Submitted to: Anaerobe
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2013
Publication Date: 6/1/2013
Citation: Ducey, T.F., Hunt, P.G. 2013. Microbial community analysis of swine wastewater anaerobic lagoons by next-generation DNA sequencing. Anaerobe. 21:50-57.
Interpretive Summary: Anaerobic lagoons are a passive treatment system for swine wastewater. This wastewater is a combination of swine feces and urine, collected in pits underneath the swine houses before being flushed into earthen, lined, outdoor basins. This waste is treated by microorganisms living off of the various organic materials which are flushed into the system. Despite our reliance on these microorganisms, we know very little about the biochemical functions they perform. These biochemical functions not only lead to a decrease in organic material and other nutrients in the waste, but also lead to production of odors and potential reductions in pathogens. In this study, we undertook the first high-throughput 16S rDNA sequencing project on anaerobic, swine wastewater lagoons in the United States. We identified almost one thousand genera of bacteria, some of which could be attributed to biochemical functions performed in the lagoons. Of the genera we identified, about a quarter were found across all lagoons, with an additional portion being lagoon-specific. These results demonstrate that anaerobic lagoons have a very complex microbial structure, a structure which is controlled by the many site-specific environmental factors.
Technical Abstract: Anaerobic lagoons are a standard practice for the treatment of swine wastewater. This practice relies heavily on microbiological processes to reduce concentrated organic material and nutrients. Despite this reliance on microbiological processes, research has only recently begun to identify and enumerate the myriad and complex interactions that occur in this microbial ecosystem. To further this line of study, we utilized a next-generation sequencing technology to gain a deeper insight into the microbial communities along the water column of four anaerobic swine wastewater lagoons. Analysis of roughly one million 16S rDNA sequences revealed a predominance of operational taxonomic units (OTUs) classified as belonging to the phyla Firmicutes (54.1%) and Proteobacteria (15.8%). At the family level, 33 bacterial families were found in all twelve lagoon sites and accounted for between 30 - 50% of each lagoon’s OTUs. Analysis by nonmetric multidimensional scaling (NMS) revealed that total kjeldahl nitrogen, chemical oxygen demand, oxidation-reduction potential, total suspended solids, and dissolved oxygen were the major environmental variables in affecting microbial community structure. Overall, 839 individual genera were classified, with 223 found in all four lagoons, and 321 identified in only one. The top 25 genera accounted for approximately 20% of the OTUs identified in the study, and the low abundances of most of the genera suggests that most OTUs are present at low levels. Overall, these results demonstrate that anaerobic lagoons have distinct microbial communities which are strongly controlled by the environmental conditions present in each lagoon.