Morphological and physiological changes in Microcystis aeruginosa as a result of interactions with heterotrophic bacteria

Shen, Hong; Niu, Yuan; Xie, Ping; Tao, Min; Yang, Xi

doi:10.1111/j.1365-2427.2010.02551.x

Cited by 140 publications

(91 citation statements)

References 68 publications

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“…A potential clue to colony formation in Trichodesmium, or at least a testable hypothesis, may come from recent research with the freshwater cyanobacteria, Microcystis spp., which showed that certain distinct "specialist bacteria" may trigger extracellular polysaccharide production and colony formation of otherwise single cells of Microcystis spp. (Shen et al, 2011).…”

Section: Trichodesmium Morphologymentioning

confidence: 99%

Temporal Variability of Trichodesmium spp. and Diatom-Diazotroph Assemblages in the North Pacific Subtropical Gyre

2018

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In oligotrophic ocean regions such as the North Pacific Subtropical Gyre (NPSG), N 2 fixation (i.e., diazotrophy) by a diverse consortium of microorganisms has been shown to contribute significantly to new production and particle export. In 2015 and 2016, we measured near-monthly abundances of the large cell-sized (> 10 µm) diazotrophic genera Trichodesmium and diatom-associated Richelia and Calothrix spp. in the NPSG via microscopy and quantitative PCR of nifH genes. Of these genera, we find Trichodesmium to be the more abundant over our study period, with cell concentrations in the upper water column (0-45 m) ranging from 1 to 5,988 cells L −1 , while the sum of Richelia and Calothrix spp. abundances ranged from 4 to 157 heterocysts L −1 . Significant discrepancies between absolute abundances were noted between cell and gene-based approaches to biomass determination (nifH copies L −1 were up to 10 2 -10 3 higher than cell concentrations). Potential explanations for these striking discrepancies are discussed. Using the maximum N fixation rates per cell found in the existing literature for these genera, we estimate potential N 2 fixation rates via these large diazotroph communities to be between 0.01 and 1.5 nmol N L −1 d −1 . When comparing these rates to available 15 N 2 tracer measurements, we conclude that large diazotrophs were generally minor (<10%) contributors to bulk N 2 fixation in the surface ocean during our study period. Conversely, high concentrations of Trichodesmium observed in fall-winter of 2015 and 2016 were estimated to drive >50% of measured N 2 fixation rates. While these large cell-sized and heterogeneously distributed organisms may still disproportionately contribute to export, cell-abundance based rate estimates suggests that other diazotrophs are largely responsible for N 2 fixation rates measured in bottle-based incubations.

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Section: Trichodesmium Morphologymentioning

confidence: 99%

Temporal Variability of Trichodesmium spp. and Diatom-Diazotroph Assemblages in the North Pacific Subtropical Gyre

2018

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“…To date, research efforts have broadly identified nutrient inputs and temperature as contributing factors in the development of such blooms, but little focus, due primarily to methodological limitations, has been allocated to the study of the cellular physiology and metabolism of the entire bloom community. Not only do bloom-forming organisms such as Microcystis aeruginosa live in competition with other phytoplankton species, they also live in concert with heterotrophic bacteria, which can attach to the mucilaginous matrix produced by M. aeruginosa colonies (15,16). There is a dearth of information concerning the functional role that co-occurring bacteria may play in bloom dynamics, although recent studies suggest that heterotrophs may play an important role in the metabolism of some nutrients (17,18).…”

mentioning

confidence: 97%

Metatranscriptomic Evidence for Co-Occurring Top-Down and Bottom-Up Controls on Toxic Cyanobacterial Communities

Steffen

Belisle

Watson

et al. 2015

Appl Environ Microbiol

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Little is known about the molecular and physiological function of co-occurring microbes within freshwater cyanobacterial harmful algal blooms (cHABs). To address this, community metatranscriptomes collected from the western basin of Lake Erie during August 2012 were examined. Using sequence data, we tested the hypothesis that the activity of the microbial community members is independent of community structure. Predicted metabolic and physiological functional profiles from spatially distinct metatranscriptomes were determined to be >90% similar between sites. Targeted analysis of Microcystis aeruginosa, the historical causative agent of cyanobacterial harmful algal blooms over the past ϳ20 years, as well as analysis of Planktothrix agardhii and Anabaena cylindrica, revealed ongoing transcription of genes involved in microcystin toxin synthesis as well as the acquisition of both nitrogen and phosphorus, nutrients often implicated as independent bottom-up drivers of eutrophication in aquatic systems. Transcription of genes involved in carbon dioxide (CO 2 ) concentration and metabolism also provided support for the alternate hypothesis that high-pH conditions and dense algal biomass result in CO 2 -limiting conditions that further favor cyanobacterial dominance. Additionally, the presence of Microcystis-specific cyanophage sequences provided preliminary evidence of possible top-down virus-mediated control of cHAB populations. Overall, these data provide insight into the complex series of constraints associated with Microcystis blooms that dominate the western basin of Lake Erie during summer months, demonstrating that multiple environmental factors work to shape the microbial community. F reshwater ecosystems are considered among the most endangered in the biosphere (1). One threat to fresh waters around the world is the now nearly annual occurrence of blooms of toxic cyanobacteria. Molecular signatures of cyanobacterial harmful algal blooms (cHABs) have been identified on all seven continents, and these blooms have been occurring with increased frequency and duration in recent years (2-4). The accumulation of bloom biomass has been associated with fish, avian, and mammal intoxication (5, 6); the formation of hypoxic zones (7); the production of taste and odor compounds (8, 9); and even human liver failure in extreme cases (10).The Laurentian Great Lakes are an important freshwater resource, holding ϳ18% of the world's potable water and ϳ84% of the surface waters in North America (11). cHABs have had a persistent presence in Lake Erie and other Laurentian Great Lakes for several decades (3, 12, 13). Nuisance biomass and toxin production associated with cHABs in the Great Lakes have had a detrimental effect not only on ecosystem health but also on the economic health of the surrounding communities; indeed, in August 2014, a bloom event led to the shutdown of the water supply for some ϳ500,000 residents in the region of the city of Toledo, OH (14). To date, research efforts have broadly identified nutrient inputs an...

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“…Free-living bacteria may not influence aggregation whereas bacteria attaching to these microalgal cells may increase aggregate formation (Gardes et al, 2011). Shen et al (2011) used PCR-DGGE to reveal the role of aquatic heterotrophic bacteria in the process of development of Microcystis aeruginosa blooms in natural waters. Their results suggested that Porphyrobacter, Flavobacteriaceae and one uncultured bacterium could be specialist bacteria responsible for aggregation of M. aeruginosa.…”

Section: Harvesting Of Biofuel Producing Microalgaementioning

confidence: 99%

Effects of bacterial communities on biofuel-producing microalgae: stimulation, inhibition and harvesting

Wang

Hill

Zheng

et al. 2014

Critical Reviews in Biotechnology

104

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Despite the great interest in microalgae as a potential source of biofuel to substitute for fossil fuels, little information is available on the effects of bacterial symbionts in mass algal cultivation systems. The bacterial communities associated with microalgae are a crucial factor in the process of microalgal biomass and lipid production and may stimulate or inhibit growth of biofuel-producing microalgae. In addition, we discuss here the potential use of bacteria to harvest biofuel-producing microalgae. We propose that aggregation of microalgae by bacteria to achieve 490% reductions in volume followed by centrifugation could be an economic approach for harvesting of biofuel-producing microalgae. Our aims in this review are to promote understanding of the effects of bacterial communities on microalgae and draw attention to the importance of this topic in the microalgal biofuel field.

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Morphological and physiological changes in Microcystis aeruginosa as a result of interactions with heterotrophic bacteria

Cited by 140 publications

References 68 publications

Temporal Variability of Trichodesmium spp. and Diatom-Diazotroph Assemblages in the North Pacific Subtropical Gyre

Temporal Variability of Trichodesmium spp. and Diatom-Diazotroph Assemblages in the North Pacific Subtropical Gyre

Metatranscriptomic Evidence for Co-Occurring Top-Down and Bottom-Up Controls on Toxic Cyanobacterial Communities

Effects of bacterial communities on biofuel-producing microalgae: stimulation, inhibition and harvesting

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