12 research outputs found
Study of transhydrogenase systems features in the mutants of the yeast pachysolen tannophilus for the production of ethanol and xylitol from agricultural wastes
The key catabolic enzymes of D-xylose, an important structural component of different
agricultural wastes, were studied in cells of mutant strains of the xylose-assimilating yeast
Pachysolen tannophilus. The evaluation of catalytic activity and cofactor specificity of xylose
reductase (ЕС 1.1.1.307) and xylitol dehydrogenase (ЕС 1.1.1.9) confirmed the dependence of
intracellular catabolic pathway for D-xy lose on the NADĂ—H/NADPĂ—H ratio, formed under
microaerobic conditions. The study of total activity of some NAD+
/NAPĂ—H-dependent
dehydrogenases revealed the metabolic characteristics of the yeast cells, which could ensure
selective ethanol or xylitol production. Thus, the efficient involvement of D-xylose into the
Embden–Meyerhof–Parnas pathway provided not only the high activities of xylose reductase and
xylitol dehydrogenase, but also of 1-glycerophosphate dehydrogenase (EC 1.1.1.8) and lactate
dehydrogenase (ЕС 1.1.1.27), respectively. The inhibition of activity of these enzymes led to
selective production of xylitol from D-xylose. On the base of the experimental results, the
principles of metabolic engineering of xylose-assimilating yeasts were formulated. The
possibility of bioethanol and xylitol production from different agricultural wastes using xyloseassimilating yeasts are discussed
Design of high efficiency centrifugal compressors stages
The modern trend in compressor industry is an extension of the use of multi-shaft centrifugal compressors. Multi-shaft compressors have a number of advantages over single-shaft. The design of such compressors gives opportunity to use an axial inlet for all stages and select the optimum rotational speed for each pair of impellers, which, along with the cooling of the gas after each stage, makes possible to achieve high levels of efficiency. The design of high-efficiency centrifugal compressor stages can be performed on the basis of highly effective stage elements. Such elements are: impellers with spatial blades, vaned and channel diffusers with given velocity distribution. In this paper, impellers with axial-radial blades are considered. The blade profile is determined by the specified pressure distribution along the blade. Such design improves the structure of the gas flow in the interblade channels of the impeller, which leads to an increase in its efficiency. Characteristics of loss coefficients from attack angles for impellers were obtained experimentally. Vaned and channel diffusers, the characteristics of which are given in this article, are designed with the given velocity distribution along the vane. Compared to the classic type of diffuser, such diffusers have lower losses and a wider range of economical operation. For diffusers as well as for impellers, characteristics of loss coefficients from attack angles were obtained. High efficient impellers and diffusers and obtained gas-dynamic characteristics were used in the design of a multi-shaft compressor unit for the production of liquefied natural gas. The initial pressure of the unit is 3bar. The obtained characteristics of loss coefficients from attack angles for the considered impellers and diffusers make it possible to calculate the gas-dynamic characteristics of high-efficient centrifugal compressors stages. The high-efficient centrifugal compressors stages can be designed using high-efficient elements, such as: impeller with spatial blades and vaned diffuser with given velocity distribution
Obtaining of Polyclonal Antibodies against <i>B. anthracis</i> S-layer Proteins and Study of their Specificity in Enzyme Immunoassay
Purified preparations of B. anthracis S-layer proteins - Sap and EA1 were obtained. Developed was the scheme of laboratory animals` immunization, that enabled to receive rabbits' polyclonal antibodies against Sap and EA1 proteins in high titer. 12 strains of B. anthracis, 53 strains of closely-related bacilli and 4 strains of other heterogeneous bacteria were tested in enzyme-linked immunosorbent assay and DOT-immunoassay with the use of polyclonal anti-Sap and anti-EA1 antibodies. Analysis of specificity of the obtained antibodies revealed cross-reactions with B. cereus, B. subtilis, B. mycoides and B. megaterium. The specificity of polyclonal anti-EA1 and anti-Sap antibodies was 75 and 83 % respectively. Sensitivity of reaction was 105 and106 m.c. in applying polyclonal antibodies against B. anthracis S-layer protein