Isolation of diverse members of the Aquificales from geothermal springs in Tengchong, China.

Brian P Hedlund,John C Ong,Anna-Louise Reysenbach,Weiguo Hou,Amanda J Williams,Zizhang Liu,Reham Ahmed,Liuquin Huang,Jeremy A Dodsworth,Yitai Liu,Brandon R Briggs,Hailiang Dong

doi:10.3389/fmicb.2015.00157

Abstract

The order Aquificales (phylum Aquificae) consists of thermophilic and hyperthermophilic bacteria that are prominent in many geothermal systems, including those in Tengchong, Yunnan Province, China. However, Aquificales have not previously been isolated from Tengchong. We isolated five strains of Aquificales from diverse springs (temperature 45.2–83.3°C and pH 2.6–9.1) in the Rehai Geothermal Field from sites in which Aquificales were abundant. Phylogenetic analysis showed that four of the strains belong to the genera Hydrogenobacter, Hydrogenobaculum, and Sulfurihydrogenibium, including strains distant enough to likely justify new species of Hydrogenobacter and Hydrogenobaculum. The additional strain may represent a new genus in the Hydrogenothermaceae. All strains were capable of aerobic respiration under microaerophilic conditions; however, they had variable capacity for chemolithotrophic oxidation of hydrogen and sulfur compounds and nitrate reduction.

Highlights

The phylum Aquificae is composed of a single order, Aquificales, and three families, Aquificaceae, Hydrogenothermaceae, and Desulfurobacteriaceae (Reysenbach et al, 2005; L’Haridon et al, 2006)
ISOLATION AND PHYLOGENETIC ANALYSIS Chemolithotrophic isolates were obtained from five geochemically diverse sites in the Rehai Geothermal field (Table 1), which were chosen based on previous reports of Aquificales in Rehai (Hou et al, 2013; Song et al, 2013; Briggs et al, 2014) and identification of additional streamer communities deemed likely to host Aquificales
Two Hydrogenobacter strains were isolated, designated T-2 and T-8, from sites differing in pH by > 2.5 units

Summary

Introduction

The phylum Aquificae is composed of a single order, Aquificales, and three families, Aquificaceae, Hydrogenothermaceae, and Desulfurobacteriaceae (Reysenbach et al, 2005; L’Haridon et al, 2006). Aquificales are present in many terrestrial and marine geothermal systems where they often form multicellular “streamer” assemblages (Huber et al, 1998; Reysenbach et al, 2000, 2005; Takacs et al, 2001; Eder and Huber, 2002; Spear et al, 2005; Hou et al, 2013; Takacs-Vesbach et al, 2013) but can be prominent members of planktonic microbial communities (Cole et al, 2013; Hou et al, 2013; Murphy et al, 2013). Two families of Aquificales dominate in terrestrial geothermal systems, the Aquificaceae and Hydrogenothermaceae.

Methods

Results

Discussion

Conclusion