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ARS Home » Midwest Area » Bowling Green, Kentucky » Food Animal Environmental Systems Research » Research » Publications at this Location » Publication #360948

Research Project: Developing Safe, Efficient and Environmentally Sound Management Practices for the Use of Animal Manure

Location: Food Animal Environmental Systems Research

Title: Temporal effects of organic and synthetic fertilizers on selected antibiotic resistant bacteria in the soil

item Agga, Getahun
item Durso, Lisa
item Sistani, Karamat

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2019
Publication Date: 6/23/2019
Citation: Agga, G.E., Durso, L.M., Sistani, K.R. 2019. Temporal effects of organic and synthetic fertilizers on selected antibiotic resistant bacteria in the soil. American Society for Microbiology. Paper No. AES-1037.

Interpretive Summary:

Technical Abstract: Poultry litter (PL) can introduce antibiotic resistant bacteria into the soil which can be further disseminated into the environment through runoff from crop fields. We monitored the impacts of PL and chemical fertilizer soil amendments on the levels of antibiotic resistant bacteria from May to October during the 2017 corn production season. Two winter cropping systems (fallow and cover crop) were assigned to whole plots and three spring applied fertilizer treatments (unfertilized control [UC], PL, and synthetic commercial fertilizer [CF]) were assigned to subplots. Soil samples were collected 7 days pre-treatment (May 1, baseline), and on May 15 (7 days post treatment [dpt]), June 6 (28 dpt), July 17 (70 dpt), August 14 (98 dpt), and October 27 (172 dpt). Concentrations and prevalence of generic- and tetracycline resistant (TETR)-E. coli, and generic- and TETR-Enterococcus species were determined. Prevalence of 3rd generation cephalosporin resistant (3GCR) E. coli and erythromycin resistant (ERYR) enterococci were also determined. Concentrations of generic E. coli, TETR E. coli, generic enterococci and TETR enterococci significantly increased in the PL amended soils 7 dpt compared to UN or CF. The prevalence of TETR- and 3GCR- E. coli, TETR- and ERYR- enterococci also increased in the PL amended soils 7 dpt. However, these levels were similar on 28 dpt and in the subsequent sampling days. Differences in the levels of generic or the resistant bacteria populations were not observed between UC and CF applied soils. Cover crop was associated with higher concentration of generic enterococci, higher prevalence of generic E. coli, lower concentration of TETR E. coli, and similar levels of 3GCR E. coli and ERYR enterococci compared to farrow fields regardless of fertilizer treatment or sampling day. These results show that poultry litter amendment temporarily increases the levels of total and resistant bacterial populations in the soil with subsequent decline to the baseline one month after application. Whether reductions in the levels of total and resistant bacterial populations after initial increase is due to dilution effect by resident bacteria in the soil or due to runoff from rain fall, as well as changes in the soil microbiome and resistome composition requires further investigations. Quantitative risk assessments need to consider the temporal dynamics associated with antibiotic resistant bacteria from organic soil amendments such as poultry litter.