Chemolithoautotrophic arsenite oxidation by a thermophilic Anoxybacillus flavithermus strain TCC9-4 from a hot spring in Tengchong of Yunnan, China

Abstract

A new facultative chemolithoautotrophic arsenite (AsIII)-oxidizing bacterium TCC9-4 was isolated from a hot spring microbial mat in Tengchong of Yunnan, China. This strain could grow with AsIII as an energy source, CO2–HCO3- as a carbon source and oxygen as the electron acceptor in a minimal salts medium. Under chemolithoautotrophic conditions, more than 90% of 100 mg/L AsIII could be oxidized by the strain TCC9-4 in 36 h. Temperature was an important environmental factor that strongly influenced the AsIII oxidation rate and AsIII oxidase (Aio) activity; the highest Aio activity was found at the temperature of 40∘C. Addition of 0.01% yeast extract enhanced the growth significantly, but delayed the AsIII oxidation. On the basis of 16S rRNA phylogenetic sequence analysis, strain TCC9-4 was identified as Anoxybacillus flavithermus. To our best knowledge, this is the first report of arsenic (As) oxidation by A. flavithermus. The Aio gene in TCC9-4 might be quite novel relative to currently known gene sequences. The results of this study expand our current understanding of microbially mediated As oxidation in hot springs.

Phylogenetic Structure and Metabolic Properties of Microbial Communities in Arsenic-Rich Waters of Geothermal Origin

“…It is known that the investigation of As-related functional genes through PCR approaches as well as through metagenome sequencing is currently difficult in ecological studies ( Fahy et al, 2015 ). A wide variety of aioA -like genes exists in natural environments and often these genes show low homology to currently known gene sequences ( Hamamura et al, 2009 ; Jiang et al, 2015 ). Hence, new primer designs should integrate the most recent sequencing data as well as biochemical data and genetic context ( Fahy et al, 2015 ).…”

Microbial communities and arsenic biogeochemistry at the outflow of an alkaline sulfide-rich hot spring

“…Minimal salt medium (MSM) was used for enrichment of As(III)-oxidizer and assays for the detection of As oxidization under chemolithoautotrophic conditions. MSM contained (g/L): Na 2 SO 4 , 0.031; KH 2 PO 4 , 0.17; KCl, 0.15; MgCl 2 ·6H 2 O, 0.04; CaCl 2 ·2H 2 O, 0.05; (NH 4 ) 2 SO 4 , 0.4; NaHCO 3 , 1.68; trace elements, 5 mL and vitamins solution, 10 mL 5 . The pH of the medium was adjusted to 8.5 to match that of Zimeiquan.…”

“…Hot springs provide a unique environment for examining the evolution of microbial communities in response to geochemistry as these environments harbor versatile microorganisms involved in various metabolic processes for hydrogen gas (H 2 ), sulfur (S), iron (Fe) and arsenic (As), as well as having high temperature and a wide range of pH values 1 2 3 4 5 . Arsenic biogeochemistry has been studied extensively in acidic hot springs and it is well-documented that high concentrations of sulfide can inhibit microbial As(III) oxidation in acidic springs by inactivating expressed As(III) oxidase (AioA) in microorganisms such as Hydrogenobacter 6 , Hydrogenobaculum 7 and Acidicaldus 8 .…”

Genome sequence of Anoxybacillus ayderensis AB04T isolated from the Ayder hot spring in Turkey

“…Several Anoxybacillus spp. efficiently reduce metal ions such as Hg 2+ , Cr 4+ ,Al 3+ , and As 3+ [ 4 , 23 – 25 ]. The genome of strain AB04 T contains at least six heavy metal resistance genes.…”

“…Apart from their hydrolytic capabilities, Anoxybacillus spp. have been proposed as agents for bioremediation of Hg 2+ , Cr 2+ , Al 3+ , As 3+ ions [ 4 , 23 – 25 ], and nitrogen oxide [ 26 ], and as possible candidates for biohydrogen production [ 4 ].…”