Ammonia-oxidizing bacterial communities in tropical soils under N and organic amendment

ABSTRACTOrganic vinasse, a residue produced during bioethanol production, increases nitrous oxide (N2O) emissions when applied with inorganic nitrogen (N) fertilizer in soil. The present study investigated the role and the diversity of ammonia-oxidizing bacteria (AOB) community on the N2O emissions in soils amended with different organic vinasses (CV: concentrated and V: non-concentrated) plus inorganic N fertilizer. Soil samples and N2O emissions were evaluated at day 11, 19 and 45 after fertilizer application, and the bacterial gene (amoA) encoding the ammonia monooxygenase enzyme and total bacteria were quantified by real time PCR. We also employed a deep amoA amplicon sequencing approach to evaluate the community structure and diversity of the soil AOB community. Both vinasse types plus inorganic N application increased the total N2O emissions and the abundance of AOB. Nitrosospira sp. was the dominant AOB correlated with N2O emissions. However, the diversity and the community structure of AOB were resistant to vinasses and inorganic N fertilizer.