4.3.4 S cycling
Sulfur metabolism in microorganisms consists of redox reactions of
organic and inorganic sulfur substrates that can play a major part in
the biogeochemical cycle (Zerkle et al., 2010; Zopfi et al., 2008; Li et
al., 2010; Treude et al., 2014; Gomes et al., 2017). As the same of
denitrification, sulfate reduction is an anaerobic respiration that
might be stronger in stagnant area. Nine of the fourteen detected sulfur
metabolic genes had higher relative abundance in stagnant area than in
runoff area (Fig.9c), suggesting enhanced microbial functional capacity
for S cycling in stagnant area. These genes included dsrAB encoding
dissimilatory sulfite reductase (p < 0.001), sir encoding
sulfate reductase (p = 0.003), cysN encoding sulfate adenylyltransferase
(p = 0.008), sat encoding sulfate adenylyltransferase (p = 0.00008),
aprAB encoding adenylylsulfate reductase (p < 0.02) and PAPSS
encoding 3’-phosphoadenosine 5’-phosphosulfate synthase (p = 0.03).