title: Effects of repeated application of sulfadiazine-contaminated pig manure on the abundance and diversity of ammonia and nitrite oxidizers in the root-rhizosphere complex of pasture plants under field conditions.
abstract: In a field experiment, the impact of repeated application of the antibiotic sulfadiazine (SDZ)-contaminated pig manure was assessed on functional microbial communities involved in ammonia and nitrite oxidation in the root-rhizosphere complexes (RRCs) of diverse plants composing a pasture. We surveyed the abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) as well as Nitrobacter- and Nitrospira-like nitrite-oxidizing bacteria (NOB) by quantitative PCR (qPCR), and the diversity of amoA AOA and Nitrobacter-like nxrA amplicons using a cloning-sequencing approach. Whereas the first SDZ-contaminated manure application caused only slight effects on the investigated microbial communities and did not change the diversity and abundance pattern significantly, the second application of SDZ-contaminated manure induced an up to 15-fold increased ratio of AOA:AOB and a reduction of nrxA genes. The diversity of AOA amoA increased after the second application of SDZ-contaminated manure compared to the control treatment whereas a clear reduction of nrxA OTUs was visible in the same samples. The results indicate that the application of SDZ may principally affect nitrite oxidation by NOB and alternative pathways like nitrite reduction might be favored under these conditions.
authors: Institute of Soil Ecology, Technical University Munich Neuherberg, Germany ; Research Unit Environmental Genomics, Helmholtz Zentrum München Neuherberg, Germany.
authors: Julien
authors: J
authors: Ollivier
authors: Daniela
authors: D
authors: Schacht
authors: Reimo
authors: R
authors: Kindler
authors: Joost
authors: J
authors: Groeneweg
authors: Marion
authors: M
authors: Engel
authors: Berndt-Michael
authors: BM
authors: Wilke
authors: Kristina
authors: K
authors: Kleineidam
authors: Michael
authors: M
authors: Schloter
keywords: ammonia-oxidizing microbes; nitrification; nitrite-oxidizing bacteria; rhizosphere; sulfadiazine