Hydrogenase from the unicellular cyanobacterium, Microcystis aeruginosa

1987 ◽  
Vol 26 (3) ◽  
pp. 637-640 ◽  
Author(s):  
Yasuo Asada ◽  
Sugio Kawamura ◽  
Kwok-Ki Ho
Keyword(s):  
Microcystis Aeruginosa ◽  
Unicellular Cyanobacterium

scholarly journals The mcyF gene of the microcystin biosynthetic gene cluster from Microcystis aeruginosa encodes an aspartate racemase

2003 ◽  
Vol 373 (3) ◽  
pp. 909-916 ◽  
Author(s):  
Heike SIELAFF ◽  
Elke DITTMANN ◽  
Nicole TANDEAU de MARSAC ◽  
Christiane BOUCHIER ◽  
Hans von DÖHREN ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Microcystis Aeruginosa ◽  
Biosynthetic Gene Cluster ◽  
Sequence Motifs ◽  
Independent Manner ◽  
Unicellular Cyanobacterium ◽  
Reading Frame ◽  
Glutamate Racemase ◽  
Aspartate Racemase ◽  
Mcy Gene

Microcystins are hepatotoxic, non-ribosomal peptides produced by several genera of freshwater cyanobacteria. Among other enzymic activities, in particular those of peptide synthetases and polyketide synthases, microcystin biosynthesis requires racemases that provide d-aspartate and d-glutamate. Here, we report on the cloning, expression and characterization of an open reading frame, mcyF, that is part of the mcy gene cluster involved in microcystin biosynthesis in the Microcystis aeruginosa strain PCC 7806. Conserved amino acid sequence motifs suggest a function of the McyF protein as an aspartate racemase. Heterologous expression of mcyF in the unicellular cyanobacterium Synechocystis PCC 6803 yielded an active His6-tagged protein that was purified to homogeneity by Ni2+-nitriloacetate affinity chromatography. The purified recombinant protein racemized in a pyridoxal-5′-phosphate-independent manner l-aspartate, but not l-glutamate. Furthermore, we have identified a putative glutamate racemase gene that is located outside the mcy gene cluster in the M. aeruginosa PCC 7806 genome. Whereas homologues of this glutamate racemase gene are present in all the Microcystis strains examined, mcyF could only be detected in microcystin-producing strains.

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.

Structure and Replication of Cryptic Plasmids, pMA1 and pMA2, from a Unicellular Cyanobacterium,Microcystis aeruginosa

1995 ◽  
Vol 59 (7) ◽  
pp. 1217-1220 ◽  
Author(s):  
Hiroshi Tominaga ◽  
Shouichi Kawagishi ◽  
Hiroyuki Ashida ◽  
Yoshihiro Sawa ◽  
Hideo Ochiai
Keyword(s):  
Microcystis Aeruginosa ◽  
Unicellular Cyanobacterium ◽  
Cryptic Plasmids

Influence of increased nutrient supply on Microcystis aeruginosa at cellular and proteomic levels

2020 ◽  
Vol 85 ◽  
pp. 47-58
Author(s):  
Y Jiang ◽  
Y Liu
Keyword(s):  
Microcystis Aeruginosa ◽  
Regulatory Protein ◽  
Acid Synthesis ◽  
Nutrient Supply ◽  
Nitrogen Supply ◽  
Nitrogen And Phosphorus ◽  
Comprehensive Description ◽  
Amino Acid Synthesis ◽  
High Nutrient ◽  
Proteomic Responses

Various studies have observed that increased nutrient supply promotes the growth of bloom-forming cyanobacteria, but only a limited number of studies have investigated the influence of increased nutrient supply on bloom-forming cyanobacteria at the proteomic level. We investigated the cellular and proteomic responses of Microcystis aeruginosa to elevated nitrogen and phosphorus supply. Increased supply of both nutrients significantly promoted the growth of M. aeruginosa and the synthesis of chlorophyll a, protein, and microcystins. The release of microcystins and the synthesis of polysaccharides negatively correlated with the growth of M. aeruginosa under high nutrient levels. Overexpressed proteins related to photosynthesis, and amino acid synthesis, were responsible for the stimulatory effects of increased nutrient supply in M. aeruginosa. Increased nitrogen supply directly promoted cyanobacterial growth by inducing the overexpression of the cell division regulatory protein FtsZ. NtcA, that regulates gene transcription related to both nitrogen assimilation and microcystin synthesis, was overexpressed under the high nitrogen condition, which consequently induced overexpression of 2 microcystin synthetases (McyC and McyF) and promoted microcystin synthesis. Elevated nitrogen supply induced the overexpression of proteins involved in gas vesicle organization (GvpC and GvpW), which may increase the buoyancy of M. aeruginosa. Increased phosphorus level indirectly affected growth and the synthesis of cellular substances in M. aeruginosa through the mediation of differentially expressed proteins related to carbon and phosphorus metabolism. This study provides a comprehensive description of changes in the proteome of M. aeruginosa in response to an increased supply of 2 key nutrients.

Inhibitory effects of Cyperus alternifolius on growth of Microcystis aeruginosa and identification of algicidal substances

2019 ◽  
Vol 46 (1) ◽  
pp. 73-84
Author(s):  
L. Zhou ◽  
S. Nakai ◽  
G. F. Chen ◽  
Q. Pan ◽  
N. X. Cui ◽  
...  
Keyword(s):  
Microcystis Aeruginosa ◽  
Inhibitory Effects ◽  
Cyperus Alternifolius

Asymmetric warming enhances Microcystis aeruginosa resistance to macrophytic anti-cyanobacterial coumarin

2018 ◽  
Vol 43 (2) ◽  
pp. 265-274 ◽  
Author(s):  
W.X. Hong ◽  
S.P. Zuo ◽  
L.T. Ye ◽  
B.Q. Qin
Keyword(s):  
Microcystis Aeruginosa

Screening of Extremophile Microalgae Isolated from High Background Radiation Areas as Source of Bioactive Materials

2020 ◽  
Vol 16 (4) ◽  
pp. 407-414
Author(s):  
Fatemeh Heidari ◽  
Zeinab Shariatmadari ◽  
Hossein Riahi
Keyword(s):  
Antioxidant Activity ◽  
Hot Springs ◽  
Background Radiation ◽  
Cadmium Stress ◽  
Total Phenol ◽  
Total Phenolic ◽  
Extreme Conditions ◽  
Unicellular Cyanobacterium ◽  
High Background ◽  
Cadmium Adsorption

Background: Microalgae are the source of various compounds with high potentials for being used in different industries. The production of such compounds can be raised under extreme conditions. In the present study, four cyanobacteria and one coccoid green alga were examined which were isolated from hot springs in high background radiation areas in Ramsar, a city in the north of Iran. Methods: Cadmium adsorption from aqueous solution, response towards cadmium stress, antioxidant activity, total phenolic compound and drought tolerance were investigated in these microalgae. Results: The results showed that these extremophile microalgae contain valuable biological compounds which can be useful in remediation of heavy metals from contaminated water and soils and pharmaceutical applications. The unicellular cyanobacterium, Chroococidiopsis thermalis IBRC-M50002, was the best strain with the highest biological activity in various testes such as cadmium adsorption (225 mg g-1), cadmium tolerance stress (100 mg ml-1), antioxidant activity (IC50= 18 μg mg-1) and total phenol content (100 μg ml-1). The coccoid green algae Grasiella emersonii IBRC-M50001, also exhibited significant antioxidant activity (IC50=10 μg mg-1) and total phenol compound (116 μg ml-1), but its cadmium adsorption, tolerance at cadmium stress and desiccation were lower than Chroococidiopsis thermalis. Conclusion: HBRAs microalgae, isolated from extreme conditions, are useful microorganisms for the production of bioactive substances and natural antioxidants. In other words, they exhibited high capacity to be used in pharmaceutical, industrial and commercial applications.

scholarly journals Chemical Characterization of Microcystis aeruginosa for Feed and Energy Uses

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3013
Author(s):  
Larissa Souza Passos ◽  
Éryka Costa Almeida ◽  
Claudio Martin Pereira de Pereira ◽  
Alessandro Alberto Casazza ◽  
Attilio Converti ◽  
...  
Keyword(s):  
Microcystis Aeruginosa ◽  
Animal Feed ◽  
Renewable Energy Sources ◽  
Chemical Characterization ◽  
Cyanobacterial Blooms ◽  
Energy Sources ◽  
Carbohydrate Source ◽  
Heating Value ◽  
Adverse Health Effects ◽  
Degradation Reactions

Cyanobacterial blooms and strains absorb carbon dioxide, drawing attention to its use as feed for animals and renewable energy sources. However, cyanobacteria can produce toxins and have a low heating value. Herein, we studied a cyanobacterial strain harvested during a bloom event and analyzed it to use as animal feed and a source of energy supply. The thermal properties and the contents of total nitrogen, protein, carbohydrate, fatty acids, lipid, and the presence of cyanotoxins were investigated in the Microcystis aeruginosa LTPNA 01 strain and in a bloom material. Microcystins (hepatotoxins) were not detected in this strain nor in the bloom material by liquid chromatography coupled to mass spectrometry. Thermogravimetric analysis showed that degradation reactions (devolatilization) initiated at around 180 °C, dropping from approximately 90% to 20% of the samples’ mass. Our work showed that despite presenting a low heating value, both biomass and non-toxic M. aeruginosa LTPNA 01 could be used as energy sources either by burning or producing biofuels. Both can be considered a protein and carbohydrate source similar to some microalgae species as well as biomass fuel. It could also be used as additive for animal feed; however, its safety and potential adverse health effects should be further investigated.

Sign in / Sign up

Export Citation Format

Share Document