The Amazon region contains a great diversity of species, and the Amazon River basin accounts for almost 20% of all the freshwater in the world. Despite the favorable environmental conditions in this region, little is known about the cyanobacterial diversity of this waterbody, especially at the mouth of the river. In this paper, we used the polyphasic approach to identify 14 cyanobacterial strains isolated in the Amazon River on the inlet site from a drinking water supply located close to the river mouth. The isolated strains were characterized based on morphology, behavior in culture, 16S rRNA gene sequencing, phylogenetic analysis and potential for toxin production. The isolated strains belong to seven different genera, namely, Alkalinema, Cephalothrix, Limnothrix, Leptolyngbya, Phormidium, Pseudanabaena and an unidentified Nostocales taxa that may represent a new genus. Strikingly, there were no new species, nor detection of gene clusters associated with cyanotoxin production. However, the phylogenetic placements of the Amazonian strains of Limnothrix and Pseudanabaena provide new insight into the taxonomy of these genera, reinforcing the need for taxonomic revision.
Human poisoning by microcystin has been recorded in many countries, including Brazil, where fatal cases have already occurred. The Amazon River is the main source of drinking water in municipalities such as Macapá, where there is no monitoring of cyanobacteria and cyanotoxins. This study investigated the presence of cyanobacteria and cyanotoxins in samples from a drinking water treatment plant (DWTP) that catches water from the Amazon River. The toxin analyses employed ELISA, LC/MS, and molecular screening for genes involved in the production of cyanotoxins. The sampling was carried out monthly from April 2015 to April 2016 at the intake (raw water) and exit (treated water) of the DWTP. This study reports the first detection of microcystin-LR (MC-LR) in the Amazon River, the world’s largest river, and in its treated water destined for drinking water purposes in Macapá, Brazil. The cyanobacterial density and MC-LR concentration were both low during the year. However, Limnothrix planctonica showed a density peak (± 900 cells mL−1) in the quarter of June–August 2015, when MC-LR was registered (2.1 µg L−1). Statistical analyses indicate that L. planctonica may produce the microcystin.
O fitoplâncton é formado por microalgas e cianobactérias, fornecedores de oxigênio para o meio aquático. Em ecossistemas desequilibrados esses organismos podem se multiplicar e produzir toxinas que afetam a saúde humana e animal. Este estudo teve como objetivo identificar padrões de densidade no fitoplâncton da água bruta da ETAm e relacionar a influência de fatores físicos, químicos e ambientais sobre a densidade das espécies. As amostragens foram realizadas entre maio de 2019 e agosto de 2020 (exceto em março-maio/2020, devido ao isolamento social). Foram identificados 86 táxons: Bacillariophyta (45), Cyanophyta (18), Chlorophyta (10), Charophyta (10), Dinophyta (1), Euglenophyta (1) e Rhodophyta (1), sendo as cianobactérias e diatomáceas os grupos mais abundantes. E as espécies mais abundantes foram Aulacoseira granulata e Limnothrix planctonica, respectivamente. Em relação à densidade de cianobactérias, observou-se que há padrão de aumento no período maio-agosto similar aos anos anteriores (2015-2016). Porém a densidade de cianobactérias observada neste estudo em 2019 (7083,2 cels. mL-1) foi 7x maior que em anos anteriores (1090 cels.mL-1 em 2015), todavia ainda estão em conformidade com os padrões estabelecidos pelo Ministério da Saúde (<10.000 cels.mL-1). Em junho e julho de 2020, quando era esperado o pico de cianobactérias, ocorreu queda expressiva na densidade. Pode-se inferir que isto ocorreu pela relação entre o aumento do isolamento social em Macapá e a diminuição da abundância de cianobactérias observada neste período de 2020 (R2= 0,94). Quanto à influência dos parâmetros ambientais, a transparência da água foi o parâmetro com maior influência na densidade de cianobactérias.
Phytoplankton is formed by photosynthesizing microorganisms that act as primary producers in distinct water bodies. These include microalgae and cyanobacteria. It is essential to know the phytoplankton in water catchment areas intended for drinking water treatment once their excessive density may result in problems, such as taste and odor in the water, toxin production, filter clogging, and other damages. This study investigated the phytoplankton dynamics and the environmental factors that may influence phytoplankton density in the drinking water catchment zone of Macapá, a city located on the Amazon River mouth. The sampling was carried out monthly from April/2015 to March/2016. The study reports the first detailed information on the phytoplankton in the study area since previously published studies regarded only cyanobacteria. The species Limnothrix planctonica and Aulacoseira granulata may substantially influence the water treatment due to their great abundance in the study area, especially in July and November, when their density peaks occur, respectively. Nevertheless, Aulacoseira granulata is the primary constituent of the phytoplankton biovolume. This study provides biological and sanitary information to guide public administration towards improving the quality and safety of water supply services, and also to increase the biodiversity knowledge of Amazonian phytoplankton.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.