Ugan古河道胡杨可培养内生细菌的多样性

Phylogenetic diversity of culturable endophytic bacteria Isolated from the Populus euphratica at the disused ancient Ugan River

【目的】为了了解塔河废弃古河道胡杨可培养内生细菌的多样性。【方法】从2棵胡杨树干部抽出其内存液,采用3种不同的培养基对样品的内生细菌进行了分离纯化;对它们进行16S rDNA测定和系统进化分析。【结果】分离纯化不同表型的细菌62株,对它们的16S rDNA序列分析表明,62株菌分别属于4个大类群;厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)、α-变形菌纲(Alpha Proteobacteria)、γ-变形菌纲(Gamma Proteobacteria),18个属,32个种;芽孢杆菌属和假单胞菌属是胡杨可培养内生细菌的优势细菌种群,它们分别占已测种群的40.32%、16.13%。其中菌株KTH-63为葡萄球菌科的潜在的新属新种,它与最近源菌株的16S rDNA序列相似率为92.491%;9株菌KLH-21、KLH-1、KTH-8、KTH-14、KNA-26、KLH-18、KTH-20、KNA-3、KLH-25是潜在的新种(16S rDNA相似率为96.089%-97.769%),胡杨树干内存液中潜在新种的发现率高达总分离检测菌株的16.13%。本研究获得的胡杨可培养内生细菌的群落结构数据给植物内生细菌新增了10个属,18个种。【结论】胡杨具有多样性极其丰富的可培养内生细菌菌种资源,土著新种的发现频率超出了预期,胡杨可培养内生细菌的群落结构极大地刷新了植物内生细菌的种群记录,极具进一步发掘的潜力。

[Objective]The aim of this study was to identify the culturable endophytic bacteria recovered from the Populus euphratica at the disused（122 years ago） ancient Ugan river of middle reachs of Tarim river,and to understand their Phylogenetic diversity and community structure.[Methods]Bacteria were isolated from the storage liquid in the stem of 2 Populus euphratica stands by using 3 types of different cultural medium（Luria-Bertani,Trypticase Soy Agar and Nutrient Agar）,followed carry out 16S rDNA identifications and analysis of their biodiversity.[Results ] A total of 62 phenotypically different isolates were sequenced and according to their 16S rDNA sequence similarities to type strains of described organisms,they have been placed into four phylogenetic groups（1,Firmicutes;2,Actinobacteria;3,Alpha Proteobacteria and 4,Gamma Proteobacteria）,18 genera and 32 species.Among them,Bacillus and pseudomonas were the most widely distributed and predominant,occupied the majority of isolates 40.32% and 16.13%,respectively.Isolate KTH-63（HM371419） formed a distinct clade with Macrococcus brunensis in phylogenetic tree based on 16S rDNA sequence among the family Staphylococcaceae,so it was demonstrated that the KTH-63 represents a potential novel genus and novel species within the family Staphylococcaceae with 92.491% sequence similarity with the described species Macrococcus brunensis of this family.Isolates KLH-1,KLH-21,KLH-18,KLH-25,KNA-3,KTH-8,KTH-14,KTH-20 and KNA-26 with 96.089%-97.769% sequence similarities to their closely related members were presumed to be potential novel species,and the discovery rate of potential novel species in the endophytic bacterial community of Populus euphratica was reach up to 16.13%.Furthermore,10 genera and 18 species have been added to the plant endophytic bacterial categoria by the data obtained in this work.[Conclusion]The result showed that the cultivable endophytic bacterial diversity in Populus euphratica at Ugan river was very abundant and have high percentage of potential novel species,and it have greatly refreshed the plant endophytic bacterial records.The community structure obtained in this study also may be presumed as a miniature of the endophytic bacterial flora in the Populus euphratica during the recent ages before the affect of modern civilization prossessing to Tarim river valley,which deserve further study and exploitation.