Isolation and characterization of two Acinetobacter species able to degrade 3-methylindole

Abstract

3-Methylindole (3MI) or Skatole is a volatile lipophilic organic compound produced by anoxic metabolism of L-tryptophan and associated with animal farming and industrial processing wastes. Pure cultures of bacteria capable of utilizing 3MI were isolated from chicken manure using enrichment culture techniques. The bacteria were identified as Acinetobacter toweneri NTA1-2A and Acinetobacter guillouiae TAT1-6A, based on 16S rDNA gene amplicon sequence data. The optimal temperature and pH for degradation of 3MI were established using single factor experiments. Strain tolerance was assessed over a range of initial concentrations of 3MI, and the effects of initial concentration on subsequent microbial 3MI degradation were also measured. During the degradation experiment, concentrations of 3MI were quantified by reverse-phase high-performance liquid chromatography (HPLC). The strains were capable of degrade initial concentrations of 3MI ranging from 65–200 mg/L. The degradation efficiency was >85% in 6 days for both strains when the initial concentration is less than 200 mg/L. The strains were tested for enzymatic activity using 65 mg/L 3MI. The enzyme extracts of NTA1-2A and TAT1-6A from the 3MI medium degraded 71.46% and 60.71% of 3MI respectively, but no appreciable change in 3MI concentration in the control group was witnessed. Our experiment revealed betaine and choline were identified as 3MI degradation metabolites by both strains while nitroso-pyrrolidine and beta-alaninebetaine formed by NTA1-2A and TAT1-6A strains respectively. The NTA1-2A and TAT1-6A strains removed 84.32% and 81.39% 3MI respectively from chicken manure during fermentation in 8 days and showed a statistically significant difference (P < 0.05) compared with the control group. The optimum temperature and pH were 31°C and 6 respectively, for 3MI degradation by A. toweneri NTA1-2A and A. guillouiae TAT1-6A. We concluded that A. toweneri NTA1-2A and A. guillouiae TAT1-6A are potential strains of interest to degrade 3MI and control odorant in poultry and other livestock industries.

Soybean oligosaccharide, stachyose, and raffinose in broilers diets: effects on odor compound concentration and microbiota in cecal digesta

“…Many types of odorous compounds have been identified and classified into 4 main groups: 1) sulfur compounds, 2) phenolic and indolic compounds, 3) volatile fatty acids ( VFAs ), 4) ammonia and amines ( Mackie et al., 1998 ). Among these compounds, indole and skatole (3-methylindole), which are produced from anoxic metabolism of L-tryptophan by microbial degradation, are well-known foul-smelling fecal odorants in mammalian and avian feces ( Benoît et al., 2001 , Trabue et al., 2010 , Tesso et al., 2019 ). Acetic acid, propionic acid, and butyric acid are the most common VFAs produced from the microbial conversion of dietary residues.…”

“…Acetic acid, propionic acid, and butyric acid are the most common VFAs produced from the microbial conversion of dietary residues. A few strategies directed at reducing odorants arising from livestock and poultry breeding have been evaluated, including the modification of diets ( Cho et al., 2015 , Sharma et al., 2015 , Recharla et al., 2017 ) and addition of oligosaccharides ( Rideout et al., 2004 , Yang et al., 2016 ), enzymes ( O'Shea et al., 2014 , Sharma et al., 2016 ), organic acids ( Claus et al., 2003 , Øverland et al., 2008 ), probiotics, or minerals ( Armstrong et al., 2000 , Borowski et al., 2017 , Tesso et al., 2019 ).…”

Indole Degradation in a Model System and in Poultry Manure by Acinetobacter spp.

“…Yin et al [20] reported Pseudomonas aeruginosa Gs degrading indole completely in four days when the concentration was 3.0 mM. Recently, Acinetobacter strains named NTA1-2A and TAT1-6A obtained from 3-methylindole acclimated samples [47] were used to degrade indole. The strains also utilized indole as their sole carbon source and efficiently removed <300 mg/L indole within six days when cultured in simple mineral salt medium at 31 • C and pH 6.…”

“…The strains of Acinetobacter used in this experiment therefore degraded indole efficiently under aerobic conditions. In this study, two Acinetobacter strains previously isolated from chicken manure and acclimated in 3-methylindole [47] were used to degrade indole, and demonstrated strong ability of indole removal from culture medium and poultry manure. Hence, this study evaluates in vivo and in vitro degradation of indole under different conditions using Acinetobacter toweneri NTA1-2A and Acinetobacter guillouiae TAT1-6A strains.…”

New Provisional Function of OmpA from Acinetobacter sp. Strain SA01 Based on Environmental Challenges

“…The most important clinically relevant species, such as Acinetobacter baumannii , are usually multidrug resistant and can trigger several diseases ( 4 ). Also, a variety of potential biotechnological applications have been proposed for environmental strains of Acinetobacter , such as bioremediation of environmental pollutants or the production of emulsifying agents with the capability of stabilizing oil particles in water ( 5 – 8 ). One of the emulsifiers produced by Acinetobacter radioresistens strain KA53 is an OmpA-like protein with 349 amino acids, called AlnA, which shares clear sequence similarity with OmpA of Escherichia coli and OprF, the major porin of Pseudomonas aeruginosa ( 9 , 10 ).…”