The Evaluation of Bacterial Abundance and Functional Potentials in the Three Major Watersheds, Located in the Hot Spring Zone of the Tatun Volcano Group Basin, Taiwan

Abstract

The Tatun Volcanic Group (TVG), located in northern Taiwan, is characterized by acidic hot springs where the outflow of the hot springs may affect the properties of the associated lotic water bodies. We investigated the bacterial diversity and functional profiles of the Peihuang (PHC), HuangGang (HGC), and Nanhuang Creeks (NHC) located in the TVG basin using 16S rRNA gene sequencing coupled with statistical analyses. Water samples were collected from various streams of the creeks for two months of the year. The NHC showed the highest diversity, richness, and a unique number of phyla, which was followed by the HGC. A reduced number of phyla and a lower diversity was noticed in the PHC. The NHC was found to be abundant in the genera Armatimonas, Prosthecobacter, Pirellula, and Bdellovibrio, whereas the HGC was rich in Thiomonas, Acidiphilium, Prevotella, Acidocella, Acidithiobacillus, and Metallibacterium. The PHC was abundant in Thiomonsa, Legionella, Acidocella, and Sulfuriferula. The samples did not show any strong seasonal variations with the bacterial diversity and abundance; however, the relative abundance of each sampling site varied within the sampling months. The iron transport protein- and the sulfur metabolism-related pathways were predicted to be the key functions in all the creeks, whereas the heavy metal-related functions, such as the cobalt/nickel transport protein and the cobalt-zinc-cadmium efflux system were found to be abundant in the HGC and PHC, respectively. The abundance of Bdellovibrio in the NHC, Diplorickettsia in the HGC, and Legionella in the PHC samples indicated a higher anthropogenic impact over the creek water quality. This study provides the data to understand the distinct bacterial community structure, as well as the functional potentials of the three major watersheds, and helps the knowledge of the impact of the physicochemical properties of the TVG hot springs upon the watersheds.

Keywords: 16S rRNA gene sequencing; Tatun volcanic group; bacterial abundance; functional prediction; hot spring; waterbodies.

Figure 1

Distribution of sampling locations of HGC, NHC and PHC, TVG basin. The exact sampling site details are given in Table S1.

Figure 2

Box plot representing the bacterial alpha diversity and richness indices (A) Chao1, (B) Shannon index, and (C) Simpson index of the samples from the three watersheds. (D) PCA representing the beta diversity among the samples from the three watersheds.

Figure 3

The stacked bar graphs illustrate the relative bacterial phyla abundance of the samples of three watersheds in two sampling months.

Figure 4

Venn diagram illustrating the proportions of unique and common bacterial genera noticed among the three watersheds.

Figure 5

The stacked bar graphs illustrate the relative bacterial genera abundance of the samples of three watersheds in two sampling months.

Figure 6

LDA combined with LEfSe showed the abundant bacterial clades. (A) Histogram of LDA score between the HGC and NHC samples. (B) LEfSe analysis of significant bacterial clades between the HGC and NHC samples.

Figure 7

Functional prediction of the bacterial communities. (A) PCA showing the grouping of samples based on their predicted metabolic functions; significantly enriched bacterial functions among the (B) NHC and HGC, (C) PHC and NHC, and (D) PHC and HGC.

Figure 8

Spearman correlation analysis between bacterial genera of the three watersheds and their metabolic functional predictions. The positive and negative correlations are shown in red and blue colors, respectively.