Yeast Growth Research Articles

In vitro Evaluation of Antifungal Activity of Terbinafine Nano Form against Yeast Organism Isolated in Thumby Labs Ajman

The goal of this study is to evaluate the antifungal activity of terbinafine in its nano form against yeast organisms in vitro and compare its effectiveness to the normal form of terbinafine. Thirty isolated yeast organisms from Thumbay Labs were included in the study. Terbinafine was serially diluted to concentrations of 50 mg, 25 mg, 12 mg, and 6 mg for both the nano and normal forms. After preparing the serial dilutions, fungal suspensions were exposed to these dilutions for 7 minutes. The suspensions were then cultured on Sabouraud dextrose agar and incubated at 37°C overnight. Growth was measured using a colony count. The results for the normal form of terbinafine revealed growth at all concentrations, with varying colony counts with a highest growth was observed at the 6 mg concentration. In contrast, the nano form of terbinafine exhibited distinct development patterns. At the 50 mg concentration, seven samples showed no growth; at the 25 mg concentration, two samples showed no growth; and the remaining samples exhibited limited growth compared to the normal form. According to the results of this study, there were significant differences in the number of colonies between the two forms of terbinafine, with the nano form demonstrating greater efficacy. The most potent antifungal response was observed at the 50 mg concentration of nano terbinafine, which inhibited yeast growth in several samples. In conclusion, terbinafine nanoemulsions are more effective than the normal form against Candida.

Quality evaluation of innovative buttermilk biscuits produced from orange-flesh sweet potato flour infused with coconut

IntroductionThis study was undertaken to evaluate a value-added innovative buttermilk biscuit made from orange flesh sweet potato (OFSP) flour, infused with coconut. It underscores the importance of food utilisation through alternatives to wheat flour contributing to food and nutrition security amidst evolving global challenges. The objectives of this study were: to investigate the effect of different levels of OFSP flour with and without shredded coconut on the physical, microbiological, nutritional and sensory properties of buttermilk biscuits. The hypotheses were: Ho: There is no effect of different levels of OFSP flour and shredded coconut on the physical, microbiological, nutritional and sensory properties on buttermilk biscuits at ∝ = 0.05 and Ha: There is an effect of different levels of OFSP flour and shredded coconut on the physical, microbiological, nutritional and sensory properties on buttermilk biscuits at ∝ = 0.05.MethodsOFSP flour was produced and combined with wheat flour at different ratios and infused with desiccated shredded coconut to produce six formulations of buttermilk biscuits: 100% wheat flour + 5% coconut (control 1), 100% wheat flour (control 2), 70% wheat flour + 30% OFSP flour + 5% coconut, 70% wheat flour + 30% OFSP flour, 50% wheat flour + 50% OFSP flour + 5% coconut and 50% wheat flour + 50% OFSP flour. The study followed a randomised 3 × 2 factorial design where each treatment was replicated four times giving 24 treatments. Physical, nutritional, sensory, microbiological and shelf-life analyses were determined for each buttermilk biscuit treatment.ResultsThe study’s findings revealed that buttermilk biscuits formulated with 30% OFSP flour received the highest (p < 0.05) sensory evaluation scores for the majority of attributes and overall acceptability while the 100% wheat flour formulations received the lowest scores according to the 9-point hedonic scale. Notably, the inclusion of shredded coconut did not improve sensory attributes or overall acceptance of the buttermilk biscuits. The OFSP flour buttermilk biscuits contained protein, fat, fibre, moisture and ash. The 100% wheat flour treatments contained significantly higher levels of proteins and moisture than the OFSP flour buttermilk biscuits. The colour L* of the OFSP flour treatments were significantly lower than the 100% wheat flour treatments. There were no significant changes in spread-ratio, diameter and thickness of the buttermilk biscuits during storage. Furthermore, the microbiological quality was maintained as no growth of bacteria, yeasts and molds were observed.DiscussionThe OFSP flour with and without desiccated coconut produced acceptable buttermilk biscuits with less reliant on wheat flour. It is noteworthy that the protein content of the OFSP flour buttermilk biscuits was at an acceptable level even though it was lower than that in 100% wheat flour buttermilk biscuits. Food safety was maintained throughout storage which is crucial in the elimination of food borne diseases. The use of different baking parameters can be used for future studies to assess the effect of temperature on the quality of buttermilk biscuits.

Identification and Preliminary Functional Analysis of Responsive Genes to Short-term Heat Stress in Lettuce

Lettuce is a commonly consumed vegetable worldwide, due to its crisp edible organs and rich nutrition. Heat stress is known to seriously threaten its growth and development. However, research on lettuce response to heat stress focusing on molecular aspects is limited. Therefore, we aimed to understand the complex molecular mechanisms underlying the regulation of lettuce plant response to heat stress (37 °C), by transcriptomic analysis of a heat-resistant lettuce variety (K482) following heat stress treatment for 1.5 and 3 days. A total of 3798 and 4121 differentially expressed genes (DEGs) were identified at 1.5 and 3 days vs. the control after heat treatment, respectively; they were mostly enriched in protein processing in the systemic lupus erythematosus, alcoholism, neurotrophin signaling pathways, and the cell cycle. Most DEGs were NACs, HSPs, MYBs, bHLHs, and WRKYs. Transcriptome analysis showed that the NAC domain transcription factor LsNAC28, which is associated with heat response, is up-regulated during heat stress and LsNAC28 inhibited yeast growth under heat stress (37 °C). These findings provide a basis to comprehensively understand the complex molecular mechanism of lettuce response to heat stress.

Fermentation Performance of Carob Flour, Proso Millet Flour and Bran for Gluten-Free Flat-Bread

Sourdough fermentation is rarely used for gluten-free flatbread (GFFB), a product that is challenging to produce, especially when using high-fiber ingredients that bring nutritional benefits but lead to physical deterioration. The aim of this study was therefore to evaluate the fermentation performance of carob flour (CSPF), proso millet flour (PMF), and proso millet bran (PMB) individually and in combination with Limosilactobacillus fermentum and Kluyveromyces marxianus (LF + KM) and to compare the performance of LF + KM with a commercial starter (LIVENDO® LV1). A mixture design (n = 13) was used to evaluate the fermentation performance of LF + KM (total titratable acidity (TTA); lactobacilli and yeast growth; acetic and lactic acid, fructose, glucose, and saccharose content) at 35 °C for 16 h. The comparison of LF + KM with LV1 fermentation was based on the acidity rate, fermentation quotient, TTA, and finally by determining the physical properties (texture, shape, color) of a rice–corn GFFB in which 10% of flour was supplemented with the sourdoughs. PMB promoted the growth of lactobacilli and the production of organic acids, especially in combination of CSPF and PMF. The optimum flour ratio was 2.4:1:1.2 (PMB:PMF:CSPF). LF + KM shortened the sourdough fermentation time by 2.5 times compared to LV1. The use of LF + KM sourdough reduced the hardness (32%) and chewiness (28%) of the GFFB, while the volume (35%) was increased compared to LV1 sourdough. This study shows the potential of using local alternative flours in sourdough fermentation for the production of GFFB.

Elucidating Bile Acid Tolerance in Saccharomyces cerevisiae: Effects on Sterol Biosynthesis and Transport Protein Expression

The tolerance of Saccharomyces cerevisiae to high concentrations of bile acids is intricately linked to its potential as a probiotic. While the survival of yeast under high concentrations of bile acids has been demonstrated, the specific mechanisms of tolerance remain inadequately elucidated. This study aims to elucidate the tolerance mechanisms of S. cerevisiae CEN.PK2-1C under conditions of elevated bile acid concentrations. Through growth curve analyses and scanning electron microscopy (SEM), we examined the impact of high bile acid concentrations on yeast growth and cellular morphology. Additionally, transcriptomic sequencing and molecular docking analyses were employed to explore differentially expressed genes under high bile acid conditions, with particular emphasis on ATP-binding cassette (ABC) transporters and steroid hormone biosynthesis. Our findings indicate that high concentrations of bile acids induce significant alterations in the sterol synthesis pathway and transporter protein expression in S. cerevisiae. These alterations primarily function to regulate sterol synthesis pathways to maintain cellular structure and sustain growth, while enhanced expression of transport proteins improves tolerance to elevated bile acid levels. This study elucidates the tolerance mechanisms of S. cerevisiae under high bile acid conditions and provides a theoretical foundation for optimizing fermentation processes and process control.

Addition of commercial lactic acid bacteria as starter cultures in anaerobic fermentations of Coffea arabica L., in cherry or raisin stages

The objective of this research was to verify the efficiency of adding commercial lactic acid bacteria (LAB) on anaerobic fermentation of (cherry and raisin) arabica Yellow Catuaí coffees, studying the microbiological succession and its influence in modulating sensorial characteristics on their beverages. The study took place in a rural property in Marília region, Sao Paulo State, Brasil, and was performed according to three different treatments: 1) FNC = spontaneous fermentation of cherry coffees; 2) FCBAL = cherry coffee fermentation using Sacco Lyofast SYAB1 BAL; 3) FPBAL = raisin coffee fermentation using Sacco Lyofast SYAB1 BAL. Fermentations occurred in individual (60 liters) high density polyethylene containers, properly sealed to guarantee anaerobic conditions. After a 48-hour fermentation, all the coffee fruits were washed, beans were depulped and dried on suspended terrace until a 12% humidity was observed. Physical, chemical, microbiological and sensory analysis were performed in samples collected from each fermented batch. Fermentation processes of raisin coffees occurred more slowly than fermentations using cherry coffees and resulted in a lesser consumption of soluble solids and in a slower acidification. Fermentation treatments FNC, FCBAL and FPBAL reached the necessary reduction of Enterobateriaceae and molds. The addition of BAL stimulated the growth of yeasts, which are responsible for the inclusion of the most desired flavor. The fermentations conducted in this experiment resulted in coffee beverages that reached notes of specialty coffees (> 80 points). Even though the raisin coffee achieved a lower note than cherry, the LAB inclusion raised it from 77 (non-fermented raisins) to 80 (FPBAL) points. In cherry fruits, FCBAL got 2 points on final comparation to non-fermented cherries. Thus, the inclusion of LAB presented itself beneficial to anaerobic fermentations of cherry or raisin coffees.

Influence of Ensiling Timing and Inoculation on Whole Plant Maize Silage Fermentation and Aerobic Stability (Preliminary Research)

Despite efforts to prevent atypical ensiling conditions, such as delayed ensiling or sealing, these issues frequently occur in practice. This study aimed to investigate the effects of delayed ensiling (forage held for 24 h) and sealing, along with inoculation using a blend of Lentilactobacillus buchneri and Lactococcus lactis, on the characteristics of the resulting silages. Whole-plant maize (Zea mays L.) was treated with or without a commercial inoculant and ensiled (36% dry matter) for 60 days in 3.0 L glass containers. The forage was either ensiled immediately or subjected to a 24 h delay before ensiling. During the delay, the forage was either covered or left uncovered. Each treatment was replicated five times. All data were analyzed using the MIXED procedure of SAS statistical software (version 9.4; SAS Institute Inc., Cary, NC, USA). Delaying the ensiling process by 24 h worsens fermentation parameters, significantly increases dry matter (DM) losses (p < 0.01), and significantly reduces aerobic stability and the hygienic quality of the silage (p < 0.01), as evidenced by higher concentrations of undesirable fermentation products and elevated yeast and mold counts. The inoculation has a significant impact on both forage before ensiling and the characteristics of the resulting silage. Maize forage treated with inoculant showed a lower temperature increase by 8.2–8.1 °C (p < 0.01) when delayed for 24 h before ensiling. In silages, it also resulted in a reduced pH (p < 0.01); increased concentrations of lactic acid; acetic acid; and 1,2-propanediol (p < 0.01); and decreased levels of negative fermentation indicators such as ammonia-N, alcohols, and butyric acid (p < 0.01) During both the fermentation and aerobic exposure periods, inoculated silages exhibited up to 36% and 2.6 times lower (p < 0.01) dry matter loss, while suppressing the growth of yeasts and molds by up to 2.6 and 3.1 times (p < 0.01), respectively, compared to non-inoculated silages. The results of this study support the recommendation to minimize the duration of aerobic exposure of fresh forage during silo filling and to use LAB-based inoculants.

Knock-out of the major regulator Flo8 in Komagataella phaffii results in unique host strain performance for methanol-free recombinant protein production

Flo8 is a main transcriptional regulator of flocculation and pseudohyphal growth in yeast. Disruption of FLO8 in the popular recombinant protein production host Komagataella phaffii (Pichia pastoris) prevents pseudohyphal growth and reduces cell-to-surface adherence, making the mutant an interesting platform for research and industry. However, knowledge of the physiological impact of the mutation remained scarce. In-depth analysis of transcriptome data from FLO8-deficient K. phaffii revealed that Flo8 affects genes involved in cell cycle, mating, respiration, and catabolite repression additionally to flocculation targets. One gene with considerably increased expression in flo8 was GTH1, encoding a high-affinity glucose transporter in K. phaffii. Its promoter (PG1) was previously established as a strong, glucose-regulatable alternative to methanol-induced promoters. PG1 and its improved derivatives PG1-3, D-PGS4 and D-PGS5, proved to be promising candidates for controlling recombinant protein production in the FLO8-deficient background. In small-scale screenings, PG13-controlled intracellular EGFP levels were 2.8-fold higher, and yields of different secreted recombinant proteins were up to 4.8-fold increased. The enhanced productivity of the flo8 mutant in combination with the PG1 variants was transferrable to glucose-limited fed-batch processes and could largely be attributed to higher transcriptional activity of the promoter, leading to a much higher productivity per chromosomally integrated gene copy. K. phaffii flo8 has many advantageous characteristics, such as reduced surface growth and increased transcriptional strength of glucose-regulatable promoters. These features turn the flo8 strain into a valuable new base strain for various experimental designs and establish flo8 as an excellent strain background for methanol-free recombinant protein production processes.

Revised mechanism of hydroxyurea-induced cell cycle arrest and an improved alternative

Replication stress describes endogenous and exogenous challenges to DNA replication in the S-phase. Stress during this critical process causes helicase-polymerase decoupling at replication forks, triggering the S-phase checkpoint, which orchestrates global replication fork stalling and delayed entry into G2. The replication stressor most often used to induce the checkpoint response in yeast is hydroxyurea (HU), a clinically used chemotherapeutic. The primary mechanism of S-phase checkpoint activation by HU has thus far been considered to be a reduction of deoxynucleotide triphosphate synthesis by inhibition of ribonucleotide reductase (RNR), leading to helicase-polymerase decoupling and subsequent activation of the checkpoint, facilitated by the replisome-associated mediator Mrc1. In contrast, we observe that HU causes cell cycle arrest in budding yeast independent of both the Mrc1-mediated replication checkpoint response and the Psk1-Mrc1 oxidative signaling pathway. We demonstrate a direct relationship between HU incubation and reactive oxygen species (ROS) production in yeast and human cells and show that antioxidants restore growth of yeast in HU. We further observe that ROS strongly inhibits the in vitro polymerase activity of replicative polymerases (Pols), Pol α, Pol δ, and Pol ε, causing polymerase complex dissociation and subsequent loss of DNA substrate binding, likely through oxidation of their integral iron-sulfur (Fe-S) clusters. Finally, we present "RNR-deg," a genetically engineered alternative to HU in yeast with greatly increased specificity of RNR inhibition, allowing researchers to achieve fast, nontoxic, and more readily reversible checkpoint activation compared to HU, avoiding harmful ROS generation and associated downstream cellular effects that may confound interpretation of results.

Antifungal properties of abnormal cannabinoid derivatives: Disruption of biofilm formation and gene expression in Candida species

Abnormal cannabinoids (including comp 3) are a class of synthetic lipid compounds with non-psychoactive properties and regioisomer configurations, but distinct from traditional cannabinoids since they do not interact with the established CB1 and CB2 receptors. Previous research showed the cardioprotective and anti-inflammatory potentials of comp 3 and more recently its antimicrobial effect on methicillin-resistant Staphylococcus aureus (MRSA). Given the escalating challenges posed by Candida infections and the rise of antifungal drug resistance, the exploration of novel therapeutic avenues is crucial. This study aimed to assess the anti-Candida properties of newly synthesized AbnCBD derivatives. AbnCBD derivatives were synthesized by acid catalysis-induced coupling and further derivatized. We evaluated the potential of the AbnCBD derivatives to inhibit the growth stages of various Candida species. By in vitro colorimetric assays and in vivo mice experiments, we have shown that AbnCBD derivatives induce differential inhibition of Candida growth. The AbnCBD derivatives, especially comp 3, comp 10, and comp 9 significantly reduced the growth of C. albicans, including FLC-resistant strains, and of C. tropicalis and C. parapsilosis but not of C auris compared to their controls (FLC and 0.5 % DMSO). Comp 3 also disrupted C. albicans biofilm formation and eradicated mature biofilms. Notably, other derivatives of AbnCBD disrupted the biofilm formation and maturation of C. albicans but did not affect yeast growth. In a murine model of VVC, comp 3 demonstrated significant fungal clearance and reduced C. albicans burden compared to vehicle and FLC controls. These findings highlight the potential of AbnCBDs as promising antifungal agents against Candida infections.

Growth-phase-dependent control of rRNA synthesis in Saccharomyces cerevisiae.

Saccharomyces cerevisiae is one of the most well-studied model organisms used in the scientific community. Its ease of manipulation, accessible growth conditions, short life cycle, and conserved eukaryotic metabolic pathways make it a useful model organism. Consequently, yeast has been used to investigate a myriad of phenomena, from microbial to human studies. Most of the research performed using this model organism utilizes yeast cell populations when they are growing exponentially, a growth phase aptly termed exponential or log phase. However, log phase encompasses several yeast generations and ranges several hours of yeast growth, meaning that there is a potential for variability during this "homogenous" growth phase. Cells in log phase require robust ribosome biogenesis to support their rapid growth and cell division. Interestingly, during log phase, ribosomal RNA (rRNA) synthesis (which is the first and rate limiting step in ribosome biosynthesis) has been shown to decrease prior to growth rate decline in stationary phase. In this study, we utilized several genomic and biochemical methods to elucidate the relationship between subphases of log phase and rRNA synthesis. Our results indicate that as yeast cells progress through subphases of log growth, both polymerase I transcription and rRNA processing are repressed. Overall, this study establishes a growth-phase-dependent control of rRNA synthesis that unexpectedly begins prior to the switch to stationary phase (i.e., pre-diauxic shift) as a putative mechanism of anticipating nutrient starvation.IMPORTANCESaccharomyces cerevisiae is a ubiquitously used model organism in a wide range of scientific research fields. The conventional practice when performing yeast studies is to investigate its properties during logarithmic growth phase. This growth phase is defined as the period during which the cell population doubles at regular intervals, and nutrients are not limiting. However, this growth phase lasts hours and encompasses several yeast cell generations which consequently introduce heterogeneity to log growth phase depending on their time of harvest. This study reveals significant changes in the transcriptomic landscape even in early stages of exponential growth. The overall significance of this work is the revelation that even the seemingly homogenous log growth phase is far more diverse than was previously believed.

Yeast mycobiome of fruit and vegetable biowastes revealed by culture-dependent and metabarcoding approaches: Screening for the production of succinic acid and single cell oils

Fruit and vegetable by-products and agro-residues from food processing industries and households negatively impact the environment, economy, and society. Yeasts are metabolically efficient at converting food wastes into value-added products such as biopeptides, single-cell oils, single-cell proteins, and organic acids. This work explores the valorization of twelve fruit and vegetable-derived wastes as inexpensive substrates for obtaining high-value products and metabolically efficient yeasts. Culture-dependent and metabarcoding methods provided a comprehensive overview of the yeast mycobiome, revealing 33 common species. From a biobank of 252 isolates obtained from the twelve biowastes, the 31 most promising isolates were evaluated using a synthetic medium that mimicked fruit and vegetable waste. The results showed that the metabolism was mainly directed towards the Krebs cycle, with lower production of single-cell oil compared to organic acids. Kazachstania humilis stood out from the general metabolic heterogeneity, producing 0.9 g/L of succinic acid and 1.4 g/L of acetic acid. Our results demonstrate that these natural isolates can produce high-value compounds at levels comparable to those obtained under optimal conditions for yeast growth.

MONITORING OF BENZOIC ACID LEVELS IN SOFT DRINKS CONSUMED IN ADEN, YEMEN

Benzoic acid is widely used as a food preservative due to its effectiveness in inhibiting the growth of yeast and mold. The undissociated form of benzoic acid is the most potent. In acidic beverages like soft drinks, benzoic acid can react with additives such as ascorbic acid to release benzene, which can pose health concerns. This study aimed to determine the levels of benzoic acid in soft drink samples commonly consumed in Aden, Yemen. Eighteen soft drink samples were analyzed using high-performance liquid chromatography with a UV detector. The highest benzoic acid concentration was found in a FIFA orange sample at 173.87 ppm, while the lowest was 8.40 ppm in a DREAM red sample. Some samples, including MIRINDA orange, FANTA apple, and DILSI red, had no detectable levels of benzoic acid, despite their labels indicating its presence. Overall, the benzoic acid concentrations in all tested samples were within the permissible limits set by local, regional, and international standards.

Mining for antifungal agents to inhibit biofilm formation of Candida albicans: A study on green synthesis, antibiofilm, cytotoxicity, and in silico ADME analysis of 2-amino-4H-pyran-3-carbonitrile derivatives

Candida albicans (C. albicans) biofilm infections are quite difficult to manage due to their resistance against conventional antifungal drugs. To address this issue, there is a desperate need for new therapeutic drugs. In the present study, a green and efficient protocol has been developed for the synthesis of 2-amino-4H-pyran-3-carbonitrile scaffolds 4a-i, 6a-j, and 8a-g by Knoevenagel-Michael-cyclocondensation reaction between aldehydes, malononitrile, and diverse enolizable C-H activated acidic compounds using guanidinium carbonate as a catalyst either under grinding conditions or by stirring at room temperature. This protocol is operationally simple, rapid, inexpensive, has easy workup and column-free purification. A further investigation of the synthesized compounds was conducted to examine their antifungal potential and their ability to inhibit the growth and development of biofilm-forming yeasts like fungus C. albicans. According to our findings, 4b, 4d, 4e, 6e, 6f, 6g, 6i, 8c, 8d, and 8g were found to be active and potential inhibitors for biofilm infection causing C. albicans. The inhibition of biofilm by active compounds were observed using field emission scanning electron microscopy (FESEM). Biofilm inhibiting compounds were also tested for in vitro toxicity by using 3T3-L1 cell line, and 4b, 6e, 6f, 6g, 6i, 8c, and 8d were found to be biocompatible. Furthermore, the in silico ADME descriptors revealed drug-like properties with no violation of Lipinski's rule of five. Hence, the result suggested that synthesized derivatives could serve as a useful aid in the development of novel antifungal compounds for the treatment of fungal infections and virulence in C. albicans.

The Addition of Glutamine Enhances the Quality of Huangjiu by Modifying the Assembly and Metabolic Activities of Microorganisms during the Fermentation Process.

In this study, the effects of adding glutamate (Glu), glutamine (Gln), aspartate (Asp), and asparagine (Asn) on the flavor formation of Huangjiu were investigated, and the effect of Gln concentration on the quality, microbial community structure, and flavor development of Huangjiu was further explored. Varied Gln concentrations influenced yeast growth, sugar utilization, microbial communities, and quality attributes. Additional Gln promoted yeast cell counts and sugar depletion. It increased the complexity of bacterial co-occurrence networks and reduced the impact of stochastic processes on assembly. Correlation analysis linked microorganisms to flavor compounds. Isolation experiments verified the role of Saccharomyces cerevisiae, Aspergillus chevalieri, Bacillus altitudinis, and Lactobacillus coryniformis in flavor production under Gln conditions. This research elucidated the microbiological mechanisms by which amino acid supplementation, especially Gln, enhances Huangjiu quality by modulating microbial metabolic functions and community dynamics during fermentation. This research is significant for guiding the production of Huangjiu and enhancing its quality.

Improving the Storage Quality of Ready-to-Eat Clementine Fruits Using Lemon By-Products

In this study, the effect of the antioxidant extract from lemon by-products (Citrus × Limon L.) integrated into an edible alginate-based coating was evaluated to preserve the storage quality of ready-to-eat Clementine (Citrus × Clementina) fruits. The effects of different coatings (1.5% of alginate and 1.5% of alginate + 2–4% of lemon by-product extract) were assessed by the physical, chemical, microbiological, sensorial, and structural analyses of ready-to-eat Clementine fruits stored for 21 d at 4 °C. Ready-to-eat Clementine fruits coated with alginate and extract from lemon by-products showed greater levels of polyphenols, flavonoids, antioxidant activity, and organic acids. A microbiological analysis revealed the dose-dependent effect of the extract to contrast the growth of mesophilic bacteria, yeast, and molds during storage. A sensory analysis confirmed that the enriched coating improved the visual, structural, and olfactory parameters until the end of storage. The evidence in this study proves that an antioxidant extract from lemon by-products is a great sustainable treatment to preserve ready-to-eat fruits.

Modification of Regulatory Tyrosine Residues Biases Human Hsp90α in its Interactions with Cochaperones and Clients

The highly conserved Hsp90 chaperones control stability and activity of many essential signaling and regulatory proteins including many protein kinases, E3 ligases and transcription factors. Thereby, Hsp90s couple cellular homeostasis of the proteome to cell fate decisions. High-throughput mass spectrometry revealed 178 and 169 posttranslational modifications (PTMs) for human cytosolic Hsp90α and Hsp90β, but for only a few of the modifications the physiological consequences are investigated in some detail. In this study, we explored the suitability of the yeast model system for the identification of key regulatory residues in human Hsp90α. Replacement of three tyrosine residues known to be phosphorylated by phosphomimetic glutamate and by non-phosphorylatable phenylalanine individually and in combination influenced yeast growth and the maturation of 7 different Hsp90 clients in distinct ways. Furthermore, wild-type and mutant Hsp90 differed in their ability to stabilize known clients when expressed in HepG2 HSP90AA1−/− cells. The purified mutant proteins differed in their interaction with the cochaperones Aha1, Cdc37, Hop and p23 and in their support of the maturation of glucocorticoid receptor ligand binding domain in vitro. In vivo and in vitro data correspond well to each other confirming that the yeast system is suitable for the identification of key regulatory sites in human Hsp90s. Our findings indicate that even closely related clients are affected differently by the amino acid replacements in the investigated positions, suggesting that PTMs could bias Hsp90s client specificity.

ADP-glucose pyrophosphorylase gene family in soybean and implications in drought stress tolerance.

ADP-glucose pyrophosphorylase (AGPase) is the key rate-limiting enzyme in starch biosynthesis pathway, and has been identified as a potential target for manipulation strategies aimed at improving crop yield and quality. To identify the AGPase gene family members in soybean, and explore the potential implications of GmAGPS2 in drought stress tolerance. Thegenome-wide identification and sequence analysis of soybean AGPase gene family was carried out by bioinformatics methods. The GmAGP gene expression was analyzed using transcriptome data and quantitative real-time PCR (qRT-PCR). Furthermore, transgenic yeast strains overexpressing GmAGPS2 were generated, and their growth was observed under drought stress. In this study, we searched for AGPase genes (GmAGP) in the soybean genome and identified a total of 14 GmAGP genes. The GmAGP proteins had a unique conserved NTP_transferase domain and were mainly located in the chloroplast and cytosol. Evolutionarily, theGmAGP proteins can be clustered into two distinct subgroups; within the same subgroup, they displayed a similar distribution pattern of conserved motifs. The GmAGP genes exhibited an uneven distribution on 10 chromosomes, and segmental duplication contributed to AGPase gene family expansion in soybean. The GmAGP genes presented different tissue expression pattern, in which GmAGPL6, GmAGPL9, and GmAGPL10 mainly exhibited tissue-specific expression pattern. The promoter of GmAGP genes had multiple cis-acting elements related to phytohormones and stress responses, and 8 GmAGP genes contained drought-responsive cis-acting elements. qRT‒PCR analysis demonstrated a significant upregulation expression of GmAGPL6, GmAGPL10, and GmAGPS2 in response to drought stress. Further functional analysis indicated that GmAGPS2 gene could improve yeast growth under drought stress conditions and enhance the drought tolerance of yeast. These results will contribute to further elucidation of the function of GmAGP genes, and offer important candidate genes for the genetic improvement of starch and yield-related traits and the breeding of high drought stress tolerance varieties in soybean.

Critical areas for <i>Brettanomyces bruxellensis</i> contamination and biofilm formation in the cellar: on the origin of wine spoilage

The cellar environment harbours a consortium of microorganisms on the material surfaces and in the air. Among these microorganisms, the spoilage yeast Brettanomyces bruxellensis can colonise surfaces due to its specific bioadhesive properties. In this study, air and surface samples were collected in several wineries during the winter period. B. bruxellensis was detected in the cellar environment either in the air or on the surfaces of various materials, including in tartaric acid precipitates. Difficult-to-clean tank equipment (taps, wall angles, valves) were identified as critical areas where B. bruxellensis was frequently detected. To confirm that surfaces contaminated by B. bruxellensis could be involved in wine contamination, yeast growth and volatile phenol production were monitored in wine in contact with stainless steel harbouring biofilms. The presence of bioadherent cells and biofilms in contact with the wine resulted in significant cell release into the wine, leading to population growth and the production of volatile phenols at concentrations above the olfactory detection threshold. This study demonstrates the possibility of wine spoilage by resident and adherent populations of B. bruxellensis and confirms the need to pay special attention to the hygiene of hard-to-reach areas such as valves.

Genome-wide identification of metal tolerance protein genes in Quercus dentata and their roles in response to various heavy metal stresses

Metal tolerance protein (MTP) is a cation transporter that plays an important role in tolerance to heavy metal stress. However, thus far, there has been no genome-wide investigation of the MTP gene family in Quercus plants. Quercus dentata is one of the main constructive species of forest in northern China. It has strong tolerance to a variety of heavy metal stresses. In this study, 25 MTPs were identified from the Q. dentata genome and classified into three subfamilies and seven groups according to their sequence characteristics and phylogenetic relationships. Both tandem and segmental duplication events contributed to the expansion of the QdMTP gene family. Interestingly, all 10 tandem duplication events contributed to the expansion of the Mn-CDF subfamily. The expression of Mn-CDF subfamily members in different organs and tissues of Q. dentata was different, and they responded differently to manganese, iron, zinc and cadmium stress treatments. QdMTP10.7, a member of the Mn-CDF subfamily, enhanced yeast growth under manganese, zinc and iron stresses. The subcellular localization in tobacco leaf epidermis cells showed that QdMTP10.7 was located in vacuoles. These data generated from this study provide an important foundation to elucidate the biological roles of QdMTP genes related to heavy metal tolerance in Q. dentata.