Adaptive laboratory evolution induces cell wall alterations for succinic acid tolerance in Saccharomyces cerevisiae.

Succinic acid (SA) is a valuable chemical with broad applications; however, its high concentrations can inhibit yeast cells, reducing fermentation efficiency. In this study, adaptive laboratory evolution was used to enhance yeast tolerance to SA, resulting in several strains capable of growing in medium with 40 g/L SA. Subsequently, whole genome sequencing of the evolved strains was conducted to identify beneficial genetic adaptations.

Revealing the Microbial Origins of -Lactoyl Amino Acids in Soy Sauce: Synthesis Conditions, Potential Enzymes, and Utilization Preference.

The flavor contribution of -lactoyl amino acids (Lac-AAs) to soy sauce is gradually gaining attention. However, research on their formation mechanism is limited. In this study, the production of Lac-AAs of 12 species of yeasts commonly detected in soy sauce was investigated, and , , and were identified as key yeasts because of their productivity and high correlation coefficients with peak areas of Lac-AAs ( > 0.

Exploring the practice and attitudes of psychiatrists and psychologists towards patient-targeted googling in China.

Background: Patient-targeted Googling (PTG) is an unavoidable aspect of the internet era, offering both opportunities and risks. However, no PTG studies have been conducted in Asian contexts to date. Additionally, existing research has provided limited exploration of factors influencing PTG practices, particularly regarding the professional differences between psychiatrists and psychologists.

Revealing metabolite profiles in soy sauce and exploring their correlation with umami taste using UPLC-Orbitrap-MS/MS and GC-Tof-MS derivatization.

Soy sauce has a rich base of non-volatile substances, but existing studies are insufficient. This study analyzed the metabolites of 19 Chinese commercial soy sauces by UPLC-Orbitrap-MS/MS and GC-Tof-MS derivatization, and detected 674 and 230 kinds of substances, respectively, that could be grouped into 12 different classes of compounds, such as peptides, amino acid derivatives, organic acids, sugars, sugar alcohols, amino acids and so on. For the first time, 215 dipeptides and 91 amino acid derivatives in soy sauce were analyzed in detail and systematically from the perspective of composition and amino acid structure.

Synthesis, taste characteristics and taste mechanism of N-lactoyl leucine from soy sauce using sensory analysis and UPLC-MS/MS.

Recently, amino acid derivatives gradually gained attention, but studies on N-lactoyl-leucine (Lac-Leu) and N-lactoyl-isoleucine (Lac-Ile) are limited. This study aims to explore the contributions of Lac-Leu and Lac-Ile to soy sauce. Lac-Leu and Lac-Ile were synthesized via enzymatic synthesis method catalyzed by Tgase.

Tailored UPRE2 variants for dynamic gene regulation in yeast.

Genetic elements are foundational in synthetic biology serving as vital building blocks. They enable programming host cells for efficient production of valuable chemicals and recombinant proteins. The unfolded protein response (UPR) is a stress pathway in which the transcription factor Hac1 interacts with the upstream unfolded protein response element (UPRE) of the promoter to restore endoplasmic reticulum (ER) homeostasis.

Effect of fermentation containers on the taste characteristics and microbiota succession of soy sauce.

Modernization of the traditional fermentation industry has been a major trend recently, such as the upgrading of fermentation containers. This study investigated the taste differences and their material basis of soy sauce fermented in tank and pond (SSFT and SSFP), and further explore the key influencing factors of taste. The intensities of umami, kokumi and sour taste in SSFT were weaker than SSFP, which were associated with 9 basic taste-active compounds, including acetic acid, lactic acid, propanedioic acid, citric acid, glutamic acid, alanine, tyrosine, d-galactose and erythritol.

Decoding temperature-driven microbial community changes and flavor regulation mechanism during winter fermentation of soy sauce.

The flavor regulation of soy sauce fermented in winter is imminent challenge for the industry, while fermentation temperature is considered as an effective method to fortify soy sauce flavor. Thus, industrial-level fermentation systems with controlled temperature at 30°C (SSCT) and regular temperature (SSRT) in winter were designed to elucidate molecular basis and microbial regulatory mechanism of temperature-controlled flavor enhancement of soy sauce. Sensory evaluation suggested 30°C fermentation enhanced caramel-like, floral, fruity, roasted nut and smoky aroma.

Exploration of optimal preparation strategy of Chenpi (pericarps of Citrus reticulata Blanco) flavouring essence with great application potential in sugar and salt-reduced foods.

To obtain flavouring essence with application potential in sugar and salt-reduced foods, the optimal strategy for extraction and microencapsulation of essential oil (EO) from Chenpi was investigated. UPLC-QTOF-MS/MS and liquid-liquid-extraction-GC-MS confirmed the selectivity for volatiles ranked in hydrodistillation > supercritical fluid extraction > solvent extraction. The aroma characteristic of Chenpi EO was distinguished by 33 key volatiles (screened out via headspace-SPME-GC-MS) and quantitative descriptive analysis.

Enhancing Sensation and Reducing Bitterness in Acid-Hydrolyzed Vegetable Proteins through Lactate and Thermal Processing.

Previous studies have demonstrated that thermal processing in the presence of lactate and amino acids can produce taste-active -lactoyl amino acids. This study aimed to investigate the impact of lactate and thermal processing on the sensory characteristics of acid-hydrolyzed vegetable proteins (aHVP). The results showed that the processed aHVP exhibited enhanced , a milder umami taste, and reduced bitterness on treatment with 1% lactate at 110 °C for 3 h or 3% lactate at 120 °C for 2 h compared to the unprocessed samples.

Preparation and Kokumi Properties of N-Acetyl-Val/Leu/Ile/Met/Phe in the Presence of Acetic Acid and Amino Acid: A Commercially Available Transglutaminase and Protease A 2SD.

Kokumi is a beneficial feeling for the evaluation of food quality, and thus, preparing and understanding the taste properties of kokumi compounds are important for the flavor of food. N-acetyl-Val/Leu/Ile/Met/Phe/Trp/Tyr is a type of kokumi compound found in food and usually prepared by chemical reagents. In this study, we first prepared these six kokumi compounds using transglutaminase and protease A2SD in aqueous solution by using amino acids and acetic acid as substrates and evaluated their kokumi characteristics.

Exploring the core functional microbiota related with flavor compounds in fermented soy sauce from different sources.

Flavor, the most important quality index of soy sauce, is mostly influenced by the microbiota in fermented food ecosystem, however, the association between microorganisms and soy sauce flavor is still poorly understood. Therefore, the bacterial and fungal profiles, physicochemical parameters, and flavor compounds (9 organic acids, 17 free amino acids and 97 volatile flavor compounds) of 5 different source soy sauce were investigated using high-throughput sequencing, HPLC, amino acid analyzer and SPME/LLE-GC-MS, and their correlations were explored. A total of 3 fungal genera and 12 bacterial genera were identified as potential flavor-producing microorganisms by multivariate data and correlation analysis.

KokumiEnhancing Mechanism of -l-lactoyl-l-Met Elucidated by Sensory Experiments and Molecular Simulations.

Recent research indicates that -lactoyl amino acid derivatives have the potential as kokumi substances, with their kokumi profile closely linked to that of amino acids. This study aimed to explore the unexplored effects resulting from the introduction of lactate groups into l-Methional (l-Met), a prevalent flavor compound found in foods, such as tomatoes, known for its ability to activate the monosodium glutamate response. -l-Lac-l-Met was enzymatically synthesized using food grade, and its taste profile and underlying mechanisms were investigated.

Improved protein production in yeast using cell engineering with genes related to a key factor in the unfolded protein response.

The yeast Saccharomyces cerevisiae is a widely used cell factory for protein production. Increasing the protein production capacity of a yeast strain may be beneficial for obtaining recombinant proteins as a product or exerting its competence in consolidated bioprocessing. However, heterologous protein expression usually imposes stress on cells.

Six categories of amino acid derivatives with potential taste contributions: a review of studies on soy sauce.

During the fermentation of soy sauce, the metabolism of microorganisms and the Maillard reaction produce a wide variety of metabolites that contribute to the unique and rich flavor characteristics of soy sauce, such as amino acids, organic acids and peptides. Amino acid derivatives, a relatively new taste compounds, formed by the reaction of enzymes or non-enzymes from sugars, amino acids, and organic acids released through metabolism by microorganisms during soy sauce fermentation, have begun to gain more and more attention in recent years. This review focused on our existing knowledge of the sources, taste characteristics and synthesis methods of the 6 categories of amino acid derivatives, including Amadori compounds, γ-glutamyl peptides, pyroglutamyl amino acids, N-lactoyl amino acids, N-acetyl amino acids and N-succinyl amino acids.

Discovery of -l-Lactoyl-l-Trp as a Bitterness Masker via Structure-Based Virtual Screening and a Sensory Approach.

-Lactoyl-amino acid derivatives (-Lac-AAs) are of increasing interest as potential taste-active compounds. The complexity and diversity of -Lac-AAs pose a significant challenge to the effective discovery of taste-active -Lac-AAs. Therefore, a structure-based virtual screening was used to identify taste-active -Lac-AAs.

Comprehensive Analysis of Signal Peptides in Saccharomyces cerevisiae Reveals Features for Efficient Secretion.

Signal peptides (SPs) are N-terminus sequences on the nascent polypeptide for protein export or localization delivery, which are essential for maintaining cell function. SPs are also employed as a key element for industrial production of secreted recombinant proteins. Yet, detailed information and rules about SPs and their cellular interactions are still not well understood.

Quantitative studies, taste recombination, and omission experiments on the key taste compounds in Chinese and Japanese soy sauce.

The non-volatile compounds in Chinese soy sauce (CSS) and Japanese soy sauce (JSS) were qualitatively and quantitatively identified by amino acid analyser and gas-chromatography mass-spectrometry combined with derivatization method (DER-GC-MS). Forty-nine compounds were identified, including 19 amino acids, 8 sugars, 6 sugar alcohols, 8 organic acids and 8 others. Six groups of taste compounds were added to the water at natural concentration in soy sauce were able to reconstitute taste models of CSS and JSS, with no remarkable differences from the soy sauce taste profiles.

Flavor differences of soybean and defatted soybean fermented soy sauce and its correlation with the enzyme profiles of the kojis.

Background: Soybeans and defatted soybeans, commonly used as protein ingredients, have different flavors of their fermented soy sauce. Clarifying the differences between the two soy sauces, as well as the formation mechanism, is an important prerequisite for improving the flavor of defatted soybean soy sauce. To this goal, the aroma characteristics of two soy sauces and their volatile profiles were compared by sensory evaluation and gas chromatography-mass spectrometry, and eight enzyme activities and volatile profiles of matured koji were determined.

Secretion of collagenases by Saccharomyces cerevisiae for collagen degradation.

Background: The production and processing of animal-based products generates many collagen-rich by-products, which have received attention both for exploitation to increase their added value and to reduce their negative environmental impact. The collagen-rich by-products can be hydrolyzed by collagenases for further utilization. Therefore, collagenases are of benefit for efficient collagen materials processing.

Community structure of yeast in fermented soy sauce and screening of functional yeast with potential to enhance the soy sauce flavor.

Yeast plays an important role in the formation of desirable aroma during soy sauce fermentation. In this study, the structure and diversity of yeast communities in seven different soy sauce residues were investigated by ITS sequencing analysis, and then the aroma characteristics of selected yeast species were examined by a combination of gas chromatography-mass spectrometry (GC-MS), headspace solid-phase microextraction (SPME) and liquid-liquid extraction (LLE). A total of 18 yeast genera were identified in seven soy sauce residues.