College of Public Health, Division of Environmental Health Sciences, The Ohio State University, Columbus, OH, 43210, USA.
Department of Biology, Kyungsung University, Busan, South Korea.
Food Microbiol. 2021 Apr;94:103655. doi: 10.1016/j.fm.2020.103655. Epub 2020 Oct 6.
Cyanobacteria are a threat to the safety of water sources for drinking, recreation, and food production, because some cyanobacteria, such as Microcystis, produce cyanotoxins. However, the colonization of plants by Microcystis and the fate of their toxin, microcystins (MCs), in agricultural environments have not been thoroughly studied. This study examined the colonization of lettuce, as a representative of leafy greens, by Microcystis and its potential impact on food safety and crop health. The surfaces of lettuce leaves were exposed to environmentally relevant concentrations of M. aeruginosa (10, 10, and 10mcyE gene copies/mL) by mimicking contamination scenarios during cultivation, such as spraying irrigation with contaminated water or deposits of airborne Microcystis. Scanning electron microscope (SEM) and droplet digital PCR were used. The results showed that M. aeruginosa colonized the surface of leaves and MCs accumulated in the edible part of the lettuce (>20 μg/kg of lettuce). Crop productivity (length, weight, and number of leaves) was negatively affected. The SEM images provide evidence that M. aeruginosa deposited on the lettuce surface can be internalized via natural opening sites of the leaves and then proliferate within the plants. Our findings imply that toxic cyanobacteria contamination in agricultural environments can be a significant cyanotoxin exposure pathway.
蓝藻是饮用水、娱乐和食品生产水源安全的威胁，因为一些蓝藻，如微囊藻，会产生蓝藻毒素。然而，微囊藻在植物上的定殖及其毒素微囊藻毒素（MCs）在农业环境中的命运尚未得到彻底研究。本研究考察了微囊藻对生菜（作为绿叶蔬菜的代表）的定殖及其对食品安全和作物健康的潜在影响。通过模拟栽培过程中的污染情景，如用受污染的水喷雾灌溉或空气传播的微囊藻沉积物，使生菜叶片表面暴露于环境相关浓度的铜绿微囊藻（10、10 和 10mcyE 基因拷贝/mL）。扫描电子显微镜（SEM）和液滴数字 PCR 用于检测。结果表明，铜绿微囊藻定殖于叶片表面，且 MCs 在生菜可食用部分积累（超过 20μg/kg 生菜）。作物生产力（长度、重量和叶片数）受到负面影响。SEM 图像提供了证据表明，沉积在生菜表面的铜绿微囊藻可以通过叶片的自然开口部位进入植物内部，并在植物内部增殖。我们的研究结果表明，农业环境中有毒蓝藻的污染可能是一种重要的蓝藻毒素暴露途径。
