODSSituation and sampling strategy. Samples were collected during the TEMPANO cruise on board of RV 'BIO-Hespérides', from 30 November to 16 December 2002. The area of st...

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Measurement of ectoenzyme activities as an indication of inorganic nutrient imbalance in microbial communities

Cited by 118 publications

References 58 publications

Cell-surface proteolytic activity of photosynthetic dinoflagellates

Cell-surface proteolytic activity of photosynthetic dinoflagellates

The influence of substratum type and nutrient supply on biofilm organic matter utilization in streams

Functional diversity of bacterioplankton assemblages in western Antarctic seawaters during late spring

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