Changes in Soil and Plant Microbial Community Populations Following Administration of Manure Containing Oxytetracycline or Monensin

Abstract

Many veterinary antibiotic classes are shared by agriculture and human medicine. When manure from treated animals is land applied, antibiotics can accumulate in soils, as well as livestock forage and human food. Veterinary antibiotic use, high excretion levels, and plant antibiotic uptake have raised concerns regarding antibiotic resistance. This massively parallel sequencing study was designed to determine if the presence of antibiotics in dairy manure can affect plant and soil microbial communities. This was tested in a greenhouse study involving soil and untreated manure or manure spiked with monensin or oxytetracycline. Tifton 85, a forage Bermuda grass, was grown for 6 weeks in these various treatment groups. The soil and harvested plant leaf or root microbial profiles were compared with and without manure as well as in the presence or absence of monensin or oxytetracycline. Results of the study showed that the addition of both antibiotics affected plant prokaryotic community composition, and soil microbial communities were affected by the presence of Tifton 85, both antibiotics, or manure. The influences of manure addition were different if the manure was just applied to the surface or if it was mixed throughout. This study summarizes the considerations that must be addressed prior to using animal manure for land application, especially if those animals were treated with antibiotics.