Stibal Marek, Sabacká Marie, Kastovská Klára
Faculty of Biological Sciences, University of South Bohemia, Branisovská 31, Ceské Budejovice 37005, Czech Republic.
Microb Ecol. 2006 Nov;52(4):644-54. doi: 10.1007/s00248-006-9083-3. Epub 2006 Oct 28.
Microbial communities occurring in three types of supraglacial habitats--cryoconite holes, medial moraines, and supraglacial kames--at several glaciers in the Arctic archipelago of Svalbard were investigated. Abundance, biovolume, and community structure were evaluated by using epifluorescence microscopy and culturing methods. Particular emphasis was laid on distinctions in the chemical and physical properties of the supraglacial habitats and their relation to the microbial communities, and quantitative multivariate analyses were used to assess potential relationships. Varying pH (4.8 in cryoconite; 8.5 in a moraine) and texture (the proportion of coarse fraction 2% of dry weight in cryoconite; 99% dw in a kame) were found, and rather low concentrations of organic matter (0.3% of dry weight in a kame; 22% dw in cryoconite) and nutrients (nitrogen up to 0.4% dw, phosphorus up to 0.8% dw) were determined in the samples. In cryoconite sediment, the highest numbers of bacteria, cyanobacteria, and algae were found, whereas relatively low microbial abundances were recorded in moraines and kames. Cyanobacterial cells were significantly more abundant than microalgal ones in cryoconite and supraglacial kames. Different species of the cyanobacterial genus Leptolyngbya were by far the most represented in all samples, and cyanobacteria of the genera Phormidium and Nostoc prevailed in cultures isolated from cryoconite samples. These species are considered opportunistic organisms with wide ecological valency and strong colonizing potential rather than glacial specialists. Statistical analyses suggest that fine sediment with higher water content is the most suitable condition for bacteria, cyanobacteria, and algae. Also, a positive impact of lower pH on microbial growth was found. The fate of a microbial cell deposited on the glacier surface seems therefore predetermined by the physical and chemical factors such as texture of sediment and water content rather than spatial factors or the origin of sediment.
对斯瓦尔巴德北极群岛若干冰川上三种类型的冰上栖息地——冰尘穴、中碛和冰上冰砾阜——中存在的微生物群落进行了调查。通过落射荧光显微镜和培养方法评估了微生物的丰度、生物体积和群落结构。特别强调了冰上栖息地化学和物理性质的差异及其与微生物群落的关系，并采用定量多变量分析来评估潜在关系。研究发现，不同栖息地的pH值不同（冰尘穴中为4.8；冰碛中为8.5），质地也不同（冰尘穴中粗颗粒比例占干重的2%；冰砾阜中为99%），并且样品中有机物（冰砾阜中占干重的0.3%；冰尘穴中为22%）和养分（氮含量最高达0.4%干重，磷含量最高达0.8%干重）的浓度相当低。在冰尘沉积物中发现了数量最多的细菌、蓝细菌和藻类，而在冰碛和冰砾阜中记录到的微生物丰度相对较低。在冰尘穴和冰上冰砾阜中，蓝细菌细胞的数量明显多于微藻细胞。蓝细菌属的不同物种在所有样本中占比最大，从冰尘穴样本中分离出的培养物中，席藻属和念珠藻属的蓝细菌占优势。这些物种被认为是具有广泛生态价和强大定殖潜力的机会性生物，而非冰川特化生物。统计分析表明，含水量较高的细沉积物是细菌、蓝细菌和藻类最适宜的生存条件。此外，还发现较低的pH值对微生物生长有积极影响。因此，沉积在冰川表面的微生物细胞的命运似乎由沉积物质地和含水量等物理化学因素决定，而非空间因素或沉积物来源。
