Location: Northwest Irrigation and Soils Research
Title: The characterization of microorganisms in dairy wastewater storage ponds Authors
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 26, 2013
Publication Date: September 2, 2013
Citation: Dungan, R.S., Leytem, A.B. 2013. The characterization of microorganisms in dairy wastewater storage ponds. Journal of Environmental Quality. 42:1583-1588. Interpretive Summary: Idaho is the third largest dairy state in the United States. With over 500,000 milk cows, a vast quantity of solid and liquid manure is generated, much of which is land applied. Given the fact that cattle feces contain a variety of microorganisms, we undertook a study using a culture-independent approach (i.e. no cultivation) to characterize microbial communities in wastewaters from south-central Idaho. After the microbial DNA was extracted from the wastewaters, it was amplified and then a sequence library was created for identification of putative matches. In general, the dairy wastewaters contained a variety of microorganisms affiliated with the domains Archaea and Bacteria. However, a statistical analysis of the data revealed that an insufficient number of sequences were obtained to sufficiently characterize microbial diversity at the species level. Despite this limitation, the results from our study enhanced our understanding of microbial species and communities in dairy wastewaters more so then if culture-dependent techniques were utilized.
Technical Abstract: Dairy wastewaters from storage ponds are commonly land applied to irrigate silage crops. Given that diverse microbial populations are associated with cattle feces, the objective of this study was to use a culture-independent approach to characterize Bacteria and Archaea in dairy wastewaters. Using domain-specific primers, a region of the 16S rRNA gene was amplified from pooled DNA extracts from 30 dairy wastewaters and subsequently used to create a clone library. A total of 152 bacterial clones were examined and sequence matches were affiliated with the following groups: Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Synergistetes. Firmicutes was identified as the largest phylum representing up to 69% of the clone sequences. Of 167 clones representing Archaea, 7 genera were found to be closely related (91–100% sequence similarity) to isolates obtained from sediments and feces. Most of the putative sequence matches (98%) represented members from the class Methanomicrobia. With respect to the archaeal clones, only one of the putative sequence matches was affiliated with a methanogenic bacterium known to inhabit the rumen. Our results suggest that the dairy wastewater ponds do not support populations of methanogenic bacteria normally found in the cattle rumen.