Migration Characteristics of Manure-Derived Antibiotic-Resistant Bacteria in Vegetables Under Different Soil Types

The application of livestock manure can introduce antibiotic-resistant bacteria (ARB) into soil-vegetable systems, potentially shaping the antibiotic resistance profiles of plants. This study investigated the effects of manure containing chlortetracycline (CTC) on antibiotic resistance in pakchoi grown in three distinct soil types (black soil, fluvo-aquic soil, and red soil). The results demonstrated that CTC-manure application significantly increased the relative abundance of CTC-resistant endophytic bacteria (CREB), with the magnitude of the increase following the order: black soil (235.43%) > fluvo-aquic soil (64.5%) > red soil (10.68%). Furthermore, the presence of CTC promoted the proliferation of <i>Acinetobacter</i> and increased the abundance of potential pathogens (such as <i>Klebsiella</i>, <i>Rhodococcus</i>, and <i>Corynebacterium</i>), thereby elevating the risk of antibiotic resistance transmission. Metabolomic analysis revealed that CTC induced the most substantial metabolic alterations in pakchoi grown in red soil. Correlation analysis indicated that the CREB community structure was primarily shaped by soil properties, including total nitrogen, total phosphorus, and organic matter, and was significantly correlated with indigenous soil ARB (<i>Pseudomonas</i>, <i>Bacillus</i>, and <i>Stenotrophomonas</i>). This study elucidates the mechanisms underlying manure-driven antibiotic resistance dissemination in vegetable production systems and offers a theoretical foundation for developing agricultural practices to mitigate associated risks.