Antibiotic Resistome Biomarkers associated to the Pelagic Sediments of the Gulfs of Kathiawar Peninsula and Arabian Sea.

Antibiotic resistance has been one of the most persistent global issue. Specifically, marine microbiomes have served as complex reservoirs of antibiotic resistant genes. Molecular advancements have enabled exploration of the uncultured microbial portion from hitherto difficult to sample niches such as deeper oceans. The Gulfs of Kathiawar Peninsula have been known for their unique properties like extreme tidal variations, different sediment textures and physicochemical variations. Pelagic sediment cores across four coordinates each of the Gulf of Kutch, Gulf of Khambhat and an open Arabian Sea were collected, processed for metagenomic sequencing and assessed for antibiotic and metal resistome. The dominant genes were mostly resistant to macrolides, glycopeptides and tetracycline drugs. Studied samples divided into three clusters based on their resistome with carA, macB, bcrA, taeA, srmB, tetA, oleC and sav1866 among the abundant genes. Samples from creek of Gulf of Kutch and mouth of Gulf of Khambhat were most diverse in resistance gene profile. Biomarkers observed include gyrA mutation conferring resistance gene in the Arabian Sea; Proteobacteria species in Gulf of Kutch and Arabian sea; while Aquificae, Acidobacteria and Firmicutes species in the Gulf of Khambhat. Region-wise differentially abundant 23 genes and 3 taxonomic biomarkers were proposed for antibiotic resistance monitoring.