Characteristics of the Freshwater Cyanobacterium Microcystis aeruginosa Grown in Iron-Limited Continuous Culture

Dang, T C; Fujii, Manabu; Rose, Arthur W.; Bligh, Mark W.; Waite, T. David

doi:10.1128/aem.06908-11

Cited by 42 publications

(42 citation statements)

References 62 publications

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“…Steady-state cell concentrations, determined by the balance established between the wash-out rate and the cellular growth rate in the reactor, increased with decreasing growth rates (i.e., at lower dilution rates). These observations were consistent with previous chemostat studies (31,40) and batch culture experiments where identical Fe concentrations and media were used (data not shown). This trend resembled conventional batch culture growth curves, where low cell densities seen at high dilution rates are associated with early stages of growth, while high cell densities achieved at low dilution rates are associated with the later (stationary) stages of batch growth (41).…”

Section: Discussionsupporting

confidence: 82%

“…The chemostat system employed was developed in a previous study (31). All culture vessels and plumbing were constructed from metal-free materials.…”

Section: Methodsmentioning

confidence: 99%

“…All culture vessels and plumbing were constructed from metal-free materials. Under steady-state conditions, the dilution rate (D) was equal to the specific growth rate () with D set to 0.07 day Ϫ1 , 0.15 day Ϫ1 , 0.30 day Ϫ1 , and 0.45 day Ϫ1 by adjusting the diameter of the feed tubes (31). The Fe concentrations in Fraquil*BG11 were the same as those described in reference 13, i.e., 100 nM (Fe-limited conditions) and 1,000 nM (Fereplete conditions).…”

Section: Methodsmentioning

confidence: 99%

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Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Yeung

D’Agostino

Poljak

et al. 2016

Appl Environ Microbiol

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The hepatotoxin microcystin (MCYST) is produced by a variety of freshwater cyanobacterial species, including Microcystis aeruginosa. Interestingly, MCYST-producing M. aeruginosa strains have been shown to outcompete their nontoxic counterparts under iron-limiting conditions. However, the reasons for this are unclear. Here we examined the proteomic response of M. aeruginosa PCC 7806 continuous cultures under different iron and growth regimes. Iron limitation was correlated with a global reduction in levels of proteins associated with energy metabolism and photosynthesis. These proteomic changes were consistent with physiological observations, including reduced chlorophyll a content and reduced cell size. While levels of MCYST biosynthesis proteins did not fluctuate during the study period, both intra-and extracellular toxin quotas were significantly higher under iron-limiting conditions. Our results support the hypothesis that intracellular MCYST plays a role in protecting the cell against oxidative stress. Further, we propose that extracellular MCYST may act as a signaling molecule, stimulating MCYST production under conditions of iron limitation and enhancing the fitness of bloom populations. IMPORTANCEMicrocystin production in water supply reservoirs is a global public health problem. Understanding the ecophysiology of hepatotoxic cyanobacteria, including their responses to the presence of key micronutrient metals such as iron, is central to managing harmful blooms. To our knowledge, this was the first study to examine proteomic and physiological changes occurring in M. aeruginosa continuous cultures under conditions of iron limitation at different growth rates. C yanobacteria ("blue-green algae") proliferate in warm stratified water bodies rich in nitrogen and phosphorus (1, 2). Cyanobacterial blooms can have a negative impact on the appearance, taste, and odor of water, and their subsequent decay can lead to oxygen depletion and fish kills (3). However, of greatest concern to public health is their production of potent toxins. Microcystis aeruginosa (Kützing) Lemmermann is a common bloom-forming cyanobacterial species that produces hepatotoxic microcystins (MCYSTs) (1). These nonribosomally synthesized peptides inhibit eukaryotic protein phosphatases, leading to liver necrosis in acute doses and hepatocellular carcinoma in chronic low doses (4, 5).There is strong evidence that the production of MCYST is a direct function of cell division (6). It is therefore not surprising that parameters affecting cyanobacterial growth rate (e.g., nutrients, trace metals, temperature, pH, and light) have been correlated with fluctuating MCYST levels in batch culture experiments (7-9).Recent molecular studies suggest that iron (Fe) and nitrogen (N) also play a role in regulating the expression of MCYST biosynthesis (mcy) genes. In M. aeruginosa, for example, the mcy promoter region contains binding sites for the ferric uptake regulator (Fur) and the global nitrogen regulator (NtcA) (10, 11). Despite these genetic clu...

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Section: Discussionsupporting

confidence: 82%

“…The chemostat system employed was developed in a previous study (31). All culture vessels and plumbing were constructed from metal-free materials.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Yeung

D’Agostino

Poljak

et al. 2016

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…Several works on the effect of nutrient concentration (macronutrients such as nitrogen and phosphorus and trace metals, particularly iron) in the physiology, metabolism and biochemical composition of photototrophic microorganisms have been carried out in the last years using continuous cultivation as a tool (Bougaran et al, 2010;Collins et al, 2001;Dang et al, 2012;Gauthier and Turpin, 1997;Gress et al, 2004;Hagstrom et al, 2010;Klok et al, 2013aKlok et al, , 2013bLyck et al, 1996;Middlemiss et al, 2001;Sonier and Weger, 2010;Su et al, 2012;Utkilen and Gjølme, 1995;Weger and Espie, 2000;Weger et al, 2002Weger et al, , 2006Weger et al, , 2009Wirtz et al, 2010).…”

Section: Research Toolmentioning

confidence: 99%

“…Among all the characteristics inherent to continuous cultivations, the ones that justify its use as a research tool in physiological, ecological genetic and biochemical studies (Hoskisson and Hobbs, 2005) are: i) possibility to pre-set and control specific growth rate; ii) select and control the metabolic state; iii) significant amount of cells with defined properties possible to be obtained using a lab-scale PBR; iv) single independent variables (e.g., pH, temperature, specific growth rate) can be manipulated one at a time; v) possibility to choose one, or combinations of, limiting nutrient(s) and; and vi) defined, constant and controllable physico-chemical conditions (Cooney, 1979;Dang et al, 2012;Fiechter, 1975;Hoskisson and Hobbs, 2005).…”

Section: Research Toolmentioning

confidence: 99%

Continuous cultivation of photosynthetic microorganisms: Approaches, applications and future trends

Fernandes

Mota

Teixeira

et al. 2015

Biotechnology Advances

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The possibility of using photosynthetic microorganisms, such as cyanobacteria and microalgae, for converting light and carbon dioxide into valuable biochemical products has raised the need for new cost-efficient processes ensuring a constant product quality. Food, feed, biofuels, cosmetics and pharmaceutics are among the sectors that can profit from the application of photosynthetic microorganisms. Biomass growth in a photobioreactor is a complex process influenced by multiple parameters, such as photosynthetic light capture and attenuation, nutrient uptake, photobioreactor hydrodynamics and gas-liquid mass transfer. In order to optimize productivity while keeping a standard product quality, a permanent control of the main cultivation parameters is necessary, where the continuous cultivation has shown to be the best option. However it is of utmost importance to recognize the singularity of continuous cultivation of cyanobacteria and microalgae due to their dependence on light availability and intensity. In this sense, this review provides comprehensive information on recent breakthroughs and possible future trends regarding technological and process improvements in continuous cultivation systems of microalgae and cyanobacteria, that will directly affect cost-effectiveness and product quality standardization. An overview of the various applications, techniques and equipment (with special emphasis on photobioreactors) in continuous cultivation of microalgae and cyanobacteria are presented. Additionally, mathematical modeling, feasibility, economics as well as the applicability of continuous cultivation into large-scale operation, are discussed.

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Microalgal phycocyanin productivity: strategies for phyco‐valorization

Querques

Cesta

Chiang

2015

J of Chemical Tech & Biotech

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Phyco-valorization is the exploitation of microalgae and microalgal chemicals as valuable products. This paper discusses the optimization of microalgal bioreactor-based systems for C-phycocyanin pigment production. Various aspects contributing to system development and enhancement of phycocyanin productivity are described. A wide range of potential microalgal species have been identified for phycocyanin production; the selection of a species for mass culturing can be determined by desired bioreactor trophic mode and symbiotic relations. Research has demonstrated that species amenability to local lighting and climatic conditions, and to variations in bioreactor substrate concentrations and operational parameters, have significant impact on phycocyanin production. The simultaneous optimization of all factors contributing to system productivity may be accomplished efficiently through process modelling. A summary of established models for microalgal phycocyanin production is presented. A suggested strategy for increasing economic viability of phycocyanin production systems is their application in integrated resource recovery. Through the incorporation of phycocyanin productivity optimization principles within a phycoremediation process, the valorization of waste resources may be achieved. The simultaneous economic potential and environmentally-forward concept of phyco-valorization through phycocyanin production is a promising application of microalgal biotechnology awaiting further development for industrial implementation.

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Characteristics of the Freshwater Cyanobacterium Microcystis aeruginosa Grown in Iron-Limited Continuous Culture

Cited by 42 publications

References 62 publications

Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Physiological and Proteomic Responses of Continuous Cultures of Microcystis aeruginosa PCC 7806 to Changes in Iron Bioavailability and Growth Rate

Continuous cultivation of photosynthetic microorganisms: Approaches, applications and future trends

Microalgal phycocyanin productivity: strategies for phyco‐valorization

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