排序方式: 共有59条查询结果,搜索用时 46 毫秒
1.
Dipl. Geol. Jens Hefter Dipl. Geol. Volker Thiel Dr. Angela Jenisch Dr. Ursula Galling Dr. Stephan Kempe Dr. habil. Walter Michaelis 《Facies》1993,29(1):93-105
Summary Biomarker investigations were applied to the hydrocarbon fractions of three Recent (cyanobacterial mat, Lake Van microbialite
and Lake Satonda microbialite) and two Late Jurassic carbonate samples obtained from sponge bioherms. The relative concentrations
ofn-alkanes, monomethyl alkanes, acyclic isoprenoids, steroids and hopanoids in these samples are studied and their probable
biological precursors are discussed. Normal alkanes with carbon chain lengths ranging from C15 to C34 and monomethyl alkanes ranging from C17 to C21 with a varying methyl branching pattern are found. The major hydrocarbons are low molecular weight (LMW)n-alkanes (C15–C21) with a slight to strong predominance ofn-heptadecane (C17). High molecular weight (HMW)n-alkanes occur in low to moderate relative concentrations showing a preference of odd-carbon numbered compounds with a maximum
at C29. Within the acyclic isoprenoids, pristane, phytane/phytene, pentamethyl-eicosane, squalane and lycopane could be identified.
Polycyclic terpenoids of the sterane and/or hopane type are present in all carbonate samples. The carbon numbers of these
components range from 27 to 29 and 27 to 32, respectively. These organic compounds identified can be attributed to various
source organisms such as cyanobacteria, archaebacteria, algae and vascular plants. All hydrocarbon fractions of the samples
are characterized by moderate to high relative concentrations of compounds derived from cyanobacteria, signifying the role
of these organisms as contributors to the Recent as well as to the Late Jurassic carbonate deposits. 相似文献
2.
《Systematic and applied microbiology》2023,46(2):126403
Two heterotrophic bacteroidetes strains were isolated as satellites from autotrophic enrichments inoculated with samples from hypersaline soda lakes in southwestern Siberia. Strain Z-1702T is an obligate anaerobic fermentative saccharolytic bacterium from an iron-reducing enrichment culture, while Ca. Cyclonatronum proteinivorum OmegaT is an obligate aerobic proteolytic microorganism from a cyanobacterial enrichment. Cells of isolated bacteria are characterized by highly variable morphology. Both strains are chloride-independent moderate salt-tolerant obligate alkaliphiles and mesophiles. Strain Z-1702T ferments glucose, maltose, fructose, mannose, sorbose, galactose, cellobiose, N-acetyl-glucosamine and alpha-glucans, including starch, glycogen, dextrin, and pullulan. Strain OmegaT is strictly proteolytic utilizing a range of proteins and peptones. The main polar lipid fatty acid in both strains is iso-C15:0, while other major components are various C16 and C17 isomers. According to pairwise sequence alignments using BLAST Gracilimonas was the nearest cultured relative to both strains (<90% of 16S rRNA gene sequence identity). Phylogenetic analysis placed strain Z-1702T and strain OmegaT as two different genera in a deep-branching clade of the new family level within the order Balneolales with genus. Based on physiological characteristics and phylogenetic position of strain Z-1702T it was proposed to represent a novel genus and species Natronogracilivirga saccharolityca gen. nov., sp. nov. (= DSMZ 109061T =JCM 32930T =VKM B 3262T). Furthermore, phylogenetic and phenotypic parameters of N. saccharolityca and C. proteinivorum gen. nov., sp. nov., strain OmegaT (=JCM 31662T, =UNIQEM U979T), make it possible to include them into a new family with a proposed designation Cyclonatronaceae fam. nov.. 相似文献
3.
The chemistry and crustacean zooplankton of the Seewinkel pans: a review of recent conditions 总被引:2,自引:1,他引:1
A number of shallow pans was investigated between May 1982 and May 1985 in the Seewinkel region between Neusiedlersee and
the Hungarian border. Chemical and zooplankton samples were obtained at three monthly intervals. Analyses indicated some changes
during the past decades. Human activity has resulted in some changes to water chemistry and zooplankton composition in a few
pans, and many smaller pans have now disappeared. 相似文献
4.
Characterization of Microbial Arsenate Reduction in the Anoxic Bottom Waters of Mono Lake,California
Shelley E. Hoeft Franc¸oise Lucas James T. Hollibaugh Ronald S. Oremland 《Geomicrobiology journal》2013,30(1):23-40
Dissimilatory reduction of arsenate (DAsR) occurs in the arsenic-rich, anoxic water column of Mono Lake, California, yet the microorganisms responsible for this observed in situ activity have not been identified. To gain insight as to which microorganisms mediate this phenomenon, as well as to some of the biogeochemical constraints on this activity, we conducted incubations of arsenate-enriched bottom water coupled with inhibition/amendment studies and Denaturing Gradient Gel Electrophoresis (DGGE) characterization techniques. DAsR was totally inhibited by filter-sterilization and by nitrate, partially inhibited (~50%) by selenate, but only slightly (~25%) inhibited by oxyanions that block sulfate-reduction (molybdate and tungstate). The apparent inhibition by nitrate, however, was not due to action as a preferred electron acceptor to arsenate. Rather, nitrate addition caused a rapid, microbial re-oxidation of arsenite to arsenate, which gave the overall appearance of no arsenate loss. A similar microbial oxidation of As(III) was also found with Fe(III), a fact that has implications for the recycling of As(V) in Mono Lake's anoxic bottom waters. DAsR could be slightly (10%) stimulated by substrate amendments of lactate, succinate, malate, or glucose, but not by acetate, suggesting that the DAsR microflora is not electron donor limited. DGGE analysis of amplified 16S rDNA gene fragments from incubated arsenate-enriched bottom waters revealed the presence of two bands that were not present in controls without added arsenate. The resolved sequences of these excised bands indicated the presence of members of the epsilon ( Sulfurospirillum ) and delta ( Desulfovibrio ) subgroups of the Proteobacteria , both of which have representative species that are capable of anaerobic growth using arsenate as their electron acceptor. 相似文献
5.
Saline lakes are threatened all over the world and their conservation has been a key issue. Various diversity indices are available for ecological status assessments, however, with poorly explored relevance and applicability in saline, alkaline pans. Therefore, traditional diversity measures (species richness and Shannon diversity) and taxonomic distinctness indices (Average [AvTD] and Variance of Taxonomic Distinctness [VarTD]) were tested in more than 100 sampling sites of 39 soda pans in Central-Europe to find sufficient indicators of the ecological condition and simultaneously to facilitate their preservation according to the modern conservation practices. Results of the analyses showed that healthy soda pan ecosystems with high level of natural stress and reduced habitat heterogeneity are characterized by low diversity diatom assemblages. In soda pans where the stress can be extremely high from natural reasons, oligopoly of closely related species can develop: the average taxonomic distinctness appeared between genus and family level. The non-DNA-sequence based phylogenetic diversity measures (AvTD and VarTD), were generally sensitive to the trophic state of the lakes, in contrast to traditional diversity metrics, which were unequivocally indicative for the special physical and chemical parameters (e.g. conductivity, pH) of the soda pans. In some cases, when the response of the diversity measures for a given environmental variable (pH, temperature) overlapped, the AvTD was found to be a more precise indicator of the environmental changes (pH) than traditional ones. The decreasing tendency of the AvTD along the intensified natural impact may be explained by the long available time for the species to adapt to these special environments. 相似文献
6.
Duckworth AW Grant WD Jones BE Meijer D Márquez MC Ventosa A 《Extremophiles : life under extreme conditions》2000,4(1):53-60
A number of novel alkaliphilic organotrophic bacteria have been isolated from several saline and alkaline East African soda
lakes. The new isolates grow at pH values between 7.0 and 11.0, with pH optima for growth between 9.0 and 10.0. Growth occurs
at total salts concentration between 0% and 20% (w/v) with optimum at 0%–7% (w/v). Phylogenetic analyses based on 16S rDNA
sequence comparison indicate that these isolates are related (>96% similarity) to members of the Halomonadaceae within the γ-3 subdivision of the Proteobacteria. These analyses indicate that existing species within the Halomonadaceae fell within three main groups, one group comprising the type species of Halomonas, Halomonas elongata, and a number of other known species including one soda lake isolate. A second group constituting most of the remaining known
species of Halomonas and related Chromohalobacter spp. includes 3 soda lake isolates with high DNA–DNA homologies. The third group included Halomonas halodenitrificans, Halomonas desiderata, Halomonas cupida, and 13 soda lake isolates. Phenotypic comparisons indicated that the majority of soda lake strains shared similar morphological,
phenotypic, and chemotaxonomic properties to known strains of Halomonas but grew under alkaline conditions. The 3 soda lake isolates with high DNA–DNA homologies were, however, significantly different
in antibiotic sensitivity pattern and in the utilization of several substrates, were unable to reduce nitrite, and showed
low DNA–DNA homologies with known halomonads in the same group. We propose that these isolates comprise a new species of the
genus Halomonas that we name Halomonas magadii sp. nov. The type strain is strain 21 MI (NCIMB 13595).
Received: July 20, 1999 / Accepted: October 29, 1999 相似文献
7.
Alazard D Badillo C Fardeau ML Cayol JL Thomas P Roldan T Tholozan JL Ollivier B 《Extremophiles : life under extreme conditions》2007,11(1):33-39
A new alkaliphilic and moderately halophilic, strictly anaerobic, fermentative bacterium (strain IMP-300T) was isolated from a groundwater sample in the zone of the former soda lake Texcoco in Mexico. Strain IMP-300T was Gram-positive, non-sporulated, motile and rod-shaped. It grew within a pH range from 7.5 to 10.5, and an optimum at 9.5.
The organism was obligately dependent on the presence of sodium salts. Growth showed an optimum at 35°C with absence of growth
above 45°C. It fermented peptone and a few amino acids, preferentially arginine and ornithine, with production of acetate,
propionate, and ammonium. Its fatty acid pattern was mainly composed of straight chain saturated, unsaturated, and cyclopropane
fatty acids. The G + C content of genomic DNA was 40.0 mol%. Analysis of the 16S rRNA gene sequence indicated that the new
isolate belongs to the genus Tindallia, in the low G + C Gram-positive phylum. Phylogenetically, strain IMP-300T has Tindallia californiensis, as closest relative with a 97.5% similarity level between their 16S rDNA gene sequences, but the DNA–DNA re-association
value between the two DNAs was only 42.2%. On the basis of differences in genotypic, phenotypic, and phylogenetic characteristics,
strain IMP-300T is proposed as a new species of the genus Tindallia, T. texcoconensis sp. nov. (type strain IMP-300T = DSM 18041T = JCM 13990T). 相似文献
8.
A new species of freshwater crab, Potamonautes
isimangaliso
sp. n., is described from the western shores of False Bay, Hluhluwe, within the iSimangaliso Wetland Park, South Africa. While bearing a superficial resemblance to Potamonautes
lividus, the new species has been found to be genetically distinct, diverging from the former by 7.4–7.8% in mtDNA. Potamonautes
isimangaliso most closely resembles Potamonautes
lividus, but is distinguished by a unique suite of carapace characters, colouration, and size. The new species also lives in close association with oxygen-poor, fresh ephemeral pans, while the habitat of Potamonautes
lividus is well above the surface water line of the closest water body. An updated identification key for the Potamonautes species of South Africa is provided. 相似文献
9.
Zvereva EA Fedorova TV Kevbrin VV Zhilina TN Rabinovich ML 《Extremophiles : life under extreme conditions》2006,10(1):53-60
Summary The cellulolytic activity of an alkaliphilic obligate anaerobic bacterium, Z-7026, which was isolated from the microbial community of soda-lake sediments and belongs to the cluster III of Clostridia with low G+C content, was studied. The bacterium was capable of growing in media with cellulose or cellobiose as the sole energy sources. Its maximal growth rate on cellobiose (0.042–0.046 h–1) was observed at an initial pH value of 8.5–9.0, whereas the maximal rate of cellulase synthesis, assayed by using a novel fluorimetric approach, was found to be 0.1 h–1 at pH 8–8.5. Secreted proteins revealed high affinity for cellulose and were represented by two major forms of molecular masses of 75 and 84 kDa, whereas the general protein composition of the precipitated and cellulose-bound preparations was similar to cellulosome subunits of Clostridium thermocellum. The optimum pH of the partially purified enzyme preparation towards both amorphous and crystalline cellulose was in the range 6–9, with more than 70% and less than 50% of maximal activity being retained at pH 9.2 and 5.0, respectively. 相似文献
10.
D. Y. Sorokin P. L. F. van den Bosch B. Abbas A. J. H. Janssen G. Muyzer 《Applied microbiology and biotechnology》2008,80(6):965-975
Thiopaq biotechnology for partial sulfide oxidation to elemental sulfur is an efficient way to remove H2S from biogases. However, its application for high-pressure natural gas desulfurization needs upgrading. Particularly, an
increase in alkalinity of the scrubbing liquid is required. Therefore, the feasibility of sulfide oxidation into elemental
sulfur under oxygen limitation was tested at extremely haloalkaline conditions in lab-scale bioreactors using mix sediments
from hypersaline soda lakes as inoculum. The microbiological analysis, both culture dependent and independent, of the successfully
operating bioreactors revealed a domination of obligately chemolithoautotrophic and extremely haloalkaliphilic sulfur-oxidizing
bacteria belonging to the genus Thioalkalivibrio. Two subgroups were recognized among the isolates. The subgroup enriched from the reactors operating at pH 10 clustered with
Thioalkalivibrio jannaschii–Thioalkalivibrio versutus core group of the genus Thioalkalivibrio. Another subgroup, obtained mostly with sulfide as substrate and at lower pH, belonged to the cluster of facultatively alkaliphilic
Thioalkalivibrio halophilus. Overall, the results clearly indicate a large potential of the genus Thiolalkalivibrio to efficiently oxidize sulfide at extremely haloalkaline conditions, which makes it suitable for application in the natural
gas desulfurization.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Nucleotide sequence accession numbers: The GenBank/EMBL accession numbers of the 16S rRNA gene sequence determined in this
study are EU709849–EU709878. 相似文献