Cyanobacterial occurrence and detection of microcystin by planar chromatography in surface water of Billings and Guarapiranga Reservoirs, SP, Brazil

Abstract

-(Cyanobacterial occurrence and detection of microcystins by planar chromatography in surface water of Billings and Guarapiranga Reservoirs, SP, Brazil). Billings and Guarapiranga Reservoirs were deeply affected by environmental disturbances, which more evident consequence are the cyanobacterial blooms. Microcystins are the most common cyanotoxin in freshwaters and more than 70 types are known. Different methods for microcystins analysis in water can be used, among which ELISA and HPLC are the most frequently employed. However, less sophisticated and more economic methods can also be used. This is the case of planar chromatography (thin-layer chromatography) method previously used in cyanotoxins purification but gradually replaced by others. Posterior optimization of the microcystin chromatography conditions and because of its simplicity, rapidity, efficiency and low cost, this method is again considered an option for the analysis of microcystins and nodularins. Considering the importance of Billings and Guarapiranga Reservoirs for drinking water supplies and the few scientific data about cyanobacteria and cyanotoxins in these water bodies, the aims of this work are to analyze the biodiversity of cyanobacteria in the Billings and Guarapiranga Reservoirs and the detection of dissolved microcystins in the water. It was possible to identify 17 species of cyanobacteria, 9 of them being potentially toxic. In Billings Reservoir Microcystis aeruginosa (Kützing) Kützing and Cylindrospermopsis raciborskii (Woloszynska) Seenayya & Subba Raju are the most common species, while in Guarapiranga Reservoir only M. aeruginosa was considered as a common species. Microcystins were detected in all Billings Reservoir samples and in only one sample from Guarapiranga Reservoir.Key words -cyanobacteria, drinking water, microcystins, planar chromatography, reservoirs RESUMO -(Ocorrência de cianobactérias e detecção por cromatografia planar de microcistinas dissolvidas nas águas superficiais das represas Billings e de Guarapiranga, SP, Brasil). As represas Billings e Guarapiranga foram profundamente afetadas por fatores ambientais cuja conseqüência mais evidente são as florações de cianobactérias. As microcistinas formam a classe de cianotoxinas mais freqüente em água doce e são comumente analisadas por ELISA ou CLAE. No entanto, processos menos sofisticados e mais econômicos também podem ser usados. Este é o caso da cromatografia planar (cromatografia em camada delgada), método anteriormente usado em trabalhos de purificação de cianotoxinas, mas que foi gradualmente substituído por outros. Assim, considerando a importância das represas Billings e Guarapiranga para o abastecimento público e a carência de informações científicas sobre as cianobactérias e as cianotoxinas que nelas ocorrem, nossos objetivos foram o estudo da composição desses organismos e a detecção de microcistina dissolvida na água. Foi possível identificar 19 espécies de cianobactérias, das quais 9 são consideradas potencialmente tóxicas. Microcystis aeruginosa...

Toxic Cyanobacteria in Four Brazilian Water Supply Reservoirs

“…Concentrations above 20,000 cells·ml -1 were recorded at all studied reservoirs. The high number of cyanobacteria cells and the presence of several taxa known as toxin producers found in the samples from Billings reservoir ( Table 1) have also been reported by other authors [13,20]. While evaluating the same samples used in the present work, Bittencourt-Oliveira et al [10] found concentrations of microcystins ranging from 0.43 to 2.27 µg·L -1 (Table 1).…”

Occurrence of Ceratium furcoides (Levander) Langhans 1925 bloom at the Billings Reservoir, São Paulo State, Brazil

“…For a long time, the dominant phytoplankton community on the Billings Reservoir was Cianophyceae, according to Carvalho et al (2007), and many articles on the phytoplankton of the Billings Reservoir described the transformation The phytoplankton samples were collected by vertical hauls using a plankton net with 20 µm of aperture and the concentrate material was fixed with formalin solution 4%. Qualitative and quantitative analyses of different groups were carried out by optic microscopy (Leica DMLB German), using a Sedgwick Rafter Counting Chamber with zoom of 200× and a subsample of 1.0 mL.…”

A comunidade fitoplanctônica nas represas Billings e Guarapiranga (região metropolitana de São Paulo)

“…The long retention time of Guarapiranga reservoir (185 days, CARVALHO et al, 2007) is one of the possible factors promoting the compartmentalization of the reservoir in zones exhibiting different characteristics on water quality. However, long retention time does not promote direct advective effects of water renewal on phytoplankton abundance (KIMMEL et al, 1990), interfering on the formation of clear compartments based on phytoplankton biomass.…”