Potential toxicity of chrysophytes affiliated with Poterioochromonas and related 'Spumella-like' flagellates

Boenigk, Jens

doi:10.1093/plankt/fbh139

Cited by 37 publications

(36 citation statements)

References 35 publications

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“…Poteriospumella lacustris strains JBM10, JBNZ41 and JBC07 as well as Poterioochromonas malhamensis strain DS were grown axenically in the culture collection of the working group. For details on origin, isolation procedure and axenicity of the axenic strains, see Boenigk & Stadler (2004); Boenigk et al (2004). Dinobryon strain LO226KS, Synura strain LO234KE and Ochromonas/Spumella strain LO244K-D were grown in DY-V medium (Andersen, 2007).…”

Section: Methodsmentioning

confidence: 99%

Comprehensive transcriptome analysis provides new insights into nutritional strategies and phylogenetic relationships of chrysophytes

Beißer

Graupner

Böck

et al. 2017

PeerJ

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BackgroundChrysophytes are protist model species in ecology and ecophysiology and important grazers of bacteria-sized microorganisms and primary producers. However, they have not yet been investigated in detail at the molecular level, and no genomic and only little transcriptomic information is available. Chrysophytes exhibit different trophic modes: while phototrophic chrysophytes perform only photosynthesis, mixotrophs can gain carbon from bacterial food as well as from photosynthesis, and heterotrophs solely feed on bacteria-sized microorganisms. Recent phylogenies and megasystematics demonstrate an immense complexity of eukaryotic diversity with numerous transitions between phototrophic and heterotrophic organisms. The question we aim to answer is how the diverse nutritional strategies, accompanied or brought about by a reduction of the plasmid and size reduction in heterotrophic strains, affect physiology and molecular processes.ResultsWe sequenced the mRNA of 18 chrysophyte strains on the Illumina HiSeq platform and analysed the transcriptomes to determine relations between the trophic mode (mixotrophic vs. heterotrophic) and gene expression. We observed an enrichment of genes for photosynthesis, porphyrin and chlorophyll metabolism for phototrophic and mixotrophic strains that can perform photosynthesis. Genes involved in nutrient absorption, environmental information processing and various transporters (e.g., monosaccharide, peptide, lipid transporters) were present or highly expressed only in heterotrophic strains that have to sense, digest and absorb bacterial food. We furthermore present a transcriptome-based alignment-free phylogeny construction approach using transcripts assembled from short reads to determine the evolutionary relationships between the strains and the possible influence of nutritional strategies on the reconstructed phylogeny. We discuss the resulting phylogenies in comparison to those from established approaches based on ribosomal RNA and orthologous genes. Finally, we make functionally annotated reference transcriptomes of each strain available to the community, significantly enhancing publicly available data on Chrysophyceae.ConclusionsOur study is the first comprehensive transcriptomic characterisation of a diverse set of Chrysophyceaen strains. In addition, we showcase the possibility of inferring phylogenies from assembled transcriptomes using an alignment-free approach. The raw and functionally annotated data we provide will prove beneficial for further examination of the diversity within this taxon. Our molecular characterisation of different trophic modes presents a first such example.

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Section: Methodsmentioning

confidence: 99%

Comprehensive transcriptome analysis provides new insights into nutritional strategies and phylogenetic relationships of chrysophytes

Beißer

Graupner

Böck

et al. 2017

PeerJ

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“…They can be toxic to mesozooplankton (Boxhorn et al 1998;Leeper and Porter 1995;Hiltunen et al 2012), but it is assumed that at normal field abundances of these organisms toxic effects will be hardly detectable (Boenigk and Stadler 2004). Grazing by chrysomonads on Microcystis can also reduce the toxicity of Microcystis to Daphnia .…”

Section: Golden Algae (Ochromonas)mentioning

confidence: 99%

“…While Ochromonas and Poterioochromonas might be widespread and common mixotrophs (Boenigk and Stadler 2004;Van Donk et al 2009), the incidence and intensity of cyanobacterial blooms have increased over the last decades (O'Neil et al 2012), strongly suggesting that the chrysomonads fail to control cyanobacteria in the field. Mass culture and depositing chrysomonads in the field are advised against, because of the expected lack of effect and the addition of nutrients to the receiving water.…”

Section: Golden Algae (Ochromonas)mentioning

confidence: 99%

Evaluation of several end-of-pipe measures proposed to control cyanobacteria

2015

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While reduction in nutrient loading is a prerequisite for mitigation of harmful cyanobacterial blooms in nutrient-enriched waters, in certain surface waters eutrophication control is not always feasible due to practical and economic constraints or might be effective only in the long run. Yet, the urgent need to control cyanobacteria in water for drinking, irrigation, aquaculture, industry and recreation has spurred the development of a plethora of alternative methods that claim to be fast acting. Here, we provide a critical overview of several of these end-of-pipe measures: effective microorganisms (EM Ò ), golden algae (Ochromonas), plant/tree extracts, ultrasound and artificial mixing of non-stratifying waters. Most of the end-of the pipe measures claim to provide sustainable control of harmful cyanobacterial blooms, while at best only targeting symptom relief rather than eutrophication relief. Support for ''effective'' microorganisms, golden algae, plant extracts, ultrasound and artificial mixing of non-stratifying waters to diminish eutrophication problems such that the resulting water quality meets societal and legislation demands is limited, and several proposed underlying mechanisms are doubtful. None of these curative measures seem the desired wide applicable solution to cyanobacterial nuisance; they should not be considered Columbus's egg. A critical evaluation of end-of pipe measures is crucial for water authorities in their choice for mitigating measures.

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“…M. aeruginosa and its microcystins could be removed much slower when its grazers (i.e., Poterioochromonas) were very few, especially in the case of microcystin degradation. Considering that the abundance of mixotrophic golden alga is usually less than several thousand individuals per ml under natural conditions (Boenigk & Stadler, 2004) and the cyanobacteria are in much higher abundance during blooms, it is easy to understand why cyanobacterial blooms occur even in the presence of a grazer (e.g., Poterioochromonas) under natural conditions. Intracellular MC-LR was released to the surrounding water under the grazing stress, and more was released under conditions of higher abundance of M. aeruginosa and less abundance of ZX1.…”

Section: Ecological Implicationsmentioning

confidence: 99%

The effect of Poterioochromonas abundance on production of intra- and extracellular microcystin-LR concentration

Zhang

Men

et al. 2010

Hydrobiologia

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Due to its capability for producing various microcystins, Microcystis aeruginosa is recognized as one of the most toxic, bloom-forming cyanobacteria. In this study, the fates of intra-and extracellular microcystin-LR (MC-LR) were investigated when the mixotrophic golden alga Poterioochromonas sp. (ZX1) was grazing on M. aeruginosa cells. In the control groups, the total MC-LR concentration increased with the growth of M. aeruginosa with an MC-LR content per cell of 0.5-1.5 9 10 -8 lg cell -1 . In the treatment with ZX1, the total MC-LR decreased linearly throughout the incubation period. In particular, intracellular MC-LR disappeared with a loss of M. aeruginosa cells in the first few days. Part of the intracellular MC-LR was released to the medium under the grazing stress, resulting in an increase of extracellular MC-LR. The degradation rate of MC-LR was positively related to the initial abundance of ZX1 and negatively related to that of M. aeruginosa. The inhibition ratio of MC-LR production dropped sharply from 98 to 67% when the initial abundance of M. aeruginosa increased from 10 6 to 10 7 cells ml -1 . However, it increased from 84 to 99% when the initial ZX1 abundance increased from 10 4 to 10 5 cells ml -1 . The effective removal of both M. aeruginosa cells and MC-LR was observed under lower M. aeruginosa abundance (\10 6 cells ml -1 ) and higher ZX1 abundance ([1% of M. aeruginosa abundance). Light had little impact on MC-LR degradation, but MC-LR degradation decreased due to the loss of ZX1 after 10 days of darkness. This study showed that the interactions between M. aeruginosa and ZX1 were strongly influenced by their initial abundances.

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Potential toxicity of chrysophytes affiliated with Poterioochromonas and related 'Spumella-like' flagellates

Cited by 37 publications

References 35 publications

Comprehensive transcriptome analysis provides new insights into nutritional strategies and phylogenetic relationships of chrysophytes

Comprehensive transcriptome analysis provides new insights into nutritional strategies and phylogenetic relationships of chrysophytes

Evaluation of several end-of-pipe measures proposed to control cyanobacteria

The effect of Poterioochromonas abundance on production of intra- and extracellular microcystin-LR concentration

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