青藏高原察尔汗盐湖地区可培养中度嗜盐菌的群落结构与多样性

【目的】研究青海察尔汗盐湖地区的可培养中度嗜盐菌的群落结构及多样性。【方法】采用多种选择性培养基进行中度嗜盐菌的分离、培养;通过16S r RNA基因序列扩增、测定,根据序列信息,进行系统进化树构建、群落结构组成分析及多样性指数计算。【结果】从察尔汗盐湖卤水及湖泥中分离到中度嗜盐菌421株,合并重复菌株后共83株中度嗜盐菌。菌株16S rRNA基因序列信息显示,4株中度嗜盐菌为潜在的新分类单元。83株嗜盐细菌分布于3个门的6个科16个属。其中,Bacillus属、Oceanobacillus属和Halomonas属为优势属。多样性结果显示,水样中的菌株多样性高于泥样,而泥样中的菌株优势度高于水样。【结论】察尔汗盐湖中度嗜盐菌具有丰富的遗传多样性,种群种类丰富,优势菌群集中,该盐湖地区存在可分离培养的中度嗜盐菌的疑似新物种。     

Jelly-like Microbial Mats over Subsurface Fields of Gas Hydrates at the St. Petersburg Methane Seep (Central Baikal)

Jelly-like microbial mat samples were collected from benthic surfaces at the St. Petersburg methane seep located in Central Baikal. The concentrations of certain ions, specifically chloride, bromide, sulphate, acetate, iron, calcium, and magnesium, were 2–40 times higher in the microbial mats than those in the pore and bottom water. A large number of diatom valves, cyanobacteria, and filamentous, rod-shaped and coccal microorganisms were found in the samples of bacterial mats using light, epifluorescence and scanning microscopy.Comparative analysis of a 16S rRNA gene fragment demonstrated the presence of bacteria and archaea belonging to the following classes and phyla: Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Verrucomicrobia, Cytophaga-Flavobacteria-Bacteroidetes, Cyanobacteria, and Euryarchaeota. The chemical composition and phylogenetic structure of the microbial community showed that the life activity of the mat occurs due to methane and its derivatives involved. Values of δ¹³C for the microbial mats varied from ?73.6‰ to ?65.8‰ and for animals from ?68.9‰ to ?36.6‰. Functional genes of the sequential methane oxidation (pmoA and mxaF) and different species of methanotrophic bacteria inhabiting cold ecosystems were recorded in the total DNA. Like in other psychroactive communities, the destruction of organic substances forming formed as a result of methanotrophy, terminates at the stage of acetate formation in the microbial mats of Lake Baikal (1,400 m depth). Its further transformation is limited by hydrogen content and carried out in the subsurface layers of sediments.     

Annual growth layers as proxies of past growth conditions for benthic microbial mats in a perennially ice-covered Antarctic lake

Perennial microbial mats can be the dominant autotrophic community in Antarctic lakes. Their seasonal growth results in clearly discernible annual growth layering. We examined features of live microbial mats from a range of depths in Lake Hoare, Antarctica, that are likely to be preserved in these layers to determine their potential as proxies of past growth performance. Cyanobacteria dominated the mat for all but the deepest depth sampled. Changes in areal concentrations of phycobilin pigments, organic matter and extracellular polysaccharide and in species composition did not correspond to changes in various water column properties, but showed a linear relationship with irradiance. Carbonate accumulation in the mats correlated with biomass markers and may be inferred as an index of mat performance. We examined the carbonate content of annual layers laid down from 1958–1959 to 1994–1995 in sediment cores from 12 m depth. The carbonate content in the layer showed a significant correlation with the mean summer air temperature. These data suggest a link between air temperature and microbial mat growth performance, and suggest that it is mediated via irradiance. Laminated microbial mats in Antarctic lakes have the potential to act as fine-resolution records of environmental conditions in the recent past, although interpretation is complex.     

洱海漂浮草垫的物种组成及分布

研究通过调查洱海2017年夏季和冬季漂浮草垫的物种组成及分布模式, 探究洱海在水位上升过程中, 哪些挺水植物更易形成漂浮草垫而存活下来。夏季共调查到漂浮草垫18个, 植物分属15科, 18属, 24种, 冬季共调查到漂浮草垫22个, 植物分属13科, 17属, 22种, 形成洱海漂浮草垫的植物共15科, 19属, 26个物种。草垫下水体中总氮(TN)、总磷(TP)、溶解性总磷(TDP)都明显高于开阔水域的(P<0.05), 而开阔水域的溶氧(DO)明显高于草垫下水体的(P<0.05)。结果表明在夏季和冬季漂浮草垫面积大小与其组成草垫的物种数和漂浮草垫生物量都呈显著正相关(P<0.01), 而在夏季和冬季漂浮草垫面积大小与漂浮草垫单位面积平均生物量相关性都不显著(P>0.05), 漂浮草垫面积大小与漂浮草垫下最长根在夏季相关性显著(P<0.01), 而在冬季相关性不显著(P>0.05)。漂浮草垫主要分布在离岸距离60 m以内以及水深不超过2 m的水域, 漂浮草垫面积大部分都小于600 m2(夏季占87%, 冬季占95%), 每个漂浮草垫的物种数都小于10个, 漂浮草垫下最长根主要分布在40—120 cm。组成漂浮草垫的物种中菰(Zizania latifolia)的频度和相对生物量在夏季和冬季(频度: 夏季-73.33%, 冬季-66.67%; 生物量: 夏季-43.38%, 冬季-41.91%)都是最高的, 说明菰相比其他挺水植物更容易形成漂浮草垫从而避免洱海水位上升对其生长和繁殖的影响, 这可能是菰成为洱海单优挺水植物的主要原因。而菰比其他挺水植物更容易形成漂浮草垫的机制则需要更进一步的研究。     

Groundwater shapes sediment biogeochemistry and microbial diversity in a submerged Great Lake sinkhole

For a large part of earth's history, cyanobacterial mats thrived in low‐oxygen conditions, yet our understanding of their ecological functioning is limited. Extant cyanobacterial mats provide windows into the putative functioning of ancient ecosystems, and they continue to mediate biogeochemical transformations and nutrient transport across the sediment–water interface in modern ecosystems. The structure and function of benthic mats are shaped by biogeochemical processes in underlying sediments. A modern cyanobacterial mat system in a submerged sinkhole of Lake Huron (LH) provides a unique opportunity to explore such sediment–mat interactions. In the Middle Island Sinkhole (MIS), seeping groundwater establishes a low‐oxygen, sulfidic environment in which a microbial mat dominated by Phormidium and Planktothrix that is capable of both anoxygenic and oxygenic photosynthesis, as well as chemosynthesis, thrives. We explored the coupled microbial community composition and biogeochemical functioning of organic‐rich, sulfidic sediments underlying the surface mat. Microbial communities were diverse and vertically stratified to 12 cm sediment depth. In contrast to previous studies, which used low‐throughput or shotgun metagenomic approaches, our high‐throughput 16S rRNA gene sequencing approach revealed extensive diversity. This diversity was present within microbial groups, including putative sulfate‐reducing taxa of Deltaproteobacteria, some of which exhibited differential abundance patterns in the mats and with depth in the underlying sediments. The biological and geochemical conditions in the MIS were distinctly different from those in typical LH sediments of comparable depth. We found evidence for active cycling of sulfur, methane, and nutrients leading to high concentrations of sulfide, ammonium, and phosphorus in sediments underlying cyanobacterial mats. Indicators of nutrient availability were significantly related to MIS microbial community composition, while LH communities were also shaped by indicators of subsurface groundwater influence. These results show that interactions between the mats and sediments are crucial for sustaining this hot spot of biological diversity and biogeochemical cycling.     

Photosynthesis versus Exopolymer Degradation in the Formation of Microbialites on the Atoll of Kiritimati,Republic of Kiribati,Central Pacific

Aragonitic microbialites, characterized by a reticulate fabric, were discovered beneath lacustrine microbial mats on the atoll of Kiritimati, Republic of Kiribati, Central Pacific. The microbial mats, with cyanobacteria as major primary producers, grow in evaporated seawater modified by calcium carbonate and gypsum precipitation and calcium influx via surface and/or groundwaters. Despite the high aragonite supersaturation and a high photosynthetic activity, only minor aragonite precipitates are observed in the top parts of the microbial mats. Instead, major aragonite precipitation takes place in lower mat parts at the transition to the anoxic zone. The prokaryotic community shows a high number of phylotypes closely related to halotolerant taxa and/or taxa with preference to oligotrophic habitats. Soil- and plant- inhabiting bacteria underline a potential surface or subsurface influx from terrestrial areas, while chitinase-producing representatives coincide with the occurrence of insect remains in the mats. Strikingly, many of the clones have their closest relatives in microorganisms either involved in methane production or consumption of methane or methyl compounds. Methanogens, represented by the methylotrophic genus Methanohalophilus, appear to be one of the dominant organisms in anaerobic mat parts. All this points to a significant role of methane and methyl components in the carbon cycle of the mats. Nonetheless, thin sections and physicochemical gradients through the mats, as well as the ¹²C-depleted carbon isotope signatures of carbonates indicate that spherulitic components of the microbialites initiate in the photosynthesis-dominated orange mat top layer, and further grow in the green and purple layer below. Therefore, these spherulites are considered as product of an extraordinary high photosynthesis effect simultaneous to a high inhibition by pristine exopolymers. Then, successive heterotrophic bacterial activity leads to a condensation of the exopolymer framework, and finally to the formation of crevice-like zones of partly degraded exopolymers. Here initiation of horizontal aragonite layers and vertical aragonite sheets of the microbialite occurs, which are considered as a product of high photosynthesis at decreasing degree of inhibition. Finally, at low supersaturation and almost lack of inhibition, syntaxial growth of aragonite crystals at lamellae surfaces leads to thin fibrous aragonite veneers. While sulfate reduction, methylotrophy, methanogenesis and ammonification play an important role in element cycling of the mat, there is currently no evidence for a crucial role of them in CaCO₃ precipitation. Instead, photosynthesis and exopolymer degradation sufficiently explain the observed pattern and fabric of microbialite formation.     

Community structure and pigment organisation of cyanobacteria-dominated microbial mats in Antarctica

Benthic microbial mat communities were sampled from 20 lakes, ponds and streams of the McMurdo Sound region, Antarctica. At least five distinct assemblages could be differentiated by their cyanobacterial species composition, pigment content and vertical structure. The most widely occurring freshwater communities were dominated by thin-trichome (0·5–3 µm) oscillatoriacean species that formed benthic films up to several millimetres thick. ‘Lift-off mats’ produced mucilaginous mats 1–5 cm thick at the surface and edge of certain ponds. Another group of oscillatoriacean communities was characteristic of hypersaline pond environments; these communities were dominated by species with thicker trichomes such as Oscillatoria priestleyi. Black mucilaginous layers of Nostoc commune were widely distributed in aquatic and semi-aquatic habitats. Dark brown sheath pigmentation was also characteristic of less cohesive mats and crusts dominated by Pleurocapsa, Gloeocapsa and Calothrix. High performance liquid chromatography analysis of the lipophilic pigments showed that the upper region of most of the Antarctic mats was enriched in sheath pigments (scytonemin) and/or certain carotenoids such as myxoxanthophyll and canthaxanthin. Most of the chlorophyll a (Chla), as well as phycocyanin, β-carotene and echinenone, was located in the lower strata of the mat profiles. In many of these communities most of the photosynthetic biomass occurred in a ‘deep Chla maximum’ that was well protected from short-wavelength radiation by the surface layer of light-screening pigments.     

The Phototrophic Community Found in Lake Khilganta (an Alkaline Saline Lake Located in the Southeastern Transbaikal Region)

The structure of the phototrophic community found in Lake Khilganta (the Agin-Buryat Autonomous Area), a shallow saline soda lake (depth, 35–45 cm; water mineralization, 45 g/l; alkalinity, 30 mg-equiv/l; pH 9.5) has been studied. The bottom of the lake is covered with a 10- to 15-mm microbial mat, whose basis is formed by the filamentous cyanobacterium Microcoleus chthonoplastes. The mat exhibits pronounced layering and contains a significant amount of minerals. Six zones, which have characteristic colors and consistencies and are composed of intermittent layers, have been identified along the vertical profile. Live phototrophic bacteria have been found in the three upper zones. The bulk of the cyanobacteria is concentrated in the upper zone. In the lower zones, the development of purple bacteria has been observed. The diurnal dynamics of the vertical distribution of phototrophic microorganisms, which results from variations in the physicochemical environmental parameters, is described. Ectothiorhodospira sp. are dominant among the anoxyphotobacteria present. Their number, determined according to the inoculation method, is 10⁶–10⁷ cells/ml. The purple bacteria of the genera Allochromatium, Thiocapsa, and Rhodovulum are also present. Experiments with isolated pure cultures have shown that the anoxygenic photosynthetic bacteria of Lake Khilganta are halotolerant and alkalitolerant or alkaliphilic. In liquid enrichment cultures, at pH 9.5, the ratio of anoxyphotobacteria species is close to that observed in the lake. When the pH is increased to 10.4, it is Ectothiorhodospira, which is the most adapted to life under increased mineralization and alkalinity, that predominantly develops. Photosynthetic activity has been observed in the three upper mat zones and constitutes, on average, 1.5 g C/(m²h); the share of anoxygenic photosynthesis accounts for 75–95% of the total productivity. The main role in sulfide oxidation belongs to the phototrophic anoxyphotobacteria and cyanobacteria. In terms of the physicochemical conditions and structure of the phototrophic community, Lake Khilganta is similar to shallow saline water bodies of marine origin. The main differences consist in the increased alkalinity and in the consequent prevalence of alkaliphilic and alkalitolerant microorganisms and in the absence of representatives of the neutrophilic group of green sulfur bacteria.__________Translated from Mikrobiologiya, Vol. 74, No. 3, 2005, pp. 410–419.Original Russian Text Copyright © 2005 by Kompantseva, Sorokin, Gorlenko, Namsaraev.     

Biogeochemical cycling and microbial diversity in the thrombolitic microbialites of Highborne Cay,Bahamas

Thrombolites are unlaminated carbonate build‐ups that are formed via the metabolic activities of complex microbial mat communities. The thrombolitic mats of Highborne Cay, Bahamas develop in close proximity (1–2 m) to accreting laminated stromatolites, providing an ideal opportunity for biogeochemical and molecular comparisons of these two distinctive microbialite ecosystems. In this study, we provide the first comprehensive characterization of the biogeochemical activities and microbial diversity of the Highborne Cay thrombolitic mats. Morphological and molecular analyses reveal two dominant mat types associated with the thrombolite deposits, both of which are dominated by bacteria from the taxa Cyanobacteria and Alphaproteobacteria. Diel cycling of dissolved oxygen (DO) and dissolved inorganic carbon (DIC) were measured in all thrombolitic mat types. DO production varied between thrombolitic types and one morphotype, referred to in this study as ‘button mats’, produced the highest levels among all mat types, including the adjacent stromatolites. Characterization of thrombolite bacterial communities revealed a high bacterial diversity, roughly equivalent to that of the nearby stromatolites, and a low eukaryotic diversity. Extensive phylogenetic overlap between thrombolitic and stromatolitic microbial communities was observed, although thrombolite‐specific cyanobacterial populations were detected. In particular, the button mats were dominated by a calcified, filamentous cyanobacterium identified via morphology and 16S rRNA gene sequencing as Dichothrix sp. The distinctive microbial communities and chemical cycling patterns within the thrombolitic mats provide novel insight into the biogeochemical processes related to the lithifying mats in this system, and provide data relevant to understanding microbially induced carbonate biomineralization.     

运城盐湖细菌群落结构及生态多样性分析

运城盐湖作为一个人类活动深入参与的高盐环境,其中的细菌群落结构及生态多样性既有盐湖环境的共性,又有自身的特殊性。【目的】运城盐湖湖水颜色丰富,蕴含着大量嗜盐及耐盐微生物资源。为了深入探究运城盐湖细菌资源分布规律,对不同水域中细菌多样性和群落结构进行研究,探讨运城盐湖不同水域中细菌群落结构的变化规律。【方法】基于16S rRNA基因的扩增子高通量测序,对运城盐湖不同水域的细菌群落结构进行分析,同时对微生物的潜在代谢功能进行预测。【结果】运城盐湖不同水域中的优势细菌类群有所差异,在盐湖中部,假单胞菌门(Pseudomonadota)、放线菌门(Actinobacteriota)和拟杆菌门(Bacteroidota)是优势类群;而在运城盐湖东部,芽孢杆菌门(Bacillota)则是主要类群;在运城盐湖西部,髌骨菌门(Patescibacteria)类群较为丰富。对运城盐湖不同区域的细菌多样性进行分析,数据显示盐湖中部浅黄色湖水中微生物多样性显著高于盐湖东部和西部区域,但盐湖中部红色湖水区域的微生物多样性较低。另外,在盐湖中部,湖水颜色不同的区域细菌物种分布也具有较大的差异。对运城盐湖细菌代谢功能进行预测分析发现,在盐湖不同区域的微生物参与的代谢通路活性各不相同,表现出较强的区域分布性,盐湖东部和西部的微生物代谢比盐湖中部更具有活性。【结论】运城盐湖微生物多样性丰富,不同水域的细菌多样性具有显著差异,盐湖不同水域的环境对细菌群落结构具有一定影响。本研究为运城盐湖细菌资源多样性的保育及开发利用提供了重要的理论基础。     

MOLECULAR CHARACTERIZATION OF THE DIVERSITY AND POTENTIAL TOXICITY OF CYANOBACTERIAL MATS IN TWO TROPICAL LAGOONS IN THE SOUTH PACIFIC OCEAN1

Marine benthic cyanobacteria in tropical areas have recently been associated with several human poisoning events. To enhance the characterization of these microorganisms and their potential toxicity, benthic cyanobacterial communities were sampled in the lagoons of two islands (Raivavae and Rurutu) located in French Polynesia where human poisoning events by seafood had been reported. The morphological appearance of the mats was used to identify four types of cyanobacterial mat. By a 16S rRNA sequencing approach, it appeared that these mats were usually dominated by a restricted number of operational taxonomic units (OTUs), which were closely related to Leptolyngbya, Oscillatoria, Hydrocoleum, and Anabaena sequences, as previously reported in other tropical lagoons. Interestingly, we determined that these dominant filamentous OTUs were associated in the mats with other cyanobacteria, including unicellular species. By using a population genetic approach based on the sequencing of the internally transcribed spacer (ITS) of the rRNA operon, we found a very restricted genetic diversity in the most common OTU, which displayed a high sequence similarity with Leptolyngbya sp. In addition, there was no geographic differentiation at various spatial scales in the distribution of the different genotypes, suggesting that this species is able to spread over large distances. Finally, PCR screening of genes involved in the biosynthesis of known cyanotoxins revealed the presence of the saxitoxin gene (stxG) in two mats containing a mix of filamentous and unicellular cyanobacterial species.     

Physiological Adaptation of a Nitrate-Storing Beggiatoa sp. to Diel Cycling in a Phototrophic Hypersaline Mat

The aim of this study was to investigate the supposed vertical diel migration and the accompanying physiology of Beggiatoa bacteria from hypersaline microbial mats. We combined microsensor, stable-isotope, and molecular techniques to clarify the phylogeny and physiology of the most dominant species inhabiting mats of the natural hypersaline Lake Chiprana, Spain. The most dominant morphotype had a filament diameter of 6 to 8 μm and a length varying from 1 to >10 mm. Phylogenetic analysis by 16S rRNA gene comparison revealed that this type appeared to be most closely related (91% sequence identity) to the narrow (4-μm diameter) nonvacuolated marine strain MS-81-6. Stable-isotope analysis showed that the Lake Chiprana species could store nitrate intracellularly to 40 mM. The presence of large intracellular vacuoles was confirmed by fluorescein isothiocyanate staining and subsequent confocal microscopy. In illuminated mats, their highest abundance was found at a depth of 8 mm, where oxygen and sulfide co-occurred. However, in the dark, the highest Beggiatoa densities occurred at 7 mm, and the whole population was present in the anoxic zone of the mat. Our findings suggest that hypersaline Beggiatoa bacteria oxidize sulfide with oxygen under light conditions and with internally stored nitrate under dark conditions. It was concluded that nitrate storage by Beggiatoa is an optimal strategy to both occupy the suboxic zones in sulfidic sediments and survive the dark periods in phototrophic mats.     

Structure and formation properties of the haloalkaliphilic community of Lake Khilganta

The structural features of a cyanobacterial mat from Lake Khilganta (Southeastern Transbaikal Region) developing at different values of salinity and pH were determined based on our long-term investigation of the natural community, as well as results obtained during experimentation with its laboratory analogue. At water mineralization of 40–50 g/l, Microcoleus chthonoplastes and Phormidium molle play a key role in the formation of the cyanobacterial mat. As water mineralization increases, the diversity of cyanobacteria in the natural mat increases as well, reaches its maximum at 80 g/l NaCl, and decreases at 100 g/l. In the laboratory community, Nodularia sp. prevailed. It was able to form matlike structures within a broad pH range and at a salinity of up to 50 g/l NaCl. As the water mineralization level increased up to 100 g/l or higher, a replacement of the dominant complexes occurred both in the laboratory and natural communities: cyanobacterial species were substituted with green algae.     

Phylotype diversity in a benthic cyanobacterial mat community on King George Island, maritime Antarctica

Cyanobacterial 16S ribosomal RNA gene diversity was examined in a benthic mat on Fildes Peninsula of King George Island (62o09′54.4′′S, 58o57′20.9′′W), maritime Antarctica. Environmental DNA was isolated from the mat, a clone library of PCR-amplified 16S rRNA gene fragments was prepared, and amplified ribosomal DNA restriction analysis (ARDRA) was done to assign clones to seven groups. Low cyanobacterial diversity in the mat was suggested in that 83% of the clones were represented by one ARDRA group. DNA sequences from this group had high similarity with 16S rRNA genes of Tychonema bourrellyi and T. bornetii isolates, whose geographic origins were southern Norway and Northern Ireland. Cyanobacterial morphotypes corresponding to Tychonema have not been reported in Antarctica, however, this morphotype was previously found at Ward Hunt Lake (83oN), and in western Europe (52oN). DNA sequences of three of the ARDRA groups had highest similarity with 16S rDNA sequences of the Tychonema group accounting for 9.4% of the clones. Sequences of the remaining three groups (7.6%) had highest similarity with 16S rRNA genes of uncultured cyanobacteria clones from benthic mats of Lake Fryxell and fresh meltwater on the McMurdo Ice Shelf.     

Modern conophyton‐like microbial mats discovered in Lake Vanda,Antarctica

Lake Vanda is a cold nonturbulent, perennially ice‐covered lake in the valleys of southern Victoria Land, Antarctica. Observations made and samples collected under the 3.5 m ice in 1980 by SCUBA divers reveal that an extensive benthic microbial mat dominated by the filamentous blue‐green algae (cyanobacteria) Phormidium frigidum and Lyngbya martensiana is growing there. As is the case in other Antarctic lakes investigated by us thus far, the mat in Lake Vanda traps and binds sediment and precipitates calcite and is undisturbed by grazers and burrowers. Therefore, stromatolitic laminae are being generated. Unlike the other Antarctic lakes investigated in this region, Lake Vanda has (a) an ice cover and water that transmits significantly more light; (b) an ice cover that is permeable to gases and aeolian sediment; (c) no zone of lift‐off mat where photosynthetically generated oxygen would render the mat buoyant and cause it to separate from the substrate and float away; and (d) mat that has a distinctive pinnacle macrostructure. Although the laminae being laid down by the Lake Vanda mat do not retain the cone and ridge morphology of the living mat, the pinnacle macrostructure of the mat is similar to the Precambrian Conophyton stromatolites as well as microbial structures forming in Yellowstone hot springs, freshwater marshes in the Bahamas, and hypersaline intertidal mats in Baja California, Mexico, and Shark Bay, Australia. This suggests (a) Conophyton‐like structures similar to those abundant during the Precambrian can form under widely varying environmental conditions and (b) high latitudes should not be overlooked as sites of formation of ancient stromatolites.     

新疆艾丁湖中度嗜盐苯酚降解菌多样性研究

高盐含酚废水属于极难处理的废水之一,筛选具有生物学降解能力的嗜盐菌有助于解决这一难题。从新疆艾丁湖盐湖中分离筛选能够降解苯酚的中度嗜盐菌,了解盐湖中度嗜盐苯酚降解菌的多样性组成和降解能力。研究结果表明,10%(质量分数)的盐浓度条件下,分离得到166株嗜盐菌,通过以苯酚为唯一碳源的培养基进行降解活性筛选后得到45株阳性菌,根据细菌16S rRNA基因序列系统进化分析,这45株菌分别归类到3个门,5个科,9个属。其中拟诺卡氏菌属(Nocardiopsis)是优势菌,占总量的68.8%,其余菌分布于Bacillus、Gracilibacillus、Pontibacillus、Halobacillus、Marinococcus和Halomonas属。在含100 mg/L苯酚的液体培养基,经过10 d培养后,这45株菌降解效率为1%~17%。本研究为工业应用提供了嗜盐微生物种质资源,极具进一步发掘和研究价值。     

高盐盐湖可分离嗜盐耐盐菌的种群多样性及四氢嘧啶产量评价

为了解柴达木盆地茶卡盐湖、柯柯盐湖和小柴旦盐湖等三大硫酸镁亚型高盐盐湖可分离嗜盐耐盐菌的种群多样性,采用RM中、高盐培养基筛选分离可培养的嗜盐菌和耐盐菌,扩增16S rRNA基因序列进行种属鉴定和环境因子典范对应分析(CCA),选取优势菌属构建系统发育树,并采用高效液相色谱法(HPLC)检测次级代谢产物四氢嘧啶(Ect...     

Pigment profiles and bacterial communities from Thailand thermal mats

Differently colored layers of freshwater hot spring mats at Boekleung (Western Thailand) were studied. Temperatures ranged from over 50 up to 57°C. Two mats were characterized: a laminated mat with a green and a red layers, and a monolayer, greenish-yellow mat. Bacterial communities in green, red, and yellow layers were investigated using molecular, culturing and pigment analysis methods. Pigment profiles covered a wide spectrum from chlorophylls to carotenoids. A green mat layer showed higher relative content of chlorophyll than yellow and red layers which presented higher proportion of carotenoids. Cyanobacterial isolates grow up to 55–56°C and their pigment profiles showed a relatively high content of chlorophylls suggesting the importance of other bacterial groups in the mat pigment profiles. Bacterial communities were analyzed by 16S rDNA surveys showing Cyanobacteria and Chloroflexi as the mayor components of the community. Other significant members were Candidate Division OP10, Bacteroidetes, Planctomycetes and Actinobacteria. These results highlight a major participation of Cyanobacteria and Chloroflexi in thermal mat communities, and the preferential presence of Candidate Division OP10 in green mat layers. Differently colored mat layers showed characteristic bacterial communities which could be discriminated from pigment profiles and molecular surveys.