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21.
Summary A new mutant strain,Aspergillus niger GS-III, showing resistance to manganese ions inhibition of citric acid fermentation on a sugarcane molasses containing medium was induced fromAspergillus niger KCU 520, a high citric acid-yielding strain. In submerged, surface or continuous cultures in the presence of manganese ions concentration upto 1.5 ppm the mutant strain yielded citric acid about 90 KgM–3 . The citric acid yield was comparable to that obtained with the parental strain KCU 520 in the absence of manganese ions, but it was atleast 3-fold higher than that obtained by the latter in the presence of manganese ions. The mutant strain immobilized in calcium alginate beads was used in combination with surface-stabilized cultures for about 36-days in a continuous flow horizontal fermenter without any apparent loss in citric acid productivity. These results indicate that the manganese-resistant mutant is stable and may be used in the presence of sufficient manganese ions concentration (1.5 ppm) in the fermentation medium. This capability of the mutant strainA. niger GS-III has been correlated with greatly reduced levels (about one-thirds) of the NADP+ -isocitric dehydrogenase, one of the control points for citric acid accumulation. 相似文献
22.
Y. Chandra Sekharudu V.S.R. Rao 《International journal of biological macromolecules》1984,6(6):337-347
The possible modes of binding for , , , and to concanavalin A have been investigated using theoretical methods. All these sugars, except , reach the active site of concanavalin A with a highly restricted number of binding orientations. Present investigations suggest that the failure of to bind to concanavalin A is not so much due to steric factors as to repulsive electrostatic interactions. can bind to concanavalin A in one mode whereas the other sugars can bind in more than one mode. The high potency of over is mainly due to the possibility of hydrophobic interactions of the α-methoxy group with Leu(99) or Tyr(100) and also due to the possibility of formation of better and more hydrogen bonds with the protein. A comparison of these data with those for the d-glucopyranosides suggests that the change of the hydroxyl at the C-2 atom from equatorial to axial orientation increases the stereochemically allowed region as well as the possible binding modes. From these studies it is also suggested that the overall shape of the oligosaccharides rather than the terminal or internal mannose alone affects the binding potency of saccharides to concanavalin A. 相似文献
23.
The possible modes of binding for methyl-α-d-mannopyranoside, methyl-β-d-mannopyranoside, 2-O-methyl-α-d-mannopyranoside, methyl-2-O-methyl-α-d-mannopyranoside and methyl-α-d-N-acetylmannosamine to concanavalin A have been investigated using theoretical methods. All these sugars, except methyl-α-d-N-acetylmannosamine, reach the active site of concanavalin A with a highly restricted number of binding orientations. Present investigations suggest that the failure of methyl-α-d-N-acetylmannosamine to bind to concanavalin A is not so much due to steric factors as to repulsive electrostatic interactions. Methyl-2-O-methyl-α-d-mannopyranoside can bind to concanavalin A in one mode whereas the other sugars can bind in more than one mode. The high potency of methyl-α-d-mannopyranoside over methyl-β-d-mannopyranoside is mainly due to the possibility of hydrophobic interactions of the α-methoxy group with Leu(99) or Tyr(100) and also due to the possibility of formation of better and more hydrogen bonds with the protein. A comparison of these data with those for the d-glucopyranosides suggests that the change of the hydroxyl at the C-2 atom from equatorial to axial orientation increases the stereochemically allowed region as well as the possible binding modes. From these studies it is also suggested that the overall shape of the oligosaccharides rather than the terminal or internal mannose alone affects the binding potency of saccharides to concanavalin A. 相似文献
24.
Prolific shoot bud differentiation was induced in callus and suspension cultures of hypocotyl origin in Brassica campestris cv. Yellow Sarson on MS medium supplemented with K (13.9–23.2 M) or BA (13.3–22.1 M). Plantlets were obtained by rooting the in vitro differentiated shoots. Histological studies revealed a unique mode of meristemoid formation.Abbreviations MS
Murashige and Skoog (1962)
- 2,4-D
2,4-dichlorophenoxyacetic acid
- BA
Benzyladenine
- IAA
Indole-3-acetic acid
- IBA
Indolebutyric acid
- K
Kinetin
- NAA
Naphthalene acetic acid 相似文献
25.
Glutamine synthetase I fromRhizobium meliloti was found to be inhibited by adenosine 5-monophosphate, alanine, glycine, carbamyl phosphate, cytidine 5-triphosphate, tryptophan, histidine, and glucosamine-6-phosphate. Each inhibitor was independent in its action and the effect was cumulative when more than one inhibitor was added. 相似文献
26.
27.
Callus cultures of two cultivars of Vigna aconitifolia (IPCMO-926, RDM-120) were raised and their growth and differentiation studied. In IPCMO-926 callus cultures, numerous shoot buds differentiated on MS medium with BA (0.4–22.2 μM) alone or in combination with IAA (5.7 μM). In RDM-120 best differentiation of shoot buds was observed on a medium with K (23.2 μM) and IAA (5.7 μM). Kinetin alone, however, induced rhizogenesis in callus cultures. In suspension cultures of IPCMO-926 embryoids differentiated on MS medium with K (0.5 μM) and 2,4-D (0.4 and 0.9 μM). 相似文献
28.
A new antifungal antibiotic named acmycin was isolated from a soil streptomycete. Detailed comparative taxonomic studies showed
that the organism differed from three related species of streptomycetes. The organism was referred to asStreptomyces sp. AC2. The isolated antibiotic appears to be of polyene nature. 相似文献
29.
A soil actinomycete hydrolyzed collagen extracted from bovine Achilles tendon, calf skin, carp swim-bladder and rat tail tendon.
Glucose, mannose, aspartic acid and asparagine increased its collagenolytic activity which was optimum at 28 °C and at pH
7.2 – 7.5. Metallic ions, NaEDTA, cysteine, 4-chloromercuribenzoate, glutathione and sodium azide were inhibitory. 相似文献
30.
Girish Chandra 《BioControl》1980,25(2):187-192
Three new techniques of rearing dryinids parasitising rice hoppers were developed, namely, laboratory rearing technique for
detailed observations, device for transporting and rearing field-collected hoppers to estimate percentage parasitism and a
breeding technique.
Résumé Trois nouvelles techniques d’élevage de dryiinides parasites des cicadelles du riz ont été mises au point. L’une pour l’élevage en laboratoire en vue d’observations précises, un système pour le transport et l’élevage de cicadelles récoltées dans la nature afin d’évaluer le pourcentage de parasitisme et une technique d’élevage permanent.相似文献