Methanotrophic Bacteria of Acidic Sphagnum Peat Bogs

Acidic Sphagnum peat bogs cover a considerable part of the territory of Russia and are an important natural source of biogenic methane, which is formed in their anaerobic layers. A considerable portion of this methane is consumed in the aerobic part of the bog profile by acidophilic methanotrophic bacteria, which comprise the methane filter of Sphagnum peat bogs and decrease CH₄ emission to the atmosphere. For a long time, these bacteria escaped isolation, which became possible only after the elucidation of the optimal conditions of their functioning in situ: pH 4.5–5.5; temperature, from 15 to 20°C; and low salt concentration in the solution. Imitation of these conditions and rejection of earlier used media with a high content of biogenic elements allowed methanotrophic bacteria of two new genera and species—Methylocella palustris and Methylocapsa acidiphila—to be isolated from the peat of Sphagnum peat bogs of European northern Russia and western Siberia. These bacteria are well adapted to the conditions in cold, acidic, oligotrophic Sphagnum peat bogs. They grow in a pH range of 4.2–7.5 with an optimum at 5.0–5.5, prefer moderate temperatures (15–25°C) and media with a low content of mineral salts (200–500 mg/l), and are capable of active dinitrogen fixation. Design of fluorescently labeled 16S rRNA–targeted oligonucleotide probes for the detection of Methylocella palustris and Methylocapsa acidiphila and their application to the analysis of sphagnum peat samples showed that these bacteria represent dominant populations of methanotrophs with a density of 10⁵–10⁶ cells/g peat. In addition to Methylocella and Methylocapsa populations, one more abundant population of methanotrophs was revealed (10⁶ cells/g peat), which were phylogenetically close to the genus Methylocystis.     

Evaluation of the Phylogenetic Diversity of Prokaryotic Microorganisms in Sphagnum Peat Bogs by Means of Fluorescence In Situ Hybridization (FISH)

The microbial population of sphagnum peat bogs of northern Russia was analyzed with respect to the presence and cell numbers of representatives of particular phylogenetic groups of prokaryotes by means of in situ hybridization with fluorescently labeled group-specific rRNA-targeted oligonucleotide probes with broad detection spectra. The total number of cells that hybridized with universal Archaea- and Bacteria-specific probes varied, in peat samples of different bogs, from 45 to 83% of the number of cells revealed by DAPI staining. Down the bog profiles, the total number of prokaryotes and the fraction of archaea among them increased. Application of a set of oligonucleotide probes showed that the number of microorganisms belonging to such phylogenetic lineages of the domain Bacteria as the phyla Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Acidobacteria, and Planctomycetes constituted, in total, 14.0–26.5% of the number of eubacteria detected in the samples. Among the bacteria identified in the peat samples, the most abundant were representatives of the classes Alphaproteobacteria and Betaproteobacteria and the phyla Acidobacteria, Bacteroidetes, and Actinobacteria.     

The Variation of Microbial Communities in a Depth Profile of Peat in the Gahai Lake Wetland Natural Conservation Area

The Gahai Lake wetland natural conservation area in northwestern China includes peatland that has been accumulating over hundreds of years and is seldom disturbed by industry. Bacteria and archaea in peat soil, which is a reservoir for carbon and water, may influence its ecological function. The objective of this study was to obtain a clearer understanding of peat microbial ecology and its relationship to the environmental conditions of this area. Hence, the microbial community of the peatland ecosystem was investigated by sequencing bacterial and archaeal DNA extracted from samples collected at different peat depths. Results showed that in all samples the dominant bacterial phyla were Proteobacteria (relative abundance 0.39 ± 0.12) and Chloroflexi (0.16 ± 0.09), while the dominant archaeal phyla were Miscellaneous Crenarchaeotic Group (MCG) (0.62 ± 0.21) and Euryarchaeota (0.27 ± 0.16). The diversity and microbial community structure at deeper depths (90 and 120 cm below the peat surface) significantly differ from that at shallower depths (10, 30 and 50 cm deep). In contrast to the shallow layers, the deeper layers became more abundant in the bacterial phyla Chloroflexi, Bacteroidetes, Atribacteria, Aminicenantes, Chlorobi, TA06, Caldiserica and Spirochaetae; and in the archaeal phyla MCG and Miscellaneous Euryarchaeotic Group (MEG). This study revealed a significant shift in microbial community in peat between 50 cm and 90 cm deep, as probably influenced by the oxygen supply at different depths. Furthermore, new insights into the microbial taxa were obtained, thus providing a baseline for future studies of this peat ecosystem.     

Changes in Biomass, Aboveground Net Primary Production, and Peat Accumulation following Permafrost Thaw in the Boreal Peatlands of Manitoba, Canada

Permafrost thaw resulting from climate warming may dramatically change the succession and carbon dynamics of northern ecosystems. To examine the joint effects of regional temperature and local species changes on peat accumulation following thaw, we studied peat accumulation across a regional gradient of mean annual temperature (MAT). We measured aboveground net primary production (AGNPP) and decomposition over 2 years for major functional groups and used these data to calculate a simple index of net annual aboveground peat accumulation. In addition, we collected cores from six adjacent frozen and thawed bog sites to document peat accumulation changes following thaw over the past 200 years. Aboveground biomass and decomposition were more strongly controlled by local succession than regional climate. AGNPP for some species differed between collapse scars and associated permafrost plateaus and was influenced by regional MAT. A few species, such as Picea mariana trees on frozen bogs and Sphagnum mosses in thawed bogs, sequestered a disproportionate amount of peat; in addition, changes in their abundance following thaw changed peat accumulation. ²¹⁰Pb-dated cores indicated that peat accumulation doubles following thaw and that the accumulation rate is affected by historical changes in species during succession. Peat accumulation in boreal peatlands following thaw was controlled by a complex mix of local vegetation changes, regional climate, and history. These results suggest that northern ecosystems may show responses more complex than large releases of carbon during transient warming. Received 8 August 2000; accepted 12 January 2001.     

The Structure of the Micromycete Complexes of Oligotrophic Peat Deposits in the Southern Taiga Subzone of West Siberia

The analysis of the micromycete complexes of oligotrophic peat deposits in the Vasyugan Marsh by direct count and culture methods showed that micromycete carbon comprises no more than 3% of the total peat carbon and that the microscopic fungal biomass varies from 2 to 13 tons/hectare, depending on the season and the peat deposit thickness. Fungal spores were found in all layers of the peat deposits, whereas the mycelium was found only in the active peat layer. The high abundance of eukaryotic cells in the peats was due to the presence of yeastlike cells rather than fungal spores. Analyses by culture methods showed that micromycetes were present in all peat layers and that their abundance tended to decrease with depth, except for yeasts, which were uniformly distributed in a vertical direction. The micromycete complexes of the peat deposits were similar in their diversity and abundance of dominant species but differed in the composition of minor species. Peat yeasts were dominated by ascomycetes.     

Storage and mobility of black carbon in permafrost soils of the forest tundra ecotone in Northern Siberia

Boreal permafrost soils store large amounts of organic carbon (OC). Parts of this carbon (C) might be black carbon (BC) generated during vegetation fires. Rising temperature and permafrost degradation is expected to have different consequences for OC and BC, because BC is considered to be a refractory subfraction of soil organic matter. To get some insight into stocks, variability, and characteristics of BC in permafrost soils, we estimated the benzene polycarboxylic acid (BPCA) method‐specific composition and storage of BC, i.e. BPCA‐BC, in a 0.44 km²‐sized catchment at the forest tundra ecotone in northern Siberia. Furthermore, we assessed the BPCA‐BC export with the stream draining the catchment. The catchment is composed of various landscape units with south‐southwest (SSW) exposed mineral soils characterized by thick active layer or lacking permafrost, north‐northeast (NNE) faced mineral soils with thin active layer, and permafrost‐affected raised bogs in plateau positions showing in part thermokarst formation. There were indications of vegetation fires at all landscape units. BC was ubiquitous in the catchment soils and BPCA‐BC amounted to 0.6–3.0% of OC. This corresponded to a BC storage of 22–3440 g m^?2. The relative contribution of BPCA‐BC to OC, as well as the absolute stocks of BPCA‐BC were largest in the intact bogs with a shallow active layer followed by mineral soils of the NNE aspects. In both landscape units, a large proportion of BPCA‐BC was stored within the permafrost. In contrast, mineral soils with thick active layer or lacking permafrost and organic soils subjected to thermokarst formation stored less BPCA‐BC. Permafrost is, hence, not only a crucial factor in the storage of OC but also of BC. In the stream water BPCA‐BC amounted on an average to 3.9% of OC, and a yearly export of 0.10 g BPCA‐BC m^?2 was calculated, most of it occurring during the period of snow melt with dominance of surface flow. This suggests that BC mobility in dissolved and colloidal phase is an important pathway of BC export from the catchment. Such a transport mechanism may explain the high BC concentrations found in sediments of the Arctic Ocean.     

Biogeochemical Processes of Methane Cycle in the Soils,Bogs, and Lakes of Western Siberia

The biogeochemical processes of methane production and oxidation were studied in the upper horizons of tundra and taiga soils and raised bogs and lake bottom sediments near the Tarko-Sale gas field in western Siberia. Both in dry and water-logged soils, the total methane concentration (in soil particles and gaseous phase) was an order of magnitude higher than in the soil gaseous phase alone (22 and 1.1 nl/cm³, respectively). In bogs and lake bottom sediments methane concentration was as high as 11 l/cm³. Acetate was the major precursor of the newly formed methane. The rate of aceticlastic methanogenesis reached 55 ng C/(cm³day), whereas that of autotrophic methanogenesis was an order of magnitude lower. The most active methane production and oxidation were observed in bogs and lake sediments, where the ¹³C values of CO₂were inversely related to the intensity of bacterial methane oxidation. Methane diffusing from bogs and lake bottom sediments showed ¹³C values ranging from –78 to –47, whereas the ¹³C value of carbon dioxide ranged from –18 to –1. In these ecosystems, methane emission comprised from 3 to 206 mg CH₄/(m²day). Conversely, the dry and water-logged soils of the tundra and taiga took up atmospheric methane at a rate varying from 0.3 to 5.3 mg CH₄/(m²day). Methane consumption in soils was of biological nature. This was confirmed by the radioisotopic method and chamber experiments, in which weighting of methane carbon was observed (the ¹³C value changed from –51 to –41).     

First Isolation of the Yeast <Emphasis Type="Italic">Saccharomyces paradoxus</Emphasis> in Western Siberia

Two ascomycetous yeast strains have been isolated near Novosibirsk from oak exudate. The strains have been identified as Saccharomyces paradoxus Bachinskaya based on the results of biochemical tests. The conspecificity of the isolates with S. paradoxus was confirmed by electrophoretic karyotyping and restriction analysis of the ITS region of its rDNA. This first isolation of S. paradoxus in Siberia provides evidence for the continuity of its natural habitats.__________Translated from Mikrobiologiya, Vol. 74, No. 4, 2005, pp. 533–536.Original Russian Text Copyright © 2005 by Yurkov.     

Holocene Carbon Accumulation of Fen Peatlands in Boreal Western Canada: A Complex Ecosystem Response to Climate Variation and Disturbance

Understanding the long-term ecological dynamics of northern peatlands is essential for assessment of the possible responses and feedbacks of these carbon-rich ecosystems to climate change and natural disturbance. I used high-resolution macrofossil and lithological analyses of a fen peatland in western Canada to infer the Holocene developmental history of the peatland, to document the temporal pattern of long-term peat accumulation, and to investigate ecosystems responses to climate changes in terms of species composition and carbon accumulation. The peatland has been dominated by sedges and brown mosses during its 10,000-year history, despite interruption by tephra deposition. Peat accumulation rates vary by more than an order of magnitude and decline from 5500 to 1300 cal BP, resulting in a convex depth–age curve, which contrasts with the carbon accumulation patterns documented for oceanic peatlands. The synthesis of regional data from continental western Canada indicates that fens tend to accumulate more carbon than bogs of the same ages. These data suggest that the carbon sink potential of northern peatlands has varied dramatically in the past, so estimates of the present and projected carbon sink strengths of these peatlands need to take this temporal variation into consideration. Widespread slowdown of peat accumulation over the last 4000 years may have resulted from climate cooling in northern latitudes after the Holocene insolation maximum. The findings indicate that long-term peatland dynamics are modified by many local and regional factors and that gradual environmental change may be capable of triggering abrupt shifts and jumps in ecosystem states.     

How Phosphorus Availability Affects the Impact of Nitrogen Deposition on <Emphasis Type="Italic">Sphagnum</Emphasis> and Vascular Plants in Bogs

To elucidate the impact of high nitrogen (N) deposition on intact bog vegetation, as affected by phosphorus (P) availability, we conducted a 4-year fertilization experiment with N and P at six sites, one with moderate N deposition and five with high N deposition. During the growing season, N (40 kg ha^–1 ya^–1), P (3 kg ha^–1 y^–1), or a combination of both elements was applied to the vegetation. The fertilization effects turned out to be additive in nature. Adding P decreased the inorganic N concentration and increased the P concentration in the rhizosphere at two sites. Furthermore, P stimulated Sphagnum growth and Sphagnum net primary productivity (NPP) at two sites; it also seemed to encourage growth at two other sites including the moderate-deposition site. Vascular plant growth remained largely unaffected but was depressed at one high-deposition site. Adding N increased the concentration of inorganic N in the rhizosphere at the moderate-deposition site and at two of the three high-deposition sites; vascular plant growth and litter production were encouraged at three high-deposition sites. The addition of N depressed Sphagnum height increment at four high deposition sites and reduced Sphagnum NPP at two sites. Shading by vascular plants was of minor importance in explaining the negative effects of N on Sphagnum. We conclude that because P alleviates the negative impact N has on Sphagnum by enhancing its capability to assimilate the deposited N, P availability is a major factor determining the impact of N deposition on Sphagnum production and thus on carbon sequestration in bogs.     

The biology of stone loach Barbatula barbatulus in the Rivers Goloustnaya and Olkha, East Siberia

Five hundred and four stone loach 63–202 mm in total length, of I + to 8 + age groups, were sampled in two rivers of East Siberia from April to October 1989–90. This paper presents data on the seasonal dynamics of fecundity, ripening, fatness and feeding intensity. A second spawning from the end of August to October has been identified for the first time for this species. The absolute fecundity ranged from 1710 to 27600, and the relative fecundity varied from 216 to 833 eggs g⁻¹: (fish weight). Stone loach in the River Olkha grew faster than those in the River Goloustnaya and, according to this index, are closer to stone loach from streams of northern England.     

The Dynamics of the Size and Structure of the Soil Bacterial Complex in the Presence of Azobenzene

Azobenzene exerted no significant effect on the dynamics and the species composition of the saprophytic soil bacterial complex, which remained almost the same as in the control and was characterized by the predominance of Curtobacteriumsp., Arthrobacter globiformis, and Bacillus megateriumin all stages of succession. Some heterotrophic bacteria were found to be able to accumulate azobenzene. Bacillus cereusand Bac. polymyxadegraded azobenzene during their cultivation in nutrient media.     

The oligotrophic peatlands of Western Siberia-the largest peino-helobiome in the world

Summary The paper summarizes the vegetation pattern of the largest swamp (peat bog) area in the world. The core area covers about 800×1800 km (NS x EW) in West Siberia between the Ural mountains and the river Yenisey. The core area is one gigantic oligotrophic swamp (Peino-Helobiome acc), the new classification suggested in Walter 1976, see also summary in Vegetatio 32, 1976, pp. 75–81. A map of the entire area is presented.Intensive recent field studies were executed by the geobotanical-soil science faculty of the University of Moscow and the first five publication under the editorship of A. I. Popov (1971–1975) are the basis for this paper. The original papers are in Russian, still unavailable for most western scientists.The bog genetics was stratigraphically analyzed. The analysis revealed that the majority of the Northern bogs started in taiga forests. The peat in these areas is now 4–7 m deep. About 60% of the peat consists of the mixed (Sphagnum) fuscum type deposit. Peat type profiles are shown in Figure 4. The figure illustrates the different peat deposits in relation to depth as well as to surface pattern of strings and hollows.The surface vegetation shows the pattern typical for many northern peat bogs on very slightly inclined land: parallel strings of peat moss and Pinus trees alternating with hollows filled with rain water and hydrophytic Sphagna (Sph. dusenii, Sph. balticum). A cross section through this vegetation pattern is given in Figure 5. Details of the pattern: strings and hollows are given in Chapter 4 of the paper.The second chapter of this paper deals with regression phenomena in the vegetation development due to excessive water logging caused by the development of the strings. Under such conditions black water lakes are formed which grow in size through the erosive action of wind and waves on the expense of the peat moss surface.Bog development in the middle and northern Taiga zone of the biome are discussed in Section 3. The hydrology of this area is ruled by the seasonal fluctuation of water level. The amplitude of the Ob river amounts to 12 m with the amplitude of the tributaries ranging around 4–6 m. The annual flood is aggravated in spring by huge ice packages. The entire area is for extended periods one great lake which dissects into hundreds of thousands of little lakes during the low water season.In some parts of this area local drainage is responsible for the development of small forest patches. The crown cover in this forest is reported up to 50%; the species composition changes from Pinus sibirica, P. sylvestris, Picea spec. near the drainage creeks to Pinus sylvestris f. willkommii and Betula in the drained upland portions.In this area the general peat bog is eutrophic because of the high influence of the flood. The local development of oligotrophic raised bogs is frequent, however. These bogs are obviously a successional stage in series that leads eventually to a boreal forest.Section 5 deals with the vegetation typology of the entire area. Three different subdivisions of the Helobiome are distinguished, with several regional subdivisions in each. The principle for the biome division is the environmental change from oligotrophic water on the northern lower end of the watershed to the eutrophic water condition further south in the forest steppe zone. In the area of the southern eutrophic biome are forest islands Ryami and even the first salt soil patches noticeable especially in the northern steppe zone. This indicates the regional transition to the Halo-Helobiome. Some vegetational and floristic details for the subdivisions are summarized in this chapter.Supplement to H. Walter: The vegetation of Eastern Europe, North and Central Asia, 1974.Translated by: Stephen S. Talbot, Forest Management Institute, 396 Cooper Street, Ottawa, Ontario, Canada K1A OH3, and Runhild E. Eessell, 54 Spindle Road Hicksville, New York 11801, USA.

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The Auchenorrhyncha fauna of peat bogs in the Austrian part of the Bohemian Forest (Insecta,Hemiptera)

The first overview on the Auchenorrhyncha fauna of peat bogs of the Austrian Bohemian Forest is presented. Seven oligotrophic peat bog sites were studied in 2011 by suction sampler (“G-Vac”) and 93 Auchenorrhyncha species (with 7465 adult specimens) were recorded. Eleven species (about 18 % of the individuals) are tyrphobiontic or tyrphophilous. The relative species abundance plot is not very steep; the six most abundant species represent 50 % of the individuals. The most common species is Conomelus anceps (17 % of the individuals). Compared to the whole Austrian Auchenorrhyncha fauna, the fauna of peat bogs comprises distinctly more univoltine species and more species hibernating in nymphal stage. Densities of adult Auchenorrhyncha in peat bogs are low in spring (about 10–60 individuals per m²) and high in July, with up to 180 (±50) individuals per m². Disturbed peat bogs have higher species numbers and higher Auchenorrhyncha densities in total, but lower numbers and densities in peat bog specialists.     

Bacterial and Archaeal Community Structure in the Surface Diatom Sediments of Deep Freshwater Lake Baikal (Eastern Siberia)

Diatom sediment records of large lakes can be used to decipher the history of ancient phytoplankton. The upper layer of the sediment is an important area of remineralization of the sedimenting phytoplankton biomass. It hosts a bacterial community different from those of both the water column and deeper sediment layers. In this work, we analyzed the structure and diversity of the communities of Bacteria and Archaea in the surface sediment core containing valves of diatoms, the major producers in Lake Baikal. Pyrosequencing of the bacterial V3–V4 region of the 16 S ribosomal RNA (rRNA) and archaeal V1–V3 16 S rRNA gene regions yielded 29,168 and 36,997 reads, respectively. In total, we have identified 33 bacterial phyla; uncultured Actinobacteria were the most abundant in the upper layers, while lower sediment was dominated by Firmicutes and Alphaproteobacteria. The composition of the archaeal community changed with depth, but was generally dominated by Crenarchaeota from the classes Marine Group I and Miscellaneous Crenarchaeotic Group, as well as Euryarchaeota from the class Thermoplasmata. These dominant bacterial and archaeal taxa are presumed to participate in the destruction of buried organic matter, which eventually leads to degradation of the diatom valves.     

Morphotypic variability of masticatory surface pattern of molars in the recent and Pleistocene Lemmus and Myopus (Rodentia,Cricetidae) of Europe and Western Siberia

In this article, we present the results of morphological study, applying multivariate statistical analysis, of seven samples of recent Lemmini species (Lemmus lemmus, L. sibiricus, Myopus schisricolor) and eight samples of the ancient Siberian lemmings from the Middle and Late Pleistocene localities, mainly in northeastern Europe. On the basis of studying variability of masticatory surface pattern of molars, 24 morphotypes have been described. The differences in morphotypes frequencies were found between the recent Myopus and Lemmus and between the two Norwegian lemming samples. There are some indications of an evolutionary trend in molar morphology of the Siberian lemmings of the Middle, Late Pleistocene, and the recent of Eastern Europe. The distinctions, at least, between the Middle Pleistocene and modern lemmings exceed a species level.     

Associations of APOE Gene Variants rs429358 and rs7412 with Parameters of the Blood Lipid Profile and the Risk of Myocardial Infarction and Death in a White Population of Western Siberia

The present study aimed to analyze possible associations of rs7412 and rs429358 of the APOE gene with lipid profile parameters, the risk of myocardial infarction, and death in the mostly white population of Western Siberia (Russia). The study population was selected from a sample surveyed within the framework of the Health, Alcohol and Psychosocial Factors In Eastern Europe (HAPIEE) study (9360 subjects, age 53.8 ± 7.0 years, males/females 50/50). PCR was conducted with fluorescence detection according to the TaqMan principle on a real-time PCR machine. The frequency of a minor allele (C) of rs429358 was 0.13, and the frequency of a minor allele (T) of rs7412 was 0.09. In our study, the woman with the rare ɛ1/ɛ4 genotype had substantial aberrations in blood lipid levels. In Kaplan–Meier curves, statistically significant differences were revealed in the prognosis of survival within the subgroup of females who had a myocardial infarction (p = 0.0006): the prognosis was worse for carriers of the ɛ2/ɛ2 genotype and for ɛ4/ɛ4 carriers. Survival analysis regarding deaths from all causes showed (p = 0.0238) that female carriers of the ɛ2/ɛ4 genotype had a worse prognosis than did carriers of other genotypes. Thus, in the population of Western Siberia (Russia), we confirmed statistically significant associations between rs7412 & rs429358 genotypes and lipid profile parameters.     

暗褐网柄牛肝菌子实体内生细菌群落结构研究

暗褐网柄牛肝菌（Phlebopus portentosus）是第一个栽培成功的牛肝菌目（Boletales）真菌,一般采用覆土栽培模式,覆土微生物对子实体的发育具有重要作用,目前的研究主要集中在覆土微生物上,但缺少对子实体内生菌的研究。为揭开暗褐网柄牛肝菌子实体内生菌的组成,本研究基于Illumina MiSeq平台,利用16S rRNA V3~V4区高通量测序进行细菌群落结构分析。结果表明子实体（fruiting body,FB）内部存在很高丰度的细菌,主要以变形菌门（Proteobacteria）为主,在属水平上以贪铜菌属（Cupriavidus）（64.98%）、不动杆菌属（Acinetobacter）（7.62%）、苍白杆菌属（Ochrobactrum）（6.02%）为主。与覆土（casing soil,CS）基质固有的细菌种群进行比较,VENN分析显示子实体内有468个OTUs为独有,占总序列的26.65%,分类上隶属于贪铜菌属、不动杆菌属和Delftia。FB和CS差异性分析以及Lefse标志性微生物分析均显示贪铜菌属、苍白杆菌属、不动杆菌属、嗜糖假单胞菌属（Pelomonas）等为FB特异性、标志性类群。利用Picrust（Phylogenetic investigation of communities by reconstruction of unobserved states）进行Kyoto Encyclopedia of Genes and Genomes（KEGG）通路预测发现,子实体内生菌群的主要代谢途径为膜传输、氨基酸代谢、碳水化合物代谢、外源生物降解与代谢,与覆土菌群有20个代谢通路的差异,并且外源生物降解与代谢、信号转导、其他氨基酸代谢、脂质代谢、细胞过程和信号5个通路的比例要高于覆土,微生物类群的差异可能是导致产生这些功能差异的原因。     

Bacterial Diversity among the Sediments of Glacial Lakes in the Western Balkans: Exploring the Impact of Human Population

16S rRNA gene-based metagenomic approach was used to assess the biodiversity of bacterial communities in the sediments of selected glacial lakes in the Western Balkans and to assess the impact of human population on these microbial communities. Sediment samples were collected from three glacial lakes, viz., Plav Lake (in a zone of the highest impact of human population), Black Lake (a zone of medium impact of human population), and Donje Bare Lake (a remote lake with minimal impact of human population).

Canonical correlation analysis analysis indicated correlation between the distance of the lake from urbanized population and bacterial diversity in Donje Bare Lake sediment. Bacterial diversity of Black Lake sediment was correlated with high content of phosphorous and pH value. Chemical compounds exhibiting the most prominent correlation with bacterial diversity of Plav Lake were NH₄-N, K₂O, CaCo₃, and total nitrogen . Additionally, CCA analysis indicated that population density was correlated with biodiversity of bacterial communities in Plav Lake sediment, which is the most exposed to human population. Multivariate regression revealed the highest correlation between the presence of Proteobacteria classes and population density and levels of NH₄-N.

The influence of human population was observed to be important for shaping the sediment communities in addition to biological and chemical factors.     

药用植物刺山柑不同部位细菌群落结构及其多样性

【目的】研究传统药用植物刺山柑（Capparis spinosa L.）不同部位细菌群落结构、物种组成和多样性特征,为药用植物微生物资源的开发及微生物与宿主互作提供理论依据。【方法】本研究以刺山柑地上部植物组织（果实、茎）和地下部土壤（根际土壤、非根际土壤）为研究材料,采用高通量测序技术分析刺山柑不同部位细菌的16S rRNA基因多样性,比较其细菌群落结构和物种组成特征。【结果】刺山柑4种样本共获得的3 649个操作分类单元（operational taxonomic unit,OTU）,属于34门、88纲、248目、464科和1 051属。土壤样本的细菌多样性大于植物组织,细菌群落多样性以根际土壤、非根际土壤、茎和果实的顺序逐渐降低,果实内生细菌群落多样性始终最低,显著低于根际土壤。不同部位相对丰度较高的细菌门如下：植物组织中以变形菌门为主,根际土壤中为变形菌门和放线菌门,非根际土中为厚壁菌门和放线菌门。无色杆菌属（Achromobacter）、欧文氏菌属（Erwinia）、肠球菌属（Enterococcus）、微小杆菌属（Exiguobacterium）、乳杆菌属（Lactobacillus）和克雷伯氏菌属（Klebsiella）主要存在于刺山柑植物组织中。游动球菌属（Planomicrobium）、库克菌属（Kocuria）、类芽孢杆菌属（Paenibacillus）、链霉菌属（Streptomyces）、微枝形杆菌属（Microvirga）和节杆菌属（Arthrobacter）主要分布于土壤中。β多样性分析结果表明,刺山柑植物组织和土壤的细菌群落结构具有显著差异,同类型样本的细菌群落结构相似。【结论】刺山柑土壤样本中细菌群落的多样性和丰富度均高于植物组织,刺山柑不同部位的细菌群落组成不同。本研究对刺山柑不同部位细菌群落结构进行了初步分析,鉴定了各部位细菌群落中的核心菌群,为以后挖掘刺山柑的功能研究和利用提供了准确的微生物信息。