ARS | Publication request: CHARACTERIZATION OF SKATOLE-PRODUCING MICROBIAL POPULATIONS IN ENRICHED SWINE LAGOON SLURRY

Submitted to: Proceedings of the Workshop on Agricultural Air Quality: State of the Science
Publication Type: Proceedings
Publication Acceptance Date: February 14, 2006
Publication Date: June 5, 2006
Citation: Cook, K.L., Loughrin, J.H. 2006. Characterization of Skatole-Producing Microbial Populations in Enriched Swine Lagoon Slurry. Proceedings of the Workshop on Agricultural Air Quality: State of the Science. pp 547-551

Technical Abstract: Skatole is a potent odorant in animal waste produced by anaerobic degradation of L-tryptophan. Little is known of the biochemistry involved in skatole production, the phylogeny of skatole-producing microorganisms or the conditions that favor their growth. These deficiencies hamper attempts to reduce skatole production. Our goals were to enrich for skatole-producers in swine waste and evaluate the microbial community structure. We supplemented swine lagoon slurry with 100 µM L-tryptophan, indole pyruvic acid (IPA) or IAA. Control treatments received no additional substrate. GC-MS was used to measure indole and skatole production in the slurries. Very little indole (0.9 ± 0.02 µM) or skatole (1.8 ± 0.07 µM) was produced in the control over the course of the 14 day experiment. The final concentration of skatole was 50.4 ± 1.6 µM, 61.6 ± 1.1 µM and 68.4 ± 24.8 µM in the L-tryptophan, IPA, and IAA supplemented treatments, respectively. DGGE analysis was performed on DNA extracts from samples taken on days 0, 7 and 14 to evaluate changes in the microbial populations over time. The average number of bands or operational taxonomic units (OTU’s) for samples from unsupplemented swine lagoon slurry taken on days 7 and 14 was lower than for any of the other treatments. OTU’s increased in all supplemented treatments, with the greatest differences seen in samples supplemented with IPA or IAA. Future studies will evaluate phylogenetic differences in diluted populations having high skatole concentrations. Knowledge concerning the organisms producing this odorant should provide information vital to controlling microbes responsible for its production.