Effects of Ca and Mg levels on colony formation and EPS content of cultured M. aeruginosa

Zhao, Lei; Lu, Li Xia; Li, Ming; Xu, Zhi-Rong; Zhu, Wei

doi:10.1016/j.proenv.2011.09.232

Cited by 34 publications

(11 citation statements)

References 14 publications

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“…The CPs in mucilage are very similar to pectin (Parker et al, ), the gelling of which can involve appropriate levels of dissolved polysaccharides (May & Stainsby, ), low pH and high Ca 2+ concentration (Thakur, Singh & Handa, ). Addition of Ca 2+ has been reported to induce colony formation from unicellular cells in M. aeruginosa (Sato et al, ; Wang et al, ; Zhao et al, ). It is plausible that increased levels of Ca 2+ could lead to gelation of polysaccharides in the mucilage, thereby inducing a morphological change from M. ichthyoblabe to M. wesenbergii .…”

Section: Colony Formation In Laboratory Studies and Implications For mentioning

confidence: 99%

Colony formation in the cyanobacterium Microcystis

2018

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Morphological evolution from a unicellular to multicellular state provides greater opportunities for organisms to attain larger and more complex living forms. As the most common freshwater cyanobacterial genus, Microcystis is a unicellular microorganism, with high phenotypic plasticity, which forms colonies and blooms in lakes and reservoirs worldwide. We conducted a systematic review of field studies from the 1990s to 2017 where Microcystis was dominant. Microcystis was detected as the dominant genus in waterbodies from temperate to subtropical and tropical zones. Unicellular Microcystis spp. can be induced to form colonies by adjusting biotic and abiotic factors in laboratory. Colony formation by cell division has been induced by zooplankton filtrate, high Pb concentration, the presence of another cyanobacterium (Cylindrospermopsis raciborskii), heterotrophic bacteria, and by low temperature and light intensity. Colony formation by cell adhesion can be induced by zooplankton grazing, high Ca concentration, and microcystins. We hypothesise that single cells of all Microcystis morphospecies initially form colonies with a similar morphology to those found in the early spring. These colonies gradually change their morphology to that of M. ichthyoblabe, M. wesenbergii and M. aeruginosa with changing environmental conditions. Colony formation provides Microcystis with many ecological advantages, including adaption to varying light, sustained growth under poor nutrient supply, protection from chemical stressors and protection from grazing. These benefits represent passive tactics responding to environmental stress. Microcystis colonies form at the cost of decreased specific growth rates compared with a unicellular habit. Large colony size allows Microcystis to attain rapid floating velocities (maximum recorded for a single colony, ∼ 10.08 m h ) that enable them to develop and maintain a large biomass near the surface of eutrophic lakes, where they may shade and inhibit the growth of less-buoyant species in deeper layers. Over time, accompanying species may fail to maintain viable populations, allowing Microcystis to dominate. Microcystis blooms can be controlled by artificial mixing. Microcystis colonies and non-buoyant phytoplankton will be exposed to identical light conditions if they are evenly distributed over the water column. In that case, green algae and diatoms, which generally have a higher growth rate than Microcystis, will be more successful. Under such mixing conditions, other phytoplankton taxa could recover and the dominance of Microcystis would be reduced. This review advances our understanding of the factors and mechanisms affecting Microcystis colony formation and size in the field and laboratory through synthesis of current knowledge. The main transition pathways of morphological changes in Microcystis provide an example of the phenotypic plasticity of organisms during morphological evolution from a unicellular to multicellular state. We emphasise that the mechanisms and factors influencing competiti...

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Section: Colony Formation In Laboratory Studies and Implications For mentioning

confidence: 99%

Colony formation in the cyanobacterium Microcystis

2018

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“…In the previous study, the influences of Ca 2+ and Mg 2+ concentrations on extracellular polysaccharides (EPS) content and colony formation of Microcystis were investigated [49]. It was also revealed that the addition of EPS and Ca 2+ into the medium could lead M. aeruginosa to form colonies effectively when the EPS and Ca 2+ concentrations Fig.…”

Section: Isolation Of Eps and Protocol Of Colony Formation And Buoyanmentioning

confidence: 99%

Control of the buoyancy of Microcystis aeruginosa via colony formation induced by regulating extracellular polysaccharides and cationic ions

et al. 2019

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It is well recognized that gas vesicles influence the buoyancy of Microcystis and control the migration in the water column. Some of Microcystis strains do not have gas vesicles, so these strains cannot obtain buoyancy from them. In this study, we used two types of Microcystis strains such as the non-gas vesicle synthesizing strain M. aeruginosa UTEX-2061 and the gas vesicle synthesizing strain M. aeruginosa NIES-843 in the buoyancy control experiments of M. aeruginosa. By inducing colony formation and calculating the relative buoyancy rate of each strain, it was proven that the colony formation was strictly related to the buoyancy of both Microcystis strains. M. aeruginosa NIES-843 possessing gas vesicles could obtain buoyancy under the lower concentration of calcium and magnesium than M. aeruginosa UTEX-2061 possessing no gas vesicles. With the addition of the extracellular polysaccharides (EPS) extracted from Microcystis blooms into the culture medium, M. aeruginosa NIES-843 and UTEX-2061 could present higher buoyancy at the lowest concentrations of calcium and magnesium. It was suggested that EPS combined with the divalent metal cations such as calcium and magnesium made Microcystis form colony effectively. Calcium and magnesium ions enhanced the ability of colony formation of Microcystis and had a significant influence on buoyancy.

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“…Since the specific growth rate can be controlled by adjusting the dilution rate [32], a high dilution rate of the PBR may help to keep cells active for minimized DOC production. The excretion of DOC also changes with nutrient availability [33,34], mechanical mixing, and so on. Further study is necessary to elucidate the effect of those conditions on the production and inhibitive characteristics of DOC.…”

Section: Effect Of Medium Recyclingmentioning

confidence: 99%

Carbon Mass Balance in Arthrospira platensis Culture with Medium Recycle and High CO2 Supply

et al. 2019

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Medium recycling combined with CO2 recovery helps sustainable use of the alkaline medium in Arthrospira culture. However, high CO2 supply may cause inorganic carbon accumulation and pH reduction, which could result in low CO2 recovery and reduced algal growth. This study aimed to elucidate the effect of medium recycling and high CO2 supply through carbon mass balance analysis in Arthrospira culture. In all CO2 supply conditions, carbon supply was higher than Arthrospira carbon assimilation, which accounted for 30–58% of supply. However, CO2 recovery of nearly 100% and 63% for lower (0.20 and 0.39 gC L−1 d−1) and higher (0.59 gC L−1 d−1) CO2 supply rates were achieved, respectively, because of the high concentration of the alkaline agent. The excess carbon accumulated in the medium and ultimately escaped from the system in a form of dissolved inorganic carbon (DIC). Dissolved organic carbon (DOC) contributed to 16–24% of the total photosynthetically assimilated carbon, and the final concentration reached 260–367 mgC L−1, but there was no significant growth reduction caused by DIC and DOC accumulation. This study demonstrated the stability of the medium-recycling process even at high CO2 supply rates although a balanced supply is recommended for longer operations.

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Effects of Ca and Mg levels on colony formation and EPS content of cultured M. aeruginosa

Cited by 34 publications

References 14 publications

Colony formation in the cyanobacterium Microcystis

Colony formation in the cyanobacterium Microcystis

Control of the buoyancy of Microcystis aeruginosa via colony formation induced by regulating extracellular polysaccharides and cationic ions

Carbon Mass Balance in Arthrospira platensis Culture with Medium Recycle and High CO2 Supply

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