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Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 6/27/2011 Publication Date: 10/16/2011 Citation: Miller, D.N. 2011. Nitrifier activity and diversity in swine lagoon covers [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. Paper No. 355-6. Available: http://a-c-s.convex.com/crops/2011am/webprogram/Paper64750.html. Interpretive Summary: Ammonia emission from swine waste lagoons presents a serious environmental challenge to pork producers. Semi-permeable swine waste lagoon biocovers have been developed to serve as a physical barrier and as a site for beneficial microbes to grow, but microbial analysis of these attached (biofilm) communities is needed. Samples of mature biocover and its associated biofilm and lagoon liquids were collected from swine waste lagoons, and their potential ammonia-oxidizing activities were determined in laboratory incubations. Activities were measured in biocover samples having mature biofilms, but little to no activity was observed in new biocover (no biofilm) and lagoon wastewater samples. Molecular analyses of genes responsible for ammonia oxidation were consistent with the activity assays and indicated that bacterial ammonia-oxidizers were present. We conclude that the biocover served as a useful support for the production of a beneficial biofilm community capable of utilizing NH3, which reduces the amount of ammonia emitted to the atmosphere from these systems. Technical Abstract: Ammonia emissions from swine waste lagoons pose an environmental challenge to current pork production practices. Semi-permeable lagoon covers limit ammonia emissions by minimizing the effect of wind on the lagoon surface. Additionally, semi-permeable covers may also act as an attachment site for biofilm development, but microbial analysis of cover biofilm is needed to better assess this aspect of the technology. Samples of biofilm-encrusted mature cover and underlying lagoon wastewater liquids were collected from three swine waste sites, and their potential nitrifying activities were assessed relative to new cover material in laboratory experiments. Potential nitrification activity for the biofilm samples ranged from 0 to 1.6 mmoles nitrite m-2 d-1 during a 24-hour period. No nitrite accumulated in new cover (no biofilm) and negative control samples during the three experiments. Lagoon wastewater samples had limited nitrification potential and produced from 0 to 0.5 mmoles nitrite m-2 d-1 (5 L volume for comparison). Molecular analysis (PCR, DGGE, sequencing, and qPCR) of the amoA genes indicated that the community was dominated by ammonia oxidizing bacteria and not archaea. Molecular and functional analysis of the semi-permeable cover material demonstrated that a nitrifying community was established and enriched in the cover material relative to the underlying lagoon water. |
