AUTHOR=Habteselassie Mussie Y., Xu Li , Norton Jeanette M.

TITLE=Ammonia-oxidizer communities in an agricultural soil treated with contrasting nitrogen sources

JOURNAL=Frontiers in Microbiology

VOLUME=4

YEAR=2013

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2013.00326

DOI=10.3389/fmicb.2013.00326

ISSN=1664-302X

ABSTRACT=<p>The community of ammonia-oxidizing prokaryotes was examined in an agricultural soil treated for six seasons with contrasting nitrogen (N) sources. Molecular tools based on the genes encoding ammonia monooxygenase were used to characterize the ammonia oxidizer (AO) communities and their abundance. Soil DNA was extracted from soils sampled from silage corn plots that received no additional N (control), dairy waste compost, liquid dairy waste (LW), and ammonium sulfate (AS) treatments at approximately 100 and 200 kg available N ha<sup>-1</sup> over 6 years. The N treatment affected the quantity of AO based on estimates of <italic>amoA</italic> by real-time PCR. Ammonia oxidizing bacteria (AOB) were higher in soils from the AS200, AS100, and LW200 treatments (2.5 × 10<sup>7</sup>, 2.5 × 10<sup>7</sup>, and 2.1 × 10<sup>7</sup>copies g<sup>-1</sup> soil, respectively) than in the control (8.1 × 10<sup>6</sup> copies g<sup>-1</sup> soil) while the abundance of <italic>amoA</italic> encoding archaea [ammonia oxidizing archaea (AOA)] was not significantly affected by treatment (3.8 × 10<sup>7</sup> copies g<sup>-1</sup> soil, average). The ratio of AOA/AOB was higher in the control and compost treated soils, both treatments have the majority of their ammonium supplied through mineralization of organic nitrogen. Clone libraries of partial <italic>amoA</italic> sequences indicated AOB related to <italic>Nitrosospira multiformis</italic> and AOA related to uncultured <italic>Nitrososphaera</italic> similar to those described by soil fosmid 54d9 were prevalent. Profiles of the <italic>amoC-amoA</italic> intergenic region indicated that both <italic>Nitrosospira-</italic> and <italic>Nitrosomonas</italic>-type AOB were present in all soils examined. In contrast to the intergenic <italic>amoC-amoA</italic> profile results, <italic>Nitrosomonas</italic>-like clones were recovered only in the LW200 treated soil-DNA. The impact of 6 years of contrasting nitrogen sources applications caused changes in AO abundance while the community composition remained relatively stable for both AOB and AOA.</p>