Bärlocher F, Nikolcheva L G, Wilson K P, Williams D D
Department of Biology, Mount Allison University, 63B York Street, Sackville, NB, Canada, E3L 1G7.
Microb Ecol. 2006 Nov;52(4):708-15. doi: 10.1007/s00248-006-9102-4. Epub 2006 Aug 15.
Eight bimonthly sediment core samples (n = 6) were collected, to a depth of 64 cm, from the hyporheic zone of a springbrook in southern Ontario, Canada. Sediment cores were divided into three to four sections, and organic matter was subdivided into six different categories. Twigs were the most common substrate, followed by roots, cedar leaves, wood, grass, and deciduous leaves. The contributions of deciduous and cedar leaves declined with depth, whereas that of wood increased. On each sampling date and from each section, three randomly chosen substrates >3 cm were examined for conidia of aquatic hyphomycetes. The number of identified species significantly decreased with depth, and was highest on deciduous leaves and lowest on wood. Season had no significant effect on species numbers. DNA from substrates was extracted, amplified with fungal primers, and differentiated into phylotypes with denaturing gradient gel electrophoresis (DGGE). Absence/presence patterns of phylotype were significantly affected by season but not by section level. Both season and section level significantly affected relative densities of the bands of the 10 most common phylotypes. Our data suggest that aquatic hyphomycetes and other fungi readily disperse within the hyporheic zone, and that their relative scarcity in this habitat is due to a lack of suitable substrates.
从加拿大安大略省南部一条小溪的潜流带采集了8个双月沉积物岩芯样本（n = 6），深度达64厘米。沉积物岩芯被分成三到四段，有机物质被细分为六种不同类别。细枝是最常见的基质，其次是根、雪松叶、木材、草和落叶。落叶和雪松叶的占比随深度下降，而木材的占比则增加。在每个采样日期和每一段中，随机选取三个长度大于3厘米的基质，检查其中水生真菌的分生孢子。已鉴定物种的数量随深度显著减少，在落叶上最多，在木材上最少。季节对物种数量没有显著影响。从基质中提取DNA，用真菌引物进行扩增，并通过变性梯度凝胶电泳（DGGE）将其区分成不同的系统型。系统型的有无模式受季节显著影响，但不受分段水平影响。季节和分段水平都显著影响10种最常见系统型条带的相对密度。我们的数据表明，水生真菌和其他真菌很容易在潜流带内扩散，它们在这个栖息地相对稀少是由于缺乏合适的基质。
