一株新颖的Providencia sp.菌降解吲哚及合成靛蓝的特性研究

Degradation characteristics of indole and biosynthesis of indigo by a novel bacteria Providencia sp.

吲哚是一种典型的氮杂环芳烃污染物,在焦化废水和畜牧废水中大量存在.本研究从近海泥沙中分离纯化得到一株高效吲哚降解菌DCX,经16S rRNA基因序列比对分析,鉴定其为普罗维登斯菌属(Providencia sp.).该菌株能够以吲哚为唯一碳源,在28 h内将100 mg·L^(-1)吲哚完全降解.液相色谱/飞行时间-质谱联用(LC/TOF-MS)的结果表明,靛蓝、靛红、靛红酸及邻氨基苯甲酸是菌株DCX降解吲哚过程中的中间产物.此外,本研究中发现,外加营养物质可以促进菌株DCX降解吲哚,特别是加入酵母浸粉后,反应体系中会产生大量靛蓝.利用表面响应法确定菌株DCX转化吲哚合成靛蓝的最优条件为:吲哚207.49 mg·L^(-1),酵母浸粉2.9 g·L-1,接菌量4.23%(V/V),并且在最优条件下,靛蓝产率达到最高(9.90%),比初始条件提高了4.38倍.

As a typical aromatic N-heterocyclic pollutant,indole is often found in coking and livestock wastewater. An efficient novel indole-degrading strain DCX was isolated from inshore soil sample and identified as Providencia sp. according to 16 S rRNA gene sequencing analysis. When utilizing indole as the sole carbon source,strain DCX could degrade 100 mg·L^-1 indole in 28 h. Indigo,isatin,o-aminobenzoic acid and isatin acid were identified as the intermediate metabolites according to the results of LC/TOF-MS,and a degradation pathway was proposed. The effects of various environmental parameters for indole degradation were studied. The additional nutrients promoted the indole degradation,and large amounts of indigo were produced when yeast extract was added. The optimal conditions for indigo production were determined using response surface methodology（ RSM） as follows： 207.49 mg·L^-1 indole,2.9 g·L^-1 yeast extracts and 4.23%（ V/V） of inoculum. The biosynthesis rate of indigo by strain DCX was up to 9.90%,which increased by 4.38 folds compared to the original yield.