Accumulation of Microcystin from Oscillatoria limnetica Lemmermann and Microcystis aeruginosa (Kützing) in Two Leafy Green Vegetable Crop Plants Lactuca sativa L. and Eruca sativa

Abstract

The use of contaminated water to irrigate crop plants poses a risk to human health from the bioaccumulation potential of microcystins (MCs) in the edible tissues of vegetable plants. The main objective of this study is to determine the concentration of total microcystins (MC-LR and MC-RR) in leafy green plants (Lactuca sativa L. var. longifolia and Eruca sativa) that have previously been irrigated with polluted water. Integrated water samples were collected by cleaned plastic bottles at a depth of about 30 cm from one of the sources of water used to irrigate agricultural lands for crop plants. At the same time, samples from plants were also collected because this water from the lake farm is used for the irrigation of surrounding vegetable plants such as Lactuca sativa L. var. longifolia and Eruca sativa. The dominant species of cyanobacteria in water samples are Microcystis aeruginosa (Kützing) and Oscillatoria limnetica Lemmermann, which were detected with an average cell count 2,300,000 and 450,000 cells/mL, respectively. These two dominant species in water produced two MCs variants (MC-LR, -RR) that were quantified by high-performance liquid chromatography (HPLC). Dissolve and particulate MCs were detected in the irrigation waters by HPLC with concentrations of 45.04–600 μg/L. MCs in the water samples exceeded the WHO safety limit (1 μg/L) of MC in drinking water. In addition, the total concentration of Microcystin in Lactuca sativa L. var. longifolia and Eruca sativa were 1044 and 1089 ng/g tissues, respectively. The estimated daily intake (EDI) of microcystins by a person (60 kg) consuming 300 g of fresh plants exceeded the total daily intake guidelines (0.04 μg kg−1 body weight) for human food consumption. According to the findings of this study, irrigation water and plants used for human consumption should be tested for the presence of MCs regularly through critical and regularly monitored programs to prevent the accumulation and transfer of such toxins through the food web.

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“…Os resultados indicaram níveis de bioacumulação que excedem até 4 vezes o IDT da OMS, em caso de ingestão dessas hortaliças. Bakr et al (2022) avaliaram cultivos de alface e rúcula irrigados com águas de um lago no Sul do Egito, contendo entre 45-600 μg MCs.L -1 . A pesquisa revelou a bioacumulação de MCs em ambas as hortaliças, alcançando níveis que ultrapassariam o IDT com o consumo de 300 g desses vegetais.…”

Microcystin-LR Induces and Aggravates Colitis through NLRP3 Inflammasome-Mediated Pyroptosis in Mice

“…Via the aforementioned routes, MC-LR accumulates in the human body. Existing studies have shown that the adult EDI of MCs in plants ranges from 3480–3630 ng/kg/d, both of which are 87–90-fold higher than the WHO detection limit [ 25 ], and the mean concentrations of MCs in the kidney, liver, and muscle of the silver carp were 45.1, 40.0, and 29.1 ng/g, dm, respectively. However, in the presence of dense cyanobacteria blooms, the mean concentrations of MCs in the kidney, liver, and muscle of the silver carp were 782, 957, and 197 ng/g, dm, respectively.…”

Allelopathic Potential of the Cyanotoxins Microcystin-LR and Cylindrospermopsin on Green Algae

“…Microcystins have been shown to cause adverse allelopathic effects on both higher plants [ 33 , 34 , 35 , 36 , 37 ] and phytoplankton [ 9 , 25 , 38 , 39 ]. For example, the three most commonly detected forms of microcystin in water bodies (MC-LR, MC-RR, and MC-YR) cause morphological and physiological changes in Scenedesmus quadricauda , inducing cell aggregation, increasing cell volume, and increasing the production of photosynthetic pigments.…”