Microbial community of Ayer Hangat saline hot spring: Comparative analysis with bicarbonate hot springs and seawater using 16S rRNA sequencing

Aims: Research on hot spring microbiota has predominantly focused on volcanic hot springs with bicarbonate-or sulfate-type waters, leaving saline hot springs underexplored due to their rarity.In this work, we examined the microbiota of the Langkawi Ayer Hangat (AHA), a saline hot spring.The AHA hot spring receives both seawater and groundwater, has a temperature range of 40-45 C, a pH of 6.6, and a salinity of about 3.0%. Methodology and results:We sequenced the 16S rRNA V3-V4 region using Illumina technology on total community DNA extracted from the hot spring.The microbiota of AHA was heavily dominated by Roseobacteraceae, a family commonly found in seawater, along with several sulfur-oxidizing bacteria.We then compared the microbiota of AHA with other reported chloride-type saline hot springs, bicarbonate hot springs, and selected seawater microbiota.Based on beta-diversity analyses, AHA and other saline hot springs share higher microbiota similarity with bicarbonate hot springs than with seawater.Conclusion, significance and impact of study: AHA and saline hot springs exhibit a higher prevalence and abundance of Phycisphaeraceae, Alteromonadaceae, Saprospiraceae, Alcanivoracaceae, Oceanospirillaceae, Parvibaculaceae, Thalassobaculaceae, and Thalassospiraceae, which are absent or lacking in bicarbonate hot springs.This study provides insights into the distinct microbiota of saline hot springs like AHA, highlighting their unique characteristics compared to bicarbonate hot springs and advancing our understanding of microbial diversity in these environments.