scholarly journals Systematic Investigation of Ergosterol Fermentation by Kluyveromyces marxianus Y.00243 via Statistical Design

2021 ◽  
Author(s):  
Aladár Vidra ◽  
Zoltán Kaleta ◽  
Áron Németh
Keyword(s):  
Salt Concentration ◽  
Kluyveromyces Marxianus ◽  
Biomass Concentration ◽  
Statistical Design ◽  
Structural Features ◽  
Systematic Investigation ◽  
Yeast Cells ◽  
Yeast Growth ◽  
Ergosterol Content ◽  
Negative Effect

Ergosterol, an important pharmaceutical intermediate, is the precursor of liposoluble vitamin D2 and cortisone. It is also a main sterol in yeast cells and responsible for structural features of membranes such as the integrity, fluidity, permeability and activity of membrane-bound enzymes. Kluyveromyces marxianus is able to utilize various sugars such as lactose, xylose and arabinose against Saccharomyces cerevisiae and is also thermotolerant. Based on these aforementioned characteristics, K. marxianus can be of great importance in the utilization of whey and lignocellulosic biomass. In this paper, the effect of four factors on the specific ergosterol content and yeast growth was investigated using two statistical experimental designs. The factors examined were initially added alcohol, temperature, salt concentration and pH. The initially added alcohol had a positive effect on the specific ergosterol content, resulted in 37 % specific ergosterol content increasement. The temperature had a negative effect on yeast growth reducing the biomass concentration by 50 % when increased from 25 °C to 30 °C. The pH had a significant effect only on the specific ergosterol content, having an optimum at pH 5.5. The salt concentration had no significant effect in either case. Based on the results, it is suggested that the setup which facilitates higher ergosterol content but does not slow down the growth of the yeast remarkably should be selected, which are 25 °C, pH 5.3 and 3 % of initial ethanol content.

scholarly journals Magnesium capability to attenuate the toxicity of aluminum on the growth of Saccharomyces cerevisiae PE-2

2016 ◽  
Vol 19 (0) ◽  
Author(s):  
Samuel Mariano-da-Silva ◽  
Rafael Dal Bosco Ducatti ◽  
Ivan Pedro Murari ◽  
Fabio Pilon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Biomass Concentration ◽  
Anaerobic Growth ◽  
Yeast Cells ◽  
Yeast Growth ◽  
Yeast Viability ◽  
The Media ◽  
Total Reducing Sugars ◽  
Orbital Shaker ◽  
Trehalose Content

Summary The magnesium (Mg) capability to attenuate the toxicity of aluminum (Al) for the trehalose content, anaerobic growth, viability and budding rate of Saccharomyces cerevisiae, was studied in this work. Fermentations were carried out in triplicate with sterilized and diluted sugar cane media (4% total reducing sugars/pH 4.0) containing different Al (0.0, 50, 100 and 150 mg L-1) and Mg (0.0, 50 and 100 mg L-1) concentrations. The media were inoculated with 1 mL of 1% (wet basis) yeast suspension and incubated at 30ºC, 70 rpm for 20 hours in orbital shaker. At specific times during fermentation portions of cell suspension were taken out and the biomass concentration, yeast viability, budding rate and trehalose content on cells determined. The increase of Al levels, from 0.0 up to 150 mg L-1, showed a reduction on the yeast growth of approximately 95%, 55% and 18% as Mg increased from 0.0 to 50 and 100 mg L-1, respectively. The trehalose content experienced its lowest reduction when greater amounts of Mg were added to the fermentation process. Cell viability showed greater reductions as the content of Al in the media increased. Magnesium effectively protected yeast cells against the deleterious effects of Al on cell growth, viability, budding and trehalose content.

scholarly journals Bottlebrush polymers in the melt and polyelectrolytes in solution share common structural features

2020 ◽  
Vol 117 (10) ◽  
pp. 5168-5175 ◽  
Author(s):  
Joel M. Sarapas ◽  
Tyler B. Martin ◽  
Alexandros Chremos ◽  
Jack F. Douglas ◽  
Kathryn L. Beers
Keyword(s):  
Neutron Scattering ◽  
Correlation Length ◽  
Salt Concentration ◽  
Polymer Concentration ◽  
Structural Features ◽  
Peak Position ◽  
Correlation Peak ◽  
Grafting Density ◽  
Scattering Measurements ◽  
Polyelectrolyte Solutions

Uncharged bottlebrush polymer melts and highly charged polyelectrolytes in solution exhibit correlation peaks in scattering measurements and simulations. Given the striking superficial similarities of these scattering features, there may be a deeper structural interrelationship in these chemically different classes of materials. Correspondingly, we constructed a library of isotopically labeled bottlebrush molecules and measured the bottlebrush correlation peak position q*=2π/ξ by neutron scattering and in simulations. We find that the correlation length scales with the backbone concentration, ξ∼cBB−0.47, in striking accord with the scaling of ξ with polymer concentration cP in semidilute polyelectrolyte solutions (ξ∼cP−1/2). The bottlebrush correlation peak broadens with decreasing grafting density, similar to increasing salt concentration in polyelectrolyte solutions. ξ also scales with sidechain length to a power in the range of 0.35–0.44, suggesting that the sidechains are relatively collapsed in comparison to the bristlelike configurations often imagined for bottlebrush polymers.

scholarly journals The Impact of Pressure and Hydrocarbons on NOx Abatement over Cu- and Fe-Zeolites at Pre-Turbocharger Position

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 336
Author(s):  
Deniz Zengel ◽  
Simon Barth ◽  
Maria Casapu ◽  
Jan-Dierk Grunwaldt
Keyword(s):  
Catalytic Reduction ◽  
Elevated Pressure ◽  
Systematic Investigation ◽  
Diesel Oxidation Catalyst ◽  
Zeolite Catalysts ◽  
Oxidation Catalyst ◽  
Pollutant Concentrations ◽  
Oxidation Of Hydrocarbons ◽  
Negative Effect ◽  
The Impact

Positioning the catalysts in front of the turbocharger has gained interest over recent years due to the earlier onset temperature and positive effect of elevated pressure. However, several challenges must be overcome, like presence of higher pollutant concentrations due to the absence or insufficient diesel oxidation catalyst volume at this location. In this context, our study reports a systematic investigation on the effect of pressure and various hydrocarbons during selective catalytic reduction (SCR) of NOx with NH3 over the zeolite-based catalysts Fe-ZSM-5 and Cu-SSZ-13. Using a high-pressure catalyst test bench, the catalytic activity of both zeolite catalysts was measured in the presence and absence of a variety of hydrocarbons under pressures and temperatures resembling the conditions upstream of the turbocharger. The results obtained showed that the hydrocarbons are incompletely converted over both catalysts, resulting in numerous byproducts. The emission of hydrogen cyanide seems to be particularly problematic. Although the increase in pressure was able to improve the oxidation of hydrocarbons and significantly reduce the formation of HCN, sufficiently low emissions could only be achieved at high temperatures. Regarding the NOx conversion, a boost in activity was obtained by increasing the pressure compared to atmospheric reaction conditions, which compensated the negative effect of hydrocarbons on the SCR activity.

scholarly journals The Influence of the Concentration of Calcium Ions on the Comparative Absorption of Metallic Ions by the Yeast Cells and on the Yeast Growth

CYTOLOGIA ◽  
1958 ◽  
Vol 23 (1) ◽  
pp. 9-13
Author(s):  
Krishna Bahadur ◽  
Harish Chandra Verma
Keyword(s):  
Calcium Ions ◽  
Yeast Cells ◽  
Metallic Ions ◽  
Yeast Growth

scholarly journals Modelling of ergosterol production by S. cerevisiae in presence of n-dodecane as oxygen-vector

2021 ◽  
Vol 26 (2) ◽  
pp. 2464-2470
Author(s):  
ANCA-IRINA GALACTION ◽  
◽  
ALEXANDRA CRISTINA BLAGA ◽  
ALEXANDRA TUCALIUC ◽  
LENUŢA KLOETZER ◽  
...  
Keyword(s):  
Batch Fermentation ◽  
Fermentation Process ◽  
Biomass Concentration ◽  
Aeration Rate ◽  
Yeast Cells ◽  
Fed Batch ◽  
Volumetric Fraction ◽  
Fed Batch Fermentation ◽  
Oxygen Vector ◽  
Efficient Fermentation

The previous studies on ergosterol production by Saccharomyces cerevisiae in presence of n-dodecane as oxygen-vector have been continued by mathematical modelling the fermentation process. In this purpose, the most efficient fermentation regime has been considered, namely fed-batch fermentation, and was based on the influences of hydrocarbon volumetric fraction, biomass concentration, and aeration rate on the ergosterol content inside the yeast cells. The model describing the fermentation process has been established by means of the statistical analysis, using a factorial experiment of second order. The considered variables control the ergosterol production in a 94.4% extent, the biomass concentration exhibiting the most important influence.

scholarly journals Deletion of the trehalose tps1 gene in Kluyveromyces lactis does not impair growth in glucose

2020 ◽  
Vol 367 (10) ◽  
Author(s):  
Antonio M V Gomes ◽  
Ana Carolina A L Orlandi ◽  
Nádia S Parachin
Keyword(s):  
Dairy Products ◽  
Gene Disruption ◽  
Sole Carbon Source ◽  
Gene Deletion ◽  
Kluyveromyces Lactis ◽  
Growth Failure ◽  
Yeast Cells ◽  
Yeast Growth ◽  
Tps1 Gene ◽  
Encoding Gene

ABSTRACT Trehalose is a non-reducing disaccharide composed of two α-glucose molecules and synthesized by an enzyme complex containing four subunits TPS1 (EC 2.4.1.15), TPS2 (EC 3.1.3.12), TPS3 and TSL1. First reports about trehalose classified this sugar as an energy reserve compound like glycogen. However, lately, trehalose is known to assist yeast cells during heat, osmotic and starvation stresses. In Saccharomyces cerevisiae, the deletion of the tps1 encoding gene eliminated the yeast ability to grow on glucose as the sole carbon source. Kluyveromyces lactis is a yeast present in various dairy products and is currently utilized for the synthesis of more than 40 industrial heterologous products. In this study, the deletion of the tps1 gene in K. lactis showed that unlike S. cerevisiae, tps1 gene disruption does not cause growth failure in glucose, galactose, or fructose. The µMAX rate values of K. lactis tps1Δ strains were equal than the non-disrupted strains, showing that the gene deletion does not affect the yeast growth. After gene disruption, the absence of trehalose into the metabolism of K. lactis was also confirmed.

scholarly journals Effect of Adhesive Debonding on the Performance of Piezoelectric Sensors in Structural Health Monitoring Systems

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5070 ◽  
Author(s):  
Liu ◽  
Xu ◽  
Li ◽  
Wang ◽  
Zhang
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Research Work ◽  
Piezoelectric Sensor ◽  
Systematic Investigation ◽  
Monitoring Method ◽  
Structural Health ◽  
Negative Effect ◽  
Inherent Frequency ◽  
Slow Rise

Piezoelectric (PZT) ceramic elements are often subjected to complex loads during in- service lifetime in structural health monitoring (SHM) systems, and debonding of both excitation actuators and receiving sensors have a negative effect on the monitoring signals. A first systematic investigation of debonding behaviors by considering actuators and sensors simultaneously was performed in this paper. The debonding areas of actuators were set in different percentage range from 0% to 70%, and sensors in 0%, 20%, 40% and 60%. The signal-based monitoring method was used to extract the characteristic parameters of both the amplitudes and phases of received signals. Experimental results revealed that as the debonding areas of the actuators increase, the normalized amplitude appears a quick decrease before 35% debonding area of actuators and then a slow rise until 60% of debonding reached. This may be explained that the 35% debonding turning point correspond to the coincidence of the excitation frequencies of peripheral actuators with the inherent frequency of the central piezoelectric sensor, and the 60% be the result of the maximum ability of piezoelectric sensor. The degrees of debonding of actuators and sensors also have significant influence on the phase angle offset, with large debonding of actuators increases the phase offset sharply. The research work may provide useful information for practical monitoring of SHM systems.

Enhancement of bifidobacteria survival by Williopsis saturnus var. saturnus in milk

2016 ◽  
Vol 7 (1) ◽  
pp. 135-144 ◽  
Author(s):  
A.Y.Y. Yeo ◽  
M.Z. Toh ◽  
S.Q. Liu
Keyword(s):  
Viable Cell ◽  
Oxygen Removal ◽  
Physical Contact ◽  
Yeast Cells ◽  
Yeast Growth ◽  
Bifidobacterium Lactis ◽  
Enhancing Effect ◽  
Uht Milk ◽  
Williopsis Saturnus ◽  
Dairy Beverages

The viability of three strains of probiotic Bifidobacterium lactis that were inoculated into UHT milk was examined with and without the presence of the yeast, Williopsis saturnus var. saturnus NCYC 22, in polypropylene tubes at 30 °C. The B. lactis viable cell count for strains HN019 and BB-12 remained above 6.0 Log cfu/ml, while strain B94 had 5.7 Log cfu/ml after six weeks of incubation in the presence of the co-inoculated yeast. Incubating the bifidus milk without added yeast under anaerobic condition did not improve the survival of B. lactis HN019, indicating that oxygen removal may not be responsible for W. saturnus NCYC 22’s viability enhancing property. The addition of yeast supernatant or non-viable yeast also did not show any stabilising effects, suggesting that physical contact and/or interaction between viable W. saturnus and B. lactis plays an important role in sustaining the viability of the probiotic. W. saturnus NCYC 22 could increase the survival of B. lactis in bifidus milk under ambient temperature regardless of the initial concentration of yeast cells inoculated due to yeast growth. This study demonstrated the viability enhancing effect of viable W. saturnus NCYC 22 on B. lactis HN019, which could help towards extending the shelf-life of dairy beverages containing probiotic bifidobacteria.

A Reverse Transcriptase PCR Technique for the Detection and Viability Assessment of Kluyveromyces marxianus in Yoghurt

2006 ◽  
Vol 69 (9) ◽  
pp. 2210-2216 ◽  
Author(s):  
MARÍA BELÉN MAYORAL ◽  
ROSARIO MARTÍN ◽  
PABLO E. HERNÁNDEZ ◽  
ISABEL GONZÁLEZ ◽  
TERESA GARCÍA
Keyword(s):  
Reverse Transcriptase ◽  
Kluyveromyces Marxianus ◽  
18S Rrna ◽  
Yeast Cells ◽  
Rt Pcr ◽  
Viability Assessment ◽  
Reverse Transcriptase Pcr ◽  
Low Concentrations ◽  
Pcr Method ◽  
High Level

A fast and sensitive reverse transcriptase PCR (RT-PCR) method was developed for the detection of viable Kluyveromyces marxianus in yoghurt. Yeast-specific primers were used with the RT-PCR to evaluate the suitability of 18S rRNA as a target for the detection of viable yeasts in pure culture and yoghurt. The RT-PCR assay was able to detect down to 102 CFU ml−1 in yoghurt samples contaminated with viable yeast cells. Application of the RT-PCR method to commercial yoghurt samples demonstrated the utility of this technique for detection of low concentrations of viable yeast cells in naturally contaminated dairy products. The 18S rRNA molecule is an appropriate target for cell viability assessment because of its limited persistence after cell death and the resultant high level of sensitivity of the assay.

The stimulation of yeast growth and respiration by compounds produced by yeast cells irradiated with ultraviolet light

1952 ◽  
Vol 40 (2) ◽  
pp. 269-278 ◽  
Author(s):  
S. James Adelstein ◽  
Falls B. Hershey ◽  
John R. Loofbourow ◽  
Irwin W. Sizer
Keyword(s):  
Ultraviolet Light ◽  
Yeast Cells ◽  
Yeast Growth ◽  
Stimulation Of
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