Composition of the sheath produced by the green alga Chlorella sorokiniana

Watanabe, Keiji; Imase, Masato; Sasaki, Kazuhiro; Ohmura, Naoya; Saiki, Hiroshi; Tanaka, Hideo

doi:10.1111/j.1472-765x.2006.01886.x

Cited by 45 publications

(31 citation statements)

References 21 publications

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“…and Mg 2? (Watanabe et al 2006) or the positively charged residues of aminoacids (Kawaguchi and Decho 2002) may play a role. The night time decrease in pH seemed to liberate exchangeable and loosely bound P, which moved, in the soluble reactive form, from the green to the yellow layer joining the SRP pool in the same fraction there.…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal changes in phosphorus partitioning within a freshwater cyanobacterial mat community

et al. 2010

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Spatial and temporal changes in phosphorus (P) distribution, partitioning and mobility in the benthic cyanobacterial mat (CBM) were evaluated using sequential chemical fractionation. Total P (TP) content was extremely low, ranging from 0.025 to 0.1 mg g -1 DW. Exchangeable and loosely bound P, which we consider to be mainly associated with extracellular polymeric substances (EPS), constituted the most significant proportion of TP (up to 52%, 55 lg g -1 DW), followed by P associated with the authigenic apatites (up to 35% of TP or 18 lg g -1 DW). While we found virtually no exchange of P with the ambient environment, our results show that the partitioning of P forms within CBM is dependent on spatial and temporal fluctuations of physico-chemical parameters, mainly pH and dissolved oxygen. A conspicuous diurnal increase in the reactive, exchangeable and loosely bound P in the top CBM layers was observed. This observation has important ecological implications, as CBM microorganisms therefore have an increased possibility for P ''luxury'' uptake during the night. This hypothesis is further supported by the fact that P in the organic fraction rises by as much as 53% in the upper layers during the night, indicating some form of cellular uptake. The P-binding potential of EPS also has ecological or biogeochemical consequences and should be considered in stoichiometrical studies where it represents potential danger for great overestimates of cellular P values or the nutritional status of cells.

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Section: Discussionmentioning

confidence: 99%

Spatial and temporal changes in phosphorus partitioning within a freshwater cyanobacterial mat community

et al. 2010

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“…5a) could be tentatively attributed to two taxa: a member of i) the Chlorellaceae (Chlorella, Dictyosphaerium) or ii) the Chroococcaceae (Aphanocapsa, Aphanothece). Chlorella has been identified in the integrated phytoplankton counts, and these colonial taxa may have mucilaginous envelopes (Bock et al, 2011;Watanabe et al, 2006). Grouped under a small eukaryotes category, they have been found in summer in lakes Annecy, Bourget and Geneva (Personnic et al, 2009).…”

Section: Micro-environmentmentioning

confidence: 99%

“…Cyanobacteria (Pereira et al, 2009;Dittrich and Sibler, 2010) and some strains of Chlorella (Watanabe et al, 2006) are known to secrete extracellular polysaccharides, which may act as binding sites for Ca 2+ and CO 3 2-. The importance of biofilms in freshwater carbonate precipitation has been demonstrated by Rogerson et al (2008) in their experiments on tufa systems.…”

Section: Introductionmentioning

confidence: 99%

Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland)

Jaquet¹,

Nirel

Martignier

2013

J Limnol

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In the course of a routine water-quality survey in meso-oligotrophic lake Geneva (Switzerland), suspended matter was collected by filtration on 0.2 μm membranes in July and August 2012 at the depth of maximal chlorophyll a (Chl a) concentration (2 mg m^–3). Examination by scanning electron microscopy revealed the presence of numerous dark and gelatinous patches occluding the pores of the membranes, containing high numbers of picoplanktonic cells and, in places, clusters of high-reflectance smooth microspheres (1-2 μm in diameter). Their chemical composition, determined by semi-quantitative, energy-dispersive X ray spectroscopy (EDS) showed magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) (alkaline earth metals) to be the dominant cations. Among the anions, phosphorus (P) and carbon (C) were present, but only the latter is considered here (as carbonate). The microspheres were subdivided into four types represented in a Ca-Sr-Ba ternary space. All types are confined within a domain bound by Ca>45, Sr<10 and Ba<50 (in mole %). Type I, the most frequent, displays a broad variability in Ba/Ca, even within a given cluster. Types II and III are devoid of Ba, but may incorporate P. Type IV contains only Ca. The Type I composition resembles that of benstonite, a Group IIA carbonate that was recently found as intracellular granules in a cyanobacterium from alkaline lake Alchichica (Mexico).Lake Geneva microspheres are solid, featureless and embedded in a mucilage-looking substance in the vicinity of, but seemingly not inside, picoplanktonic cells morphologically similar to Chlorella and Synechococcus. In summer 2012, the macroscopic physico-chemical conditions in lake Geneva epilimnion were such as to allow precipitation of Ca but not of Sr and Ba carbonates. Favourable conditions did exist, though, in the micro-environment provided by the combination of active picoplankton and a mucilaginous envelope. Further studies are ongoing to investigate the vertical distribution of the microspheres, their internal structure and their exact mineralogical composition, as well as the taxonomy of the picoplankton and the nature of the mucilage, in order to gain a proper understanding of this intriguing process of alkaline-earth metals sequestration.

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“…Such close association was confirmed by SEM observation, which demonstrated the growth of bacteria on the algal surface. Direct attachment of symbiotic bacteria on the surface of microalga and indirect attachment on the sheath produced by the microalga has been observed in other microalga-bacteria combinations [28].…”

Section: Discussionmentioning

confidence: 93%

“…Heterotrophic demineralization supplies continuous nutrients and algae also produce some organic compounds to contribute to the smooth running of the nutrient cycle. This phenomenon is critical in a symbiotic relationship [8,28]. Croft et al [9] Croft et al [9] separated Halomonas sp., a vitamin B12-producing bacterium, from a non-axenic culture of Amphidinium operculatum and cocultured it with two auxotrophic vitamin B12-requiring algae, Porphyridium purpureum and A. operculatum, in a mineral medium without organic carbon sources.…”

Section: Discussionmentioning

confidence: 99%

Growth Promotion of Pavlova viridis by Bacteria Isolated from the Microalga

Ahamed¹,

Kim²,

Tae-O³

et al. 2015

Journal of Life Science

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The marine microalga Pavlova viridis can grow fast and has the ability to accumulate essential nutrients for culturing marine animals, such as EPA and DHA, and it has been used as food for raring larval fish and prawn. The symbiotic relationship between the flagellate microalga Pavlova viridis and its associated bacteria was investigated. An axenic culture of P. viridis was obtained by repeated treatment of the microalga with an antibiotic cocktail. The axenic status was confirmed after sub-culturing three times in a sterile f/2 medium without an antibiotic. The axenic alga was then co-inoculated with five bacteria, arbitrarily designated as I1-I5, isolated from the alga to test the growth promotion of the algae. All bacterial strains promoted the growth of P. viridis, and bacterial isolate I3 was the most effective among the five bacteria tested. The cell number of P. viridis in the co-culture with I3 was significantly higher than that of the control culture. A sequence analysis of the 16S rRNA gene isolated from I3 revealed a 97% nucleotide sequence similarity to that of Citrobacter sp. The growth of strain I3 was also significantly enhanced by co-culturing with P. viridis, indicating a symbiotic relationship between the microalga and its associated bacterium. The association between the microalga and bacterium was confirmed by scanning electron microscopy.

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Composition of the sheath produced by the green alga Chlorella sorokiniana

Cited by 45 publications

References 21 publications

Spatial and temporal changes in phosphorus partitioning within a freshwater cyanobacterial mat community

Spatial and temporal changes in phosphorus partitioning within a freshwater cyanobacterial mat community

Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland)

Growth Promotion of Pavlova viridis by Bacteria Isolated from the Microalga

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