Serratia spp. Are Responsible for Nitrogen Fixation Fueled by As(III) Oxidation, a Novel Biogeochemical Process Identified in Mine Tailings

Abstract

Biological nitrogen fixation (BNF) has important environmental implications in tailings by providing bioavailable nitrogen to these habitats and sustaining ecosystem functions. Previously, chemolithotrophic diazotrophs that dominate in mine tailings were shown to use reduced sulfur (S) as the electron donor. Tailings often contain high concentrations of As(III) that might function as an alternative electron donor to fuel BNF. Here, we tested this hypothesis and report on BNF fueled by As(III) oxidation as a novel biogeochemical process in addition to BNF fueled by S. Arsenic (As)-dependent BNF was detected in cultures inoculated from As-rich tailing samples derived from the Xikuangshan mining area in China, as suggested by nitrogenase activity assays, quantitative polymerase chain reaction, and 15 N 2 enrichment incubations. As-dependent BNF was also active in eight other As-contaminated tailings and soils, suggesting that the potential for As-dependent BNF may be widespread in As-rich habitats. DNAstable isotope probing identified Serratia spp. as the bacteria responsible for Asdependent BNF. Metagenomic binning indicated that the essential genes for As-dependent BNF [i.e., nitrogen fixation, As(III) oxidation, and carbon fixation] were present in Serratia-associated metagenome-assembled genomes. Over 20 Serratia genomes obtained from NCBI also contained essential genes for both As(III) oxidation and BNF (i.e., aioA and nif H), suggesting that Asdependent BNF may be a widespread metabolic trait in Serratia spp.

Primary Succession Changes the Composition and Functioning of the Protist Community on Mine Tailings, Especially Phototrophic Protists

“…Genomic DNA was extracted from tailings with a DNeasy Powersoil kit (QIAGEN, Dresden, Germany) following the manufacturer’s instructions. , The DNA quality and quantity were measured using a NanoDrop ND-2000 spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA) . The 18S rRNA V9 was amplified on the ABI 2720 thermocycler (Applied Biosystems, Carlsbad, CA, USA) using the primer pair 1380F (5′-CCCTGCCHTTTGTACACAC-3′) and 1510R (5′-CCTTCYGCAGGTTCACCTAC-3′) .…”

Microbial Communities of Seawater and Coastal Soil of Russian Arctic Region and Their Potential for Bioremediation from Hydrocarbon Pollutants

“…Bacteria of the genus Serratia are able to effectively remove ammonium from polluted waters by participating in the nitrogen cycle [ 39 ]. In members of the genus Serratia , nitrogen fixation has recently been demonstrated in conjunction with As(III) oxidation, a new process identified in mine tailings [ 40 ].…”

“…[ 50 ]. Among the representatives of this genus, there are known bacteria that fix molecular nitrogen, reduce oxidized nitrogen compounds to ammonium or molecular nitrogen, psychrotolerant phosphate-solubilizing bacteria, as well as reducing oxidized forms of metals, metalloids, and radionuclides [ 40 , 51 ].…”

Nitrogen use aggravates bacterial diversity and network complexity responses to temperature

“…Microbial diversity is closely related to a variety of ecosystem processes and functions, such as soil nutrient cycling, and is associated with ecosystem stability and health 5 – 7 . Several studies have found that warming exerts strong effects on microbial diversity; however, results have not been consistent 8 – 12 .…”