Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2008
Publication Date: 2/4/2009
Citation: Doerner, K., Mason, B., Kridelbaugh, D., Loughrin, J.H. 2009. Fe(III) stimulates 3-methylindole and 4-methylphenol production in swine lagoon enrichments and Clostridium scatologenes ATCC 25775. Letters in Applied Microbiology. 48 118-124
Interpretive Summary: In order to determine if compounds that stimulate anaerobic bacterial respiration can affect the production of the malodorous compounds p-cresol and 3–methylindole by swine waste, sediment from a swine waste lagoon was incubated in a variety of media. Swine waste incubated with the respiratory stimulants nitrate, manganese, dimethyl sulfoxide, or iron resulted in only iron increasing the production of the two malodorous compounds. When Clostridium scatalogenes, a bacterium known to produce 3-methylindole and p-cresol, was incubated with iron, production of the malodorants was also enhanced without enhancing the growth of the bacteria. Previous studies have suggested that addition of iron to swine waste can reduce the production of malodorous acids. Our data, however, shows that iron addition could have the negative effect of increasing the production of other malodorous compounds.
Technical Abstract: Aims: To determine the effects of anaerobic electron acceptors on 3-methylindole (3-MI) and 4-methylphenol (4-MP) production in swine waste lagoon enrichments and Clostridium scatologenes ATCC 25775. Methods and Results: Swine waste lagoon sediment was incubated anaerobically in tryptone-yeast extract (TY) medium with (10 mM) sodium sulfate, potassium nitrate, dimethyl sulfoxide, or Fe(III). With Fe(III), 3-MI and 4-MP levels increased significantly above controls to 138 µM and 187 µM, respectively. C. scatologenes ATCC 25775 cultured in brain heart infusion medium amended with 10 mM of either sodium sulfate, potassium nitrate, manganese oxide, or Fe(III), resulted in only Fe(III) significantly increasing 3-MI (1,308 µM)) and 4-MP (367 µM) levels. In semi-defined medium, Fe(III) alone and Fe(III) plus L-tryptophan caused a 1.85-fold and 15.6-fold increase in 3-MI levels over media supplemented with 1 mM L-tryptophan alone, respectively. Fe(III) alone and Fe(III) plus L-tyrosine caused a 4.4-fold and 22.9-fold increase in 4-MP levels over tyrosine alone, respectively. Interestingly, Fe(III) addition did not increase cell growth. Conclusions: Fe(III) increases 3-MI and 4-MP levels in swine waste lagoon enrichments and pure cultures of C. scatologenes ATCC 25775. Significance and Impact of Study: Studies suggest addition of Fe(III) to swine waste lagoon could remediate malodorous volatile fatty acids; however, data presented here suggest Fe(III) could also adversely increase production of malodorous indolic and phenolic compounds.