Abstract. Polymetallic mine tailings have great potential as carbon sequestration tools
to stabilize atmospheric CO2 concentrations. However, previous
studies focused on carbonate mineral precipitation, whereas the role of
autotrophic bacteria in mine tailing carbon sequestration has been neglected.
In this study, carbon sequestration in two samples of mine tailings treated
with FeS2 was evaluated using 13C isotope, pyrosequencing
and DNA-based stable isotope probing (SIP) analyses to identify carbon
fixers. Mine tailings treated with FeS2 exhibited a higher percentage
of 13C atoms (1.76±0.06 % for Yangshanchong and 1.36±0.01 % for Shuimuchong) than did controls over a 14-day incubation,
which emphasized the role of autotrophs in carbon sequestration with pyrite
addition. Pyrite treatment also led to changes in the composition of
bacterial communities, and several autotrophic bacteria increased, including
Acidithiobacillus and Sulfobacillus. Furthermore, pyrite
addition increased the relative abundance of the dominant genus
Sulfobacillus by 8.86 % and 5.99 % in Yangshanchong and
Shuimuchong samples, respectively. Furthermore, DNA SIP results indicated a
8.20–16.50 times greater gene copy number for cbbL than
cbbM in 13C-labeled heavy fractions, and a
Sulfobacillus-like cbbL gene sequence (cbbL-OTU1) accounted
for 30.11 %–34.74 % of all cbbL gene sequences in
13C-labeled heavy fractions of mine tailings treated with
FeS2. These findings highlight the importance of the cbbL
gene in bacterial carbon sequestration and demonstrate the ability of
chemoautotrophs to sequester carbon during sulfide mineral oxidation in mine
tailings. This study is the first to investigate carbon sequestration by
autotrophic bacteria in mine tailings through the use of isotope tracers and
DNA SIP.
Role of Microbial Activity in Fe and S Cycling in Sub-Oxic to Anoxic Sulfide-Rich Mine Tailings
