Table 1.
Descriptions of the hot springs studied.
| Name | Sample typea | Descriptions |
|---|---|---|
| Ulu Slim (US) | Water and sediment (spring heads and pond) | • The hottest spring in Malaysia. • A roughly cylindrical shallow pool (~4 m diameter, ~10 cm depth) with two moderate spring heads (110°C). • Clear water and fine clays at the bottom. • Biofilms (<5 mm thickness) with colors of yellow, orange, light brown, and light green are formed on the spring. |
| Sungai Klahb (SK) | Water and sediment (middle of stream) | • Shallow water flow stream (~150 m length, ~1.5 m width, ~5 cm depth) • Water temperatures between 50–110°C. • Multiple spring heads with clear running water. • Clays, rocks, and sands at the bottom. |
| Dusun Tua (DT) | Water and sediment (spring head and pond) | • A shallow pool with small spring source (75°C) outflow continually from a 1.5-m man-made cement-fountain landscape. • Multiple thick biomats (1–5 cm) of various colors (dark brown, red, white, dark green, and orange) are formed on the fountain, while a green filamentous mat is present on the bank of the collecting pool. • Clear water with silicate sands and clays at the bottom. |
| Sungai Serai (SS) | Water and sediment (center and edge of pool) | • Roughly round-shaped pool with diameter ~10 m, and depth ~0.5 m. • Many bubbling sources, but non-visible spring head. • Murky water with green biomats on the bank of the pool. • Loam soil at the bottom. |
| Semenyih (SE) | Water and sediment (center and edge of pool) | • Roughly round-shaped pool with diameter ~10 m, and depth ~0.7 m. • Many bubbling sources and no visible outflow. • Non-visible spring head. • Murky water with green biomats on the bank of the spring. • Fine silicate sands at the bottom. |
| Ayer Hangat (AH) | Water | • The only saline hot spring in Malaysia. • Water is trapped in a deep, cylindrical man-made pond with ~1-m diameter. • Formation of small degassing bubbles with slow outflow. • Gray-yellowish water mixed with fine salt. • Thin light-brown and green biomats (<1 cm) are formed on the surrounding wall. |
a
Sample type used for genomic DNA extraction.
b
Data collected from Diversity of thermophiles in a Malaysian hot spring determined using 16S rRNA and shotgun metagenome sequencing (Chan et al., 2015).