3-Methylindole production is regulated inClostridium scatologenesATCC 25775

Abstract

Aims: 3‐Methylindole (3‐MI) is a degradation product of l‐tryptophan and is both an animal waste malodorant and threat to ruminant health. Culture conditions influencing 3‐MI production in Clostridium scatologenes ATCC 25775 were investigated. Methods and Results: Extracellular 3‐MI levels in cells cultured in brain heart infusion (BHI) medium (pH 7·0) at 33°C and 37°C for 72 h were 907 ± 38 and 834 ± 121 μmol l−1, respectively. Cells cultured in tryptone‐yeast (TY) extract medium at 37°C for 48 h produced 104 ± 86 μmol l−1 3‐MI; however, addition of 1 mmol l−1 l‐tryptophan failed to increase extracellular levels (113 ± 50 μmol l−1 3‐MI). Specific activity of indole acetic acid decarboxylase measured in BHI, TY and TY plus 1 mmol l−1 tryptophan‐grown cells displayed 35‐, 33‐ and 76‐fold higher levels than in semi‐defined medium‐grown cells. Conclusions: When cultured in rich medium, at 33°C or 37°C and pH 7·0, Cl. scatologenes ATCC 25775 optimally produced 3‐MI. Addition of l‐tryptophan to medium did not lead to significant increases in extracellular 3‐MI levels. Whole cell assays indicate growth in rich medium significantly up‐regulated 3‐MI production. Significance and Impact of the Study: Information presented here may prove useful in understanding what factors influence 3‐MI production in malodorous animal wastes.

Inhibitory effect of skatole (3-methylindole) on enterohemorrhagic Escherichia coli O157:H7 ATCC 43894 biofilm formation mediated by elevated endogenous oxidative stress

“…Skatole is responsible for offensive odours associated with food animal production and waste, including boar taint generated when the pork from an intact male swine is cooked (Doerner et al . ). For this reason, until now, the focus surrounding skatole has been centred on its harmful effects to the host due to metabolite toxicity.…”

“…Similar to an indole, skatole is also one of the predominant metabolites produced during tryptophan catabolism in the large intestine of humans and animals (Yokoyama and Carlson 1979). Skatole is responsible for offensive odours associated with food animal production and waste, including boar taint generated when the pork from an intact male swine is cooked (Doerner et al 2009). For this reason, until now, the focus surrounding skatole has been centred on its harmful effects to the host due to metabolite toxicity.…”

Feeding Jerusalem artichoke reduced skatole level and changed intestinal microbiota in the gut of entire male pigs

“…It is possible that pH in the hindgut is an environmental factor that can reduce the amount of skatole-producing bacteria present or alter the metabolic activity in the bacteria towards indol production at the expense of skatole. A study on 3-methylindole production in Clostridium scatologenes ATCC 25775 by Doerner et al (2009) found that skatole production decreased if pH was reduced from 7 to 5, and they further suggested that skatole production can be downregulated because it is not an essential metabolic function. A study by Jensen et al (1995b) measuring skatole and indole formation from L-tryptophan in pig faecal slurries in vitro, reported that the amount of L-tryptophan converted to skatole at the expense of indole was increased at pH 5 compared with pH 8.…”

“…Xu et al, 2002). Bacteria reported as skatole producers often belong to the genus Clostridium (Jensen et al, 1995b;Attwood et al, 2006;Doerner et al, 2009). The amount of C. perfringens in the digesta can potentially be used as an indicator on the amount of bacteria from the genus Clostridium present (H. Sørum, personal communication).…”

Skatole remediation potential of Rhodopseudomonas palustris WKU-KDNS3 isolated from an animal waste lagoon

“…L‐tryptophan addition to C. scatologenes growing in defined medium did not result in 3MI production, but the addition of glucose or fructose with L‐tryptophan resulted in 3MI production (Doerner et al . ).…”