Submitted to: Federation of European Microbiological Societies Microbiology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2007
Publication Date: March 30, 2007
Citation: Cook, K.L., Rothrock Jr, M.J., Loughrin, J.H., Doerner, K. Characterization of skatole-producing microbial populations in enriched swine lagoon slurry.Federation of European Microbiological Societies Microbiology Letters. 60:329-340 Interpretive Summary: Skatole is one of the most malodorous compounds produced within animal waste. Little is known about biochemistry of skatole production or the microorganisms that produce it. These deficiencies hamper attempts to reduce skatole production. Our goals were to enrich for skatole producers in swine lagoon slurry (SLS) and evaluate the resulting microbial community structure using chemical and molecular microbiological techniques. We were able to enrich for skatole producers (~99% increase over the course of the experiment) and found that the microbial communities present within the SLS samples were dependent upon the level of skatole being produced. We observed as definite shift in the microbial communities towards a dominance of 2 groups of microbes (low GC gram positives and Bacteroides) as skatole production increased. Results from this study should provide valuable new information concerning the organisms responsible for production of this odorant, a necessary first step towards controlling skatole production
Technical Abstract: Skatole is one of the most malodorous compounds produced as a by-product of anaerobic degradation of animal waste materials. 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 lagoon slurry (SLS) and evaluate the resulting microbial community structure using denaturing gradient gel electrophoresis (DGGE) and 16S rDNA sequence analysis. Skatole producers were enriched by incubating dilutions of SLS with 100 µM indole-3-acetic acid (IAA). GC-MS was used to measure skatole production in the slurries after 0, 7 and 17 days incubation. Based on MPN analysis, skatole producers increased hundred fold (2-12 x 102 cells mL-1 on day 7 to 3-14 X 104 cells mL-1 on day 17) in SLS samples supplemented with IAA. Based on DGGE fingerprint patterns from triplicate samples taken from day 0, 7 and 17 treatments with high, mid or low levels of skatole production, changes in the SLS population occurred as skatole production increased. Samples producing high concentrations of skatole were distinct from those that produced no skatole. Based on analysis of DGGE band intensity and the corresponding 16S rDNA clone sequences, changes in the bacterial community fingerprints were associated with an increase in the low-GC gram positives and in the Bacteroides groups. Results from this study should provide valuable new information concerning the organisms responsible for production of this odorant, a necessary first step towards controlling skatole production.