Title: Characterization of Microbial Populations in Swine Lagoon Slurries Enriched for Skatole Production Authors
Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: April 7, 2006
Publication Date: May 21, 2006
Citation: Cook, K.L., Loughrin, J.H., Rothrock Jr, M.J. 2006. Characterization of microbial populations in swine lagoon slurries enriched for skatole production. American Society for Microbiology Annual Meeting. ISBN 1-55581-389-5 Pg A127 Technical Abstract: Skatole (3-methylindole) is responsible for some of the most offensive odors emitted from livestock wastes. It has a low threshold for detection and has a distinctly fecal odor. Skatole is produced by anaerobic metabolism of L-tryptophan, however, little is known of the phylogeny of skatole-producing microorganisms or the conditions that favor their growth. The goals of this study were to enrich for skatole-producers in swine lagoon slurry (SLS) and evaluate the microbial community structure. SLS enriched for skatole producers was diluted (10-1 to 10-9) to reduce the background population of non-skatole producers and dilutions were spiked with 100 µM indole acetic acid, a possible intermediate in production of skatole from L-tryptophan metabolism. Skatole concentrations were determined by GC-MS, denaturing gradient gel electrophoresis (DGGE) was used to evaluate differences in microbial community structure, and significant bands were extracted and sequenced for phylogenetic analysis. After 17 days incubation, skatole concentrations in the enrichment cultures were greater than 7,500 ppb in the first 5 dilutions. DGGE analysis suggests that the population structure of skatole enriched communities was similar in the first six dilutions, but shifted notably thereafter. The dominant group in sequenced DGGE band extracts were Bacteriodes sp. Two other groups of clones had 16S rRNA sequences similar to those of cellulolytic bacteria (Ruminococcus sp. and Anoxynatronum sp.) or methanotrophs (Methylocapsa sp.). This information should aid in development of primers and probes to target populations which are important in the production of skatole.