Cultivation Of Candida Utilis Research Articles

The scale-up cultivation of Candida utilis in waste potato juice water with glycerol affects biomass and \u03b2(1,3)/(1,6)-glucan characteristic and yield

New ideas on production of yeast origin β-glucan preparations for industrial application are attracting interest considering market development of that high-value functional polysaccharide. Sellecting an efficient yeast producer and designing culture conditions are a prerequisite for obtaining high yield of β-glucan. The aim of this study was to describe at the first time the influence of the mode of cultivation (shake-flasks and batch fermentation) and time of culture on characteristic and yield of biomass and β(1,3)/(1,6)-glucan preparations of Candida utilis ATCC 9950 after cultivation in medium based on waste potato juice water supplemented with 10% of glycerol. After shake-flask culture, the biomass was characterized by higher protein content (app. 26.5%) compared to 19% after batch fermentation while the cultivation on a biofermentor scale promoted polysaccharides biosynthesis. The highest output of purified β(1,3)/(1,6)-glucan preparation (5.3 gd.w./L), containing app. 85% of that polysaccharide, was found after 48 h cultivation in biofermentor. Batch fermentation promoted biosynthesis of alkali-insoluble β(1,3)/(1,6)-glucan fraction, decreasing the content of β(1,6)-glucan. The yield of β(1,3)/(1,6)-glucan synthesis was 0.063 (g/g glycerol), while the productivity of that polysaccharide reached 0.094 (g/L/h). Longer batch fermentation (72 h) resulted in reduction of production efficiency of β-glucan preparation under studied conditions. The results of the study provide a new efficient biotechnological solution to produce high-value β-glucan preparations of C. utilis origin based on valorization of agro-waste potato juice water with glycerol.

Combined amino acids modulation with H 2 O 2 stress for glutathione overproduction in Candida utilis

Strategies of amino acids addition coupled with H 2 O 2 stresses were developed for glutathione (GSH) overproduction in high cell density (HCD) cultivation of Candida utilis . Based on the fact that glycine shows two functions of promoting cells growth as well as GSH production, precursor amino acids modulations of feeding glycine at 4 mmol/l/h at exponential phase and adding precursor amino acids (glutamic acid 42 mmol/l, glycine 40 mmol/l, and cysteine 36 mmol/) at stationary phase were conducted. As a result, cell density reached 114.8 g/l at 45 h and glutathione yield of 2136 mg/l was achieved at 60 h, which was 12.5 and 90.2% higher than the control, respectively. Furthermore, the novel strategies of amino acids modulation combined with H2O2 additions (24 mmol/l at 21 h, 26 mmol/l at 29 h, 28 mmol/l at 37 h and 30 mmol/l at 45 h) were adopted to maximize glutathione production. Final glutathione yield reached 2448 mg/l after 60 h cultivation, suggesting the strategies developed as being feasible for GSH overproduction. Keywords: Amino acids, glutathione (GSH), high cell density (HCD) cultivation, Candida utilis , H 2 O 2 stresses African Journal of Biotechnology Vol. 9(33), pp. 5399-5406, 16 August, 2010

Continuous culture ofCandida utilis growing under cell-cycle-period changes of aeration

Periodic interruption of oxygen supply in a cell-cycle period decreases the RNA content in the biomass ofCandida utilis. The effect was observed in a mineral medium in slowly as well as in rapidly growing cultures.

Replacement of potassium ions by ammonium ions in potassium-limited chemostat cultures of Candida utilis NCYC 321

Potassium-limited cultures of Candida utilis grown with ammonium chloride as the sole nitrogen source attained a higher dry weight than similar cultures grown with sodium nitrate as the sole nitrogen source. This increase depended on the extracellular ammonia concentration and was not due to accumulation of storage polymers. We conclude that in this yeast ammonium ions can fulfill to some extent the physiological role of potassium ions and that the intracellular concentration of ammonium ions is predominantly determined by the ammonia concentration in the culture medium.

Age-related distribution of cells in cell cycle phases in dependence on specific rate of growth in chemostat cultures ofCandida utilis

Individual cells in chemostat cultures of Candida utilis (D = 0.05, 0.1, 0.2, 0.25, 0.3 and 35/h) were analyzed according to the number of bud scars and according to their position in the cell cycle. The distribution in the cell cycle phases depends both on the genealogical age and the specific rate of growth.

Population study of cell cycle in a continuous culture ofCandida utilis

The mean lengths of G1, S, G2 and M phases of the cell cycle were determined on the basis of the population distribution of Candida utilis grown in a continuous culture under steady-state conditions by using an original mathematical method. The length of the G2 phase was proportional to that of G1; the length of M was effectively independent of the growth rate. The length of S was proportional to the mean number of mitochondria in the cell.

Continuous growth ofCandida utilis under periodic change of growth-limiting substrate

A periodic change of limitation by glucose and ammonia was effected during continuous cultivation of Candida utilis. Values of feed parameters providing periodic nitrogen limitation were established. Cell biomass yield, macromolecular composition and parameters of individual cells (cell mass, budding percentage and cell-wall polysaccharide per surface square unit) were examined. The cyclic regime was found to result in culture synchrony. Parameters obtained on the basis of cell counts displayed a high sensitivity to changes in limitation where as the remaining parameters were less sensible.

Distribution of cells in different stages of the cell cycle and some age-related physiological characteristics in dependence on the dilution rate in chemostat cultures ofCandida utilis

Position of cells in their cell cycle was determined microscopically in chemostat cultures of Candida utilis. Proportion of cells in phase G1 decreased in a linear manner from 86% to 58% with dilution rate. Proportion of cells in phase S increased in the same range of D from 5.6 to 13.5% and in the (G2 + M) phase from 8.4 to 28.5%, again linearly. Differential centrifugation was used to separate chemostat cultures to mother and daughter cells. Analyses showed that, relative to mother cells, daughter cells contain 2.1-11.9% more protein and 25.5-34.6% more RNA in dry matter. Their mass is 34.4-5.6% lower and volume is 154-19% smaller.

Physiological changes ofCandida utilis in transient state during continuous cultivation

In a continuous culture ofCandida utilis, the air supply was interrupted for 15 min at 1-d intervals after the steady state had been reached. Analysis of morphology and physiology of the cell showed that after this intervention the indicators of the physiological state changed their values with different time delays and needed different times to resume their steady-state values. Another consequence of the interrupted aeration was a higher degree of the culture synchronization. The possibility to bring about a transient (i. e. unsteady) state offers a tool for a directed control of mutual proportion of intracellular components.

Isolation of aCandida utilis variant by using a nitrogen-limited continuous culture

During continuous culture ofCandida utilis the appearance of a morphologic variant yeast was detected. The new microorganism developed systematically whenever it was changed from normal to stressed propagation conditions. A simple system was used for the isolation of the yeast variant, which was defective in cellular division and showed improved kinetic parameters and oxygen uptake rate. An asynchronic nitrogen-limited continuous culture ofCandida utilis allowed us to enrich the population in the chemostat with the modified yeast and isolate it in a defined medium. Assimilation and fermentation tests indicated it to be a variant ofCandida utilis that showed stable morphologic and physiologic differences with the parental yeast.Candida utilis growing in this nitrogen-limited continuous culture also showed a high mutation rate.

Buffering capacity as an indicator of physiological state in a continuous culture ofCandida utilis

Alkalimetric titration of the supernatant and the whole steady-state cell suspension was used to determine the buffering capacity of aCandida utilis culture during continuous cultivation at different dilution rates. Differences in the two types of titration curves were used to calculate, by means of the theory of dissociation of polyelectrolytes, the change in Gibbs free energy necessary to remove one proton from a live cell. The energy, 4.5 × 10-20 J (0.28 eV), corresponded to the energy of hydrogen bonds. With increasing growth rate the quantity of these bonds per unit dry mass increased, in direct proportion to the sum of the content of proteins and RNA per unit biomass. They reflect the weak buffering forces exerted by cell macromolecules, which are measurable under our experimental conditions and may serve as a marker of the physiological state of the cells.

Continuous cultivation ofCandida utilis yeasts growing on calcium bisulphite waste liquors

For automated process control it is necessary to know the data of the actual substrate concentration, activity and concentration of the biomass at any time of the fermentation. We have therefore proposed models balancing either the main biogenic elements or the key element only, which fulfil these demands. By measuring CO2 production rate and O2 uptake rate a better approximation of the actual state of the culture has been achieved. The model described is capable of simulating the concentration of the physiologically active biomass and substrate in the course of several days without changes in parameters, the relative deviation being 4–12%.

Utilization of formate as an additional energy source by glucose-limited chemostat cultures ofCandida utilis CBS 621 andSaccharomyces cerevisiae CBS 8066

Candida utilis CBS 621 andSaccharomyces cerevisiae CBS 8066 were grown in glucose-limited chemostat cultures with formate as an additional energy source. In both yeasts formate was oxidized via a cytoplasmic NAD+-linked formate dehydrogenase. Other formate-oxidizing enzymes could not be detected.

A glucose electrode for fermentation control

An oxygen-stabilized enzyme electrode was applied to monitor the glucose concentration in a fermentor during a batch culture ofCandida utilis. The electrode contains an electrolysis circuit for generation of oxygen within the enzyme layer that keeps the oxygen activity in that layer at the same level as that of the surrounding broth. The electrolysis current is used as a measure of the glucose concentration in the broth.The glucose analysis continued without major disturbances when the dissolved oxygen pressure gradually decreased during the fermentation and also when the broth was subjected to a sudden increase in dissolved oxygen tension. The electrode could also be used in an anaerobic broth. Then the reference electrode was replaced by a constant reference potential that simulated a reference oxygen activity.

Oscillatory accumulation of total cellular protein in synchronous cultures ofCandida utilis

Oscillatory accumulation of total cellular protein in synchronous cultures of<i>Candida utilis</i>

Kultivace kvasinky Candida Utilis na etanolovém substrátu. V. Vliv některých biogenních prvků na růst ve čtvrtprovozním měřítku.

Kultivace kvasinky Candida Utilis na etanolovém substrátu. V. Vliv některých biogenních prvků na růst ve čtvrtprovozním měřítku.

Measurement of bubble size distribution in fermentors

The “photoelectric probe method” for measuring bubble size distributions was adapted for application in turbid liquids. It can now be used for investigations of the influence of hydrodynamics and liquid phase properties on bubble formation, dispersion, and coalescence in submersed fermentation systems. With cultures of Candida utilis, cell concentrations showed little effect on bubble size and gas-liquid interface.

Evaluation of the SCP from Opuntia juice

In deseeded opuntia juice medium batch and continuous cultivation ofCandida utilis produced 12 and 19.9gl−1 yield of the SCP respectively. Its biological value(72), digestibility coefficient(70) and protein score(58) indicated it to be a good protein.

An immunofluorescent technique for rapid control of the purity of yeast cultures

A rapid technique for control of purity of cultures ofCandida utilis can be based on fluorescent labeling of cells using an antiserum raised in rabbits and rendered specific by absorption with cross-reacting strains. Microscopical observation under mixed ultraviolet/visible illumination permits detection of one non-fluorescent contaminant cell among 103 fluorescent cells. Cells of all ages of allC.utilis strains tested reacted with the antiserum. Seven cross-reacting species were found among the 53 species from 15 genera of yeast tested.

Changing patterns of 32 P and 33 P utilization in cells of Candida utilis during the cell cycle.

Incorporation of 33P and 32P into different fractions of continuous phased (synchronized) cultures of Candida utilis was studied. Two different growth conditions (on C-limited and N-limited media) were used at a doubling time of 6 h. Incorporation of 33P and 32P into four fractions (lipid, cold-water ex-tractable, RNA and DNA) showed a variable, nonuniform, behavior during the cell cycle. Different patterns of incorporation between cells on the two media were observed.