Skatole Production Research Articles

The effect of diet on skatole concentrations in the intestine and adipose tissue of growing pigs

Microbial metabolism of dietary tryptophan in the gastro-intestinal tract results in the production of skatole and indole. These compounds, collectively classed as indoles, may be absorbed and deposited in carcass tissue and have been associated with taints especially in entire male pigs (Hansson et al., 1980). As indoles are readily absorbed over the entire tract in humans (Fordtran et al., 1964), it was suggested by Lundstrom et al. (1988) that diet may influence skatole production and hence levels in the carcass. The objectives of this study were to determine the sites of skatole production in the gastrointestinal tract and the effect of diet on production and carcass levels.

Preliminary observations on skatole production in pigs

Skatole and indole, compounds formed in the large intestine by microbial breakdown of tryptophan, are associated with carcass taint (Hansson et al., 1980). The present work involved the development of a method for detecting the absolute values of the analytes in fat and faeces. The effect on faecal excretion of skatole was also examined following infusion of skatole directly into the caecum. Finally as substrate effects the type and extent of fermentation in the large intestine, different diets were fed and the corresponding faecal and fat skatole levels were determined.Skatole analysis involved homogenising adipose tissue with methanol and removal of fat by cooling and filtering. Solid phase extraction columns concentrated the analytes to produce samples which gave good resolution by gas liquid chromatography (Porter, Hawe and Walker, 1989). Due to higher levels of skatole in faeces, no concentrating phase was required before detection.

Production of Skatole and para -Cresol by a Rumen Lactobacillus sp

The objective of this study was to examine the substrate specificity of several ruminal strains of a Lactobacillus sp. which previously was shown to produce skatole (3-methylindole) by the decarboxylation of indoleacetic acid. A total of 13 compounds were tested for decarboxylase activity. The Lactobacillus strains produced p-cresol (4-methylphenol) by the decarboxylation of p-hydroxyphenylacetic acid, but did not produce either o-cresol or m-cresol from the corresponding hydroxyphenylacetic acid isomers. These strains also decarboxylated 5-hydroxyindoleacetic acid to 5-hydroxyskatole and 3,4-dihydroxyphenylacetic acid to methylcatechol. Skatole and p-cresol were produced in a 0.5:1 ratio, when indoleacetic acid and p-hydroxyphenylacetic acid were combined in equimolar concentrations. Competition studies with indoleacetic acid and p-hydroxyphenylacetic acid suggested that two different decarboxylating enzymes are involved in the production of skatole and p-cresol by these strains. This is the first demonstration of both skatole production and p-cresol production by a single bacterium.

Isolation and characteristics of a skatole-producing Lactobacillus sp. from the bovine rumen

A bacterium that is capable of decarboxylating indoleacetic acid to skatole (3-methylindole) has been isolated from an L-tryptophan enrichment of bovine rumen fluid. The bacterium is a gram-positive, nonmotile, nonsporeforming rod. It is an obligate anaerobe, and strains predominatly produce D-(-)-lactic acid, with smaller amounts of L-(+)-lactic acid and acetic acid, from sugar. All four strains isolated gave a negative reaction to the indole test because they cannot form skatole directly from tryptophan. This is the first report of indoleacetic acid decarboxylation to skatole in pure culture and the demonstration of skatole production by a Lactobacillus species.

Production of Volatile Amines and Skatole at Anthesis in Some Arum Lily Species

The odoriferous compounds produced at the time of flowering by the inflorescences of 5 arum lily species were condensed in dry ice traps. The components of the condensates were separated by paper chromatography and identified on the basis of position and color reactions in comparison with known compounds. The concentration of free amino acids in the appendix of Sauromatum guttatum Schott increased 20-fold during flowering.