Metagenomic profiling reveals structural composition and functions of the microbial community in the mangrove (Avicennia marina) rhizosphere of Pattani Bay, Thailand

Mangrove ecosystems in Pattani Bay (Thailand) face increasing anthropogenic threats. In this harsh environment, microbial activity is essential for maintaining ecosystem functioning, productivity, and resilience. This study used amplicon and shotgun metagenomic sequencing to characterize the diversity, abundance, and broad functional potential of mangrove rhizosphere prokaryotic communities across five locations. Physicochemical properties and the accumulation of potentially toxic elements (PTEs) were also analyzed. 16S rRNA gene analysis revealed that Proteobacteria dominated across all locations, followed by Bacteroidota, Acidobacteriota, Actinobacteriota, and Chloroflexi. Across all locations, functional prediction identified 10,145 shared clusters of orthologous genes (COGs) and 5,907 shared KEGG orthologs (KOs), predominantly associated with signaling, signal transduction, transport, and metabolism. This pattern indicates a broad yet tightly structured functional potential that underpins the functioning and stability of mangrove ecosystems. Iron and aluminum were among the most concentrated PTEs, and indices of PTE accumulation (geo-accumulation index, contamination factor, and pollution load index) indicated varying contamination risks across locations. Rhizosphere properties, particularly available potassium (Ava_K), magnesium (Mg), and cation exchange capacity (CEC), along with chromium and aluminum, were significant determinants of Thalassospira and SZB85 abundances, suggesting that soil properties and PTEs jointly shaped the composition and assembly of microbial taxa. Meanwhile, electrical conductivity, Ava_K, calcium, Mg, and CEC were major drivers of PTE distribution. Our preliminary findings provide the first dataset on rhizosphere microbial communities and their interactions with environmental properties in Pattani Bay, revealing their broad functional potential and supporting microbe-informed understanding and management of mangrove ecosystem functioning.