Metagenomic analysis reveals environmental drivers of Actinobacteriota-associated antibiotic resistance and biosynthetic genes in colombian caribbean resource islands

Resource islands (RIs) or fertility islands are patches of vegetation in semi-arid regions known to serve as sources of bioactive compounds. However, the effects of seasonality and the presence of nurse trees on microbial diversity and functional potential in these microhabitats are not well understood. This study aimed to determine how these factors influence the abundance of Actinobacteriota and genes associated with antimicrobial resistance and biosynthesis in a semi-arid region of the Colombian Caribbean. Soil samples were collected under the canopy of three nurse trees (V: vegetation) and in bare soil without vegetation influence (C: control) during wet (W) and dry (D) seasons. Shotgun sequencing revealed a higher abundance of Actinobacteriota in the CD samples, with Solirubrobacterales, Frankiales, Propionibacteriales, and Pseudonocardiales being the most represented orders. Sixteen biosynthetic pathways for antimicrobial compounds were identified, with monobactam antibiotics, prodigiosin, and streptomycin representing the most abundant compounds, predominantly in VD. Additionally, ten antibiotic resistance pathways, such as rifamycin, MLS, tetracycline, aminoglycosides, and quinolones, were more prevalent in VW. These findings indicate that seasonality and vegetation in RIs significantly influence Actinobacteriota biodiversity and the distribution of resistance and biosynthetic genes, highlighting RIs as vital reservoirs of microbial diversity and potential sources of novel bioactive compounds in arid ecosystems.