Separation of forms of Microcystis from Anabaena in mixed populations by the application of pressure

1994 ◽  
Vol 45 (5) ◽  
pp. 863 ◽  
Author(s):  
JD Brookes ◽  
GG Ganf ◽  
MD Burch
Keyword(s):  
Microcystis Aeruginosa ◽  
Critical Pressure ◽  
Relative Toxicity ◽  
Gas Vesicles ◽  
Reservoir Water ◽  
Pure Material ◽  
Pressure Distributions ◽  
Sucrose Solutions ◽  
Mixed Populations ◽  
Anabaena Circinalis

Critical-pressure distributions of gas vesicles in Anabaena circinalis, Microcystis aeruginosa f. aeruginosa and M. a. f. flos-aquae were determined for suspensions both in hypertonic sucrose solutions and in reservoir water. The differences between the critical and apparent critical pressures of gas vesicles suggested that differential pressurization could be used to separate these taxa. Subsequent experiments successfully separated (>90%) the two formae of Microcystis by the application of 500 kPa and M. a. f. aeruginosa from A. circinalis by the application of 300 kPa. This technique has the potential to provide sufficiently pure material to distinguish the relative toxicity of the two formae of Microcystis in the presence of a neurotoxic A. circinalis.

Trihalomethanes and haloacetic acid species from the chlorination of algal organic matter and bromide

2011 ◽  
Vol 63 (6) ◽  
pp. 1111-1120 ◽  
Author(s):  
Y. Y. Wei ◽  
Y. Liu ◽  
R. H. Dai ◽  
X. Liu ◽  
J. J. Wu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Fish Oil ◽  
Microcystis Aeruginosa ◽  
Bovine Serum ◽  
Algal Species ◽  
Haloacetic Acid ◽  
Model Compounds ◽  
Reservoir Water

Bromide and algal pollution are important factors influencing disinfection byproduct (DBP) formation and speciation in reservoir water in coastal areas. In this study, the chlorination of model algal cellular compounds (bovine serum albumin, fish oil and starch), Microcystis aeruginosa and its extra-cellular organic matter (EOM) were conducted in the absence and presence of bromide. The main aim of the present study is to explore their potential as precursors for trihalomethanes (THMs) and haloacetic acid (HAAs) speciation upon chlorination in the presence of bromide. The results showed that all brominated THMs species were generated, whereas only bromochloroacetic acid (BCAA) or/and dibromoacetic acid (DBAA) was/were produced as for brominated HAAs (Br-HAAs) from the three model compounds in the presence of bromide. The effect of bromide on Br-HAAs speciation upon fish oil chlorination was more evident than with BSA and starch. There was a good correlation between the species predicted from the model compounds and those obtained from specific algal species. Br-HAAs and Br-THMs species from Microcystis aeruginosa cells or EOM were the same as those from bovine serum albumin in the presence of bromide.

scholarly journals Analysis of tryptic digests indicates regions of GvpC that bind to gas vesicles of Anabaena flos-aquae

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1661-1669 ◽  
Author(s):  
Peter G. Dunton ◽  
William J. Mawby ◽  
Virginia A. Shaw ◽  
Anthony E. Walsby
Keyword(s):  
Cylindrical Shell ◽  
Binding Sites ◽  
Critical Pressure ◽  
Gas Vesicles ◽  
Tryptic Peptides ◽  
Collapse Pressure ◽  
Partial Digestion ◽  
N Terminus ◽  
The Mean ◽  
Tof Ms

The gas vesicles of the cyanobacterium Anabaena flos-aquae contain two main proteins: GvpA, which forms the ribs of the hollow cylindrical shell, and GvpC, which occurs on the outer surface. Analysis by MALDI-TOF MS shows that after incubating Anabaena gas vesicles in trypsin, GvpA was cleaved only at sites near the N-terminus, whereas GvpC was cleaved at most of its potential tryptic sites. Many of the resulting tryptic peptides from GvpC remained attached to the underlying GvpA shell: the pattern of attachment indicated that there are binding sites to GvpA at both ends of the 33-residue repeats (33RRs) in GvpC, although one of the tryptic peptides within the 33RR did not remain attached. Tryptic peptides near the two ends of the GvpC molecule were also lost. The mean critical collapse pressure of Anabaena gas vesicles decreased from 0.63 MPa to 0.20 MPa when GvpC was removed with urea or fully digested with trypsin; partial digestion resulted in partial decrease in critical pressure.

Impact of sonication at 20 kHz on Microcystis aeruginosa, Anabaena circinalis and Chlorella sp.

2012 ◽  
Vol 46 (5) ◽  
pp. 1473-1481 ◽  
Author(s):  
Pradeep Rajasekhar ◽  
Linhua Fan ◽  
Thang Nguyen ◽  
Felicity A. Roddick
Keyword(s):  
Microcystis Aeruginosa ◽  
Chlorella Sp ◽  
Anabaena Circinalis

Lower limit of the gas permeability coefficient of gas vesicles

1984 ◽  
Vol 223 (1231) ◽  
pp. 177-196 ◽  
Keyword(s):  
Permeability Coefficient ◽  
Critical Pressure ◽  
Gas Permeability ◽  
Aqueous Suspension ◽  
Pressure Rise ◽  
Gas Pressure ◽  
Gas Vesicles ◽  
Minimum Diameter ◽  
Vesicle Wall ◽  
The Difference

The gas vesicles found in various planktonic prokaryotes are hollow, rigid structures permeable to gases. They collapse when the difference between the external hydrostatic pressure and internal gas pressure exceeds their critical pressure (usually about 0.6 MPa). It was found that dried gas vesicles would survive exposure to gas pressures considerably in excess of this value (4 MPa or more), because gas diffused into them as the pressure was raised and the pressure difference required to cause collapse was not established. They survived the most rapid rates of pressure rise, 0–4.6 MPa in less than 2.5 ms, to which they were exposed. From this it can be calculated that the gas permeability coefficient of the average gas vesicle ( α ) exceeds 22 x 10 3 s -1 and the permeability of the gas vesicle wall ( k ) is greater than 332 μm s -1 . Gas molecules may diffuse through fixed pores in the gas vesicle wall. Since a gas molecule of collision diameter 0.63 nm is known to penetrate the gas vesicle, this would be the minimum diameter of such a fixed pore. It is shown by kinetic theory that the permeability coefficient of an average gas vesicle with one pore of this size would be 2.1 x 10 3 s -1 : there would, therefore, have to be at least 11 such pores to account for the observed minimum permeability coefficient. Gas vesicles in aqueous suspension will also survive a rapid rise in the overlying gas pressure in excess of their critical pressure if they are near enough to the gas-water interface for sufficient gas to reach them by diffusion during the pressure rise. The distance from the interface at which the gas vesicles survive can be used to calculate the diffusivity of the gas through the suspension. A modification of this method can be used to measure the gas-permeability of certain types of cells containing gas vesicles.

Chelating agents and blue-green algae

1974 ◽  
Vol 20 (10) ◽  
pp. 1311-1321 ◽  
Author(s):  
Willy Lange
Keyword(s):  
Microcystis Aeruginosa ◽  
Green Algae ◽  
Chelating Agents ◽  
Algal Species ◽  
Anacystis Nidulans ◽  
Water Soluble ◽  
Nostoc Muscorum ◽  
Artificial Agents ◽  
Blue Green Algae ◽  
Anabaena Circinalis

Many planktonic blue-green algae produce natural chelators which enable them to grow at high pH's in the absence of artificial chelators. The growth of 10 cyanophytes without an added chelator was found to differ widely with the algal species. Bacteria-containing cultures of Anabaena cylindrica, Anacystis nidulans, Lyngbya sp., Microcystis aeruginosa, Nostoc muscorum, and Phormidium foveolarum produced their own chelators and grew just as well as the controls with artificial chelating agents. Bacteria-containing cultures of Anabaena circinalis, Gloeotrichia echinulata, Oscillatoria rubescens, and Aphanizomenon flos-aquae did not produce chelators and, in the absence of artificial agents, grew poorly or perished early. The alga-produced, extracellular chelators were water-soluble and capable of chelating and controlling metal compounds that would exist in colloidal form at pH's above 7. Accordingly, in the absence of artificial chelators, the non-chelator-forming species grew in the filtrates of the chelator-forming algae the same as in the presence of artificial agents. Bacteria were not involved in the formation of natural chelators, since axenic cultures of Anabaena circinalis, Anacystis nidulans, Microcystis aeruginosa, Nostoc muscorum, and Phormidium foveolarum in the absence of artificial chelators performed about the same as the bacteria-associated species. Also, the filtrates of axenic, chelator-forming Anacystis cultures had the same growth-stimulating effect on non-chelator-forming species as filtrates from bacteria-associated cultures. The natural chelators showed partial thermolability.While the growth of chelator-forming species in the absence of artificial chelators was normal during the logarithmic phase, a peculiar, continuing production of total organic matter was observed with strongly declining cell numbers of Lyngbya, Microcystis, and Phormidium. The terminal cultures of these species were gelatinous, owing to the presence of extracellular matter, probably consisting of polysaccharides.

Structure of the gas vesicle protein GvpF from the cyanobacteriumMicrocystis aeruginosa

2014 ◽  
Vol 70 (11) ◽  
pp. 3013-3022 ◽  
Author(s):  
Bo-Ying Xu ◽  
Ya-Nan Dai ◽  
Kang Zhou ◽  
Yun-Tao Liu ◽  
Qianqian Sun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Gene Cluster ◽  
Microcystis Aeruginosa ◽  
Immunogold Labelling ◽  
Gas Vesicles ◽  
Structural Protein ◽  
Apparent Variation ◽  
Vesicle Protein

Gas vesicles are gas-filled proteinaceous organelles that provide buoyancy for bacteria and archaea. A gene cluster that is highly conserved in various species encodes about 8–14 proteins (Gvp proteins) that are involved in the formation of gas vesicles. Here, the first crystal structure of the gas vesicle protein GvpF fromMicrocystis aeruginosaPCC 7806 is reported at 2.7 Å resolution. GvpF is composed of two structurally distinct domains (the N-domain and C-domain), both of which display an α+β class overall structure. The N-domain adopts a novel fold, whereas the C-domain has a modified ferredoxin fold with an apparent variation owing to an extension region consisting of three sequential helices. The two domains pack against each otherviainteractions with a C-terminal tail that is conserved among cyanobacteria. Taken together, it is concluded that the overall architecture of GvpF presents a novel fold. Moreover, it is shown that GvpF is most likely to be a structural protein that is localized at the gas-facing surface of the gas vesicle by immunoblotting and immunogold labelling-based tomography.

scholarly journals Formation of Gas Vesicles in Phosphorus-limited Cultures of Microcystis aeruginosa

Microbiology ◽  
1989 ◽  
Vol 135 (7) ◽  
pp. 1933-1939 ◽  
Author(s):  
J. Kromkamp ◽  
A. Van Den Heuvel ◽  
L. R. Mur
Keyword(s):  
Microcystis Aeruginosa ◽  
Gas Vesicles

scholarly journals The Gas Vesicle Gene Cluster from Microcystis aeruginosa and DNA Rearrangements That Lead to Loss of Cell Buoyancy

2004 ◽  
Vol 186 (8) ◽  
pp. 2355-2365 ◽  
Author(s):  
Alyssa Mlouka ◽  
Katia Comte ◽  
Anne-Marie Castets ◽  
Christiane Bouchier ◽  
Nicole Tandeau de Marsac
Keyword(s):  
Electron Microscopy ◽  
Gene Cluster ◽  
Microcystis Aeruginosa ◽  
Gas Vesicles ◽  
Structural Protein ◽  
Dna Rearrangements ◽  
Unicellular Cyanobacterium ◽  
Laboratory Cultures ◽  
Insertion Elements ◽  
Freshwater Environments

ABSTRACT Microcystis aeruginosa is a planktonic unicellular cyanobacterium often responsible for seasonal mass occurrences at the surface of freshwater environments. An abundant production of intracellular structures, the gas vesicles, provides cells with buoyancy. A 8.7-kb gene cluster that comprises twelve genes involved in gas vesicle synthesis was identified. Ten of these are organized in two operons, gvpAI AII AIII CNJX and gvpKFG, and two, gvpV and gvpW, are individually expressed. In an attempt to elucidate the basis for the frequent occurrence of nonbuoyant mutants in laboratory cultures, four gas vesicle-deficient mutants from two strains of M. aeruginosa, PCC 7806 and PCC 9354, were isolated and characterized. Their molecular analysis unveiled DNA rearrangements due to four different insertion elements that interrupted gvpN, gvpV, or gvpW or led to the deletion of the gvpAI -AIII region. While gvpA, encoding the major gas vesicle structural protein, was expressed in the gvpN, gvpV, and gvpW mutants, immunodetection revealed no corresponding GvpA protein. Moreover, the absence of a gas vesicle structure was confirmed by electron microscopy. This study brings out clues concerning the process driving loss of buoyancy in M. aeruginosa and reveals the requirement for gas vesicle synthesis of two newly described genes, gvpV and gvpW.

The pressure relationships of gas vacuoles

1971 ◽  
Vol 178 (1052) ◽  
pp. 301-326 ◽  
Keyword(s):  
Critical Pressure ◽  
Sucrose Solution ◽  
Turgor Pressure ◽  
Gas Vesicles ◽  
Vesicle Membrane ◽  
Collapse Pressure ◽  
Blue Green Algae ◽  
Gas Vacuoles ◽  
Cell Turgor ◽  
Purple Sulphur Bacterium

The gas vacuoles which occur in various prokaryotic organisms can be estimated quantitatively by the change in light scattering which takes place when they are destroyed by pressure. The gradual disappearance of gas vacuoles under rising pressure is explained by the intrinsic variation in critical collapse pressure of their constituent gas vesicles. These collapse instantaneously at pressures exceeding their critical pressure, but withstand repeated and prolonged application of pressures below this value. Gas vesicle membranes are freely permeable to gases, and as a consequence the vacuole gas is at atmospheric pressure in aerated suspensions. Increasing or decreasing the pressure of gas in the gas vacuoles brings about a corresponding change in the pressure required to collapse them, indicating that the vacuole gas helps to support the structure. Pressures in excess of the vacuole gas pressure are borne by the membrane itself. The pressure required to collapse gas vacuoles present in blue-green algae is increased if the cells are suspended in a hypertonic sucrose solution, because this removes the cell turgor pressure acting on them. This observation, which confirms the classical theory on the osmotic relationships of plant cells, provides the first reliable method of estimating turgor pressures in prokaryotic organisms. Cell turgor pressure was found to be higher in a blue-green alga than in a purple sulphur bacterium investigated; no cell turgor could be detected in a halobacterium which grows in saturated brines, suggesting that the salt concentration must be the same inside and outside the cell. The gas vesicles in these organisms seemed to be adapted to withstand the pressures they were likely to encounter, those of the alga being the strongest, and those of the halobacterium the weakest. Even so, the range of turgor pressure overlapped the critical pressure range of the gas vesicles in the alga and purple sulphur bacterium so that turgor pressure alone may effect their collapse under certain circumstances. With the alga this seems to happen in conditions promoting photosynthesis, providing the organism with a means of regulating its buoyancy. It is suggested that the width of a gas vesicle is important in determining its strength, and that this explains the differences in size and shape of the gas vesicles which have evolved in the three organisms. Interfacial tension could in theory exert considerable pressures on the highly curved surface of a gas vesicle but this effect would be minimized if its outer surface were of a hydrophilic nature. Several observations have been made which support this idea. Pressures generated by centrifugation will collapse isolated gas vesicles and must be considered when using this technique to purify them. Sufficient pressure to collapse gas vesicles can also be developed in small columns by the massive negative accelerations developed in collisions. This phenomenon, which may have application in engineering fields, must also be reckoned with in handling these pressure-sensitive structures. It is concluded that even though the gas vesicle membrane must tear during its collapse, the gas it contains diffuses away rather than escaping as a bubble.

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