Diversity, abundance, and distribution of NO ‐forming nitrite reductase–encoding genes in deep‐sea subsurface sediments of the S outh C hina S ea

Abstract

In marine ecosystems, both nitrite‐reducing bacteria and anaerobic ammonium‐oxidizing (anammox) bacteria, containing different types of NO ‐forming nitrite reductase–encoding genes, contribute to the nitrogen cycle. The objectives of study were to reveal the diversity, abundance, and distribution of NO ‐forming nitrite reductase–encoding genes in deep‐sea subsurface environments. Results showed that higher diversity and abundance of nir S gene than nir K and S calindua‐nir S genes were evident in the sediments of the S outh C hina S ea ( SCS ), indicating bacteria containing nir S gene dominated the NO ‐forming nitrite‐reducing microbial community in this ecosystem. Similar diversity and abundance distribution patterns of both nir S and S calindua‐nir S genes were detected in this study sites, but different from nir K gene. Further statistical analyses also showed both nir S and S calindua‐nir S genes respond similarly to environmental factors, but differed from nir K gene. These results suggest that bacteria containing nir S and S calindua‐nir S genes share similar niche in deep‐sea subsurface sediments of the SCS , but differed from those containing nir K gene, indicating that community structures of nitrite‐reducing bacteria are segregated by the functional modules ( N ir S vs. N ir K ) rather than the competing processes (anammox vs. classical denitrification).