Search results for " biotechnology"
showing 10 items of 3723 documents
Synthesis of the neurotoxin quinolinic acid in apoptotic tissue from Suberites domuncula: cell biological, molecular biological and chemical analyses
2002
Sessile marine animals, such as sponges, are prone to infection by prokaryotic as well as by eukaryotic attacking organisms. In the present study we document for the first time that in tissue from sponges which underwent apoptosis, a toxic compound is produced which very likely controls the elimination of the dying tissue. The marine sponge Suberites domuncula develops in the field occasionally apoptotic tissue areas which are rapidly eliminated. In the present study apoptosis was induced in S. domuncula by exposing the specimens in aquaria to 5 µg/ml Dip or by maintaining the sponges for 3 - 5 days under non-aeration conditions. After that treatment only one eukaryotic epibiont, the mollus…
Mannosyl transferases inSaccharomyces cerevisiae: Evidence for the occurrence of ectomannosyltransferase activity
1981
The subcellular distribution of mannosyltransferases inSaccharomyces cerevisiae was studied following the separation of the plasma membrane from other intracellular membranous systems. Most of the activity was linked to internal membranes, and the rest was located at the level of the plasma membrane. Yeast plasma membranes coated on their external face with concanavalin A when incubated with GDP-[U-14C]mannose incorporated 20% less [U-14C]mannose in glycoproteins and 110% more in glycolipids than plasma membranes alone. This suggested that part of the total mannosyltransferase activity of the plasma membrane is located on its outer surface. A significant incorporation of radioactive mannose…
Addition of reducing agent dithiothreitol improves 4-decanolide synthesis by the genus Sporidiobolus.
2000
Two species of the genus Sporidiobolus, S. johnsonii and S. ruinenii, were used to study the effect of the reducing agent, dithiothreitol (DTT), on 4-decanolide production using ricinoleic acid as the substrate. The results indicate that the addition of DTT into the cultures significantly enhanced 4-decanolide biosynthesis by the two species.
The comparative behavior of Lactococcus lactis in free and immobilized culture processes
1998
This study presents the changes in the physiological state of Lactococcus lactis in different actively growing systems. The intracellular pH (pHin), NADH/NAD ratio and lactate dehydrogenase (LDH) activity were measured in free cell batch culture with or without external pH (pHout) control, and in continuous free or immobilized cell reactors. In free cell batch culture it has been shown that the pHin is dependent both on pHout and age of the culture, while in free cell continuous culture the pHin and the pHout are close together. The NADH/NAD ratio varied inversely with the growth rate, which was related to the changes in the metabolic activities in lactococci. The specificity of the immobil…
Influence of fatty acids on the growth of wine microorganisms Saccharomyces cerevisiae and Oenococcus oeni
1998
The effects of fatty acids, extracted during prefermentation grape skin-contact on Saccharomyces cerevisiae and Oenococcus oeni, were studied. The influence of skin-contact on total fatty acid content was evaluated both in Chardonnay must and in synthetic medium. Prior to alcoholic fermentation, the skin-contact contributes to a large enrichment of long-chain fatty acids (C 16 to C 18:3 ). These results induced a positive effect on yeast growth and particularly on cell viability. In the skin-contact fermented media, levels of C 12 and especially C 10 are lower and macromolecules content higher than in controls. This production of extracellular mannoproteins and the reduction of medium-chain…
Reducing of acrylamide formation in wheat biscuits supplemented with flaxseed and lupine
2016
Abstract The use of pseudo-cereals for wheat products making is to fortify the deficiency of nutritional value in wheat flour. However rich in proteins plant additives could increase acrylamide content in baked products. The present study was focused on acrylamide reduction in wheat flour biscuits supplemented with lupine and defatted flaxseed flour treated by solid state (SSF) and submerged (SMF) fermentations by Lactobacillus sakei , Pediococcus pentosaceus and Pediococcus acidilactici strains. After fermentation the decrease in asparagine was on average of 67.6 and 80.6%, and reducing sugar contents were reduced by 18 and 79.4% in flaxseed and lupine, respectively. The most effective acr…
Production of 6-pentyl-?-pyrone byTrichoderma harzianum from 18?n fatty acid methyl esters
1992
Biosynthesis of 6-pentyl-α-pyrone byTrichoderma harzianum in two different media was evaluated. Best yields were found in nitrogen deficient medium (C/N=60). Limited growth seems to favour the production of this lactone. When fungal cells, precultured in low nitrogen medium, were incubated on methyl ricinoleate (10 g/l, C/N=60) an increase in 6-pentyl-α-pyrone production was observed in comparison with the media containing methyl oleate or methyl linoleate.
Lipase-enhanced activity in flavour ester reactions by trapping enzyme conformers in the presence of interfaces
1998
In order to improve the lipase-catalyzed synthesis of flavour esters, we have used the reported strategy of interfacial activation-based molecular (bio)imprinting [Mingarro et al. 1995. Proc. Natl. Acad. Sci. U.S.A. 92: 3308], later called trapping in the presence of amphiphile interfaces (TPI) [Mingarro et al. 1996. Biochemistry 35: 9935]. Five lipases of fungal and mammalian origin typically used for esterification process have been explored to improve production by TPI treatment. A marked enhancement of enzymatic activity has been observed in all TPI-treated lipases assayed and the activation factor obtained was up to 90-fold. The dependence on chain length of acyl donors in the esterifi…
Apple pomace: An enzyme system for producing aroma compounds from polyunsaturated fatty acids
1991
This paper reports on the possibility of obtaining C-6 (hexanal) and C-10 (2,4-dedadienal) volatile aldehydes by degradation of linoleic acid (C18∶2 Δ 9–12) under the action of the intrinsic enzyme systems found in apple pomace. More aroma compounds are produced by micronization of the pomace and by adding SO2 (60 ppm) and vitamin C (500 ppm), thereby synergistically counteracting oxidation of phenolic compounds, which is a limiting factor in bioconversion.
Separation of chitosomal chitin synthetase from cell-free extracts ofNeurospora crassa “Slime” variant agglutinated with concanavalin A
1989
Cell-free extracts of the wall-less slime variant ofNeurospora crassa were treated with concanavalin A (Con A); this treatment caused a massive agglutination of the particulate structures in the cell-free homogenate, although most (73%) of the chitin synthetase initially present in the cell-free extract remained in the supernatant obtained after sedimentation of the lectin-flocculated material. This chitin synthetase showed the sedimentation properties of chitosomes (unique microvesicular structures) and failed to bind [3H]Con A. A significant percentage (42%) of the chitin synthetase activity associated with the Con A-flocculated material probably corresponds to mechanically trapped chitos…