Nelson David M, Ohene-Adjei Samuel, Hu Feng Sheng, Cann Isaac K O, Mackie Roderick I
Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Microb Ecol. 2007 Aug;54(2):252-63. doi: 10.1007/s00248-006-9195-9. Epub 2007 Mar 16.
Sediments contain an abundance of microorganisms. However, the diversity and distribution of microorganisms associated with sediments are poorly understood, particularly in lacustrine environments. We used banding patterns from denaturing gradient gel electrophoresis (DGGE) and 16S rDNA sequences to assess the structure of bacterial communities in the Holocene sediments of a meromictic lake in Minnesota. Cluster analysis of the DGGE banding patterns indicates that the early- and middle-Holocene samples group separately from the late-Holocene samples. About 79% of the recovered bacterial sequences cluster with the alpha-, beta-, delta-, epsilon-, and gamma- Proteobacteriaceae and Firmicutes. The remaining approximately 21% lack cultured representatives. The taxonomic lineages of bacteria differ statistically among the early-, middle-, and late-Holocene samples, although the difference is smallest between early- and middle-Holocene samples. Early- and middle-Holocene samples are dominated by epsilon-Proteobacteriaceae, and late-Holocene samples are dominated by sequences from uncultured subphyla. We only recovered delta-Proteobacteriaceae in late-Holocene sediments and alpha- and gamma- Proteobacteriaceae in late- and middle-Holocene sediments. Diversity estimates derived from early-, middle-, and late-Holocene clone libraries indicate that the youngest (late-Holocene) samples had significantly greater bacterial diversity than the oldest (early-Holocene) samples, and the middle-Holocene samples contained intermediate levels of diversity. The observed patterns of diversity may be caused by increased bacterial niche-partitioning in younger sediments that contain a greater abundance of labile organic matter than older sediments.
沉积物中含有大量微生物。然而，与沉积物相关的微生物的多样性和分布情况却鲜为人知，尤其是在湖泊环境中。我们利用变性梯度凝胶电泳（DGGE）的条带模式和16S rDNA序列来评估明尼苏达州一个半咸水湖全新世沉积物中细菌群落的结构。DGGE条带模式的聚类分析表明，全新世早期和中期的样本与全新世晚期的样本分别聚类。约79%的回收细菌序列与α-、β-、δ-、ε-和γ-变形菌科以及厚壁菌门聚类。其余约21%缺乏可培养的代表菌株。尽管全新世早期和中期样本之间的差异最小，但细菌的分类谱系在全新世早期、中期和晚期样本之间存在统计学差异。全新世早期和中期样本以ε-变形菌科为主，全新世晚期样本以未培养亚门的序列为主。从全新世早期、中期和晚期克隆文库得出 的多样性估计表明，最年轻（全新世晚期）的样本细菌多样性显著高于最古老（全新世早期）的样本，全新世中期样本的多样性处于中间水平。观察到的多样性模式可能是由于较年轻沉积物中细菌生态位划分增加所致，这些沉积物比古老沉积物含有更丰富的不稳定有机物质。
