Microbial diversity of thermophiles with biomass deconstruction potential in a foliage-rich hot spring

Abstract

The ability of thermophilic microorganisms and their enzymes to decompose biomass have attracted attention due to their quick reaction time, thermostability, and decreased risk of contamination. Exploitation of efficient thermostable glycoside hydrolases (GHs) could accelerate the industrialization of biofuels and biochemicals. However, the full spectrum of thermophiles and their enzymes that are important for biomass degradation at high temperatures have not yet been thoroughly studied. We examined a Malaysian Y-shaped Sungai Klah hot spring located within a wooded area. The fallen foliage that formed a thick layer of biomass bed under the heated water of the Y-shaped Sungai Klah hot spring was an ideal environment for the discovery and analysis of microbial biomass decay communities. We sequenced the hypervariable regions of bacterial and archaeal 16S rRNA genes using total community DNA extracted from the hot spring. Data suggested that 25 phyla, 58 classes, 110 orders, 171 families, and 328 genera inhabited this hot spring. Among the detected genera, members of Acidimicrobium, Aeropyrum, Caldilinea, Caldisphaera, Chloracidobacterium, Chloroflexus, Desulfurobacterium, Fervidobacterium, Geobacillus, Meiothermus, Melioribacter, Methanothermococcus, Methanotorris, Roseiflexus, Thermoanaerobacter, Thermoanaerobacterium, Thermoanaerobaculum, and Thermosipho were the main thermophiles containing various GHs that play an important role in cellulose and hemicellulose breakdown. Collectively, the results suggest that the microbial community in this hot spring represents a good source for isolating efficient biomass degrading thermophiles and thermozymes.

Keywords: Biofilm; biofuel; biomass degradation; cellulase; hot spring; thermophile.

Figure 1

Y‐shaped Sungai Klah hot spring (SK‐Y) and types of samples. (a) Illustration of sampling site for water and foliage, (b) SK‐Y, (c) foliage with green biofilm, (d) nondegraded foliage with no apparent biofilm, and (e) degraded foliage

Figure 2

(a) Relative abundance at bacterial and archaeal phyla in SK‐Y and (b) heat map representation of abundance bacterial (≥ 0.85%) and archaeal genera in SK‐Y