Isolation, identification and characterization of a skatole-degrading bacterial strain YKSW-6

Abstract:

[Background] Skatole is the main component of organic pollutants in livestock compost, which can cause the deterioration of farms and surrounding environment. Therefore, skatole pollution needs to be solved urgently. [Objective] This study aims to isolate, identify and characterize an efficient skatole-degrading bacterial strain to provide an efficient strain for the degradation of skatole and lay a foundation for the application of this strain to the remediation of odor-polluted environments. [Methods] Using the minimal salt medium with skatole as the only carbon source, we isolated an efficient skatole-degrading strain from a pig manure compost sample. Strain YKSW-6 was identified based on morphological characteristics and 16S rRNA gene sequence, and its growth pattern and skatole degradation characteristics were analyzed. Gas chromatography-mass spectrometry (GC-MS) was employed to analyze the intermediates of skatole degradation. [Results] Strain YKSW-6 was identified as Rhodococcus gordoniae. When the strain was inoculated at a ratio of 10%, the degradation rate for 100 mg/L skatole reached 100% within 14 h. This strain can utilize 18 carbon sources such as D-sorbitol and bromosuccinic acid, and was resistant to 13 chemicals such as potassium tellurite and potassium bromate. YKSW-6 completely degraded skatole in the culture medium at 5% inoculum ratio, 30–42 ℃, and pH 6.0–9.0. The strain showed the best growth and skatole degradation performance at pH 7.2, 37 ℃ and 180 r/min. The GC-MS results showed that skatole was firstly oxidized at C2 to 3-methyloxindole, and then oxidized to N-(2-acetylphenyl)formamide by strain YKSW-6. Phenylacetaldehyde and phenylacetic acid were also the intermediates during the degradation. [Conclusion] Strain YKSW-6 is a Rhodococcus strain with strong skatole-degrading ability among the reported strains, which enriches the resource of skatole-degrading strains. The results provide a theoretical basis for the development and application of this strain.

Key words:skatole;biodegradation;Rhodococcus gordoniae;metabolic mechanism