Q-218. Effects of Borax Treatment on Hydrogen Sulfide Emissions and Sulfate Reducing Bacteria in Stored Swine Manure
Malodorous compounds and emissions produced from stored swine manure can pose both environmental and health issues. These nuisance odors largely result from compounds such as sulfides, volatile fatty acids and phenols, which are produced as a result of anaerobic digestion of materials present in the manure. Hydrogen sulfide (H2S) is one such offensive odorant and is being considered as a regulatory standard to monitor emissions from swine facilities. Production of H2S involves sulfate reduction, largely by anaerobic sulfate-reducing bacteria (SRB). Borax (sodium tetraborate decahydrate) is a naturally occurring mineral, commonly used in commercial products as a cleaning agent and in reducing odors. The objective of this study was to test the effects of borax treatment on stored swine manure in an effort to reduce odorous emissions and to target bacterial groups responsible for odor production. A quantitative real-time PCR (qRT-PCR) approach was used to target and quantify the SRB population in manure in response to treatment with borax. This assay specifically targeted the conserved dsrA gene of SRB, which encodes a key enzyme involved in sulfate respiration and production of H2S. Manure storage pits beneath nursery rooms at the Michigan State University Swine Research and Teaching Facility were treated weekly with borax powder to attain either a 1% or 2% final treatment dose based on manure volume. Air quality was monitored for H2S emissions in control and borax treated rooms, and aliquots of manure were removed weekly for enumeration of the SRB population. Denaturing gradient gel electrophoresis (DGGE) was used to analyze shifts in microbial community structure in response to treatment. qRT-PCR results demonstrated that treatment of swine manure with borax reduced numbers of Desulfovibrio-like Group 2 SRB by more than 99% after one week. This reduction in SRB correlated with an 80% reduction in H2S emissions in borax treated manure pits, compared to the control. This study demonstrates that borax treatment can suppress H2S production and reduce levels of SRB in stored swine manure.
148/Q. Pathogens in Environmental Sources
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