粪臭素高效降解菌YKSW-6的分离、鉴定及降解特性

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

摘要:

【背景】粪臭素是畜牧堆肥中有机污染物的主要成分，造成养殖场及周边环境恶化，粪臭素污染问题亟待解决，利用微生物降解粪臭素是一种环保节能的有效方法。【目的】分离鉴定粪臭素高效降解菌株，研究其降解特性，为粪臭素降解提供高效的菌种资源，为该菌株应用于臭味污染环境的净化提供基础。【方法】以粪臭素为唯一碳源的无机盐培养基作为培养基质，从猪粪堆肥样品中分离筛选粪臭素高效降解菌株，通过形态特征和16S rRNA基因序列分析进行分离菌株的初步鉴定，分析其生长规律及粪臭素降解特性，并利用气相色谱质谱联用(GC-MS)对菌株代谢粪臭素的产物进行分析。【结果】从样品中分离获得一株能以粪臭素为唯一碳源的细菌YKSW-6菌株，形态学和16S rRNA基因序列分析初步鉴定该菌株为戈登氏红球菌(Rhodococcus gordoniae)。接种量为10%时，该菌培养14 h对100 mg/L的粪臭素降解率达到100%。其能够利用D-山梨醇、溴-丁二酸等18种碳源，对亚碲酸钾、溴酸钾等13种化学敏感物具有抗性。菌株YKSW-6在5%接种量、温度30-42℃和pH值为6.0-9.0时对100 mg/L的粪臭素降解效率均能达到100%，菌株生长和降解粪臭素的最佳条件为：pH 7.2，温度37℃，转速180 r/min。GC-MS结果表明，粪臭素在菌株的作用下C2先被氧化，转变为3-甲基羟基吲哚，随后进一步被氧化为N-(2-乙酰基苯基)甲酰胺。同时中间产物还有苯乙醛和苯乙酸。【结论】红球菌YKSW-6为目前已报道的降解粪臭素能力较强的菌株，丰富了粪臭素降解菌种的资源库，为实际环境微生物修复应用提供了理论参考。

关键词:粪臭素;生物降解;戈登氏红球菌;代谢机理

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