Isolation and identification of a high-efficiency bacterial strain Rp3 to degrade skatole: An odor chemical in compost

The purpose of this study was to isolate a skatole-degrading bacterium, and provide a high efficiency microorganism for the degradation of odor chemicals released from composting manure. A liquid culturing method was used to enrich skatole-degrading bacteria, and a pure culture was isolated using plate-streaking. The degrading ability of the candidate bacteria was pre-determined by smell assessment and chemotactic responses to skatole serving as the sole nutrition. The efficacy of strain Rp3 to degrade skatole at different concentrations was analyzed by high performance liquid chromatography(HPLC), and was identified based on the morphological and physiological characteristics, in combination with 16S rRNA gene sequence analysis. A skatole-degrading bacterium, Rp3, was isolated from soil under sheep manure compost collected from Shanxi Province. This strain showed chemotactic response to skatole. HPLC analysis indicated that the degradation time extended with the increase of skatole concentration. Strain Rp3 could completely degrade skatole at a concentration of 50 mg·L-1 after co-culturing with skatole at 28℃ for 24 h, while the degrading time extended to 48 h with an efficacy of 98.4%, when the concentration was raised to 100 mg·L-1. The optimum pH for Rp3 growth was pH 7~8, and Rp3 exhibited good tolerance to salt stress, demonstrated by normal growth in a solution of 0~10% NaCl. Strain Rp3 was identified as Rhodococcus pyridinivorans, based on its morphological characteristics, the results of Biolog identification system and 16S rRNA gene sequence analysis. Strain Rp3 was identified as Rhodococcus pyridinivorans, and was shown to be a highly effective strain in degrading skatole, an odor chemical in compost.