Denitrification is important in soil nitrogen transformation and can cause nitrogen loss. Previous studies mainly focused on the bacterial denitrification. Fungal denitrifiers also play important roles in soil nitrogen cycling. However, how the soil types affected the communities of fungi denitrifiers (nirK) is still unclear.

Researchers from the Institute of subtropical agricultural (ISA) of the Chinese Academy of Science (CAS) investigated the abundance and composition of fungal nirK-containing denitrifiers across different climate zones in China, including quaternary red clay soils(QRC), alluvial soils(AS), and black soils(BS).

The team mainly used the real-time PCR and High throughput sequencing methods detected the fungi nirK gene abundance and composition in the three different soils. They found that the abundance of fungal nirK-containing denitrifiers exist significant difference among three soil types, such as the QRC owned the highest fungi nirK gene abundance (3.15×10⁹ copies·g^-1) , while the abundance of fungi nirK in AS(9.92×10⁸ copies·g^-1) was lowest among three soil types.

Their results indicated that the composition of fungal nirK-containing denitrifiers were mainly distributed in the order of Mucorales, Hypocreales, Sordariale and Eurotiales, and the dominant order is Hypocreales. It is interesting that the composition of fungal nirK-containing denitrifiers was highly homogenous among the soil types, which could be a consequence of enduring agricultural practices.

Besides, they also used a substrate-induced inhibition approach to explore N₂O emissions from fungal denitrification, and they found that QRC showed the highest  N₂O emission by fungal denitrification with 66.17%, followed by the BS soils with 53.34%. However, the lowest, with approximately 18.62%, occurred in the AS soils.

Furthermore, the team found that the abundance of fungal nirK-containing denitrifiers, rather than their composition, may play more significant roles in relation to N₂O emission from fungal denitrification.

This study was supported by the Chinese Academy of Sciences Strategic Leading Science and Technology Projects (grant number XDB15020200) and the National Research Foundation of China (grant numbers 41501277, 41330856, 41401295).

This results entitled "Characterization of Fungal nirK-containing Communities and N₂O Emission from Fungal Denitrification in Arable Soils"  has been published in Frontiers in Microbiology, and it could be download at https://www.frontiersin.org/articles/10.3389/fmicb.2019.00117/full 

Contact: SHENG Rong

E-mail: shengrong@isa.ac.cn 

Institute of Subtropical Agriculture, Chinese Academy of Sciences