Phytotoxicity of vancomycin: seed germination and root elongation in some crops

During last decades, the production and consumption of antibiotics have increased rapidly worldwide. This overuse has been highlighted as one of the biggest emerging threats to human health and ecosystems, due to the undesirable effects related to the antibiotics released into the environment. Most research focused on antibiotic resistance spread, whereas the toxicity to plants remained a quite unexplored field. Agricultural systems are recognized as a potentially significant source of antibiotics to the aquatic environment due to runoff and leaching after biosolid application from wastewater treatment plants, manure from livestock operations, or excretion from free-ranging livestock, but their effects on crops have not been well documented yet. The present study aimed at assessing the phytotoxic effects of a glycopeptide antibiotic (vancomycin) on seed germination of four different crops (Solanum lycopersicum cv. Crovarese, Solanum lycopersicum cv. San Marzano, Eruca sativa, Diplotaxis tenuifolia) during a short-term exposure (7 d). Crops were exposed to a range of concentrations (0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 7.5, 10, 15, 22 mg/L) of vancomycin. Root and shoot emergence and final length, root elongation rate and total biomass were used as endpoints. Data were analysed by multivariate exploration with a Generalised Canonical Discriminant Analysis - modelling of parameter-dose relationships via Generalised Additive Models. Results showed that vancomycin can significantly affect the germination of all the analysed cultivars, with the only exception of S. lycopersicum cv. San Marzano.