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71.
Bacteria and archaea involved in anaerobic digestion of distillers grains with solubles 总被引:1,自引:0,他引:1
Ziganshin AM Schmidt T Scholwin F Il'inskaya ON Harms H Kleinsteuber S 《Applied microbiology and biotechnology》2011,89(6):2039-2052
Cereal distillers grains, a by-product from bioethanol industry, proved to be a suitable feedstock for biogas production in
laboratory scale anaerobic digesters. Five continuously stirred tank reactors were run under constant conditions and monitored
for biogas production and composition along with other process parameters. Iron additives for sulfide precipitation significantly
improved the process stability and efficiency, whereas aerobic pretreatment of the grains had no effect. The microbial communities
in the reactors were investigated for their phylogenetic composition by terminal restriction fragment length polymorphism
analysis and sequencing of 16S rRNA genes. The bacterial subcommunities were highly diverse, and their composition did not
show any correlation with reactor performance. The dominant phylotypes were affiliated to the Bacteroidetes. The archaeal
subcommunities were less diverse and correlated with the reactor performance. The well-performing reactors operated at lower
organic loading rates and amended with iron chloride were dominated by aceticlastic methanogens of the genus Methanosaeta. The well-performing reactor operated at a high organic loading rate and supplemented with iron hydroxide was dominated by
Methanosarcina ssp. The reactor without iron additives was characterized by propionate and acetate accumulation and high hydrogen sulfide
content and was dominated by hydrogenotrophic methanogens of the genus Methanoculleus. 相似文献
72.
Recovery of microbial diversity and activity during bioremediation following chemical oxidation of diesel contaminated soils 总被引:1,自引:0,他引:1
Nora B. Sutton Alette A. M. Langenhoff Daniel Hidalgo Lasso Bas van der Zaan Pauline van Gaans Farai Maphosa Hauke Smidt Tim Grotenhuis Huub H. M. Rijnaarts 《Applied microbiology and biotechnology》2014,98(6):2751-2764
To improve the coupling of in situ chemical oxidation and in situ bioremediation, a systematic analysis was performed of the effect of chemical oxidation with Fenton's reagent, modified Fenton's reagent, permanganate, or persulfate, on microbial diversity and activity during 8 weeks of incubation in two diesel-contaminated soils (peat and fill). Chemical oxidant and soil type affected the microbial community diversity and biodegradation activity; however, this was only observed following treatment with Fenton's reagent and modified Fenton's reagent, and in the biotic control without oxidation. Differences in the highest overall removal efficiencies of 69 % for peat (biotic control) and 59 % for fill (Fenton's reagent) were partially explained by changes in contaminant soil properties upon oxidation. Molecular analysis of 16S rRNA and alkane monooxygenase (alkB) gene abundances indicated that oxidation with Fenton's reagent and modified Fenton's reagent negatively affected microbial abundance. However, regeneration occurred, and final relative alkB abundances were 1–2 orders of magnitude higher in chemically treated microcosms than in the biotic control. 16S rRNA gene fragment fingerprinting with DGGE and prominent band sequencing illuminated microbial community composition and diversity differences between treatments and identified a variety of phylotypes within Alpha-, Beta-, and Gammaproteobacteria. Understanding microbial community dynamics during coupled chemical oxidation and bioremediation is integral to improved biphasic field application. 相似文献
73.
The glycopeptide vancomycin was until recently considered a drug of last resort against Gram-positive bacteria. Increasing numbers of bacteria, however, are found to carry genes that confer resistance to this antibiotic. So far, 10 different vancomycin resistance clusters have been described. A chromosomal vancomycin resistance gene cluster was previously described for the anaerobic Desulfitobacterium hafniense Y51. We demonstrate that this gene cluster, characterized by its d-Ala-d-Lac ligase-encoding vanI gene, is present in all strains of D. hafniense, D. chlororespirans and some strains of Desulfosporosinus spp. This gene cluster was not found in vancomycin-sensitive Desulfitobacterium or Desulfosporosinus spp., and we show that this antibiotic resistance can be exploited as an intrinsic selection marker for Desulfitobacterium hafniense and D. chlororespirans. The gene cluster containing vanI is phylogenetically only distantly related with those described from soil and gut bacteria, but clusters instead with vancomycin resistance genes found within the phylum Actinobacteria that include several vancomycin-producing bacteria. It lacks a vanH homologue, encoding a D-lactate dehydrogenase, previously thought to always be present within vancomycin resistance gene clusters. The location of vanH outside the resistance gene cluster likely hinders horizontal gene transfer. Hence, the vancomycin resistance cluster in D. hafniense should be regarded a novel one that we here designated vanI after its unique d-Ala-d-Lac ligase. 相似文献
74.
Felix Molter Armin W. Thomas Scott A. Huettel Hauke R. Heekeren Peter N. C. Mohr 《PLoS computational biology》2022,18(7)
Choices are influenced by gaze allocation during deliberation, so that fixating an alternative longer leads to increased probability of choosing it. Gaze-dependent evidence accumulation provides a parsimonious account of choices, response times and gaze-behaviour in many simple decision scenarios. Here, we test whether this framework can also predict more complex context-dependent patterns of choice in a three-alternative risky choice task, where choices and eye movements were subject to attraction and compromise effects. Choices were best described by a gaze-dependent evidence accumulation model, where subjective values of alternatives are discounted while not fixated. Finally, we performed a systematic search over a large model space, allowing us to evaluate the relative contribution of different forms of gaze-dependence and additional mechanisms previously not considered by gaze-dependent accumulation models. Gaze-dependence remained the most important mechanism, but participants with strong attraction effects employed an additional similarity-dependent inhibition mechanism found in other models of multi-alternative multi-attribute choice. 相似文献
75.
Evidence for Geographic Isolation and Signs of Endemism within a Protistan Morphospecies 总被引:4,自引:0,他引:4 下载免费PDF全文
Jens Boenigk Karin Pfandl Tobias Garstecki Hauke Harms Gianfranco Novarino Antonis Chatzinotas 《Applied microbiology》2006,72(8):5159-5164
The possible existence of endemism among microorganisms resulting from and preserved by geographic isolation is one of the most controversial topics in microbial ecology. We isolated 31 strains of “Spumella-like” flagellates from remote sampling sites from all continents, including Antarctica. These and another 23 isolates from a former study were characterized morphologically and by small-subunit rRNA gene sequence analysis and tested for the maximum temperature tolerance. Only a minority of the Spumella morpho- and phylotypes from the geographically isolated Antarctic continent follow the worldwide trend of a linear correlation between ambient (air) temperature during strain isolation and heat tolerance of the isolates. A high percentage of the Antarctic isolates, but none of the isolates from locations on all other continents, were obligate psychrophilic, although some of the latter were isolated at low ambient temperatures. The drastic deviation of Antarctic representatives of Spumella from the global trend of temperature adaptation of this morphospecies provides strong evidence for geographic transport restriction of a microorganism; i.e., Antarctic protistan communities are less influenced by transport of protists to and from the Antarctic continent than by local adaptation, a subtle form of endemism. 相似文献
76.
Schönitzer V Eichner N Clausen-Schaumann H Weiss IM 《Biochemical and biophysical research communications》2011,(4):586-590
Several mollusc shells contain chitin, which is formed by a transmembrane myosin motor enzyme. This protein could be involved in sensing mechanical and structural changes of the forming, mineralizing extracellular matrix. Here we report the heterologous expression of the transmembrane myosin chitin synthase Ar-CS1 of the bivalve mollusc Atrina rigida (2286 amino acid residues, M.W. 264 kDa/monomer) in Dictyostelium discoideum, a model organism for myosin motor proteins. Confocal laser scanning immunofluorescence microscopy (CLSM), chitin binding GFP detection of chitin on cells and released to the cell culture medium, and a radiochemical activity assay of membrane extracts revealed expression and enzymatic activity of the mollusc chitin synthase in transgenic slime mold cells. First high-resolution atomic force microscopy (AFM) images of Ar-CS1 transformed cellulose synthase deficient D. discoideumdcsA− cell lines are shown. 相似文献
77.
78.
Winter J Gleiter S Klappa P Lilie H 《Protein science : a publication of the Protein Society》2011,20(3):588-596
Protein disulfide isomerase (PDI) supports proinsulin folding as chaperone and isomerase. Here, we focus on how the two PDI functions influence individual steps in the complex folding process of proinsulin. We generated a PDI mutant (PDI-aba'c) where the b' domain was partially deleted, thus abolishing peptide binding but maintaining a PDI-like redox potential. PDI-aba'c catalyzes the folding of human proinsulin by increasing the rate of formation and the final yield of native proinsulin. Importantly, PDI-aba'c isomerizes non-native disulfide bonds in completely oxidized folding intermediates, thereby accelerating the formation of native disulfide bonds. We conclude that peptide binding to PDI is not essential for disulfide isomerization in fully oxidized proinsulin folding intermediates. 相似文献
79.
80.
Community analysis of a full-scale anaerobic bioreactor treating paper mill wastewater 总被引:4,自引:0,他引:4
Roest K Heilig HG Smidt H de Vos WM Stams AJ Akkermans AD 《Systematic and applied microbiology》2005,28(2):175-185
To get insight into the microbial community of an Upflow Anaerobic Sludge Blanket reactor treating paper mill wastewater, conventional microbiological methods were combined with 16S rRNA gene analyses. Particular attention was paid to microorganisms able to degrade propionate or butyrate in the presence or absence of sulphate. Serial enrichment dilutions allowed estimating the number of microorganisms per ml sludge that could use butyrate with or without sulphate (10(5)), propionate without sulphate (10(6)), or propionate and sulphate (10(8)). Quantitative RNA dot-blot hybridisation indicated that Archaea were two-times more abundant in the microbial community of anaerobic sludge than Bacteria. The microbial community composition was further characterised by 16S rRNA-gene-targeted Denaturing Gradient Gel Electrophoresis (DGGE) fingerprinting, and via cloning and sequencing of dominant amplicons from the bacterial and archaeal patterns. Most of the nearly full length (approximately 1.45 kb) bacterial 16S rRNA gene sequences showed less than 97% similarity to sequences present in public databases, in contrast to the archaeal clones (approximately. 1.3 kb) that were highly similar to known sequences. While Methanosaeta was found as the most abundant genus, also Crenarchaeote-relatives were identified. The microbial community was relatively stable over a period of 3 years (samples taken in July 1999, May 2001, March 2002 and June 2002) as indicated by the high similarity index calculated from DGGE profiles (81.9+/-2.7% for Bacteria and 75.1+/-3.1% for Archaea). 16S rRNA gene sequence analysis indicated the presence of unknown and yet uncultured microorganisms, but also showed that known sulphate-reducing bacteria and syntrophic fatty acid-oxidising microorganisms dominated the enrichments. 相似文献