Comparative Composition of the Sheath of the Cyanobacterium Gloeothece ATCC 27152 Cultured with and without Combined Nitrogen

Tease, Bruce; Walker, Robert

doi:10.1099/00221287-133-12-3331

Cited by 29 publications

(37 citation statements)

References 29 publications

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“…In the Gloeothece wild type, the compositions of the sheath and the released polysaccharide were significantly different, indicating that the RPS is not merely due to the solubilization of the external layer(s) of the sheath, as has been previously suggested for this organism (33), but that it probably arose from another biosynthetic process. It is also worth mentioning that the monosaccharidic composition of the sheath of the Gloeothece strain PCC 6909 wild type reported here (Table 1) differs qualitatively and quantitatively from that reported previously, performed with cells grown with different amounts of nitrate (or no nitrate at all) and at different temperatures (32,33), confirming that the growth conditions may play a significant role in determining the sheath composition, as was previously suggested (32). The titration curves obtained for the sheath and the RPS of the wild type showed that only one functional group, with a pK a in the range of 5.5 to 6.9, and putatively assigned to carboxyl or phosphate groups (1,2,26), plays a significant role in their ion exchange properties toward cations.…”

Section: Discussioncontrasting

confidence: 45%

“…The efficiency of cyanobacterial EPS in the removal of metal ions has been discussed previously, with an emphasis on the monosaccharidic composition of the polymer, the isolation of EPS, and the subsequent utilization with removal assays (5,8,21). Although the chemical composition of the sheaths of several cyanobacterial strains has been determined (14,15,32,33,38,39) and the importance of the capsules and RPS in the metal-removal process has been recognized (6), information about the exact contribution of each type of EPSs and/or functional group to the biosorption of the metal is still very limited.…”

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Sheathless Mutant of Cyanobacterium Gloeothece sp. Strain PCC 6909 with Increased Capacity To Remove Copper Ions from Aqueous Solutions

Micheletti

Pereira

Mannelli

et al. 2008

Appl Environ Microbiol

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The cyanobacterium Gloeothece sp. strain PCC 6909 and its sheathless mutant were tested for their abilities to remove copper ions from aqueous solutions, with the aim of defining the role of the various outermost polysaccharidic investments in the removal of the metal ions. Microscopy studies and chemical analyses revealed that, although the mutant does not possess a sheath, it releases large amounts of polysaccharidic material (released exocellular polysaccharides [RPS]) into the culture medium. The RPS of the wild type and the mutant are composed of the same 11 sugars, although they are present in different amounts, and the RPS of the mutant possesses a larger amount of acidic sugars and a smaller amount of deoxysugars than the wild type. Unexpectedly, whole cultures of the mutant were more effective in the removal of the heavy metal than the wild type (46.3 ؎ 3.1 and 26.7 ؎ 1.5 mg of Cu 2؉ removed per g of dry weight, respectively). Moreover, we demonstrated that the contribution of the sheath to the metal-removal capacity of the wild type is scarce and that the RPS of the mutant is more efficient in removing copper. This suggests that the metal ions are preferably bound to the cell wall and to RPS functional groups rather than to the sheath. Therefore, the increased copper binding efficiency observed with the sheathless mutant can be attributed to the release of a polysaccharide containing larger amounts and/or more accessible functional groups (e.g., carboxyl and amide groups).Cyanobacteria are a large and widespread group of photoautotrophic microorganisms that combine the ability to perform an oxygenic plant-like photosynthesis with typical prokaryotic features (40). Outside their atypical gram-negative cell walls (15), many strains possess outermost structures, mainly of a polysaccharidic nature, that differ in thickness and consistency. These structures can be referred to as sheaths, capsules, and slimes (4). The term sheath is applied to the usually thin and electron-dense layer surrounding the cells or the cell groups; the capsule refers to the thick and gelatinous layer intimately associated with the cell surface and presenting sharp outlines, whereas the term slime is used to designate the mucilaginous material that is dispersed around the organism but does not reflect the shape of the cells. During cell growth, aliquots of these polysaccharides can be released into the surrounding medium (referred to as released exocellular polysaccharides [RPS]), causing a progressive increase in its viscosity (4). The cyanobacterial exopolysaccharides (EPSs; a general term which includes both the polysaccharidic structures that remain intimately associated with the cell, i.e., the sheath and capsule, and those released into the culture medium, i.e., the RPS) exhibit some typical characteristics that distinguish them from the polymers synthesized by other bacteria: they frequently contain two different uronic acids, they build a polymer particularly rich in negatively charged groups, they possess a larger number o...

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Section: Discussioncontrasting

confidence: 45%

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confidence: 99%

Sheathless Mutant of Cyanobacterium Gloeothece sp. Strain PCC 6909 with Increased Capacity To Remove Copper Ions from Aqueous Solutions

Micheletti

Pereira

Mannelli

et al. 2008

Appl Environ Microbiol

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“…The storage of water is another important role of EPS (Potts, 2000) and water content was higher in larger colonies (Table 3). Furthermore, the sheath of cyanobacteria has been found to contain metal elements (Tease & Walker, 1987). We also found that the loss of water was slow in larger colonies (unpublished data).…”

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confidence: 59%

Photosynthetic physiology and growth as a function of colony size in the cyanobacteriumNostoc sphaeroides

Gao

2004

European Journal of Phycology

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Algal size can affect the rate of metabolism and of growth. Different sized colonies of Nostoc sphaeroides were used with the aim of determining the effects of colony size on photosynthetic physiology and growth. Small colonies showed higher maximum photosynthetic rates per unit chlorophyll, higher light saturation point, and higher photosynthetic efficiency (a) than large colonies. Furthermore, small colonies had a higher affinity for DIC and higher DIC-saturated photosynthetic rates. In addition, small colonies showed higher photosynthetic rates from 5 -458C than large colonies. There was a greater decrease in Fv/Fm after exposure to high irradiance and less recovery in darkness for large colonies than for small colonies. Relative growth rate decreased with increasing colony size. Small colonies had less chl a and mass per unit surface area. The results indicate that small colonies can harvest light and acquire DIC more efficiently and have higher maximum photosynthetic rates and growth rates than large colonies.

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“…This may be a significant phenotypic difference between the two closely related genera (see reference 14 for a discussion of the phylogeny of L. discophora and S. natans). On the other hand, it is possible that the differences reflect differences in growth conditions, which have been shown to affect the composition of extracellular polysaccharides of other bacteria (11,54 SP-6 was grown in a minimal defined medium, whereas S. natans usually is grown on richer complex media. Cultural variability might also account for the variability in uronic acid content of S. natans reported by Gaudy and Wolfe (22) and Romano and Peloquin (45) as described above.…”

Section: Discussionmentioning

confidence: 99%

Ultrastructure and chemical composition of the sheath of Leptothrix discophora SP-6

1993

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Light microscopy and transmission electron microscopy of thin sections and metal-shadowed specimens showed that the sheath of Leptothrix discophora SP-6 (ATCC 51168) is a tube-like extracellular polymeric structure consisting of a condensed fabric of 6.5-nm-diameter fibrils underlying a more diffuse outer capsular layer. In thin sections, outer membrane bridges seen to contact the inner sheath layer suggested that the sheath fabric was attached to the outer layer of the gram-negative cell wall. The capsular polymers showed an affinity for cationic colloidal iron and polycationic ferritin, indicating that they carry a negative charge. Cell-free sheaths were isolated by treatment with a mixture of lysozyme, EDTA, and N-lauroylsarcosine (Sarkosyl) or sodium dodecyl sulfate (SDS). Both Sarkosyl-and SDS-isolated sheaths were indistinguishable in microscopic appearance. However, the Mn-oxidizing activity of Sarkosyl-isolated sheaths was more stable than that of SDS-isolated sheaths. The Sarkosyl-isolated sheaths also contained more 2-keto-3-deoxyoctanoic acid and more outer membrane protein than SDS-isolated sheaths. The oven-dried mass of detergent-isolated sheaths represented approximately 9% of the total oven-dried biomass of SP-6 cultures; the oven-dried sheaths contained 38% C, 6.9%o N, 6% H, and 2.1% S and approximately 34 to 35% carbohydrate (polysaccharide), 23 to 25% protein, 8% lipid, and 4% inorganic ash. Gas-liquid chromatography showed that the polysaccharide was an approximately 1:1 mixture of uronic acids (glucuronic, galacturonic, and mannuronic acids and at least one other unidentified uronic acid) and an amino sugar (galactosamine). Neutral sugars were not detected.Amino acid analysis showed that sheath proteins were enriched in cysteine (6 mol%). The cysteine residues in the sheath proteins probably provide sulfhydryls for disulfide bonds that play an important role in maintaining the structural integrity of the sheath (D. Emerson and W. C. Ghiorse, J. Bacteriol. 175:7819-7827, 1993 (24,36,39).Leptothrix spp. are similar in physiology and cellular structure to closely related gram-negative aerobic heterotrophic pseudomonads (1, 2, 23, 55). Sheath formation and extracellular metal-oxidizing ability are the two major phenotypic criteria distinguishing them from closely related bacteria. The manganese-and iron-oxidizing activities of L. discophora SS-1 (ATCC 43182) are at least partly determined by metal-oxidizing proteins excreted by the cells in association with extracellular polymers (3, 10, 13). Presumably the excreted metaloxidizing proteins are associated with polymers located in the sheath. However, strain SS-1 irreversibly lost the ability to form a sheath soon after it was isolated (2). Recently we reported the isolation and maintenance of a new strain of L. discophora, SP-6 (ATCC 51168) (19). A sheathless variant, strain SP-6(sl) (ATCC 51169), also was isolated. Taxonomic studies (19,57) showed that strains SP-6 and SP-6(sl) are very similar but not identical to strain SS-1.

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Comparative Composition of the Sheath of the Cyanobacterium Gloeothece ATCC 27152 Cultured with and without Combined Nitrogen

Cited by 29 publications

References 29 publications

Sheathless Mutant of Cyanobacterium Gloeothece sp. Strain PCC 6909 with Increased Capacity To Remove Copper Ions from Aqueous Solutions

Sheathless Mutant of Cyanobacterium Gloeothece sp. Strain PCC 6909 with Increased Capacity To Remove Copper Ions from Aqueous Solutions

Photosynthetic physiology and growth as a function of colony size in the cyanobacteriumNostoc sphaeroides

Ultrastructure and chemical composition of the sheath of Leptothrix discophora SP-6

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