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991.
生物能源因其原料具有来源丰富、价格低廉和可再生的优点,作为可替代化石能源的潜在能源受到世界各国的高度重视。有些嗜热厌氧菌因为具有木质纤维素降解能力和高温发酵的成本优势,被视为生物质转化乙醇等能源物质的理想微生物而成为近年来研究的热点,但乙醇耐受性较低是限制嗜热厌氧菌在工业化生产中应用的主要因素之一。本文从以下三个方面介绍嗜热厌氧菌乙醇耐受机制的研究进展:(1)嗜热厌氧菌生产乙醇的代谢途径;(2)嗜热厌氧菌的乙醇耐受机制;(3)提高嗜热厌氧菌乙醇耐受性的方法。 相似文献
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994.
The formation of14CO2 from 3 μg l−1 labelled chloroform was studied in anaerobic Dutch river sediments. All incubations were performed under anaerobic conditions.
The observed first order mineralization kinetics showed half-lives of 2–37 days at 20°C in 12 muddy sediments. In contrast
most of the sandy sediment samples did not show a mineralization of chloroform. Most probable number analysis revealed about
3.104 chloroform mineralizing bacteria per g of dry sediment in a muddy sediment and 1–2.103 chloroform mineralizing bacteria per g of dry sediment in a sandy sediment. Therefore the persistence of chloroform in sandy
sediments is not caused by the absence of chloroform mineralizing bacteria but by the inactivity of these bacteria. This inactivity
of the sandy sediments might allow chloroform from infiltrating river water to reach the groundwater. Mud samples from a relatively
unpolluted site showed a similar chloroform mineralization rate compared with the polluted sediments from the rivers Rhine
and Meuse. The data indicate that the reductive dechlorination of aliphatic compounds is not influenced at the polluted sites. 相似文献
995.
996.
The effects of Cadmium (Cd) toxicity on bacterial consortia originating from an-aerobic sewage sludge and cultivated under differing enrichment conditions were studied. Cultures were enriched in minimal media developed specifically for Cd stress studies. At inoculation all Cd was soluble in free ion or chelated form. Electron donors and acceptors were varied to obtain each physiological enrichment type. Adaptation leading to higher levels of Cd resistance of the consortia over time was observed under all physiological conditions. Initial and increased Cd tolerances were consistently greatest in multiphysiological enrichments (MPH). Sulfate reducing (SRB), methanogenic (MET), and fermentative (FRM) enrichments had less tolerance however, the level of tolerance to the Cd varied from one inoculation to the next. The Cd remained soluble as free Cd in MPH and FRM conditions and was precipitated significantly in SRB and moderately in MET conditions. Denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) amplified 16S rRNA of the SRB, MPH, and FRM enrichments were followed over time. The consortia underwent succession under all physiological conditions when compared with the profile of the inoculum. Microbial population diversity decreased as the consortia were subcultured. The effects of chelators in the MPH medium were also evaluated. The addition of chelators transiently decreased toxicity. Effects of MPH medium on the Cd sorption capacity of soil were evaluated. Microbial growth decreased the amount of Cd left in solution. 相似文献
997.
L. Muxi L. Zunino S. Tarlera M. Soubes 《World journal of microbiology & biotechnology》1992,8(6):632-634
The sludge of an anaerobic lagoon treating the wastewater from a factory producing baker's yeast was evaluated as inoculum for anaerobic digestion. Specific methanogenic activity tests failed to give a good estimation of the trophic groups that were evidenced by enumerations involving Most Probable Number estimations. This failure was ascribed to the toxic effects of either the acetate concentrations used or to the ammonia content of the sludge. 相似文献
998.
Thomas Holler Friedrich Widdel Katrin Knittel Rudolf Amann Matthias Y Kellermann Kai-Uwe Hinrichs Andreas Teske Antje Boetius Gunter Wegener 《The ISME journal》2011,5(12):1946-1956
The anaerobic oxidation of methane (AOM) with sulfate controls the emission of the greenhouse gas methane from the ocean floor. AOM is performed by microbial consortia of archaea (ANME) associated with partners related to sulfate-reducing bacteria. In vitro enrichments of AOM were so far only successful at temperatures ⩽25 °C; however, energy gain for growth by AOM with sulfate is in principle also possible at higher temperatures. Sequences of 16S rRNA genes and core lipids characteristic for ANME as well as hints of in situ AOM activity were indeed reported for geothermally heated marine environments, yet no direct evidence for thermophilic growth of marine ANME consortia was obtained to date. To study possible thermophilic AOM, we investigated hydrothermally influenced sediment from the Guaymas Basin. In vitro incubations showed activity of sulfate-dependent methane oxidation between 5 and 70 °C with an apparent optimum between 45 and 60 °C. AOM was absent at temperatures ⩾75 °C. Long-term enrichment of AOM was fastest at 50 °C, yielding a 13-fold increase of methane-dependent sulfate reduction within 250 days, equivalent to an apparent doubling time of 68 days. The enrichments were dominated by novel ANME-1 consortia, mostly associated with bacterial partners of the deltaproteobacterial HotSeep-1 cluster, a deeply branching phylogenetic group previously found in a butane-amended 60 °C-enrichment culture of Guaymas sediments. The closest relatives (Desulfurella spp.; Hippea maritima) are moderately thermophilic sulfur reducers. Results indicate that AOM and ANME archaea could be of biogeochemical relevance not only in cold to moderate but also in hot marine habitats. 相似文献
999.
Land M Held B Gronow S Abt B Lucas S Del Rio TG Nolan M Tice H Cheng JF Pitluck S Liolios K Pagani I Ivanova N Mavromatis K Mikhailova N Pati A Tapia R Han C Goodwin L Chen A Palaniappan K Hauser L Brambilla EM Rohde M Göker M Detter JC Woyke T Bristow J Eisen JA Markowitz V Hugenholtz P Kyrpides NC Klenk HP Lapidus A 《Standards in genomic sciences》2011,4(2):233-243
Bacteroides coprosuis Whitehead et al. 2005 belongs to the genus Bacteroides, which is a member of the family Bacteroidaceae. Members of the genus Bacteroides in general are known as beneficial protectors of animal guts against pathogenic microorganisms, and as contributors to the degradation of complex molecules such as polysaccharides. B. coprosuis itself was isolated from a manure storage pit of a swine facility, but has not yet been found in an animal host. The species is of interest solely because of its isolated phylogenetic location. The genome of B. coprosuis is already the 5(th) sequenced type strain genome from the genus Bacteroides. The 2,991,798 bp long genome with its 2,461 protein-coding and 78 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project. 相似文献
1000.
Göker M Teshima H Lapidus A Nolan M Lucas S Hammon N Deshpande S Cheng JF Tapia R Han C Goodwin L Pitluck S Huntemann M Liolios K Ivanova N Pagani I Mavromatis K Ovchinikova G Pati A Chen A Palaniappan K Land M Hauser L Brambilla EM Rohde M Spring S Detter JC Woyke T Bristow J Eisen JA Markowitz V Hugenholtz P Kyrpides NC Klenk HP 《Standards in genomic sciences》2011,4(3):393-401
Desulfobacca acetoxidans Elferink et al. 1999 is the type species of the genus Desulfobacca, which belongs to the family Syntrophaceae in the class Deltaproteobacteria. The species was first observed in a study on the competition of sulfate-reducers and acetoclastic methanogens for acetate in sludge. D. acetoxidans is considered to be the most abundant acetate-degrading sulfate reducer in sludge. It is of interest due to its isolated phylogenetic location in the 16S rRNA-based tree of life. This is the second completed genome sequence of a member of the family Syntrophaceae to be published and only the third genome sequence from a member of the order Syntrophobacterales. The 3,282,536 bp long genome with its 2,969 protein-coding and 54 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project. 相似文献