排序方式: 共有23条查询结果,搜索用时 359 毫秒
11.
Micheva-Viteva S. Tchorbanov B. Aleksieva P. Lazarova V. 《World journal of microbiology & biotechnology》2000,16(8-9):859-863
The fungus Humicola lutea 120-5 cultivated in casein-containing media, in the presence or absence of inorganic phosphate (Pi), excretes three different molecular forms of acid phosphatase (with Mr values of approximately 140, 70 and 35 kDa). The enzyme forms were isolated and purified 30–100-fold by a procedure involving
two steps of ion-exchange chromatography and Sephadex G-200 gel chromatography. It was found that the fungus excretes only
one of the phosphatases with the highest Mr (140 kDa) during growth on medium with inorganic nitrogen source (NaNO3). This form (designed AcPh I) was assumed to be a constitutive, since it showed resistance to high Pi-concentrations (10 mM) and its biosynthesis was not affected by the type of nitrogen source (casein or NaNO3). The other two forms (AcPh II-70 and AcPh III-35 kDa) were competitively inhibited by Pi (K
i = 0.5 and 0.2 mM, respectively) and were induced by casein. The K
m values of AcPh I and AcPh II were estimated as 1.3 mM, while AcPh III showed a higher affinity for p-nitrophenylphosphate (pNPP) with K
m of 0.5 mM. The AcPh I–III fractions demonstrated a pH optimum in the range of 4.5–4.8 and an optimal temperature of 55 °C using pNPP as a substrate.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
12.
P. Aleksieva B. Tchorbanov G. Suchodol'skaya K. Koschteenko 《Applied microbiology and biotechnology》1988,29(2-3):239-241
Summary Fungal spores ofHumicola lutea 120–5 were entrapped in 5% polyacrylamide gel and were cultivated for 44–48 h to form a mycelial network inside the beads. A dense mycelial growth also occurred on the surface of the beads. It was possible to reuse the immobilized mycelium for production of acid proteinases in 12 different batches without loss of mechanical stability. The inoculum size should be controlled prior to its transfer into fresh production medium. Maximal enzyme production exceeding the level of free cell fermentation was registered in the fourth to seventh cycles. According to the size of the inoculum, half of the initial production rate was reached after 7–14 batches. 相似文献
13.
Hybrid plasmids pLRS33 and pLRB4 containing Bac. subtilis genes coding lysin biosynthesis were subjected to genetical analysis. It is shown that after pLRS33- and pLRB4- transformation of E. coli strains, auxotrophic relative to lysin and diaminopimelic acid, there occurs complementation of dapA, dapB, dapC, dapD, dapE, lysA mutations by plasmid pLRS33 and of dapC, dapB, lysA mutations by plasmid pLRB4. The plasmids are studied for their influence on the level of lysin and its precurror synthesis in E. coli strains. 相似文献
14.
Veneta Ivanova Dimitrinka Lyutskanova Margarita Stoilova-Disheva Mariana Kolarova Krasja Aleksieva Vesela Raykovska 《Preparative biochemistry & biotechnology》2013,43(1):46-56
Abstract Streptomyces sp. strain SB9 was isolated from perm frost soil samples in Spitsbergen, Arctic Ocean; it grows in a temperature range between 4°C and 28°C. During the survey of biologically active metabolites biosynthesized by this strain, significant amounts of α,α-trehalose (1) and glycerol (2) were detected. The compounds were isolated from the mycelium, were chromatographically separated, and the structures were elucidated on the basis of MS and NMR measurements. A possible role of trehalose in cold adaptation of the strain was examined. It was determined that the mycelium of the strain cultivated at 4°C accumulated 5-fold higher amounts of trehalose in comparison with the cells cultivated at 28°C. The mesofilic reference strains, Streptomyces spectabilis NRRL 2494 and Streptomyces lividans TK64, accumulated 100-fold less trahalose than the psychrotolerant Streptomyces sp. SB9. High amounts of trehalose in the cells could be a reason for adaptation of the strain to life at Arctic conditions. 相似文献
15.
Ivanova V Kolarova M Aleksieva K Gräfe U Dahse HM Laatsch H 《Preparative biochemistry & biotechnology》2007,37(2):161-168
A new sulphur-containing natural alkaloid named microbiaeratin (1a) was isolated, together with the known microbiaeratinin (2, bacillamide) from the culture filtrate of Microbispora aerata strain IMBAS-11A. The organism was isolated from penguin excrements collected on the Antarctic Livingston Island. The structure was elucidated by one- and two-dimensional NMR experiments and mass spectrometric investigations. 相似文献
16.
Spasova D Aleksieva P Nacheva L Radoevska S 《Zeitschrift für Naturforschung. C, Journal of biosciences》2007,62(1-2):65-69
Electron microscopic cytochemical procedures were used to determine the cellular location of acid phosphatase in the fungus Humicola lutea grown in casein-containing medium lacking in mineral orthophosphates. In our investigations acid phosphatase in nongerminating conidia was localized on the outer side of the cell wall, in the cell wall, and on the exterior surface of the plasma membrane. The reaction product of acid phosphatase in germinating conidia was seen in the outer wall layer while in young mycelium on the cell surface and in the exocellular space. The relationship between phosphatase activities localized in the cell wall and their role in the enzymatic degradation of the phosphoprotein casein providing available phosphates for cell growth is discussed. 相似文献
17.
T N Shevchenko E O Timashova Z M Aleksieva N V Rodnin S S Maliuta 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1988,(6):33-37
A number of B. subtilis mutants auxotrophic for lysine has been isolated and mapped in relation to the flanking ser2 marker. One of the mutants has been found to have a mutation in lys A gene coding for DAP-decarboxylase activity. The expression of DAP-decarboxylase is dependent on the product of lys R gene that is not linked with lysine genes cluster. 相似文献
18.
Ivanova V Kolarova M Aleksieva K Graefe U Schlegel B 《Preparative biochemistry & biotechnology》2007,37(1):39-45
The fungus, Tritirachium sp. HKI 0317, was isolated from the Antarctic lichen Neuropogon sp. Fermentation of this strain, extraction of the culture broth, and preparative separation of produced compounds furnished 4-carboxy-5,5'-dihydroxy-3,3'-dimethyldiphenylether (1), macrosphelide A (2), and macrosphelide J (3). The structures were elucidated on the basis of MS and NMR measurements, and the previously published data for this compounds. 相似文献
19.
P. Aleksieva I. Grigorov A. Djerova P. Sheremetska B. Tchorbanov 《Engineering in Life Science》1984,4(2):179-185
The optimal parameters for the cultivation in 10-l fermenters of a mutant strain Humicola lutea 120-5 were established:temperature 30°C, inoculum size 6%, inoculum age 24 h, aeration rate 0,6 vol/vol · min, medium agitation 620 rpm and cultivation time 72 h. A maximal proteolytic activity of 2000 µg tyrosine liberated from 2%casein ml?1 culture filtrate min?1 at pH 3.0 and 40°C was obtained under the fixed conditions. α-Amylase biosynthesis during the cultivation of H. lutea 120-5 was observed but it was insignificant to the 72nd h. It is demonstrated that starch can be used as alternative to glucose carbon source. It is proved that the mutant strain H.lutea 120-5 produced two acid proteinases. 相似文献
20.