春季青藏高原东北部湖泊细菌种类组成

Bacterial Community Structure in Lakes on the Northeastern Qinghai-Tibetan Plateau

青藏高原东北地区位于我国东部季风区、西北干旱区和青藏高原高寒区的交汇地带,人为影响较少,是研究生物种群组成的理想场所,然而目前尚缺乏大范围的分子生物学研究.2012年4-5月期间对青藏高原东北部10个湖区进行采样调查(表层、底层水各0.5 L混匀),应用16S rRNA和PCR-DGGE指纹分析研究细菌种类和组成.共鉴别出样本湖水中117个分类单元(Operational taxonomic unit,OTU)的细菌,分别隶属于12个纲,其中以α-变形菌纲(21种)和β-变形菌纲(27种)检出频次最多.细菌主要源于水生的微生物,外来扰动较少同时各湖区细菌分类单元数量(平均32.1±11.2)偏少,多样性指数(平均0.97±0.29)和均匀度指数(平均0.19±0.04)偏低,湖区之间相似性(平均0.31±0.11)较差,种群生态结构脆弱.各湖区物种分类单元数量受环境因素影响明显,温度与种群分类单元数(R=0.763,P<0.05)、多样性指数(R=0.708,P<0.05)及均匀度指数(R=0.641,P<0.05)正相关,湖水面积与种群分类单元数量(R=0.754,P<0.05)及多样性系数(R=0.668,P<0.05)呈正相关,并且细菌种类组成受到湖水水化学(如矿化度等)因素影响.本研究表明春季青藏高原东北部10个湖区细菌种类组成较为简单,生态结构脆弱,受自然环境因素限制明显,结果可为青藏高原东北部地区水生生物研究积累基础资料,亦可为群落结构的限制性气候因素分析、区域的可持续利用和保护提供科学依据.

The northeast of Qinghai-Tibetan Plateau is China, northwest arid area and Qinghai-Tibetan Plateau located in the convergence zone of the monsoon region of eastern region. During April to May 2012, an investigation was carried out on the bacterial community structure in ten lakes on northeastern Qinghai-Tibetan Plateau. With 16S rRNA sequencing and PCR-DGGE technology, twelve bacteria genus level libraries were constructed with a total of 117 operational taxonomic unit including 27 Betaproteobacteria, 8 Gamaproteobacteria, 21 Alphaproteobacteria, 7 Deltaproteobacteria,16 Acidobacteria, 2 Deinococci, 5 Sphingobacteria, 6 Flavobacteria, 5 Nitrospira, 11 Actinobacteria, 6 Gemmatimonadetes and 3 unclassified bacteria. Most sequences in these studied lakes were closer to aquatic bacteria than any other bacterial clusters. The number of operational taxonomic unit in northeastern Qinghai-Tibetan Plateau was 32.1 ± 11.2, Shannon-Wiener diversity index 0.97± 0.29, Pielou＇s evenness index 0.19 ± 0.04, and Sorenson similarity index between lakes 0.31 ± 0.11, all comparatively low. Notably, the environment factors played an important role in bacteria community, with temperature positively related to OTUs （R = 0.763, P 〈 0.05）, to Shannon-Wiener diversity index （R = 0.708, P 〈 0.05）, and to Pielou＇s evenness index （R = 0.641, P 〈 0.05）; the lake area was also positively related to OTUs （R= 0.754, P 〈 0.05） and Shannon-Wiener diversity index （R = 0.668, P 〈 0.05）. Water chemistry also played an important part in bacteria community. The result is helpful for study of climatic factors of community structure and sustainable development in this region. Fig 4, Tab 4, Ref31