Viral Community and Virus-Associated Antibiotic Resistance Genes in Soils Amended with Organic Fertilizers

Antibiotic resistance is a global health concern. Long-term organic fertilization can influence the antibiotic resistome of agricultural soils, posing potential risks to human health. However, little is known about the contribution of viruses to the dissemination of antibiotic resistance genes (ARGs) in this context. Here, we profiled the viral communities and virus-associated ARGs in a long-term (over 10 years) organic fertilized field by viral metagenomic analysis. A total of 61,520 viral populations (viral operational taxonomic units, vOTUs) were retrieved, of which 21,308 were assigned at the family level. The viral community structures were significantly correlated with the bacterial community structures (P < 0.001) and the dosage of applied sewage sludge (r2 = 0.782). A total of 16 unique ARGs were detected in soil viromes, and the number of virus-associated ARG subtypes was higher in sewage sludge treatments (except for 1 SS) than others. The network analysis showed that the application of the organic fertilizer increased the bacteria–virus interactions, suggesting that the chances of ARG exchange between viruses and their hosts may increase. Overall, our results provide a novel understanding about virus-associated ARGs and factors affecting the profile of viral community in fertilized soil.