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Comparison of unitrophic and mixotrophic substrate metabolism by acetate-adapted strain of Methanosarcina barkeri 总被引:10,自引:12,他引:10 下载免费PDF全文
We examined the unitrophic metabolism of acetate and methanol individually and the mixotrophic utilization of these compounds by using detailed 14C-labeled tracer studies in a strain of Methanosarcina barkeri adapted to grow on acetate as the sole carbon and energy source. The substrate consumption rate and methane production rate were significantly lower on acetate alone than during the unitrophic or mixotrophic metabolism of methanol. Cell yields (in grams per mole of substrate) were identical during exponential growth on acetate and exponential growth on methanol. During unitrophic metabolism of acetate, the methyl moiety accounted for the majority of the CH4 produced, but 14% of the CO2 generated originated from the methyl moiety. This correlated with the concurrent reduction of equivalent amounts of the C-1 of acetate to CH4. 14CH4 was also produced from added 14CO2, although to a lesser extent than from reduction of the C-1 of acetate. During mixotrophic metabolism, methanol and acetate were catabolized simultaneously. The rates of 14CH4 and 14CO2 generation from [2-14C]acetate were logarithmic and higher in mixotrophic than in unitrophic cultures at substrate concentrations of 50 mM. A comparison of the oxidoreductase activities in cell extracts of the acetate-adapted strain grown on acetate and of strain MS grown on methanol or on H2 plus CO2 indicated that the pyruvate, α-ketoglutarate, and isocitrate dehydrogenase activities remained constant, whereas the CO dehydrogenase activity was significantly higher (5,000 nmol/min per mg of protein) in the acetate-adapted strain. These results suggested that a significant intramolecular redox pathway is possible for the generation of CH4 from acetate, that energy metabolism from acetate by M. barkeri is not catabolite repressed by methanol, and that the acetate-adapted strain is a metabolic mutant with derepressed CO dehydrogenase activity. 相似文献
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L Alonso EC Souza MV Oliveira LFE do Nascimento PMS Dantas 《Biology of sport / Institute of Sport》2014,31(4):267-270
The objective of this study was to evaluate the genetic and environmental contribution to variation in aerobic power in monozygotic (MZ) and dizygotic (DZ) twins. The sample consisted of 20 MZ individuals (12 females and 8 males) and 16 DZ individuals (12 females and 4 males), aged from 8 to 26 years, residents in Natal, Rio Grande do Norte. The twins were assessed by a multistage fitness test. The rate of heritability found for aerobic power was 77%. Based on the results, the estimated heritability was largely responsible for the differences in aerobic power. This implies that such measures are under strong genetic influence. 相似文献
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Recht MI De Bruyker D Bell AG Wolkin MV Peeters E Anderson GB Kolatkar AR Bern MW Kuhn P Bruce RH Torres FE 《Analytical biochemistry》2008,377(1):33-39
Enthalpy arrays enable label-free, solution-based calorimetric detection of molecular interactions in a 96-detector array format. The combination of the small size of the detectors and the ability to perform measurements in parallel results in a significant reduction of sample volume and measurement time compared with conventional calorimetry. We have made significant improvements in the technology by reducing the temperature noise of the detectors and improving the fabrication materials and methods. In combination with an automated measurement system, the advances in device performance and data analysis have allowed us to develop basic enzyme assays for substrate specificity and inhibitor activity. We have also performed a full titration of 18-crown-6 with barium chloride. These results point to future applications for enthalpy array technology, including fragment-based screening, secondary assays, and thermodynamic characterization of leads in drug discovery. 相似文献
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Gibson S Kibiki Bert Mulder Wil MV Dolmans Jessica L de Beer Martin Boeree Noel Sam Dick van Soolingen Christophe Sola Adri GM van der Zanden 《BMC microbiology》2007,7(1):51
Background
Tuberculosis (TB) is a major health problem and HIV is the major cause of the increase in TB. Sub-Saharan Africa is endemic for both TB and HIV infection. Determination of the prevalence of M. tuberculosis strains and their drug susceptibility is important for TB control. 相似文献16.
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SE?Aleshin AV?Timofeev MV?Khoretonenko LG?Zakharova GV?Pashvykina JR?Stephenson AM?Shneider AD?AltsteinEmail author 《BMC microbiology》2005,5(1):45
Background
Heterologous prime-boost immunization protocols using different gene expression systems have proven to be successful tools in protecting against various diseases in experimental animal models. The main reason for using this approach is to exploit the ability of expression cassettes to prime or boost the immune system in different ways during vaccination procedures. The purpose of the project was to study the ability of recombinant vaccinia virus (VV) and bacterial plasmid, both carrying the NS1 gene from tick-borne encephalitis (TBE) virus under the control of different promoters, to protect mice against lethal challenge using a heterologous prime-boost vaccination protocol. 相似文献18.
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Background
Cancer and other disorders are due to genomic lesions. SNP-microarrays are able to measure simultaneously both genotype and copy number (CN) at several Single Nucleotide Polymorphisms (SNPs) along the genome. CN is defined as the number of DNA copies, and the normal is two, since we have two copies of each chromosome. The genotype of a SNP is the status given by the nucleotides (alleles) which are present on the two copies of DNA. It is defined homozygous or heterozygous if the two alleles are the same or if they differ, respectively. Loss of heterozygosity (LOH) is the loss of the heterozygous status due to genomic events. 相似文献20.