Toxic cyanobacteria and microcystin concentrations in a public water supply reservoir in the Brazilian Amazonia region

• Published in: Toxicon (Oxford) Vol. 45; no. 7; pp. 901 - 909
• Main Authors: Vieira, José Maria dos S., Azevedo, Maria Teresa de P., Azevedo, Sandra Maria Feliciano de Oliveira, Honda, Ricardo Yukio, Corrêa, Benedito
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-06-2005; Elsevier Science
• Subjects: Amazonia; Animals; Aphanizomenon; Bacterial Toxins - analysis; Bacterial Toxins - biosynthesis; Bacteriology; Biological and medical sciences; Brazil; Coelomoron; Cyanobacteria; Cyanobacteria - classification; Cyanobacteria - isolation & purification; Cyanobacteria - metabolism; Cyanophyta; Environmental Monitoring; Fundamental and applied biological sciences. Psychology; Mice; Microbiology; Microcystins; Microcystis; Microcystis viridis; Nostoc; Oscillatoria; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Peptides, Cyclic - analysis; Peptides, Cyclic - biosynthesis; Planktothrix; Radiocystis; Reservoir; Toxic cyanobacteria; Toxicity Tests, Acute; Water Microbiology; Water Pollutants - analysis; Water Pollutants - metabolism; Water Supply; South America; Brazil; America; South America, Amazonia; Amazonia; Reservoir; Toxic cyanobacteria; Microcystins; Human; Drinking water; Toxicity; Cyanobacteria; Bacteria; Specific identification; Biological contamination; Public health
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2005.02.008

Toxic cyanobacteria in public water supply reservoirs represent a serious health risk as they can release potent cyanotoxins into the water. In the present study we analyzed surface water collected from the Utinga Reservoir, the main source of drinking water for the city of Belém-PA, in order to characterize the reservoir's cyanobacterial biota and to determine the toxicity of these organisms and the concentration of microcystins in raw and treated water. The cyanobacterial biota included potentially toxic genera such as
Aphanizomenon,
Microcystis,
Nostoc,
Oscillatoria,
Planktothrix and
Radiocystis. Mouse bioassays revealed a 43.6% frequency of hepatotoxic strains, including 30.8%
Microcystis viridis strains and 12.8%
Radiocystis fernandoi strains, with the lowest LD
100 (
ip) of 45 and 75
mg
kg
−1 body weight, respectively. Subacute hepatotoxicity was observed for
Aphanizomenon cf.
gracile and
Coelomoron pusillum strains. HPLC analysis confirmed the production of microcystins at maximum concentrations of 4.22
μg
mg
−1 dry weight for
M. viridis and 2.47
μg
mg
−1 for
R. fernandoi. Microcystins at concentrations of up to 1.25
μg
L
−1 detected in raw water by ELISA, together with a cyanobacterial density of 20,000 cells mL
−1, represents the first report of a bloom of cyanobacteria for an Amazonian water body.