2株降解菲的植物内生细菌筛选及其降解特性

Isolation of Two Endophytic Phenanthrene-Degrading Strains and Their Degradation Capacity

为了获得具有菲降解特性的植物内生细菌,通过选择性富集培养,本研究从多环芳烃污染区植物体内分离得到2株能够降解液体培养基中高浓度菲(200 mg·L-1)的植物内生细菌(菌株P1和P3).经形态观察、生理生化特征鉴定和16S rDNA序列同源性分析,分别将菌株P1和P3鉴定为寡养单胞菌属(Stenotrophomonas sp.)和假单胞菌属(Pseudomonas sp.)的细菌.菌株P1和P3均为好氧生长,28℃、150 r·min-1摇床培养7 d,2株菌对无机盐培养基中菲(100 mg·L-1)的降解率均高于90%.条件实验表明,温度20～30℃,pH 6.0～8.0,盐含量0%～4%,装液量10～30 mL(100 mL三角瓶)2菌株生长良好且对菲降解率高于70%.其最适生长和降解温度为30℃,pH为7.0,盐含量≤4%,装液量≤30 mL.综合比较2株菌对菲的降解特性,P1菌株高温耐受性稍强,而P3菌株对环境pH改变和缺氧的耐受性稍强.

Two endophytic bacterial strains, which could degrade high concentration （ up to 200 mg. L-1 ） of phenanthrene in liquid, were isolated from plants grown in PAHs-contaminated soils by the selective enrichment culture. According to the results of morphology, physiology and the phylogenetic analyses of 16S rDNA sequence, stain P1 was identified as Stenotrophomonas sp. , and strain P3 was identified as Pseudomonas sp.. Two strains were aerobic bacteria, the degradation rates of phenanthrene （100 mg. L-1） by strain P1 and strain P3 were all greater than 90% at 28℃ on the rotation shaker at 150 r.min -1 for 7 days. The degradation rates of phenanthrene by two strains were greater than 70% when cultivated under the conditions as： 20-30℃ , pH 6-8, 0% -4% NaC1, 10-30 mL/100 mL inventory. It suggested that the optimum culture condition was： 30℃ , pH 7.0, NaCl≤4% , inventory ≤30 mL/100 mL flask. Through comprehensive comparison analyses on the degradation capacity of two strains, it showed that the tolerance of strain P1 to high temperature was higher than that of strain P3, while the tolerance of strain P3 to pH change and anoxic condition was higher than that of strain P1.