Characterization of microbiome diversity unveils substantial microbial variation in mangrove soil sediments from coastal regions of Malaysia.

The mangrove ecosystems are of great ecological importance found in tropical and subtropical coasts, including Malaysia. The microbial communities in the mangrove sediments play an indispensable role in maintaining homeostasis and supporting biodiversity. However, mangroves are facing various threats due to increasing anthropogenic activities. Thus, it is important to monitor the microbial community to improve our understanding of anthropogenic pressure on reshaping these ecosystems. This study examines the microbial community diversity in mangrove sediments of southern peninsular Malaysia. High-throughput MinION sequencing of the 16S rRNA gene was performed to compare the soil microbiome diversity in 35 samples from 8 different mangroves representing Sungai Sedili Kecil and Sungai Sedili Besar that flow into the South China Sea; Sungai Pulai, Sungai Melayu, Sungai Danga, Sungai Skudai and Sungai Johor that join the Straits of Johor; and Pulau Kukup from the Straits of Malacca. The metagenomic classification performed with 16S rRNA showed 2,573 taxa comprising 32 phyla. Total abundance analysis showed Pseudomonadota (67-69%), Bacteroidota (6-8%), Bacillota (5-8%), Campylobacterota (4-5%), Acidobacteriota (3-4%), Planctomycetota (2-4%) and Actinomycetota (1-2%) as the relatively common phyla. Alpha diversity indices revealed significantly higher richness in samples from mangroves of the South China Sea. Further, the 'Shannon' index showed a significant difference in diversity between Sungai Melayu and Sungai Pulai. Higher abundance of Burkholderiaceae, Bacillaceae and Enterobacteriaceae suggests a difference in the microbial community structure. This study stands as the first comprehensive analysis of microbial communities for future monitoring and conservation in these mangroves.