Search Results (222)

Mitochondria are central to energy production and redox regulation in spermatozoa, supporting key functions such as progressive motility, capacitation, and the acrosome reaction. These processes are essential for successful fertilization and embryo development. However, species-specific differences exist in the reliance on oxidative phosphorylation versus glycolysis. Mitochondria also generate reactive oxygen species, which at physiological levels aid in sperm function but can cause oxidative stress and damage when overproduced. Mitochondrial dysfunction and excessive ROS can impair membrane potential, induce apoptosis, and damage nuclear and mitochondrial DNA, ultimately compromising sperm quality. Sperm mitochondrial DNA is highly susceptible to mutations and deletions, contributing to reduced motility and fertility. Targeted antioxidant strategies have emerged as promising therapeutic interventions to mitigate oxidative damage. This article provides a comprehensive overview of mitochondrial regulation in spermatozoa, the consequences of redox imbalance, and the potential of mitochondria-targeted antioxidants to improve sperm function and male fertility outcomes. The paper aims to deepen our understanding of mitochondrial roles in sperm physiology and contribute to the advancement of strategies for addressing male infertility. Full article

Riboflavin (vitamin B₂) is an essential micronutrient required for all living organisms. It is naturally synthesized by plants and most microorganisms, including the bacterium Bacillus subtilis, the filamentous fungus Ashbya gossypii, and the yeast Candida famata—all of which are known to be riboflavin overproducers. The choice of production organism in industrial applications depends on factors such as yield, ease of cultivation, and the availability of genetic tools. As a result, several microorganisms are commonly used, and their relative prominence can shift over time with advances in metabolic engineering and process optimization. This review presents a comparative analysis of riboflavin biosynthesis across prokaryotic and eukaryotic systems, with a particular focus on regulatory mechanisms governing flavinogenesis. Special attention is given to recent advances in metabolic engineering strategies, including the application of CRISPR/Cas9 genome editing in Bacillus subtilis and Ashbya gossypii. In yeast systems, significant improvements in riboflavin production have been achieved primarily through the manipulation of transcriptional regulators (e.g., SEF1, SFU1, TUP1) and metabolic genes. The role of other important genes (PRS3, ADE4, ZWF1, GND1, RFE1, VMA1, etc.) in riboflavin overproduction in C. famata is described. The review also explores the use of alternative, low-cost feedstocks—including lignocellulosic hydrolysates and dairy by-products—to support more sustainable and economically viable riboflavin production. Although considerable progress has been achieved in genetic optimization and bioprocess development, further work is required to fine-tune metabolic flux and maximize riboflavin synthesis, particularly under industrial conditions. This review highlights key opportunities for future research aimed at refining metabolic interventions and expanding the use of renewable substrates for environmentally sustainable riboflavin production. Full article

Biofuels, such as ethanol (CH₃CH₂OH), remain significantly underutilized globally despite their potential to mitigate environmental effects associated with fossil fuel combustion. Ethanol (ETH) can seamlessly blend with petroleum-derived gasoline, boosting its octane rating as a virtuous side effect. However, in several countries, octane number (ON) boosters such as methyl-tert-butyl-ether (MTBE) are still blended into the gasoline (also known as gas or petrol) sold in fuel stations, despite this being restricted or banned due to deleterious effects on the environment and health. Additionally, in nations overproducing naphtha from refining petroleum condensates, such as in the Middle East, investments in extra carbon chain rearrangement units can be an outlet to enhance gasoline production, since they produce high-ON streams; however, aromatic concentration becomes a limiting constraint. A discrete-event simulation algorithm combines sixteen main (primary) manufacturing variations into two secondary manufacturing and three supply chain variations, building gasoline yield and property plots over 512 gasoline production scenarios. Full article

Background/Objectives: Clavulanic acid (CA) is produced by cell suspension cultures of Streptomyces clavuligerus ATCC 27064, and is widely used as a beta-lactamase inhibitor to combat antibiotic resistance. CA titers are moderate due to bioprocess complexity, prompting ongoing efforts to overcome these limitations. Methods: In this study, we aimed to evaluate the effect of live and inactivated Bacillus velezensis FZB42 cells on CA production in S. clavuligerus, and to explore the transcriptional response underlying this interaction using RNA-seq technology. Results: The addition of dead and live cells of B. velezensis improved CA production by 1.4 and 2.0-fold, respectively. Furthermore, the transcriptome of S. clavuligerus, obtained with live cells of B. velezensis FZB42 at the peak of maximum CA production, revealed that 410 genes were up-regulated and 594 were down-regulated under these conditions, with a padj < 0.05. Most of the genes from the cephamycin C and CA clusters were up-regulated, which correlates well with the increase in CA production. Likewise, S. clavuligerus ATCC 27064 enhanced the expression of genes encoding enzymes that scavenge endogenous H₂O₂, as well as other genes related to oxidative stress defense. Regarding downregulated genes, we found that S. clavuligerus decreased the expression of genes involved in the biosynthesis of terpenoids, polyketides, and lantibiotics, as well as the expression of the operon involved in the synthesis of the pyrroloquinoline quinone (PQQ) cofactor. Conclusions: These findings contribute to the understanding of S. clavuligerus metabolism and pave the way for future metabolic engineering efforts aimed at obtaining CA-overproducing strains. Full article

The core characteristic of the bullwhip effect is that upstream companies overproduce or hoard inventory due to information distortion, leading to resource waste and increased carbon emissions, which severely affects the economic, environmental, and social efficiency of sustainable supply chains. This paper investigates the impact of retailers’ cognitive bias, namely, overconfidence, on the bullwhip effect in the sustainable supply chain. It characterizes retailers’ overconfidence from two aspects: overprecision and overestimation. This study finds that retailers’ overestimation biases distort demand forecasts, causing product orders and inventory decisions to significantly deviate from the rational optimal level, exacerbating the bullwhip effect in sustainable supply chains. In contrast, retailers’ overprecision bias reduces the forecast error, which has a mitigating effect on the bullwhip effect on inventory; however, this effect weakens as the level of overestimation increases. Furthermore, order lead time and the autocorrelation coefficient of demand moderate the bullwhip effect. Finally, through numerical simulation analysis, the interactive effects of overconfidence bias and operational parameters are effectively captured, providing strong validation for the theoretical results and research propositions. The conclusions of this study offer valuable managerial insights for mitigating the bullwhip effect of sustainable supply chain caused by irrational factors. It also provides policy recommendations for promoting the theoretical research and practice of sustainable supply chains. Full article

Previous studies have found that second language learners can acquire sociolinguistic variation. However, there is a lack of studies that examine the L2 acquisition of second-person singular forms of address (2PS) in Spanish, especially in the immersion context of study abroad. The current study examines the acquisition of Spanish 2PS by seven adults learning Spanish in Medellin, Colombia. Participants completed an oral discourse completion task and a matched guise task to measure language perceptions toward each 2PS. Learners’ results are compared to findings from 38 native Spanish speakers from Medellin. Learners produced very few instances of the local variant vos and overproduced tú, differing greatly from native speakers. Two factors were found to significantly condition 2PS usage for learners: speaker gender and interlocutor relationship. Findings show that although learners perceive vos to a somewhat native-like extent and the role that it plays in the local variety, learners do not actually use it. Full article

Although periodontal disease (PD) is reported to be associated with changes in various genes and proteins in both invading bacteria and the host, its molecular mechanism of pathogenesis remains unclear. Changes in immune and inflammatory genes play a significant role in PD pathogenesis. Some reports relate alterations in cellular epigenetic patterns to PD characteristics, while several high-throughput analyses indicate thousands of differentially methylated genes in both PD patients and controls. Furthermore, changes in DNA methylation patterns in inflammation-related genes have been linked to the efficacy of periodontal therapy, as demonstrated by findings related to the cytochrome C oxidase II gene. Distinct DNA methylation patterns in mesenchymal stem cells from PD patients and controls persisted despite the reversal of phenotypic PD. Methyl groups for DNA methylation are supplied by S-adenosylmethionine, which is synthesized with the involvement of folate, an essential nutrient known to play a role in maintaining mitochondrial homeostasis, reported to be compromised in PD. Folate may benefit PD through its antioxidant action against reactive oxygen and nitrogen species that are overproduced by dysfunctional mitochondria. As such, DNA methylation, dietary folate, and mitochondrial quality control may interact in PD pathogenesis. In this narrative/hypothesis review, we demonstrate how PD is associated with changes in mitochondrial homeostasis, which may, in turn, be improved by folate, potentially altering the epigenetic patterns of immune and inflammatory genes in both the nucleus and mitochondria. Therefore, a folate-based dietary intervention is recommended for PD prevention and as an adjunct therapy. At the same time, further research is needed on the involvement of epigenetic mechanisms in the beneficial effects of folate on PD studies. Full article

Phenolic diterpene carnosic acid (CA) is widely used in the food, nutritional health, and cosmetic industries due to its antioxidative and antimicrobial properties. This work aimed to overproduce CA in Saccharomyces cerevisiae from sugarcane syrup in fed-batch 2 L bioreactor fermentation. A geranylgeranyl diphosphate (GGPP)-producing strain modified with genes encoding the enzymes copalyl diphosphate synthase (Pv.CPS), miltiradiene synthase (Ro.KSL2), hydroxy ferruginol synthase (Ro.HFS), CA synthase (Ro.CYP76AK8), CYP reductase (At.ATR1), and transketolase (TKL1) was used. Lowering the feed rate from 12–26 g/L/h to 7–8 g/L/h, and the use of a dynamic dissolved oxygen (DO) trigger (min. 10%, max. 40%, threshold 70%) instead of a DO trigger of 30%, enhanced CA production by 27%. As a result, the highest CA titer ever reported to date, 191.4 mg/L, was obtained in 4-day fermentation. This study shows the feasibility of engineered yeast to produce CA from the sustainable feedstock sugarcane syrup. Full article

The exopolysaccharides produced by rhizobia play an important role in their biotechnological and bioremediation properties. The characteristics and properties of an exopolysaccharide produced by Rhizobium sp. L01 were investigated. Strain Rhizobium sp. L01 was identified as Rhizobium tropici and produced a high yield of exopolysaccharides (REPS-L01), reaching 22.8 g/L after 63 h of fermentation in a 5 L bioreactor with glucose as the carbon source. REPS-L01 was composed of glucose and galactose in a ratio of 2.95:1, carrying pyruvate, acetate, and succinate groups. REPS-L01 had good shear-thinning properties in aqueous solutions at various concentrations and revealed typical non-crosslinked polymer properties. REPS-L01 revealed thermal stability up to 275 °C. REPS-L01 had the potential to be thicker, being suitable for use under conditions ranging from 4 to 60 °C, pH between 2 and 12, and salt concentrations up to 20,000 mg/L. REPS-L01 showed strong emulsifying activity, particularly with n-hexane; even at concentrations as low as 0.25 wt%, the emulsification index could reach more than 50%. Even more impressively, stable n-hexane emulsion gel was formed with 2 wt% REPS-L01 solution. Rheological studies showed that the solid-like emulsion gel had a high storage modulus, and the SEM studies of the emulsion gel indicated that n-hexane could fill the pores of REPS-L01. Full article

The prion-forming regions (PFRs) of yeast prion proteins are usually located at either the N- or C-terminus of a protein. In the Sup35 prion, the main prion structure contains 71 N-terminal residues. Here, we investigated the importance of the terminal PFR location for prion properties. Two prionogenic sequences of 29 and 30 residues and two random sequences of 23 and 15 residues were added to the Sup35 N-terminus, making the original PFR internal. These proteins were overproduced in yeast with two variants of the Sup35 prion. Mapping of the prion-like structures of these proteins by partial proteinase K digestion showed that in most cases, the extensions acquired an amyloid fold, and, strikingly, the prion structure was no longer present or was substantially altered at its original location. The addition of two to five residues to the Sup35 N-terminus often resulted in prion instability and loss when the respective genes were used to replace chromosomal SUP35. The structures of yeast prions Mot3, Swi1, Lsb2, candidate prions Asm4, Nsp1, Cbk1, Cpp1, and prions based on scrambled Sup35 PFRs were mapped. The mapping showed that the N-terminal location of a QN-rich sequence predisposes to, but does not guarantee, the formation of a prion structure by it and that the prion structure located near a terminus does not always include the actual terminus, as in the cases of Sup35 and Rnq1. Full article

Rhegmatogenous retinal detachment (RRD) is a sight-threatening condition involving retinal detachment and the accumulation of fluid in the subretinal space. Proliferative vitreoretinopathy (PVR) is a pathologic complication that develops after RRD surgery, and approximately 5–10% of RRD cases develop post-operative PVR. Prolonged inflammation in the wound healing process, epithelial–mesenchymal transition (EMT), retinal pigment epithelial (RPE) cell migration and proliferation, and epiretinal, intraretinal, and subretinal fibrosis are typical in the formation of PVR. RPE cells undergo EMT and become fibroblast-like cells that migrate to the retina and vitreous, promoting PVR formation. Fibroblasts transform into myofibroblasts, which promote fibrosis by overproducing the extracellular matrix (ECM). RPE cells, fibroblasts, glial cells, macrophages, T lymphocytes, and increased ECM production form contractile epiretinal membranes. Cytokine release, complement activation, RPE cells, glial cells, and endothelial cells are all involved in retinal immune responses. Normally, wounds heal within 4 to 6 weeks, including hemostasis, inflammation, proliferation, and remodeling phases. Properly initiated inflammation, complement activation, and the function of neutrophils and glial cells heal the wound in the first stage. In a retinal wound, glial cells proliferate and fill the injured area. Gliosis tries to protect the neurons and prevent damage, but it becomes harmful when it causes scarring. If healing is complicated, prolonged inflammation leads to pathological fibrosis. Currently, there is no preventive treatment for the formation of PVR, and it is worth studying in the future. Full article

Sphingan is a crucial exopolysaccharide (EPS) produced by Sphingomonas genus bacteria with wide-ranging applications in fields such as food, medicine, and petroleum. In this study, a novel sphingan, named MT gum, was overproduced from the wild-type strain Sphingomonas sp. MT01 at a yield of 25.6 g/L in a 5 L fermenter for 52 h at 35 °C. The MT gum was mainly composed of D-glucose (65.91%) and L-guluronic acid (30.69%), as confirmed by RP-HPLC, with Mw 7.24 × 10⁵ Da. The MT gum exhibited excellent rheology and pseudoplasticity characteristics while maintaining function in high-temperature and high-salinity environments. The viscosity retention rates of MT gum (0.1%, w/v) were 54.06% (80 °C, 50,000 mg/L salinity) and 34.78% (90 °C, 50,000 mg/L salinity), respectively. The apparent viscosity of MT solutions (0.1%, w/v) was much higher than that of welan solutions under the same conditions. The MT gum also had the property of instant dissolution and completely swelled in 40 min. Meanwhile, the MT gum was resistant to 3–10 mg/L Fe²⁺ in the reservoir conditions, ensuring its application in offshore oil fields. These findings suggested that the biopolymer MT gum produced by the strain MT01 had significant potential in enhanced oil recovery (EOR) of high-temperature and high-salinity oil reservoirs. Full article

Kombucha, a fermented tea beverage, is produced through the symbiotic interaction of several microbial strains, including acetic acid bacteria, lactic acid bacteria, and yeast, collectively known as symbiotic culture of bacteria and yeast (SCOBY). As its health benefits and distinctive flavor gain wider recognition, consumer demand and research on kombucha fermentation have increased. This study focused on developing starter cultures to produce functional kombucha through precision fermentation technology using selected microbial strains newly isolated from food sources. The isolated bacterial and yeast strains were evaluated and selected based on their fermentation characteristics. Notably, a lactic acid bacterial strain was chosen for its ability to overproduce the γ-amino butyric acid (GABA), a functional food component known to enhance cognitive function and reduce mental stress. To produce the GABA-fortified kombucha, selected single strains of Acetobacter pasteurianus, Lactiplantibacillus plantarum, and Saccharomyces cerevisiae were mixed and used as starter cultures. By optimizing the inoculation ratios and initial sugar concentration, a functional kombucha enriched with acetic acid, lactic acid, and GABA was successfully produced. The resulting kombucha demonstrated 2.2 mg/L of GABA production and 1.15 times higher antioxidant activity after the fermentation, highlighting its enhanced health-promoting properties. Full article

Long-term use of the global non-selective herbicide glyphosate for weed control has caused resistance in weeds. Overproducing of the target of glyphosate 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) is one of the resistance mechanisms in weeds. However, few studies have measured the effects on tolerance levels and metabolite content in model plant species overexpressing EPSPS from weeds. We assessed the resistance levels of transgenic Arabidopsis thaliana overexpressing EPSPS from Eleusine indica, and its effects on metabolite content using the method of both quasi-targeted and targeted metabolomics. The results showed that the average resistance index of the transgenic lines was 4.7 and the exogenous E. indica EPSPS expression levels were 265.3- to 532.0-fold higher than those in the wild-type (WT) line. The EPSPS protein ranged from 148.5 to 286.2 μg g⁻¹, which was substantially higher than that in the WT line (9.1 μg g⁻¹). 103 metabolites associated with flavone and flavonol biosynthesis, the metabolism of aromatic amino acids, energy metabolism, and auxin synthesis were significantly higher in the transgenic glyphosate-resistant individuals (R) than in the WT individuals. The results of quantitative analysis show that pyruvate, sedoheptulose 7-phosphate, and gluconic acid amounts in R plants were 1.1-, 1.6- and 1.3-fold higher than those in WT plants, respectively. However, both citric and glyceric acid levels were 0.9-fold lower than those in WT plants. The abundance of other metabolites in the glycolytic and pentose phosphate pathways of central carbon metabolism was similar in the WT and transgenic plants. Glutamic acid was significantly more abundant in the transgenic line than in the WT plants. In contrast, asparagine, glutamine, and lysine were less abundant. However, the concentration of other amino acids did not change significantly. Overexpression of E. indica EPSPS in A. thaliana conferred a moderate level of tolerance to glyphosate. Metabolites associated with flavone and flavonol biosynthesis, the metabolism of aromatic amino acids, and energy metabolism were significantly increased. The results of this study will be useful for evaluating the characterisation and risk assessment of transgenic plants, including identification of unintended effects of the respective transgenic modifications. Full article

The use of lactic acid bacteria for developing functional foods is increasing for their ability to synthesize beneficial metabolites such as vitamin B (riboflavin, RF) and postbiotic compounds. Here, the spontaneous mutant FS54 B2 was isolated by treatment of the dextran-producing Weissella confusa FS54 strain with roseoflavin. FS54 B2 overproduced RF (4.9 mg/L) in synthetic medium. The FMN riboswitch is responsible for the regulation of RF biosynthesis, and sequencing of the coding DNA revealed that FS54 B2 carries the G131U mutation. FS54 B2 retained the capacity of FS54 to synthesize high levels of dextran (3.8 g/L) in synthetic medium. The fermentation capacities of the two Weissella strains was tested in commercial oat-, soy- and rice-based beverages. The best substrate for FS54 B2 was the oat-based drink, in which, after fermentation, the following were detected: RF (2.4 mg/L), dextran (5.3 mg/L), potential prebiotics (oligosaccharides (panose (5.1 g/L), isomaltose (753 mg/L) and isomaltotriose (454 mg/L)) and the antioxidant mannitol (16.3 g/L). pH-lowering ability and cell viability after one month of storage period were confirmed. As far as we know, this is the first time that an RF-overproducing W. confusa strain has been isolated, characterized and tested for its potential use in the development of functional beverages. Full article