Yeast Suspension Research Articles

Frozen dough steamed products: Deterioration mechanism, processing technology, and improvement strategies.

Fresh dough products lead to instability in product quality, high production costs, and more production time, which seriously affects the industrial production of the food industry. The frozen dough technology mitigates the problems of short shelf-life and easy deterioration of quality during storage and transportation. It has shown a series of advantages in large-scale industrialization, high-quality standardization, and chain operation. However, the further development of frozen dough is restricted by the deterioration of the main components (gluten, starch, and yeast) caused by freezing. This review summarizes the main production process of frozen steamed bread and buns, and the deterioration reasons for the main component of frozen dough. The improvement mechanisms of raw ingredients, processing technology, processing equipment, and additives on frozen dough quality were analyzed from the perspective of improving gluten network integrity and yeast freeze tolerance. From prefermented frozen raw to steamed products without thawing has become the preferred production process to improve production efficiency. Wheat flour mixed with other flour can maintain the gluten network continuity of frozen dough. The freeze tolerance of yeast was improved by treatment with yeast suspension, yeast cell encapsulation, screening hybridization, and genetic engineering. Process optimization and new technology-assisted fermentation and freezing effectively reduce freezing damage. Various additives improve the freeze resistance of the gluten-starch matrix by promoting protein cross-linking and inhibiting water migration. In addition, ice structural proteins and ice nucleating agents have been proven to change the growth morphology and formation temperature of ice crystals. More new technologies and additive synergies need to be further explored.

Non-Invasive Characterization of Different Saccharomyces Suspensions with Ultrasound.

In fermentation processes, changes in yeast cell count and substrate concentration are indicators of yeast performance. Therefore, monitoring the composition of the biological suspension, particularly the dispersed solid phase (i.e., yeast cells) and the continuous liquid phase (i.e., medium), is a prerequisite to ensure favorable process conditions. However, the available monitoring methods are often invasive or restricted by detection limits, sampling requirements, or susceptibility to masking effects from interfering signals. In contrast, ultrasound measurements are non-invasive and provide real-time data. In this study, the suitability to characterize the dispersed and the liquid phase of yeast suspensions with ultrasound was investigated. The ultrasound signals collected from three commercially available Saccharomyces yeast were evaluated and compared. For all three yeasts, the attenuation coefficient and speed of sound increased linearly with increasing yeast concentrations (0.0-1.0 wt%) and cell counts (R2 > 0.95). Further characterization of the dispersed phase revealed that cell diameter and volume density influence the attenuation of the ultrasound signal, whereas changes in the speed of sound were partially attributed to compositional variations in the liquid phase. This demonstrates the ability of ultrasound to monitor industrial fermentations and the feasibility of developing targeted control strategies.

Antimicrobial printed linen fabric by using brewer’s yeast enzyme

BackgroundIn this research, a brewer’s yeast suspension was used to biotreat raw linen fibers under a range of different circumstances utilizing an ultrasonic cleaner device. In order to optimize circumstances for the treatment process, this extensive work is focused on examining the variables that could affect the biotreatment, such as the amount of brewer’s yeast used, the duration, the temperature of the treatment, and the pH throughout the treatment. After enzymatic treatment, the printing process utilizing turmeric natural dye was used. Variable assesses were conducted to determine the steaming time, thermofixation time, pH of the printing paste, types of dyes, and types of fabrics. How these elements affected the wettability and fabric color strength is investigated. To better comprehend, scanning electron microscope (SEM) was used to study the morphology of treated and untreated linen samples. The effects of treating the fibers with yeast enzyme on their multifunctional qualities, such as color and antibacterial activity against gram-positive bacteria like Staphylococcusaureus and gram-negative bacteria like Escherichia coli, were assessed.ResultsResults demonstrated that the enzyme extract, which predominantly contains lipase, amylase, and protease enzymes that develop the fabric printability, is responsible for the increase of color strength which increased by about 152.27% with good fastness properties compared by the untreated printed samples.ConclusionsThe overall findings showed that the treated fabrics have superior color fastness and antibacterial properties when compared to the untreated fabrics, demonstrating that the procedure of production used to create these multifunctional linen fabrics is environmentally friendly.

Evaluation of the Nonlinear Response of KCl Solution to High-Amplitude Stimulation Using a Four-Point Cylindrical Gold Electrode.

A four-electrode system and high-voltage amplitude stimulation (with a voltage of more than 1 V) are always used for nonlinear spectroscopy of biological solutions like yeast suspension. Multiple studies indicate that yeast membrane activities are the primary source of the harmonics detected from yeast suspensions. However, other investigations have demonstrated that at least part of the harmonics are mainly due to the nonlinear impedance of the electrode-electrolyte interface. Here, we want to find a mathematical model to analyze the odd harmonics generated by the interface. The KCl solution is the basis of the essential medium used in yeast culture. No study models the nonlinear behavior of the KCl solution using four-electrode. We used a sinusoidal voltage with a low frequency and a high amplitude to test an ionic solution with 1, 30, and 130 mM of potassium chloride. The voltage had no direct current component. Here, we show that the relationship between the amplitude of the excitation voltage and the third harmonic of the current can be accurately represented using the Butler-Volmer equation. Additionally, we analyze the impact of potassium chloride (KCl) concentration on the behavior of the third harmonic. This paper presents a method and model that can be used for nonlinear spectroscopy studies of biological solutions using a four-electrode system with the aim of deriving information from cells without considering the interface effect.

The role of N-acetylcysteine on adhesion and biofilm formation of Candida parapsilosis isolated from catheter-related candidemia.

Objectives. Anti-fungal agents are increasingly becoming less effective due to the development of resistance. In addition, it is difficult to treat Candida organisms that form biofilms due to a lack of ability of drugs to penetrate the biofilms. We are attempting to assess the effect of a new therapeutic agent, N-acetylcysteine (NAC), on adhesion and biofilm formation in Candida parapsilosis clinical strains. Meanwhile, to detect the transcription level changes of adhesion and biofilm formation-associated genes (CpALS6, CpALS7, CpEFG1 and CpBCR1) when administrated with NAC in C. parapsilosis strains, furthermore, to explore the mechanism of drug interference on biofilms.Hypothesis/Gap statement. N-acetylcysteine (NAC) exhibits certain inhibitory effects on adhesion and biofilm formation in C. parapsilosis clinical strains from CRBSIs through: (1) down-regulating the expression of the CpEFG1 gene, making it a highly potential candidate for the treatment of C. parapsilosis catheter-related bloodstream infections (CRBSIs), (2) regulating the metabolism and biofilm -forming factors of cell structure.Methods. To determine whether non-antifungal agents can exhibit inhibitory effects on adhesion, amounts of total biofilm formation and metabolic activities of C. parapsilosis isolates from candidemia patients, NAC was added to the yeast suspensions at different concentrations, respectively. Reverse transcription was used to detect the transcriptional levels of adhesion-related genes (CpALS6 and CpALS7) and biofilm formation-related factors (CpEFG1 and CpBCR1) in the BCR1 knockout strain, CP7 and CP5 clinical strains in the presence of NAC. To further explore the mechanism of NAC on the biofilms of C. parapsilosis, RNA sequencing was used to calculate gene expression, comparing the differences among samples. Gene Ontology (GO) enrichment analysis helps to illustrate the difference between two particular samples on functional levels.Results. A high concentration of NAC reduces the total amount of biofilm formation in C. parapsilosis. Following co-incubation with NAC, the expression of CpEFG1 in both CP7 and CP5 clinical strains decreased, while there were no significant changes in the transcriptional levels of CpBCR1 compared with the untreated strain. GO enrichment analysis showed that the metabolism and biofilm-forming factors of cell structure were all regulated after NAC intervention.Conclusions. The non-antifungal agent NAC exhibits certain inhibitory effects on clinical isolate biofilm formation by down-regulating the expression of the CpEFG1 gene, making it a highly potential candidate for the treatment of C. parapsilosis catheter-related bloodstream infections.

The Potential of AOP Pretreatment in the Biodegradation of PS and PVC Microplastics by Candida parapsilosis

Microplastics are an emerging class of recalcitrant organic pollutants that are of general scientific and public interest nowadays. It would be ideal to remove microplastics from the environment through biodegradation, as biodegradation is a highly ecological and economically acceptable approach. Unfortunately, the efficiency of biodegradation of conventional plastic polymers is low. The application of a suitable pretreatment could increase the efficiency of biodegradation. In this study, the applicability of UV-C/H2O2 and UV-C/S2O82− advanced oxidation processes as pretreatments for the biodegradation of polystyrene and poly(vinyl chloride) microplastics by the yeast Candida parapsilosis was investigated. For the investigated range (pH 4–10, peroxide concentration up to 20 mM and treatment duration up to 90 min), the UV-C/H2O2 process proved to be more effective in degrading polystyrene microplastics, while the UV-C/S2O82− process was more efficient at degrading poly(vinyl chloride) microplastics. Samples pretreated under optimal conditions (90 min treatment time at a pH of 5.7 and H2O2 concentration of 20.0 mM for polystyrene samples; 90 min treatment time at a pH of 8.6 and S2O82− concentration of 11.1 mM for poly(vinyl chloride) samples) were subjected to biodegradation by Candida parapsilosis. The biodegradation conditions included an agitation speed of 156 rpm and an initial pH of 5.7 for the experiments with the polystyrene samples, while an agitation speed of 136 rpm and an initial pH of 4.9 were used for the poly(vinyl chloride) experiments. The initial value of the optical density of the yeast suspension was 1.0 in both cases. The experiments showed a positive effect of the pretreatment on the number of yeast cells on the surface of the microplastics.

Exploring the role of impedance spectroscopy in assessing 405nm laser-induced inactivation of saccharomyces cerevisiae.

Impedance spectroscopy was employed to assess the electrical properties of yeast following 405nm laser irradiation, exploring the effects of visible, non-ionizing laser-induced inactivation as a more selective and safer alternative for photoinactivation applications compared to the use of DNA targeting, ionizing UV light. Capacitance and impedance spectra were obtained for yeast suspensions irradiated for 10, 20, 30, and 40min using 100 and 200 mW laser powers. Noticeable differences in capacitance spectra were observed at lower frequencies (40Hz to 1kHz), with a significant increase at 40min for both laser powers. β-dispersion was evident in the impedance spectra in the frequency range of 10kHz to 10MHz. The characteristic frequency of dielectric relaxation steadily shifted to higher frequencies with increasing irradiation time, with a drastic change observed at 40min for both laser powers. These changes signify a distinct alteration in the physical state of yeast. A yeast spot assay demonstrated a decrease in cell viability with increasing laser irradiation dose. The results indicate a correlation between changes in electrical properties, cell viability, and the efficacy of 405nm laser-induced inactivation. Impedance spectroscopy is shown to be an efficient, non-destructive, label-free method for monitoring changes in cell viability in photobiological effect studies. The development of impedance spectroscopy-based real-time studies in photoinactivation holds promise for advancing our understanding of light-cell interactions in medical applications.

Development of an Integrated Bioprocess System for Bioethanol and Arabitol Production from Sugar Beet Cossettes.

An innovative integrated bioprocess system for bioethanol production from raw sugar beet cossettes (SBC) and arabitol from remaining exhausted sugar beet cossettes (ESBC) was studied. This integrated three-stage bioprocess system is an example of the biorefinery concept to maximise the use of raw SBC for the production of high value-added products such as sugar alcohols and bioethanol. The first stage of the integrated bioprocess system was simultaneous sugar extraction from SBC and its alcoholic fermentation to produce bioethanol in an integrated bioreactor system (vertical column bioreactor and stirred tank bioreactor) containing a high-density suspension of yeast Saccharomyces cerevisiae (30 g/L). The second stage was the pretreatment of ESBC with dilute sulfuric acid to release fermentable sugars. The resulting liquid hydrolysate of ESBC was used in the third stage as a nutrient medium for arabitol production by non-Saccharomyces yeasts (Spathaspora passalidarum CBS 10155 and Spathaspora arborariae CBS 11463). The obtained results show that the efficiency of bioethanol production increased with increasing temperature and prolonged residence time in the integrated bioreactor system. The maximum bioethanol production efficiency (87.22 %) was observed at a time of 60 min and a temperature of 36 °C. Further increase in residence time (above 60 min) did not result in the significant increase of bioethanol production efficiency. Weak acid hydrolysis was used for ESBC pretreatment and the highest sugar yield was reached at 200 °C and residence time of 1 min. The inhibitors of the weak acid pretreatment were produced below bioprocess inhibition threshold. The use of the obtained liqiud phase of ESBC hydrolysate for the production of arabitol in the stirred tank bioreactor under constant aeration clearly showed that S. passalidarum CBS 10155 with 8.48 g/L of arabitol (YP/S=0.603 g/g and bioprocess productivity of 0.176 g/(L.h)) is a better arabitol producer than Spathaspora arborariae CBS 10155. An innovative integrated bioprocess system for the production of bioethanol and arabitol was developed based on the biorefinery concept. This three-stage bioprocess system shows great potential for maximum use of SBC as a feedstock for bioethanol and arabitol production and it could be an example of a sustainable 'zero waste' production system.

Species-Dependent Impacts on the Nutritional Profile of Tomato (Solanum lycopersicum L.) and Rocket (Eruca sativa L.) Plants Following to Foliar Application of Yeast Suspensions

The foliar application of yeast (Saccharomyces cerevisiae) suspensions is a widely used small-scale horticultural practice against stress impacts and to boost vegetative and nutritional characteristics. In this study, the impact of two strains of S. cerevisiae was investigated on tomato (Solanum lycopersicum L.) and rocket (Eruca sativa L.) plants in terms of vegetative growth and nutritional content, focusing on antioxidant properties (FRAP, DPPH, TPC, lycopene) and chlorophyll content. The treatments were applied in two dilutions (0.1 and 1% v/v) and two frequencies (once and three times). When the type strain solutions were applied, DPPH values of both tomato and rocket samples were elevated up to 7.18 and 17.98 i%, respectively, compared to control values of 6.26 and 14.11 i%, respectively. While the other investigated antioxidant traits (FRAP, TPC, lycopene) were identical or slightly lower, than the control values, total chlorophyll content was significantly increased for tomato, up to 61.18 g/100 g, from the control value of 53.46 g/100 g, and for rocket, reaching 43.14 g/100 g, from the control value of 39.13 g/100 g, after using instant yeast solutions. Among the combinations, the double-sprayed 1% suspension and the single-sprayed 0.1% suspension had the most favorable impact on the investigated nutritional traits. Species-level application technology details are still open for refinements.

Preliminary membrane screening and evaluation for the separation of bioethanol obtained from fermentation of oil palm empty fruit bunch (OPEFB)

This study evaluates the effectiveness of some commercial membranes (polytetrafluoroethylene [PTFE], polyvinylidene fluoride [PVDF], polyethersulfone [PES], and nitrocellulose [NC]) in concentrating a binary ethanol-water mixture under different conditions (volumes, temperatures, pressures, and concentrations). Then, the membrane was selected based on its performance for use in ethanol and by-product separation from OPEFB fermentation broth. The optimum result for the binary ethanol-water separation was found in the PVDF membrane with the highest separation factor of 3.03 and flux of 0.015 g.cm−2 s−1 under 10 ml permeate volume, 75 °C temperature, 60 psi pressure, and 20 % (v/v) ethanol concentration. Based on the membrane field emission-scanning electron microscope (FE-SEM) analysis, the PVDF membrane also had the lowest swelling degree. Utilization of the PVDF membrane to separate crude bioethanol resulting from OPEFB fermentation gave a separation factor of 3.66. The initial bioethanol concentration was 7.67 % (v/v), and the ethanol concentration in the permeate was 23.31 % (v/v). In addition, the separation factor of propanol from the crude mixture was 5.44, and the acetic acid rejection factor was 96.7 %. The S.cerevisiae suspension and the cellulase enzyme were also separated and recovered in the retentate phase. Hence, the PVDF membrane can be used to separate bioethanol from the yeast and enzyme suspension while pre-concentrating the bioethanol product. This could eventually help reduce the energy requirement to obtain industrial-grade bioethanol.

New Effect of Treatment with Yeast Extract and Salicylic Acid on Plant Growth of Trigonella Foenum-graecum l. Seedling

This study was conducted at the Mosul University / College of Education for Girls /Department of Biology, in November on the local variety fenugreek to study the plant response to organic fertilizer (dry yeast suspension) with three concentrations: 0, 1 and 2 g/L and soaking with salicylic acid in three concentrations. They are: 0, 40 and 80 mg/l, the factorial experiment was carried out in a completely randomized design with three replications. The results of the experiment were analyzed and tested statistically by Duncan's multiple range test at a probability level of p=0.05%. The most important results obtained can be summarized as follows: - Fertilizing with organic fertilizer (dry yeast suspension) improved most of the studied characteristics, as the germination period was reduced and its speed increased, in addition to the homogeneity of germination, especially at the concentration of 2 g/L. "Soaking the seeds in salicylic acid had a clear effect of improving most of the studied traits, especially at concentrations of 40 mg/L The results of the binary interaction between the factors under study also indicate that the best values ​​were recorded for most of the studied traits when the factors overlapped with each other, especially when fertilizing at a concentration of 2 g/L with a concentration of 40 mg/L.

Effect of Spraying with Humic Acid and Active Yeast Suspension on the Growth Indicators and Active Substances of Calendula officinalis L.

The purpose of this study was to examine the impact of spraying C. officinalis L. with Humic acid and active yeast suspension on growth indicators for both the vegetative and floral stages of development. Humic acid was sprayed on the plants in varying quantities (0, 2, or 4 g) in a factorial experiment with 9 treatments (two factors overlapped). and a suspension of live yeast at 3, 6, or 0 mg/L-1, and the treatment consisted of three sprays, with a 15-day gap between each application. Using a Factorial Experiment with three replicates and three plants per experimental unit, I compared means at the 5% probability level using the Revised Least Significant Differences (R.L.S.D.) test. The most significant findings, in her opinion, are as follows: Humic acid spraying at a dosage of 4 mg/L-1. While this concentration greatly slowed flowering, L-1 significantly increased plant height, number of lateral branches, percentage of dry matter of shoot, number of flowers, number of petals, flower diameter, flower stand length, and percentage of dry matter in flowers. The greatest concentration, 6 mg.L-1, was achieved through spraying with an active yeast suspension. Although this concentration greatly slowed flowering enhanced plant height, lateral branching, leaf count, flower count, petal count, flower diameter, and floral dry matter percentage. There was a statistically significant impact on all attributes measured by the binary interactions.

The antifungal substance from Bacillus velezensis B-3 improved the malt quality against premature yeast flocculation induced by Fusarium graminearum infection.

Malt produced from barley contaminated with Fusarium graminearum can cause premature yeast flocculation (PYF) in beer fermentation, which ultimately affects the production efficiency and flavor quality of beer. In this study, a strain of Bacillus velezensis B-3 that was isolated from soil displayed strong antifungal activity against F. graminearum. The antifungal substances were extracted and separated by ammonium sulfate fractional precipitation and semipreparative high-performance liquid chromatography to obtain fraction VI with the strongest antifungal activity. Ultra-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry was used to identify that the fraction contained lipopeptides such as iturin A, surfactant B, and surfactant C. The minimum inhibitory concentration of the fraction was 0.2mg/mL, and confocal laser scanning microscopy showed that the morphology of F. graminearum hyphae was obviously abnormal, with most of them were dead. Antifungal fraction VI could inhibit the growth of F. graminearum and avoid the production of PYF factor during malting but did not affect other qualities of malt. Therefore, the development of antimicrobial agents against Fusarium provides an effective potential strategy to control the production of PYF factors for malt-manufacturing enterprises. PRACTICAL APPLICATION: Antifungal fraction VI could inhibit the growth of F. graminearum and the formation of DON during malting but did not affect other qualities of malt. The levels of soluble nitrogen, free amino nitrogen, and color experienced a substantial reduction compared to the malt infected by F. graminearum. The PYF phenomenon was significantly improved, the number of suspended yeast cells and the degree of fermentation were increased, and the level of residual extract in the wort was low, close to that of control malt.

Using dielectrophoretic spectra to identify and separate viable yeast cells.

Immotile yeast cells were transiently moved in nonuniform sinusoidal electric fields using multiple pairs of micro-parallel cylindrical electrodes equipped with a sequential signal generator (SSG) to analyze cell viability at a clinical scale for the brewery/fermentation industry. Living yeast cells of Saccharomyces cerevisiae during the exponential-stationary phase, with a cell density of 1.15 × 105 cells mL-1 were suspended in sucrose medium. The conductivity (σs) was adjusted to 0.01 S m-1 with added KCl. Cells exposed in electric field strengths ranging from 32.89 to 40.98 kV m-1, exhibited positive dielectrophoresis (pDEP) with the lower critical frequencies (LCF) at 85.72 ± 3.59 kHz. The optimized value of LCF was shifted upwards to 780.00 ± 83.67 kHz when σswas increased to 0.10 S m-1. Dielectrophoretic and LCF spectra (translational speed of cells vs. electric field frequencies) of yeast suspensions during positive dielectrophoresis were analyzed in terms of the dielectric properties of the cell membrane and cytoplasm which reflect yeast cell viability and metabolic health status. The dielectrophoretic collection yield of cells using positive dielectrophoresis was reported on the monitor of sequential signal generator software to evaluate the number of living and dead cells through a real-time image processing analyzer. The spectra of both positive dielectrophoresis of the living and dead cells had distinguishable dielectric properties. The conductivity of the yeast cytoplasm (σc) of the dead cells was significantly less (≈ ≤ 0.05 S m-1) than that of the living yeast cells which typically had a cytoplasmic conductivity of ≈ 0.2 S m-1. This difference between viable and non-viable cells is sufficient for cell separation procedures. KEY POINTS: • Dielectrophoresis can be used to separate viable and non-viable yeast cells, • Cellular dielectric properties can be derived from the analysis of their dielectric spectra, • Cytoplasmic conductivity of viable cells is ≈ 0.2 S m-1 while that of non-viable cells ≈ ≤ 0.05 S m-1.

Transcriptional profiling of a fungal granuloma reveals a low metabolic activity of Paracoccidioides brasiliensis yeasts and an actively regulated host immune response.

Granulomas are important immunological structures in the host defense against the fungus Paracoccidioides brasiliensis, the main etiologic agent of Paracoccidioidomycosis (PCM), a granulomatous systemic mycosis endemic in Latin America. We have performed transcriptional and proteomic studies of yeasts present in the pulmonary granulomas of PCM aiming to identify relevant genes and proteins that act under stressing conditions. C57BL/6 mice were infected with 1x106 yeasts and after 8- and 12-weeks of infection, granulomatous lesions were obtained for extraction of fungal and murine RNAs and fungal proteins. Dual transcriptional profiling was done comparing lung cells and P. brasiliensis yeasts from granulomas with uninfected lung cells and the original yeast suspension used in the infection, respectively. Mouse transcripts indicated a lung malfunction, with low expression of genes related to muscle contraction and organization. In addition, an increased expression of transcripts related to the activity of neutrophils, eosinophils, macrophages, lymphocytes as well as an elevated expression of IL-1β, TNF-α, IFN-γ, IL-17 transcripts were observed. The increased expression of transcripts for CTLA-4, PD-1 and arginase-1, provided evidence of immune regulatory mechanisms within the granulomatous lesions. Also, our results indicate iron as a key element for the granuloma to function, where a high number of transcripts related to fungal siderophores for iron uptake was observed, a mechanism of fungal virulence not previously described in granulomas. Furthermore, transcriptomics and proteomics analyzes indicated a low fungal activity within the granuloma, as demonstrated by the decreased expression of genes and proteins related to energy metabolism and cell cycle.

Efficacy of aquatic yeasts to control gray mold decay, and impacts on strawberry quality during cold storage and shelf life

Strawberry (Fragaria × ananassa Duch.) is susceptible to postharvest decay, and thus its storage and shelf life are limited. Thirty-one aquatic yeasts isolated from different regions were tested by the dual culture method to assess their potential to control gray mold of strawberry fruit, and the two yeasts with the highest inhibitory effect (58 and 72% at 2 d) were selected. In the volatile metabolites test, yeasts grown for 48 h were more effective than 24 h-yeasts. Growth of Botrytis cinerea was 13, 51 and 53 mm in the MMW8 isolate, the MBC25 isolate and the control, respectively, at 5 days. In the non-volatile metabolites test, the MBC25 isolate was more effective than the MMW8 isolate. Using biochemical and molecular methods, the MBC25 isolate was identified as Yarrowia lipolytica (Y. l) and MMW8 as Debromayses hansenii (D. h). Yeast suspensions (10 6 CFU/mL) were sprayed on strawberry fruit, and the fruit were stored at 4 and 20°C. D. h had stronger establishment on the fruit surface (3.9 and 4.2 Log CFU/g at 4 and 20°C, respectively) compared with Y. l, although both yeasts did control gray mold disease in vivo. D.h and Y.l suppressed total yeasts and molds, and the populations of aerobic mesophilic bacteria were lower in both than in the control. The decay index in fruit treated with D.h. and Y.l. was lower compared to the control group. At 4 and 20°C storage, the decay index was 0.05 (at 20 days) and 0.4 (at 6 days), respectively, for fruit treated with D.h. and Y.l., while it was twice as high in controls. Weight loss of treated fruit was lower than in controls after 4 d storage at 20°C (5 and 9%, respectively). Compared to untreated fruit, the treated fruit had less change in firmness, total soluble solids, TA, pH, ascorbic acid, and antioxidant capacity. Based on the findings, application of the selected yeasts as a biocontrol method has the potential to reduce strawberry postharvest losses.

THE INFLUENCE OF THIAMINE AND ITS CATABOLITES ON THE MAGNITUDE OF ELECTROPHORETIC VELOCITY AND THE ζ-POTENTIAL OF YEAST SACCHAROMYCES CEREVISIAE

Problem: Yeast cell solutions are thought to be more stable with an increase in the negative charge of their cell surface, which can be controlled by the level of ζ-potential or electrophoretic velocity. Thiamine is known as a yeast growth stimulant, but the effect of vitamin B1 and its catabolites on the state of yeast membranes has not been investigated. Aim. The purpose of the work is to determine the effect of different concentrations of thiamine, thiaminedisulfide, 4-methyl‑5-β-oxyethylthiazole and thiochrome on the value of the ζ-potential and electrophoretic velocity in Saccharomyces cerevisiae. Methods. Determination of electrophoretic velocity and ζ-potential was carried out using a microelectrophoresis unit and a microscope, the movement of yeast cells along Hemocytometer was observed. It was determined in what time (sec) the cells will pass a path equal to the side of the square in the Hemocytometer. Parameters: voltage in the circuit – 100 V, the distance between the electrodes – 2 cm, the path traveled by the yeast cells – 0.02 cm (control test). In the test samples, thiamine and its catabolites were added to the yeast suspension 15 minutes before the measurements in final concentrations of 1, 5, 10 μmol. The main results: Incubation of yeast with thiamine, which was added to the medium at concentrations of 5 and 10 μmol, increased the ζ-potential and electrophoretic velocity, respectively, by 2.75 and 1.84 times compared with the control. Thiaminedisulfide at a concentration of 10 μmol increased the studied indicators by 2.61 times, and thiochrome at a concentration of 1 μmol – by 4.26 times compared with the control. The introduction of 4-methyl‑5-β-oxyethylthiazole into the mediumat a concentration of 1 and 5 μmol also caused an increase by 1.43 and 1.24 times, respectively, compared with the control. Conclusions. Thiamine and its metabolites increased electrophoretic velocity and ζ-potential of yeast cells. Thiaminedisulfide and thiamine increased the level of the studied indicators at concentrations, respectively 10 μmol, and 5 and 10 μmol due to enhancement of oxidation processes in yeast cells, while thiochrome and 4-methyl‑5β-oxyethylthiazole acted at concentrations, 1 μmol, 1 and 5 μmol, respectively, apparently, due to the interaction with the hydrophobic pockets of proteins.

Evaluation of Orange and Biofertilizer on Some Yield Traits of Cucumber (Cucumis sativus L.)

In the year 2021, in one of the communities in the Abu Ghraib area of Baghdad, a factorial experiment was carried out to study the effect of adding organic manure(poultry, cattle and sheep)and dry bread yeast suspension on certain yield characteristics of cucumber plants (Hadeel hybrid) grown in a greenhouse. Results showed that poultry waste had the best effects in the fruit set (67.21%), the diameter of the fruit)of 2.58 cm(, the number of fruit (36.81 fruit plant-1 ), the weight of fruit (66.00 g), and the yield (2.42 kg plant-1 ). The poultry manure caused a reduction in the peel thickness to a minimum value of (0.145mm). Compared to the control treatment, adding dry yeast suspension to plants improved all yield parameters tested. Keywords: Cucumber, sheep manure, cattle manure, dry yeast, poultry manure, yield.

Response of Cucumber Pants to the Addition of Animal Waste and Dry Yeast Suspension

A factorial experiment was carried out during the year 2021 in one of the villages in the Abu Ghraib district – Baghdad, to evaluate the effect of adding animal waste and dry bread yeast suspension on some vegetative growth characteristics of cucumber plants (Hadeel hybrid) grown under a protected environment. Three types of animal wastes (cattle, sheep and poultry) and dry bread yeast suspension were selected and the control treatment without adding any organic waste. The results indicated that poultry manure showed the best effects in the studied traits, which included leaf area ) of 31.69 cm2 (, dry weight of shoot )40.0 g(, number of leaves )32.73 leaf plant-1 ), stem diameter (11.48 mm), plant length (224.3 cm) and number of nodes 33.73 node plant-1 ).On the other hand, adding dry yeast suspension to plants improved in all studies of vegetative growth characteristics compared to the control treatment. Keywords: Cucumber, fertilize, organic manure, biofertilizer, vegetative growth.

Ascending renal infection following experimental candiduria by Candida tropicalis in immunocompromised mice

The present study evaluated renal infection resulting from the implantation of C. tropicalis in the bladder of immunosuppressed mice. Yeasts were implanted in two manners: planktonic and via preformed biofilm on a small catheter fragment (SCF). Renal histopathology and cultures was performed 72 and 144 h after cystotomy was carried out in mice from three groups: group I contained non-contaminated mice implanted with a sterile SCF; group II mice received a sterile SCF plus a yeast suspension containing 1 × 107 yeasts/mL in a planktonic form; group III mice were implanted with a SCF containing preformed C. tropicalis biofilm. Viable yeasts were found in the kidneys of mice from both groups II and III. However, after 72 h the planktonic cells (group II) invaded more quickly than the sessile cells (group III). Over a longer period (144 h), group III exhibited a more invasive infection (50% of the animals presented renal infection and the renal fungal load was 3.2 log10 CFU/g tissue) than in group II, where yeasts were not found. C. tropicalis introduced into the bladder in two ways (in planktonic or biofilm form) were able to reach the kidney and establish a renal fungal infection, causing interstitial disorders. The data of the present study therefore support the hypothesis of an ascending pathway for renal infections by C. tropicalis. Furthermore, the biofilm resulted in a greater and progressive risk of renal infection, attributed to the slow detachment of the yeasts.