Bacterial Grazing by Planktonic Lake Algae

Bird, David F.; Kalff, Jacob

doi:10.1126/science.231.4737.493

Cited by 255 publications

(194 citation statements)

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“…Considering the possibility that chrysophytes could have been missed, and taking into account the high bacterivory rates usually reported for these algae, comparables to those of purely HFs (Bird and Kalff, 1986;Nygaard and Tobiesen, 1993), chrysophytes might be responsible for a significant proportion of the total grazing impact by MFs. For instance, Dinobryon faculiferum was found at one occasion in Blanes Bay, and in spite of their very low abundance, this single species accounted for 11% of the total grazing rate exerted by all mixotrophs (Unrein et al, 2010).…”

Section: Mixotroph Impactmentioning

confidence: 99%

“…Mixotrophy in algae, defined as the combination of phagotrophy and phototrophy in a single cell (sensu Sanders, 1991), is widespread among algal groups containing flagellated species (Bird and Kalff, 1986;Tranvik et al, 1989;Nygaard and Tobiesen, 1993;Stoecker, 1999). The mixotrophic mode of nutrition is considered to be particularly beneficial when inorganic nutrients are limiting (Nygaard and Tobiesen, 1993;Rothhaupt, 1996;Flö der et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

et al. 2013

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Grazing rate estimates indicate that approximately half of the bacterivory in oligotrophic oceans is due to mixotrophic flagellates (MFs). However, most estimations have considered algae as a single group. Here we aimed at opening the black-box of the phytoflagellates (PFs) o20 lm. Haptophytes, chlorophytes, cryptophytes and pigmented dinoflagellates were identified using fluorescent in situ hybridization or by standard 4 0 ,6-diamidino-2-phenylindole staining. Their fluctuations in abundance, cell size, biomass and bacterivory rates were measured through an annual cycle in an oligotrophic coastal system. On average, we were able to assign to these groups: 37% of the total pico-PFs and 65% of the nano-PFs composition. Chlorophytes were mostly picoplanktonic and they never ingested fluorescently labeled bacteria. About 50% of the PF o20 lm biomass was represented by mixotrophic algae. Pigmented dinoflagellates were the least abundant group with little impact on bacterioplankton. Cryptophytes were quantitatively important during the coldest periods and explained about 4% of total bacterivory. Haptophytes were the most important mixotrophic group: (i) they were mostly represented by cells 3-5 lm in size present year-round; (ii) cell-specific grazing rates were comparable to those of other bacterivorous non-photosynthetic organisms, regardless of the in situ nutrient availability conditions; (iii) these organisms could acquire a significant portion of their carbon by ingesting bacteria; and (iv) haptophytes explained on average 40% of the bacterivory exerted by MFs and were responsible for 9-27% of total bacterivory at this site. Our results, when considered alongside the widespread distribution of haptophytes in the ocean, indicate that they have a key role as bacterivores in marine ecosystems.

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Section: Mixotroph Impactmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

et al. 2013

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“…Des espèces algales sont, en effet, capables d'assimiler directement le carbone organique, soit dissous par osmotrophie (DROOP, 1974 ;NEILSON et LEWIN, 1974), soit particulaire par phagotrophie (BIRD et KALFF, 1986). La mise en évidence de l'activité hétérotrophe algale en culture axénique est bien documentée depuis deux décennies (DROOP, 1974 ;NEILSON et LEWIN, 1974 ;HELLEBUST et LEWIN, 1977).…”

Section: -Introductionunclassified

“…LEWIN, 1977 ; BIRD and KALFF, 1986). In axenic cultures, numerous microalgae grow in the dark with micromolar concentrations of diverse organic nutrients as their sole sources of carbon and energy (RIVKIN and PUTT, 1987).…”

mentioning

confidence: 99%

Hétérotrophie algale : effets de la gentamycine et de la cycloheximide sur les activités hétérotrophes et photosynthétiques des bacteries et des algues

Rachiq¹,

Amblard²,

Bourdier³

2005

rseau

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Afin de tenter de déterminer les parts respectives des activités bactérienne et algale, nous avons testé d'une part, l'action d'une substance antibactérienne (la gentamycine), et d'autre part, l'action d'un inhibiteur métabolique des cellules eucaryotes (la cycloheximide) sur des cultures d'algues et de bactéries et sur des échantillons provenant du milieu naturel et soumis à des filtrations différentielles. Les effets de ces inhibiteurs ont été testés au niveau des activités hétérotrophe et photosynthétique globales, mais également au niveau de l'incorporation des marqueurs radioactifs lors de la synthèse des macromolécules et des composés de faible poids moléculaire.Les résultats obtenus laissent apparaître que l'inhibition de l'activité bactérienne par la gentamyclne est significative mais non complète (pourcentage d'inhibition moyen = 67 %). De plus, l'efficacité de la gentamycine augmente avec la durée d'incubation. Par ailleurs, les effets secondaires de la gentamycine sur les activités hétérotrophe et photosynthétique d'une culture de Melosira italica subsp. subarctica sont acceptables seulement pour des incubations de courte durée (< 4 heures).En revanche, l'emploi de la cycloheximide s'est révélé sans aucun effet significatif sur les activités photosynthétique et hérérotrophe de la culture de Melosira, même après 24 h d'incubation.A partir des échantillons prélevés en milieu naturel, l'emploi de la gentamycine a permis de réduire l'interférence bactérienne dans les mesures d'activité hétérotrophe algale. Enfin, nous avons pu constater que la gentamycine modifie l'allocation des marqueurs radioactifs dans les macromolécules.The ability of many planktonic algae to use particulate and/or dissolved organic carbon directly by phagotrophy or osmotrophy in laboratory cultures is well documented (DROOP, 1974; NEILSON and LEWIN, 1974; HELLEBUST and LEWIN, 1977; BIRD and KALFF, 1986). In axenic cultures, numerous microalgae grow in the dark with micromolar concentrations of diverse organic nutrients as their sole sources of carbon and energy (RIVKIN and PUTT, 1987). However, to demonstrate algal heterotrophy in the field, it is necessary to differentiate between bacterial and algal activities. In the course of this study, we tested the effect of an antibacterial substance (gentamycin) and of a metabolic inhibitor of eukaryotic cells (cycloheximide) on algal and bacterial cultures, and also on lake water samples submitted to differential filtration. The effect of these inhibitors was tested both at the overall heterotrophic and photosynthetic activities level and the level of the incorporation of radiolabeled tracers in macromolecules and low molecular weight compounds.Gentamycin was tested on bacteria and on an axenic culture of the diatom Melosira italica subsp. subarctica, the dominant species of the spring phyto-planktonic bloom of many temperate lakes. Bacterial culture was obtained by filtration of a senescent culture of Melosira through a 0.45 µm pore-size membrane. During exponential growth, gentamycin (40 ...

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“…These techniques can now be used to provide a variety of information about the microbial community at the level of individual cells. Although the main use of epifluorescence microscopy is to classify cell types and determine standing stocks, methods have been developed to measure bacterivory (McManus and Fuhn~an, 1986;Bird and Kalff, 1986;Sieracki et al, 1987) and uptake rates of dissolved organic molecules by protists (Sherr, 1988). Advances with fluorescent analogues and antibodies are leading to additional methods for characterizing cells by epifiuorescence microscopy (Ward, 1990 (Horan and Wheeless, 1977) and was first used for analysis of aquatic particles by Olson et al (1983) and Yentsch et al (1983).…”

mentioning

confidence: 99%

Color Image-Analyzed Fluorescence Microscopy: A New Tool for Marine Microbial Ecology

Sieracki¹,

Viles²

1990

oceanog

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Bacterial Grazing by Planktonic Lake Algae

Cited by 255 publications

References 9 publications

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

Hétérotrophie algale : effets de la gentamycine et de la cycloheximide sur les activités hétérotrophes et photosynthétiques des bacteries et des algues

Color Image-Analyzed Fluorescence Microscopy: A New Tool for Marine Microbial Ecology

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