Phagotrophy in phototrophs

Raven, John A.

doi:10.4319/lo.1997.42.1.0198

Cited by 231 publications

(199 citation statements)

References 25 publications

(32 reference statements)

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“…Phagotrophy is usually the primary nutritional mode in mixotrophic dinoflagellates, as they are only able to reach maximum growth rates phagotrophically (Raven 1997). These species have a high nutrient demand, especially when grown under autotrophic conditions, which was reflected in our experiments by total nitrate consumption within 10 d. Consequently, for mixotrophs, photosynthetic carbon fixation has been interpreted as a survival strategy when food densities are low (Andersson et al 1989, Sanders et al 1990).…”

Section: Iodide Production By Mixotrophsmentioning

confidence: 83%

Transformation of iodate to iodide in marine phytoplankton driven by cell senescence

Bluhm¹,

Croot²,

Wuttig³

et al. 2010

Aquat. Biol.

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Section: Iodide Production By Mixotrophsmentioning

confidence: 83%

Transformation of iodate to iodide in marine phytoplankton driven by cell senescence

Bluhm¹,

Croot²,

Wuttig³

et al. 2010

Aquat. Biol.

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“…Considering that assimilation of nutrients in particulate form is energetically more costly than absorbing them in dissolved inorganic form (Raven, 1997) and if phagotrophy is a way to supplement nutrients, then an inverse relationship should be expected between a given limiting nutrient and the phagotrophic activity of the mixotrophic community. We reported previously that the CSGR of PF 3-5 mm and PF 5-20 mm were both negatively significantly correlated with the soluble reactive phosphorus concentration (Unrein et al, 2007).…”

Section: Factors Controlling Ingestion Rates In the Dominant Mixotrophsmentioning

confidence: 99%

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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“…These particular results also reveal that a significant fraction of the eukaryotes that we identified as grazing specifically on Prochlorococcus and Synechococcus were likely mixotrophs -i.e. cells that utilize both phototrophy and phagotrophic heterotrophy as a way of obtaining nutrients and energy (Raven, 1997;Jones, 2000). While a few studies have provided evidence of the importance of mixotrophy in marine aquatic environments (Arenovski et al, 1995;An-Yi et al, 2007;Unrein et al, 2007), this is the first study to identify marine mixotrophs through their grazing activity on specific prey.…”

Section: Discussionmentioning

confidence: 99%

Molecular biogeochemistry of modern and ancient marine microbes

Waldbauer¹

2010

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Biological activity has shaped the surface of the earth in numerous ways, but life's most pervasive and persistent global impact has been the secular oxidation of the surface environment. Through primary production -the biochemical reduction of carbon dioxide to synthesize biomass -large amounts of oxidants such as molecular oxygen, sulfate and ferric iron have accumulated in the ocean, atmosphere and crust, fundamentally altering the chemical environment of the earth's surface. This thesis addresses aspects of the role of marine microorganisms in driving this process. In the first section of the thesis, biomarkers (hydrocarbon molecular fossils) are used to investigate the early history of microbial diversity and biogeochemistry. Molecular fossils from the Transvaal Supergroup, South Africa, document the presence in the oceans of a diverse microbiota, including eukaryotes, as well as oxygenic photosynthesis and aerobic biochemistry, by ca. 2.7Ga. Experimental study of the oxygen requirements of steroid biosynthesis suggests that sterane biomarkers in late Archean rocks are consistent with the persistence of microaerobic surface ocean environments long before the initial oxygenation of the atmosphere. In the second part, using Prochlorococcus (a marine cyanobacterium that is the most abundant primary producer on earth today) as a model system, we explored how microbes use the limited nutrient resources available in the marine environment to make the protein catalysts that enable primary production. Quantification of the Prochlorococcus proteome over the diel cell-division cycle reveals that protein abundances are distinct from transcript-level dynamics, and that small temporal shifts in enzyme levels can redirect metabolic fluxes. This thesis illustrates how molecular techniques can contribute to a systems-level understanding of biogeochemical processes, which will aid in reconstructing the past of, and predicting future change in, earth surface environments. ACKNOWLEDGMENTSI have incurred many debts of gratitude and appreciation over the course of this work. None are greater than those to my advisors, Penny Chisholm and Roger Summons, who allowed and enabled me to pursue such a wide range of scientific interests and offered their help and advice every step of the way. I have been very lucky to have had the chance to learn so much during my Ph.D., and none of that would have been possible without their guidance and support.I have also had the great fortune to know and work with all the members of the Chisholm and Summons labs, who have made this an enjoyable and rewarding place to be. I am especially grateful to Laura Sherman for her skill and dedication in analyzing biomarkers in the late Archean cores -it was truly getting blood from a stone. I was lucky to collaborate with Sébastien Rodrigue, whose expertise and collegiality made the diel experiment even more fruitful than I could have hoped. IntroductionThe coevolution of life and earth surface environments is central to the history and functionin...

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Phagotrophy in phototrophs

Cited by 231 publications

References 25 publications

Transformation of iodate to iodide in marine phytoplankton driven by cell senescence

Transformation of iodate to iodide in marine phytoplankton driven by cell senescence

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

Molecular biogeochemistry of modern and ancient marine microbes

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