中科院南京土壤研究所褚海燕团队和中科院青藏高原研究所的研究人员合作，深入研究了青藏高原碱性湖底沉积物细菌群落的空间分布及其驱动机制。相关成果近期发表在《环境微生物学》杂志上。
据了解，生物地理学是研究生物多样性时空分布规律的一门学科，是生态学的核心问题之一。目前，对于微生物分布是受当代环境因子还是历史因素（用空间距离表征）的影响以及它们的相对贡献率，还存在很大争议。已有研究表明，pH是酸性土壤中微生物空间分布的关键驱动因子，但在碱性条件下pH是否同样重要还未见报道。
此次研究人员通过454高通量测序技术，对青藏高原碱性湖底沉积物细菌群落进行研究发现，与酸性土壤相似，碱性沉积物中pH同样是控制细菌群落空间变异的关键因子，同时尽管环境因子控制了更多的细菌群落变异，但空间距离作为单一因子，解释了最高的群落变异。
据悉，此项研究首次证明了pH是驱动碱性湖泊沉积物细菌生物地理分布的关键因子，并提出了当代环境与历史因素共同驱动青藏高原湖泊沉积物的细菌空间分布。同时，研究也建议，在微生物生物地理分布研究中应选择足够的样本数以提高统计的可靠性、受到较少扰动的生态系统以减少随机传播、不同的空间尺度以提高结果的适用性。
评审专家认为，该研究将pH驱动微生物群落分布的重要作用从酸性拓展到碱性，对于更好地理解微生物群落结构的驱动因子和空间地理分布机制具有重要意义。（生物谷Bioon.com）
doi: 10.1111/j.1462-2920.2012.02799.x
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Geographic distance and pH drive bacterial distribution in alkaline lake sediments across Tibetan Plateau
Xiong J, Liu Y, Lin X, Zhang H, Zeng J, Hou J, Yang Y, Yao T, Knight R, Chu H
Continent-scale biogeography has been extensively studied in soils and marine systems, but little is known about biogeographical patterns in non-marine sediments. We used barcode pyrosequencing to quantify the effects of local geochemical properties and geographic distance for bacterial community structure and membership, using sediment samples from 15 lakes on the Tibetan Plateau (4-1670 km apart). Bacterial communities were surprisingly diverse, and distinct from soil communities. Four of 26 phyla detected were dominant: Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria, albeit 20.2% of sequences were unclassified at the phylum level. As previously observed in acidic soil, pH was the dominant factor influencing alkaline sediment community structure, phylotype richness and phylogenetic diversity. In contrast, archaeal communities were less affected by pH. More geographically distant sites had more dissimilar communities (r=0.443, P=0.030). Variance partitioning analysis showed that geographic distance (historical contingencies) contributed more to bacterial community variation (12.2%) than any other factor, although the environmental factors explained more variance when combined (28.9%). Together, our results show that pH is the best predictor of bacterial community structure in alkaline sediments, and confirm that both geographic distance and chemical factors govern bacterial biogeography in lake sediments.
