Relationships between bacteria and heterotrophic nanoflagellates in lake water examined by different techniques controlling grazing pressure

Adamczewski, Tomasz; Chróst, Ryszard J.; Kalinowska, Krystyna; Skowrońska, Agnieszka

doi:10.3354/ame01420

Cited by 8 publications

(3 citation statements)

References 46 publications

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“…[37,39,40]. Among protists, HNF plays the crucial role in shaping abundance, biomass and morphology of the active fraction of bacteria [37,41,42]. …”

Section: Discussionmentioning

confidence: 99%

Factors controlling bacteria and protists in selected Mazurian eutrophic lakes (North-Eastern Poland) during spring

et al. 2013

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BackgroundThe bottom-up (food resources) and top-down (grazing pressure) controls, with other environmental parameters (water temperature, pH) are the main factors regulating the abundance and structure of microbial communities in aquatic ecosystems. It is still not definitively decided which of the two control mechanisms is more important. The significance of bottom-up versus top-down controls may alter with lake productivity and season. In oligo- and/or mesotrophic environments, the bottom-up control is mostly important in regulating bacterial abundances, while in eutrophic systems, the top-down control may be more significant.ResultsThe abundance of bacteria, heterotrophic (HNF) and autotrophic (ANF) nanoflagellates and ciliates, as well as bacterial production (BP) and metabolically active cells of bacteria (CTC, NuCC, EST) were studied in eutrophic lakes (Mazurian Lake District, Poland) during spring. The studied lakes were characterized by high nanoflagellate (mean 17.36 ± 8.57 × 103 cells ml-1) and ciliate abundances (mean 59.9 ± 22.4 ind. ml-1) that were higher in the euphotic zone than in the bottom waters, with relatively low bacterial densities (4.76 ± 2.08 × 106 cells ml-1) that were lower in the euphotic zone compared to the profundal zone. Oligotrichida (Rimostrombidium spp.), Prostomatida (Urotricha spp.) and Scuticociliatida (Histiobalantium bodamicum) dominated in the euphotic zone, whereas oligotrichs Tintinnidium sp. and prostomatids Urotricha spp. were most numerous in the bottom waters. Among the staining methods used to examine bacterial cellular metabolic activity, the lowest percentage of active cells was recorded with the CTC (1.5–15.4%) and EST (2.7–14.2%) assay in contrast to the NuCC (28.8–97.3%) method.ConclusionsIn the euphotic zone, the bottom-up factors (TP and DOC concentrations) played a more important role than top-down control (grazing by protists) in regulating bacterial numbers and activity. None of the single analyzed factors controlled bacterial abundance in the bottom waters. The results of this study suggest that both control mechanisms, bottom-up and top-down, simultaneously regulated bacterial community and their activity in the profundal zone of the studied lakes during spring. In both lake water layers, food availability (algae, nanoflagellates) was probably the major factor determining ciliate abundance and their composition. In the bottom waters, both groups of protists appeared to be also influenced by oxygen, temperature, and total phosphorus.

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“…[37,39,40]. Among protists, HNF plays the crucial role in shaping abundance, biomass and morphology of the active fraction of bacteria [37,41,42]. …”

Section: Discussionmentioning

confidence: 99%

Factors controlling bacteria and protists in selected Mazurian eutrophic lakes (North-Eastern Poland) during spring

et al. 2013

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“…Various methods for the separation of metabolically active bacteria from metabolically inactive ones have been developed (Table 1). Results obtained using these methods showed that the share of dead (or inactive) bacterial cells in both marine and freshwater environments ranged from a few to several dozen percent (Berman et al, 2001;Adamczewski et al, 2010). In contrast to the relatively high level of information concerning many aspects of metabolic activity of living bacteria, and their role in the microbial loop (Grossart et al, 2001;Herndl et al, 2008), there is much less research focused on the influence of dead bacteria debris on the active bacteria community.…”

Section: Introductionmentioning

confidence: 99%

Persistence of bacterial proteolytic enzymes in lake ecosystems

Kiersztyn

Siuda

Chróst

2012

FEMS Microbiol Ecol

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This study analyzes proteolytic enzyme persistence and the role of dead (or metabolically inactive) aquatic bacteria in organic matter cycling. Samples from four lakes of different trophic status were used. Irrespective of the trophic status of the examined lakes, bacterial aminopeptidases remained active even 72 h after the death of the bacteria that produced them. The total pool of proteolytic enzymes in natural lake water samples was also stable. We found that the rates of amino acid enzymatic release from proteinaceous matter added to preserved lake water sample were constant for at least 96 h (r(2) = 0.99, n = 17, P ≤ 0.0001, V(max) = 84.6 nM h(-1) ). We also observed that proteases built into bacterial cell debris fragments remained active for a long time, even after the total destruction of cells. Moreover, during 24 h of incubation time, about 20% of these enzymatically active fragments adsorbed onto natural seston particles, becoming a part of the 'attached enzymes system' that is regarded as the 'hot-spot' of protein degradation in aquatic ecosystems.

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“…Treatment groups included all possible combinations of: 1) presence or absence of added nutrients (NH 4 Cl and K 3 PO 4 to final concentrations of 5 and 0.9 mmoll -1 respectively; DeMello et al, 2007) 2) presence or absence of a mixture of protist inhibitors cyclohexamide and colchicine (added to 0.5 mg/ml; Adamczewski et al, 2010) and 3) presence or absence of oxygen. Vials were placed onto a shaker table, covered with foil, and agitated at 60 revolutions per minute (rpm) at ambient temperature (15 °C) for the duration of the experiment.…”

Section: Microcosm Experimentsmentioning

confidence: 99%

Impact of protists on a hydrocarbon-degrading bacterial community from deep-sea Gulf of Mexico sediments: A microcosm study

Beaudoin

Carmichael

Nelson

et al. 2016

Deep Sea Research Part II: Topical Studies in Oceanography

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In spite of significant advancements towards understanding the dynamics of petroleum hydrocarbon degrading microbial consortia, the impacts (direct or indirect via grazing activities) of bacterivorous protists remain largely unknown. Microcosm experiments were used to examine whether protistan grazing affects the petroleum hydrocarbon degradation capacity of a deep-sea sediment microbial community from an active Gulf of Mexico cold seep. Differences in n-alkane content between native sediment microcosms and those treated with inhibitors of eukaryotes were assessed by comprehensive two-dimensional gas chromatography following 30-90 day incubations and analysis of shifts in microbial

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Relationships between bacteria and heterotrophic nanoflagellates in lake water examined by different techniques controlling grazing pressure

Cited by 8 publications

References 46 publications

Factors controlling bacteria and protists in selected Mazurian eutrophic lakes (North-Eastern Poland) during spring

Factors controlling bacteria and protists in selected Mazurian eutrophic lakes (North-Eastern Poland) during spring

Persistence of bacterial proteolytic enzymes in lake ecosystems

Impact of protists on a hydrocarbon-degrading bacterial community from deep-sea Gulf of Mexico sediments: A microcosm study

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