川西高寒森林溪流好氧不产氧光合细菌多样性

摘要

In order to understand AAPB community structure and distribution in a high-frigid forest stream with cold environment, here, a field investigation was carried out in West Sichuan, China. Water was sampled in the stream at onset of the freezing period (FP), the deep freezing period (FPD) and the thawing period (TP). The methods of real-time fluorescent quantitative PCR and clone library were used to check the richness and diversity of AAPB. Temperature and other water characters were also observed to analysis the relationships between environment and AAPB. The results showed that low abundance (2.80 ± 0.19) ×104bp / mL of AAPB was observed, at FP, but which rapidly increased to (4.65 ± 0.30) ×104bp / mL at FPD, then reached to (5.79 ± 0.19) ×104bp / mL at TP. Phylogenetic relationships from clone libraries displayed that Alphaproteobacteria classes dominated AAPB at FP, but Betaproteobacteria classes dominated AAPB at both FPD and TP. In addition, correlationships revealed that the concentration of chlorophylla and dissolved organic carbon, as well as average temperature had closely relationships with AAPB abundance and diversity during the seasonal freeze-thaw period. All the results suggest that AAPB have low abundance but exhibit highly dynamical patters in the high-frigid forest streams and their communities share low homology with those in other freshwater.%为了探明好氧不产氧光合菌(AAPB)在川西高寒森林溪流极端环境中的生态分布和群落结构及其环境影响因子,本实验结合同步温度动态和水环境特征监测,采用实时荧光定量PCR和克隆文库的方法,检测了川西高寒森林溪流季节性冻融循环3个关键时期(冻结前期、深冻期和融化期)AAPB的丰度和多样性变化及其与环境因子之间的相关性.结果表明:AAPB丰度在冻结前期非常低,仅(2.80±0.19)×104bp/mL;深冻期迅速增加到(4.65±0.30)×104bp/mL;融化期达到(5.79±0.19)×104bp/mL.系统发育分析显示,冻结前期AAPB类群主要为α-变形菌纲细菌;而深冻期和融化期以β-变形菌纲细菌占据主要地位.相关性分析表明,在季节性冻融循环过程中,叶绿素a、可溶性有机碳和温度是AAPB菌群丰度和多样性的主要影响因子.实验结果表明冬季的川西高寒森林溪流中,AAPB类群的丰度低,但是它们高度动态变化,并且与其他淡水环境中的该类群的同源性低.