Combined effects of the antibiotic sulfadiazine and liquid manure on the soil microbial‐community structure and functions

Abstract

Sulfonamides are the second most used antibiotic class in veterinary medicine and applied to livestock to treat bacterial infections. Subsequently, they are spread onto agricultural soils together with the contaminated manure used as fertilizer. Both manure and antibiotics affect the soil microbial community. However, the influence of different liquid manure loads on effects of antibiotics to soil microorganisms is not well understood. Therefore, we performed a microcosm experiment for up to 32 d to clarify whether the function and structure of the soil microbial community is differently affected by interactions of manure and the antibiotic sulfadiazine (SDZ). To this end selected concentrations of pig liquid manure (0, 20, 40, 80 g kg–1) and SDZ (0, 10, 100 mg kg–1) were combined. We hypothesized that incremental manure amendment might reduce the effect of SDZ in soils, due to an increasing sorption capacity of SDZ to organic compounds. Clear dose‐dependent effects of SDZ on microbial biomass and PLFA pattern were determined, and SDZ effects interacted with the liquid manure application rate. Soil microbial biomass increased with incremental liquid manure addition, whereas this effect was absent in the presence of additional SDZ. However, activities of enzymes such as urease and protease were only slightly affected and basal respiration was not affected by SDZ application, while differences mostly depended on the concentration of liquid manure. These results illustrated that the microbial biomass and structural composition react more sensitive to SDZ contamination than functional processes. Furthermore, effects disproportionally increased with incremental liquid manure addition, although extractable amounts of SDZ declined with increasing liquid manure application.

Fate of the antibiotic sulfadiazine in natural soils: Experimental and numerical investigations

“…When SDZ is fed to pigs, a mixture of the parent compound and two main metabolites is excreted (Lamshöft et al, 2007). When SDZ is applied together with manure to soils, current investigations by Hammesfahr et al (2011) and Fang et al (2014) indicate that manure can affect the microbial biomass by changing the biomass' structural composition and thus its functional processes.…”

Organic Xenobiotics

“…No observed effect concentrations (NOEC) of 2000-5000 mg TC kg −1 soil were determined for reproduction and mortality of earthworms, springtails and enchytreids (Baguer et al 2000). Effects of TCs on soil community and the impact of increased antibiotic resistant genes in the gene pool of soil organisms are still discussed (Halling-Sørensen et al 2005;Hammesfahr et al 2011;Thiele-Bruhn 2003). Boxall et al (2004) reviewed the toxicity of veterinary drugs on a broad range of test organisms.…”

Phosphorus in Agriculture: 100 % Zero

“…As antibiotics are designed to affect mainly microorganisms, much higher concentrations are necessary to show toxic effects on higher soil organisms. Effects of TCs on soil community and the impact of increased antibiotic resistant genes in the gene pool of soil organisms are still discussed (Halling-Sørensen et al 2005;Hammesfahr et al 2011;Thiele-Bruhn 2003). Effects of TCs on soil community and the impact of increased antibiotic resistant genes in the gene pool of soil organisms are still discussed (Halling-Sørensen et al 2005;Hammesfahr et al 2011;Thiele-Bruhn 2003).…”