UNDERSTANDING THE ROLE OF COMMENSAL ANAEROBIC BACTERIA IN ODOR, EMISSIONS, AND ANTIBIOTIC RESISTANCE FROM STORED LIVESTOCK MANURE
Location: Bioenergy Research Unit
Project Number: 3620-63000-005-00
Start Date: Jan 04, 2011
End Date: Oct 31, 2015
Objective 1: Develop methods to reduce metabolic activity of microorganisms present in stored swine manure to decrease odor and gaseous emissions during storage.
Objective 2: Characterize bacterial antibiotic resistance in swine feces and stored manure and potential for movement of resistance genes between bacterial species.
Objective 3: Determine impact of natural plant compounds and/or their gut derived metabolites (e.g., tannins, pheophorbide, diterpenes) on levels of antibiotic resistance in commensal bacteria present in stored swine manure.
Intensification of modern livestock operations has resulted in the concentration of greater numbers of animals into fewer and fewer operations. This trend has also led to the inevitable concentration of manure generated by these facilities into increasingly smaller locations. In the Midwest, deep pit storage is the predominant method used to handle swine manure and this manure is a valuable renewable resource for use as fertilizer. However, concentration of manure has been accompanied by increased public concern about environmental impacts and public health. These include real and perceived fears of the effects of odors, volatile greenhouse emissions, and potential spread of antibiotic resistant microorganisms and genes. Therefore, research is needed to target the common factor relating these various concerns. This factor is the bacteria populations naturally found in manure and its precursor, animal feces. These bacteria are generally termed the commensal bacteria found in these two ecosystems (feces and manure). As a continuation of previous research in our laboratories, both classic microbiological methods as well as modern molecular biological approaches (i.e., direct 16S rDNA sequencing, quantitative real-time polymerase chain reaction (qRT-PCR)) will allow us to investigate the bacterial basis for production of odorous compounds, greenhouse gases such as methane, and the impact of using antibiotics in feed as growth promotants on antibiotic resistance present in the commensal bacterial populations. Research will be directed towards developing methods to reduce production of odors and emissions, identifying levels of antibiotic resistance in pure cultures, and identifying and quantitating resistance genes present in the manure. The potential for movement of such resistance genes between commensal bacteria and potential pathogens will also be investigated.