Unveiling new abilities of actinobacteria: Proficiency in the bioremoval of the emerging contaminant ivermectin

Emerging contaminants are synthetic or natural compounds that remain largely unregulated in the environment but may pose ecological and health risks. Among them is ivermectin, widely used to treat bovine parasitosis and, more recently, human viral infections. Bioremediation using actinobacteria represents a promising strategy for removing such compounds, given their remarkable metabolic versatility and ability to detoxify contaminants. This study aimed to evaluate the ability of actinobacteria to remove ivermectin. A qualitative screening assay was conducted using 12 strains on solid media. Nine of them showed tolerance and were subsequently cultured in liquid medium supplemented with ivermectin (0.1 g L^-1), either as the sole carbon source or in combination with glucose, at 30 °C for 7 days under agitation. In parallel, a robust and validated HPLC-based method for ivermectin extraction and quantification was established. The strains showed differential performance when cultured with either ivermectin or ivermectin plus glucose. Notably, five strains showed growth using ivermectin as the sole carbon source. Among them, Streptomyces spp. ER1 and SG1 achieved the highest rates of ivermectin removal in the presence of glucose, reaching 84 % and 61 % elimination, respectively. This study provides the first evidence of Streptomyces strains capable of utilizing IVM as a sole carbon source and achieving high removal rates via co-metabolism, highlighting their unique potential for bioremediation applications.