Search results for " biotechnology"

l-Valine biosynthesis during batch and fed-batch cultivations of Corynebacterium glutamicum: Relationship between changes in bacterial growth rate an…

2007

Abstract A transition in the bacterial growth rate to below maximum was found to be an optimum parameter of cellular physiology to increase the activity of acetohydroxy acid synthase, a regulatory enzyme in l -valine synthesis, and amino acid overproduction by Corynebacterium glutamicum ATCC 13032 recombinants under batch and fed-batch cultivation conditions. An increase in l -valine synthesis under transient situations when cellular growth rate was downregulated was correlated to a decrease in the activity of aconitase, a key enzyme in the tricarboxylic acid cycle (TCA) of C. glutamicum , and, in contrast, to an increase in the activity of glucose-6-phosphate dehydrogenase, a key enzyme in…

Effects of ultrasound-assisted extraction on physicochemical properties, bioactive compounds, and antioxidant capacity for the valorization of hybrid…

2021

Samples of tree hybrid mandarins (´Clemenvilla`, ´Ortanique` and ´Nadorcott`) were employed to determine the physicochemical properties (increase of conductivity, brix° and pH), bioactive compounds (total phenolic, flavonoid, ascorbic acid and carotenoids content) and antioxidant capacity (DPPH and TEAC) of peels. Mandarin peel extracts were prepared employing ultrasound assisted extraction (400 W, 80% v/v duty cycle, 40ºC). The results were compared to the values of control extraction method. Aqueous ethanol solution (50%, v/v) was used as solvent in solid-liquid ratio of 1:10 (w/v). A 5, 15 and 30 min were applied in both methods to stablish the most effective extraction time. The increas…

2003

Resting cells of the yeast Rhodosporidium toruloides (UOFS Y-0471) were immobilised in calcium alginate beads for the enantioselective kinetic resolution of racemic-1,2-epoxyoctane. The initial activity exhibited by immobilised cells was almost 50% lower than that of the free counterpart but was extremely stable when compared to the free cells. The concentration of the immobilised biomass had no effect on apparent enzyme activity but did lead to a decrease in single cell activity. An increase in both the alginate and CaCl2 concentrations used for bead preparation led to a decrease in enzyme stability. An increase in the alginate concentration led to an increase in bead diameter. The stoichi…

The role of hydrology on enhanced weathering for carbon sequestration II. From hydroclimatic scenarios to carbon-sequestration efficiencies

2021

Abstract Enhanced weathering (EW) scenarios are analyzed using the model presented in Cipolla et al. (2020). We explore the role of different hydroclimatic forcing on carbon-sequestration efficiencies. We also investigate whether increasing soil carbon content improves weathering conditions. We link olivine weathering rates to pH variations and quantify the suitability of hydroclimatic regimes to EW, based on rainfall intensity and frequency. The results show that the amount of CO 2 reacting with olivine and ending up in solution in the form of HCO 3 − and CO 3 2 − increases with mean annual precipitation (MAP) up to 2000 mm, but then tapers off for higher MAPs. On the contrary, the sequest…

Patterns of wall synthesis inSaccharomyces cerevisiae

1979

Wall formation inSaccharomyces cerevisiae seems to be the result of two main patterns of wall material deposition: (i) around the whole periphery of the cell in nonbudding ones, and (ii) mainly at the tip of the daughter cell or at the cross wall that separates dividing cells. This interpretation has been obtained following experiments in which RNA or protein synthesis has been inhibited. Under these conditions, glucan formation takes place, and wall thickening is probably due to the accumulation of this polysaccharide. Furthermore, once a pattern of wall deposition has been established, it is not modified by inhibition of RNA or protein synthesis.

Regulation of chitin synthase activity inSaccharomyces cerevisiae: Effect of the inhibition of cell division and of synthesis of RNA and protein

1980

The effect of pronase and trypsin on the activation or deactivation (degradation?) of chitin synthase ofSaccharomyces cerevisiae occurs faster in membranous preparations than in toluene-treated cells. When the temperature is raised, the former preparation is deactivated earlier than the latter one. The activity found in growing cells is not modified after inhibition of protein synthesis by cycloheximide or amino acid starvation or by the inhibition of RNA synthesis. It was possible to activate the chitin synthase ofS. cerevisiae cdc 25 grown at 23°C by means of pronase, whereas trypsin had no effect. After the cells were grown at 37°C, chitin synthase could not be activated either with tryp…

DNA Sensors for the Detection of Biomolecules and Biochemical Conditions

2017

Composite clay sorbents for immobilisation of biomolecules and cells

2015

Interactions between non-volatile water-soluble molecules and aroma compounds in Camembert cheese

2002

Abstract Interactions between selected aroma compounds and non-volatile water-soluble molecules were studied using dynamic headspace-gas chromatography. A model water-soluble extract (MWSE), previously constructed in gustatory and physico-chemical accordance with the crude Camembert cheese WSE, allowed the contribution of non-volatiles to the headspace composition of volatile compounds to be assessed. The presence of the MWSE increased the headspace concentration of 2-heptanone, 1-octen-3-ol and 3-methylbutanol, showing that these three volatile compounds were released by MWSE. Omission tests performed on MWSE allowed for the impact of each MWSE component on aroma compounds release to be de…

Enzyme-assisted extraction of proteins from Citrus fruits and prediction of their cultivar using protein profiles obtained by capillary gel electroph…

2017

Abstract The suitability of protein profiles established by capillary gel electrophoresis (CGE) as a tool to discriminate between 11 cultivars of Citrus (orange and tangerine) peel and pulp was evaluated in this work. Before CGE analysis, different extraction buffers (which included enzyme-assisted treatments) were compared. The best results were achieved using 5% ( v/v ) Celluclast ® 1.5 L and 5% ( v/v ) Palatase ® 20,000 L buffers for Citrus peel and pulp protein extracts, respectively. The resulting protein profiles obtained were used to construct linear discriminant analysis (LDA) models able to distinguish Citrus peel and pulp samples according to their cultivar. In both cases, all sam…