Advances in the understanding of the production, modification and applications of xylanases in the food industry.

Xylanases have broad applications in the food industry to decompose the complex carbohydrate xylan. This is applicable to enhance juice clarity, improve dough softness, or reduce beer turbidity. It can also be used to produce prebiotics and increase the nutritional value in foodstuff. However, the low yield and poor stability of most natural xylanases hinders their further applications. Therefore, it is imperative to explore higher-quality xylanases to address the potential challenges that appear in the food industry and to comprehensively improve the production, modification, and utilization of xylanases. Xylanases, due to their various sources, exhibit diverse characteristics that affect production and activity. Most fungi are suitable for solid-state fermentation to produce xylanases, but in liquid fermentation, microbial metabolism is more vigorous, resulting in higher yield. Fungi produce higher xylanase activity, but bacterial xylanases perform better than fungal ones under certain extreme conditions (high temperature, extreme pH). Gene and protein engineering technology helps to improve the production efficiency of xylanases and enhances their thermal stability and catalytic properties.

Research on pear residue dietary fiber and Monascus pigments extracted through liquid fermentation.

Pear residue, a byproduct of pear juice extraction, is rich in soluble sugar, vitamins, minerals, and cellulose. This study utilized Monascus anka in liquid fermentation to extract dietary fiber (DF) from pear residue, and the structural and functional characteristics of the DF were analyzed. Soluble DF (SDF) content was increased from 7.9/100 g to 12.6 g/100 g, with a reduction of average particle size from 532.4 to 383.0 nm by fermenting with M. anka. Scanning electron microscopy and infrared spectroscopic analysis revealed more porous and looser structures in Monascus pear residue DF (MPDF). Water-, oil-holding, and swelling capacities of MPDF were also enhanced. UV-visible spectral analysis showed that the yield of yellow pigment in Monascus pear residue fermentation broth (MPFB) was slightly higher than that in the Monascus blank control fermentation broth. The citrinin content in MPFB and M. anka seed broth was 0.90 and 0.98 ug/mL, respectively. Therefore, liquid fermentation with M. anka improved the structural and functional properties of MPDF, suggesting its potential as a functional ingredient in food.

Deciphering layer formation in Red Heart Qu: A comprehensive study of metabolite profile and microbial community influenced by raw materials and environmental factors.

Environmental-origin microbiota significantly influences Red Heart Qu (RH_Qu) stratification, but their microbial migration and metabolic mechanisms remain unclear. Using high-throughput sequencing and metabolomics, we divided the stratification of RH_Qu into three temperature-based stages. Phase I features rising temperatures, causing microbial proliferation and a two-layer division. Phase II, characterized by peak temperatures, sees the establishment of thermotolerant species like Bacillus, Thermoactinomyces, Rhodococcus, and Thermoascus, forming four distinct layers and markedly altering metabolite profiles. The Huo Quan (HQ), developing from the Pi Zhang (PZ), is driven by the tyrosine-melanin pathway and increased MRPs (Maillard reaction products). The Hong Xin evolves from the Rang, associated with the phenylalanine-coumarin pathway and QCs (Quinone Compounds) production. Phase III involves the stabilization of the microbial and metabolic profile as temperatures decline. These findings enhance our understanding of RH_Qu stratification and offer guidance for quality control in its fermentation process.

Integrated characterization of filler tobacco leaves: HS-SPME-GC-MS, E-nose, and microbiome analysis across different origins.

This study delves into the aroma characteristics and microbial composition of filler tobacco leaves (FTLs) sourced from six distinct cigar-growing regions within Yunnan, China, following standardized fermentation. An integrated approach using gas chromatography-mass spectrometry (GC-MS), electronic nose (E-nose), and microbiome analysis was employed for comprehensive profiling. Results derived from Linear Discriminant Analysis (LDA) using E-nose data confirmed the presence of notable variability in flavor substance profiles among the FTLs from six regions. Additionally, GC-MS was used to discern disparities in volatile organic compound (VOC) distribution across FTLs from these regions, identifying 92, 81, 79, 58, 69, and 92 VOCs within each respective sample set. Significantly, 24 VOCs emerged as pivotal determinants contributing to the heterogeneity of flavor profiles among FTLs from diverse origins, as indicated by Variable Importance for the Projection (VIP) analysis. Furthermore, distinctions in free amino acid content and chemical constituents were observed across FTLs. Of noteworthy significance, solanone, isophorone, durene, (-)-alpha-terpineol, and 2,3'-bipyridine exhibited the strongest correlations with microbiome data, with fungal microorganisms exerting a more pronounced influence on metabolites, as elucidated through two-way orthogonal partial least-squares (O2PLS) modeling. These findings provide a theoretical and technical basis for accurately evaluating the synchronization of FTLs in aromas and fermentation processes, and they will enhance the quality of fermented FTLs and foster the growth of the domestic cigar tobacco industry ultimately.

Analysis of metabolic differences between Jiaosu fermented from dendrobium flowers and stems based on untargeted metabolomics.

Dendrobium officinale is an important traditional Chinese medicinal herb containing bioactive polysaccharides and alkaloids. This study characterized metabolite differences between jiaosu (fermented plant product) from Dendrobium flowers versus stems using untargeted metabolomics. The jiaosu was fermented by mixed fermentation of Saccharomyces cerevisiae, Lactobacillus bulgaricus and Streptococcus thermophilus. Liquid chromatography-mass spectrometry analysis identified 476 differentially expressed metabolites between the two Jiaosu products. Key results showed downregulation of flavonoid metabolism in Dendrobium Stems Edible Plant Jiaosu (SEP) but increased flavonoid synthesis in Dendrobium Flowers Edible Plant Jiaosu (FEP), likely an antioxidant response. SEP displayed upregulation of lignin metabolites with potential antioxidant properties. The findings demonstrate significant metabolite profile differences between SEP and FEP, providing the basis for developing functional jiaosu products targeting specific health benefits.

Enhancing simultaneous saccharification and co-fermentation of corncob by Kluyveromyces marxianus through overexpression of putative transcription regulator.

Overexpression of a gene with unknown function in Kluyveromyces marxianus markedly improved tolerance to lignocellulosic biomass-derived inhibitors. This overexpression also enhanced tolerance to elevated temperatures, ethanol, and high concentrations of NaCl and glucose. Inhibitor degradation and transcriptome analyses related this K. marxianusMultiple Stress Resistance (KmMSR) gene to the robustness of yeast cells. Nuclear localization and DNA-binding domain analyses indicate that KmMsr is a putative transcriptional regulator. Overexpression of a mutant protein with deletion in the flexible region between amino acids 100 and 150 further enhanced tolerance to multiple inhibitors during fermentation, with ethanol production and productivity increasing by 36.31 % and 80.22 %, respectively. In simultaneous saccharification co-fermentation of corncob without detoxification, expression of KmMSR with the deleted flexible region improved ethanol production by 5-fold at 42 °C and 2-fold at 37 °C. Overexpression of the KmMSR mutant provides a strategy for constructing robust lignocellulosic biomass using strains.

Correlation study on microbial communities and volatile flavor compounds in cigar tobacco leaves of diverse origins.

To elucidate the significant influence of microorganisms on geographically dependent flavor formation by analyzing microbial communities and volatile flavor compounds (VFCs) in cigar tobacco leaves (CTLs) obtained from China, Dominica, and Indonesia. Microbiome analysis revealed that the predominant bacteria in CTLs were Staphylococcus, Aerococcus, Pseudomonas, and Lactobacillus, while the predominant fungi were Aspergillus, Wallemia, and Sampaiozyma. The microbial communities of CTLs from different origins differed to some extent, and the diversity and abundance of bacteria were greater than fungi. Metabolomic analysis revealed that 64 VFCs were identified, mainly ketones, of which 23 VFCs could be utilized to identify the geographical origins of CTLs. Sixteen VFCs with OAV greater than 1, including cedrol, phenylacetaldehyde, damascone, beta-damascone, and beta-ionone, play important roles in shaping the flavor profile of CTLs from different origins. Combined with the correlation analysis, bacterial microorganisms were more closely related to key VFCs and favored a positive correlation. Bacillus, Vibrio, and Sphingomonas were the main flavor-related bacteria. The study demonstrated that the predominant microorganisms were essential for the formation of key flavor qualities in CTLs, which provided a theoretical reference for flavor control of CTLs by microbial technology. KEY POINTS: • It is the high OAV VFCs that determine the flavor profile of CTLs. • The methylerythritol phosphate (MEP) pathway and the carotenoid synthesis pathway are key metabolic pathways for the formation of VFCs in CTLs. • Microbial interactions influence tobacco flavor, with bacterial microorganisms contributing more to the flavor formation of CTLs.

Analyzing microbial community and volatile compound profiles in the fermentation of cigar tobacco leaves.

Variations in industrial fermentation techniques have a significant impact on the fermentation of cigar tobacco leaves (CTLs), consequently influencing the aromatic attributes of the resulting cigars. The entire fermentation process of CTLs can be categorized into three distinct phases: phase 1 (CTLs prior to moisture regain), phase 2 (CTLs post-moisture regain and pile fermentation), and phase 3 (CTLs after fermentation and drying). These phases were determined based on the dynamic changes in microbial community diversity. During phase 2, there was a rapid increase in moisture and total acid content, which facilitated the proliferation of Aerococcus, a bacterial genus capable of utilizing reducing sugars, malic acid, and citric acid present in tobacco leaves. In contrast, fungal microorganisms exhibited a relatively stable response to changes in moisture and total acid, with Aspergillus, Alternaria, and Cladosporium being the dominant fungal groups throughout the fermentation stages. Bacterial genera were found to be more closely associated with variations in volatile compounds during fermentation compared to fungal microorganisms. This association ultimately resulted in higher levels of aroma components in CTLs, thereby improving the overall quality of the cigars. These findings reinforce the significance of industrial fermentation in shaping CTL quality and provide valuable insights for future efforts in the artificial regulation of secondary fermentation in CTLs. KEY POINTS: • Industrial fermentation processes impact CTLs microbial communities. • Moisture and total acid content influence microbial community succession in fermentation. • Bacterial microorganisms strongly influence CTLs' aldehyde and ketone flavors over fungi.

Antifungal mechanism of rose, mustard, and their blended essential oils against Cladosporium allicinum isolated from Xinjiang naan and its storage application.

AIMS: To reveal the inhibition mechanism of rose, mustard, and blended essential oils against Cladosporium allicinum isolated from Xinjiang naan, and investigate the effect of the three essential oils on oxidative damage and energy metabolism. METHODS AND RESULTS: Rose and mustard essential oils significantly inhibited mycelial growth and spore viability in a dose-dependent relationship. After essential oil treatment, the cell membrane permeability was altered, and significant leakage of intracellular proteins and nucleic acids occurred. SEM observations further confirmed the disruption of cell structure. ROS, MDA, and SOD measurements indicated that essential oil treatment induced a redox imbalance in C. allicinum, leading to cell death. As for energy metabolism, essential oil treatment significantly reduced Na+K+-ATPase, Ca2+Mg2+-ATPase, MDH activity, and CA content, impairing metabolic functions. Finally, storage experiments showed that all three essential oils ensured better preservation of naan, with mustard essential oil having the best antifungal effect. CONCLUSIONS: Rose and mustard essential oils and their blends can inhibit C. allicinum at multiple targets and pathways, destroying cell morphological structure and disrupting metabolic processes.

Effect of Caproicibacterium lactatifermentans inoculation on the microbial succession and flavor formation of pit mud used in Chinese Baijiu fermentation.

Caproicibacterium lactatifermentans is a major caproate-producing bacterium in high-quality pit mud and has an impact on the synthesis of fatty acids during Baijiu fermentation. To develop an effective method for cultivating high-quality pit mud, we explored the role of Caproicibacterium lactatifermentans inoculation. The inoculation resulted in a high level of Caproicibacterium lactatifermentans (29.16%) and fortified pit mud produced abundant fatty acids and ethyl esters in short-term usage. Rare microbes, such as Hazenella coriacea, promoted the production of fatty acids. After long-term usage, changes in physicochemical properties led to a decrease in caproate-producing bacterium, namely Clostridium and Caproicibacterium, and an increase in microbes with limited fatty acid biosynthesis capability, including Proteiniphilum, Fastidiosipila, and Caldicoprobacter. These alterations ultimately led to a decrease in fatty acids and ethyl esters. In summary, Caproicibacterium lactatifermentans inoculation exhibited positive outcomes in obtaining high-quality pit mud. However, the maintenance of functional microbes necessitates further investigation.

Unveiling malic acid biorefinery: Comprehensive insights into feedstocks, microbial strains, and metabolic pathways.

The over-reliance on fossil fuels and resultant environmental issues necessitate sustainable alternatives. Microbial fermentation of biomass for malic acid production offers a viable, eco-friendly solution, enhancing resource efficiency and minimizing ecological damage. This review covers three core aspects of malic acid biorefining: feedstocks, microbial strains, and metabolic pathways. It emphasizes the significance of utilizing biomass sugars, including the co-fermentation of different sugar types to improve feedstock efficiency. The review discusses microbial strains for malic acid fermentation, addressing challenges related to by-products from biomass breakdown and strategies for overcoming them. It delves into the crucial pathways and enzymes for malic acid production, outlining methods to optimize its metabolism, focusing on enzyme regulation, energy balance, and yield enhancement. These insights contribute to advancing the field of consolidated bioprocessing in malic acid biorefining.

Study on cardiovascular monitoring and diagnosis of athletes / Estudo de monitoramento cardiovascular e diagnóstico de atletas / Estudio de monitoreo cardiovascular y diagnóstico de atletas

ABSTRACT Introduction: The study and collection of athletes' heart function index parameters and the correct and reasonable evaluation of body functions can effectively adjust training plans and avoid athletes' bodily exhaustion. Objective: To study the diagnosis of myocardial injury by cardiovascular monitoring in athletes from two aspects: extraction of characteristic parameters of heart function and research of signal processing. Methods: The heart function intelligent evaluation algorithm was studied by using multi-source information fusion, and embedded technology; miniature sensors were used as well. Results: The incidence of severe ventricular arrhythmia was lower in both groups. The incidence of sinus arrhythmia and intermittent second degree I atrioventricular block in the high-intensity group was significantly higher than that in the control group. The number of atrial and ventricular premature beats was lower in the control group, but increased significantly in the high-intensity group. Conclusions: This study applied the theory of multi-source information fusion to carry out representative research on the intelligent monitoring and evaluation of the heart function of elite athletes, centering on the application requirements of the heart function monitoring of elite athletes. Level of evidence II; Therapeutic studies - investigation of treatment results.

RESUMO Introdução: O estudo e a coleta de parâmetros indiciais da função cardíaca em atletas e a avaliação correta e razoável das funções corporais podem, efetivamente, levar ao ajuste de planos de treinamento e evitar a sobrecarga física de atletas. Objetivo: Estudar o diagnóstico da lesão miocárdica pelo monitoramento cardiovascular em atletas a partir de dois aspectos: a extração de parâmetros característicos da função cardíaca e a pesquisa do processamento de sinais. Métodos: O algoritmo de avaliação inteligente da função cardíaca foi estudado usando a fusão de informações de múltiplas fontes, além da tecnologia embarcada. Sensores em miniatura também foram usados. Resultados: A incidência de arritmia ventricular severa era menor nos dois grupos. A incidência de arritmia sinusal e o bloqueio atrioventricular de segundo grau do tipo I intermitente no grupo de alta intensidade foi significativamente mais alta do que no grupo de controle. O número de batidas prematuras atriais e ventriculares era menor no grupo de controle, mas aumentava consideravelmente no grupo de alta intensidade. Conclusões: Este estudo aplicou a teoria da fusão de informações de múltiplas fontes para conduzir uma pesquisa importante sobre o monitoramento e avaliação inteligentes da função cardíaca de atletas de elite, enfocando as exigências de aplicação do monitoramento da função cardíaca de atletas de elite. Nível de evidência II; Estudos terapêuticos - investigação de resultados de tratamento.

RESUMEN Introducción: El estudio y la recogida de parámetros indíciales de la función cardíaca en atletas y la evaluación correcta y razonable de las funciones corporales pueden efectivamente llevar al ajuste de planes de entrenamiento y evitar la sobrecarga física de atletas. Objetivo: Estudiar el diagnóstico de la lesión miocárdica a través del monitoreo cardiovascular en atletas a partir de dos aspectos: la extracción de parámetros característicos de la función cardíaca y la investigación del procesamiento de señales. Métodos: El algoritmo de evaluación inteligente de la función cerebral se estudió utilizando la fusión de informaciones de múltiples fuentes, además de la tecnología embebida. Sensores en miniatura también se utilizaron. Resultados: La incidencia de taquicardia ventricular severa era menor en los dos grupos. La incidencia de arritmia sinusal y bloqueo auriculoventricular de segundo grado del tipo I intermitente en el grupo de alta intensidad fue significativamente más alta que en el grupo de control. El número de contracciones prematuras auriculares y ventriculares era menor en el grupo de control, pero aumentaba considerablemente en el grupo de alta intensidad. Conclusiones: Este estudio aplicó la teoría de la fusión de informaciones de múltiples fuentes para conducir una investigación importante sobre el monitoreo y evaluación inteligentes de la función cardiaca de atletas de élite, centrando las exigencias de aplicación del monitoreo de la función cardíaca de atletas de élite. Nivel de evidencia II; Estudios terapéuticos - investigación de resultados de tratamiento.