First report of microcystins from a Brazilian isolate of the cyanobacteriumMicrocystis aeruginosa (original) (raw)
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Methods for determining microcystins (peptide hepatotoxins) and microcystin-producing cyanobacteria
Water Research, 2006
Episodes of cyanobacterial toxic blooms and fatalities to animals and humans due to cyanobacterial toxins (CBT) are known worldwide. The hepatotoxins and neurotoxins (cyanotoxins) produced by bloom-forming cyanobacteria have been the cause of human and animal health hazards and even death. Prevailing concentration of cell bound endotoxin, exotoxin and the toxin variants depend on developmental stages of the bloom and the cyanobacterial (CB) species involved. Toxic and non-toxic strains do not show any predictable morphological difference. The current instrumental, immunological and molecular methods applied for determining microcystins (peptide hepatotoxins) and microcystin-producing cyanobacteria are reviewed.
Applied and …, 1990
A strain of the filamentous cyanobacterium Nostoc sp. isolated from a lake in Finland was found to produce at least nine hepatotoxic peptides with chemical and toxicological properties similar to those of the hepatotoxic heptaand pentapeptides produced by other cyanobacteria. Toxins were isolated and purified by highperformance liquid chromatography. Amounts available for five of the purified toxins (P6, P14, P15, P16, and P18) were adequate for high-performance liquid chromatography amino acid analysis and determination of molecular weight by fast-atom bombardment-mass spectrometry (FAB-MS). Quantities of three toxins (P14, P15, and P16) were adequate for further analysis by high-resolution FAB-MS, FAB-MS/MS, and 'H-nuclear magnetic resonance. Analysis showed that the toxins are new types of microcystin-LR homologs. Microcystin-LR contains equimolar amounts of D-alanine, L-leucine, D-erythro-4-methylaspartic acid, L-arginine, ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid), D-glutamic acid, and N-methyldehydroalanine (molecular weight [MW], 994). Nostoc sp. strain 152 was found to produce the following microcystin-LR homologs: (i) P6 contains an extra methylene group most probably due to the presence of N-methyldehydrobutyrine instead of N-methyldehydroalanine (MW, 1,008); (ii) P14 is O-acetyl-O-demethyl ADDA-microcystin-LR (MW, 1,022); (iii) P15 is 3-demethyl-O-acetylADDA-homoarginine-microcystin-LR (MW, 1,036); (iv) P16 is 3-demethyl-O-acetyl-O-demethylADDA-microcystin-LR (MW, 1,008); (v) P18 is 3demethyl-O-acetyl-O-demethylADDA-homoarginine-microcystin-LR (MW, 1,022). The toxicities of the new microcystin homologs were not significantly different from those of microcystin-LR or demethylmicrocystin-LR.
The cyanotoxin-microcystins: current overview
Reviews in Environmental Science and Bio/Technology, 2014
The monocyclic heptapeptides microcystins (MCs), are a group of hepatotoxins, produced worldwide by some bloom-forming cyanobacterial species/strains both in marine and freshwater ecosystems. MCs are synthesized non-ribosomally by large multi-enzyme complexes consisting of different modules including polyketide synthases and non-ribosomal peptide synthetases, as well as several tailoring enzymes. More than 85 different variants of MCs have been reported to exist in nature. These are chemically stable, but undergo bio-degradation in natural water reservoirs. Direct or indirect intake of MCs through the food web is assumed to be a highly exposed route in risk assessment of cyanotoxins. MCs are the most commonly found cyanobacterial toxins that cause a major challenge for the production of safe drinking water and pose a serious threat to global public health as well as fundamental ecological processes due to their potential carcinogenicity. Here, we emphasize recent updates on different modes of action of their possible carcinogenicity. Besides the harmful effects on human and animals, MC producing cyanobacteria can also present a harmful effect on growth and development of agriculturally important plants. Overall, this review emphasizes the current understanding of MCs with their occurrence, geographical distribution, accumulation in the aquatic as well as terrestrial ecosystems, biosynthesis, climate-driven changes in their synthesis, stability and current aspects on its degradation, analysis, mode of action and their ecotoxicological effects.
Toxicological Studies on Microcystin Produced by Microcystis aeruginosa : Assessment and Management
2019
MICROCYSTIS aeruginosa is a kind of cyanobacteria microorganism that synthesizes and produces peptides, which could be highly toxic. The most common toxin known as microcystin (MCs) or cyanotoxins, these toxins are heptapeptides produced by cyanobacterial blooms on water surfaces. They potentially lead to acute to chronic health-related problems via increasing reactive oxygen species (ROS) and irreversible inhibition of serine/threonine protein phosphatases. The toxicological studies of MCs on experimental animal and cell models have promise interests; however, few information is known about their impacts on humans due to acute or chronic exposure. This review article aimed to present some of the information about the cyanotoxins structure, occurrence, and distribution of the cyanobacterial toxins especially excreted from M. aeruginosa. Also, toxicological studies and investigations associated with M. aeruginosa producing microcystin, their assessments and control and health problem...
Applied and Environmental Microbiology
A strain of the filamentous cyanobacterium Nostoc sp. isolated from a lake in Finland was found to produce at least nine hepatotoxic peptides with chemical and toxicological properties similar to those of the hepatotoxic heptaand pentapeptides produced by other cyanobacteria. Toxins were isolated and purified by highperformance liquid chromatography. Amounts available for five of the purified toxins (P6, P14, P15, P16, and P18) were adequate for high-performance liquid chromatography amino acid analysis and determination of molecular weight by fast-atom bombardment-mass spectrometry (FAB-MS). Quantities of three toxins (P14, P15, and P16) were adequate for further analysis by high-resolution FAB-MS, FAB-MS/MS, and 'H-nuclear magnetic resonance. Analysis showed that the toxins are new types of microcystin-LR homologs. Microcystin-LR contains equimolar amounts of D-alanine, L-leucine, D-erythro-4-methylaspartic acid, L-arginine, ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid), D-glutamic acid, and N-methyldehy-
Environmental Science & Technology, 2000
Freshwater cyanobacteria (blue-green algae) can produce numerous potent toxins and represent an increasing environmental hazard. The microcystin content (cyclic heptapeptidic toxins) of the hepatotoxic cyanobacterium Microcystis aeruginosa PCC 7820 was investigated. Ten microcystins were identified using high performance liquid microchromatography (micro HPLC) coupled to either a ultraviolet (UV) diode-array detector (DAD) or an electrospray ionization (ESI) mass spectrometer. Three new variants were identified: desmethylated microcystin LW (mcyst-dMeLW), desmethylated microcystin LF (mcyst-dMeLF), and microcystin LL (mcyst-LL) by Collision-Induced Dissociation/Post-Source Decay Matrix-assisted Laser Desorption/Ionization-Time-of-Flight mass spectrometry (CID/PSD MALDI-TOF MS). The concentration of intracellular microcystins reached 2-8 mg/g of dried cells, with a microcystin LR (mcyst-LR) equivalent of 1-5 mg/g as estimated by protein phosphatase 2A (PP2A) inhibition assay. Toxin production can be correlated to biomass increase up to the middle of the exponential phase of growth and ceases thereafter. Toxin release occurred during the stationary phase, and extracellular microcystin concentration reached 0.25 mg/L. Intracellular microcystin pool composition (MPC) was constant with 51 (2% mcyst-LR, whereas this toxin stood for only 29 (3% of extracellular MPC. Mcyst-LR, the less hydrophobic microcystin, diffuses less easily across membranes. Hydrophobicity might play a key role in microcystin release process.
FEMS Microbiology Letters, 2000
Immunoassays are increasingly used to investigate the production, properties and fates of the cyanobacterial hepatotoxic microcystins in vitro and in vivo. Responses of an ELISA immunoassay to microcystins have been determined using the authentic toxin antigen, microcystin-LR, and conjugation products between the toxin and glutathione, cysteine-glycine and cysteine. The antibodies against microcystin-LR crossreacted with the toxin conjugation products with similar affinities (96^112%) to that of microcystin-LR, when assayed at a concentration of 1 Wg l 31 . Toxicity assessment of the conjugates, in comparison to microcystin-LR, indicated a reduction according to mouse bioassay. In vitro protein phosphatase inhibition assay indicated that the conjugates possessed approximately 3^9-fold lower toxicity than microcystin-LR. ß : S 0 3 7 8 -1 0 9 7 ( 0 0 ) 0 0 2 7 0 -6