Influence of Temperature and Sulfate Concentration on the Sulfate/Sulfite Reduction Prokaryotic Communities in the Tibetan Hot Springs.

Li Ma,Jian Yang,Hongchen Jiang,Dorji Phurbu,Weiyu She,Geng Wu

doi:10.3390/microorganisms9030583

Abstract

The distribution and diversity of sulfate/sulfite reduction prokaryotic (SRP) communities in hot springs from the Quzhuomu and Daggyai Geothermal Zone of Tibetan, China, was reported for the first time. In hot springs that are naturally hyperthermal and anoxic, the sulfur cycle is one of the most active cycles of the elements. The distribution of SRP in response to temperature is of great importance to the understanding of biogeochemical cycling of sulfur in geothermal features. Little is known about the SRP in geothermal zone. In this study, the diversity of SRP was investigated in the sediments from the Daggyai and Quzhuomu geothermal zone using PCR amplification, cloning and sequencing of the dissimilatory sulfite reductase beta subunit gene (dsrB). The abundance of dsrB and 16S rRNA genes, were determined by quantitative polymerase chain reactions. In addition, correlations of the SRP assemblages with environmental factors were analyzed by the aggregated boosted tree (ABT) statistical analysis. The results showed that SRP populations were diverse, but were mainly composed of Desulfobacterales, Desulfovibrionales, Syntrophobacterales, Clostridia and Nitrospirales, and large fraction (25%) of novel sequences have branched groups in the dsrB phylogenetic tree. In Quzhuomu geothermal zone, sulfate-rich hot springs are characterized by thick bacterial mats that are green or red and the SRP populations mainly appear at mid-temperature (50 °C to 70 °C). In low-sulfate hot springs in the Daggyai geothermal zone, although gray or pink streamers are widely formed at 60 °C to 80 °C, they prefer to inhabit in green mat at lower temperature (30 °C to 50 °C). With increasing temperature, the diversity of the dsrB gene at the OTU level (cutoff 97%) decreased, while its relative abundance increased. This result suggests that temperature played an important role in affecting dsrB gene distribution.

Highlights

Sulfate respiration is one of the oldest ways for microorganisms to acquire energy on the Earth [1,2]
In Quzhuomu geothermal zone, sulfate-rich hot springs are characterized by thick bacterial mats that are green or red and the sulfite reduction prokaryotic (SRP) populations mainly appear at mid-temperature
A total of 497 dissimilatory sulfite reductase beta subunit gene (dsrB) gene clones were retrieved from the 15 samples, and they were classified into 41 operational taxonomic units (OTUs) (Table S2)

Summary

Introduction

Sulfate respiration is one of the oldest ways for microorganisms to acquire energy on the Earth [1,2]. As part of the global S cycle, biological sulfate reduction is ubiquitous in the. A majority (up to 97%) of the sulfide produced on the Earth is attributable to the activity of sulfate-reducing prokaryotes (SRPs) in mesophilic environments [5,6,7,8,9]. SRP gain energy for cell synthesis and growth by coupling the reduction of sulfate (SO4 2− ) to sulfide (H2 S, HS− ) with cycling of carbon and nitrogen [10,11,12], and play an important role in arsenic geochemistry transformation [13]. The large subunit of sulfate reductase is encoded by the conserva-

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