Optimization of fermentation conditions for the production of recombinant feruloyl esterase BpFaeT132C-D143C.

Feruloyl esterases (FAEs) are a crucial component of the hemicellulose-degrading enzyme family that facilitates the degradation of lignocellulose while releasing hydroxycinnamic acids such as ferulic acid with high added value. Currently, the low enzyme yield of FAEs is one of the primary factors limiting its application. Therefore, in this paper, we optimized the fermentation conditions for the expression of FAE BpFaeT132C-D143C with excellent thermal stability in Escherichia coli by experimental design. Firstly, we explored the effects of 11 factors such as medium type, isopropyl-ß-D-thiogalactopyranoside (IPTG) concentration, and inoculum size on BpFaeT132C-D143C activity separately by the single factor design. Then, the significance of the effects of seven factors, such as post-induction temperature, shaker rotational speed, and inoculum size on BpFaeT132C-D143C activity, was analyzed by Plackett-Burman design. We identified the main factors affecting the fermentation conditions of E. coli expressing BpFaeT132C-D143C as post-induction temperature, pre-induction period, and post-induction period. Finally, we used the steepest ascent path design and response surface method to optimize the levels of these three factors further. Under the optimal conditions, the activity of BpFaeT132C-D143C was 3.58 U/ml, which was a significant 6.6-fold increase compared to the pre-optimization (0.47 U/ml), demonstrating the effectiveness of this optimization process. Moreover, BpFaeT132C-D143C activity was 1.52 U/ml in a 3-l fermenter under the abovementioned optimal conditions. It was determined that the expression of BpFaeT132C-D143C in E. coli was predominantly intracellular in the cytoplasm. This study lays the foundation for further research on BpFaeT132C-D143C in degrading agricultural waste transformation applications.

Identification of Yeast Strain YA176 for Bio-Purification of Soy Molasses to Produce Raffinose Family Oligosaccharides and Optimization of Fermentation Conditions.

Soybean molasses, which contains high levels of raffinose family oligosaccharides (RFOs) such as stachyose and raffinose, is subjected to a process of bio-purification to remove sucrose while maintaining the RFOs, consequently increasing its value. This study employed morphological observation, physiological and biochemical studies, and molecular biology techniques to identify YA176, a yeast strain renowned for its effective bio-purification of soy molasses. Through single-factor and orthogonal experiments, optimal bio-purification conditions were established. YA176, belonging to Wickerhamomyces anomalus, demonstrated robust growth across a wide range of temperature and pH levels, coupled with remarkable tolerance to glucose, sucrose, and NaCl up to 41.2%, 47.3%, and 10%, respectively. Under these optimized conditions, YA176 efficiently utilized sucrose while preserving 93.3% of raffinose and 78.6% of stachyose, ensuring the retention of functional RFOs. In summary, yeast strain YA176 exhibits exceptional bio-purification abilities, making it an ideal candidate for producing functional RFOs from soy molasses.

Screening of a Saccharomyces cerevisiae Strain with High 3-Methylthio-1-Propanol Yield and Optimization of Its Fermentation Conditions.

3-Methylthio-1-propanol (3-Met) is an important flavor compound in various alcoholic beverages such as Baijiu and Huangjiu. To maintain the content of 3-Met in these alcoholic beverages, it is necessary to screen a micro-organism with high yield of 3-Met from the brewing environment. In this study, the ability of yeast strains from the Baijiu brewing to produce 3-Met was analyzed, aiming to obtain yeast with high-yield 3-Met, and its fermentation conditions were optimized. Firstly, 39 yeast strains were screened using 3-Met conversion medium. The results showed that the majority of the strains from Baijiu brewing sources could produce 3-Met, and nearly half of the strains produced more than 0.5 g/L of 3-Met. Among these, yeast F10404, Y03401, and Y8#01, produced more than 1.0 g/L of 3-Met, with yeast Y03401 producing the highest amount at 1.30 g/L. Through morphological observation, physiological and biochemical analysis, and molecular biological identification, it was confirmed that yeast Y03401 was a Saccharomyces cerevisiae. Subsequently, the optimal fermentation conditions for 3-Met production by this yeast were obtained through single-factor designs, Plackett-Burman test, steepest ascent path design and response surface methodology. When the glucose concentration was 60 g/L, yeast extract concentration was 0.8 g/L, L-methionine concentration was 3.8 g/L, initial pH was 4, incubation time was 63 h, inoculum size was 1.6%, shaking speed was 150 rpm, loading volume was 50 mL/250 mL, and temperature was 26 °C, the content of 3-Met produced by S. cerevisiae Y03401 reached a high level of 3.66 g/L. It was also noteworthy that, in contrast to other study findings, this yeast was able to create substantial amounts of 3-Met even in the absence of L-methionine precursor. Based on the clear genome of S. cerevisiae and its characteristics in 3-Met production, S. cerevisiae Y03401 had broad prospects for application in alcoholic beverages such as Baijiu.

Optimization of High-Density Fermentation Conditions for Saccharomycopsis fibuligera Y1402 through Response Surface Analysis.

Saccharomycopsis fibuligera, which produces enzymes like amylase and protease as well as flavor substances like ß-phenyl ethanol and phenyl acetate, plays a crucial role in traditional fermented foods. However, this strain still lacks a high-density fermentation culture, which has had an impact on the strain's industrial application process. Therefore, this study investigated the optimization of medium ingredients and fermentation conditions for high-density fermentation of S. fibuligera Y1402 through single-factor design, Plackett-Burman design, steepest ascent test, and response surface analysis. The study found that glucose at 360.61 g/L, peptone at 50 g/L, yeast extract at 14.65 g/L, KH2PO4 at 5.49 g/L, MgSO4 at 0.40 g/L, and CuSO4 at 0.01 g/L were the best medium ingredients for S. fibuligera Y1402. Under these conditions, after three days of fermentation, the total colony count reached 1.79 × 108 CFU/mL. The optimal fermentation conditions were determined to be an initial pH of 6.0, an inoculum size of 1.10%, a liquid volume of 12.5 mL/250 mL, a rotation speed of 120 r/min, a fermentation temperature of 21 °C and a fermentation time of 53.50 h. When fermentation was conducted using the optimized medium and conditions, the total colony count achieved a remarkable value of 5.50 × 109 CFU/mL, exhibiting a substantial increase of nearly 31 times the original value in the optimal culture medium. This significant advancement offers valuable insights and a reference for the industrial-scale production of S. fibuligera.

Screening, Identification, and Fermentation Condition Optimization of a High-Yield 3-Methylthiopropanol Yeast and Its Aroma-Producing Characteristics.

A high-yield 3-methylthiopropanol (3-Met) yeast Y1402 was obtained from sesame-flavored Daqu, and it was identified as Saccharomycopsis fibuligera. S. fibuligera Y1402 showed a broad range of growth temperatures and pH, as well as the maximum tolerance to glucose, NaCl, nicotine, and 3-Met at 50% (w/w), 15% (w/v), 1.2 g/L, and 18 g/L, respectively. After optimization using single-factor experiments, a Plackett-Burman design, a steepest ascent test, and a Box-Behnken design, the 3-Met yield reached 4.03 g/L by S. fibuligera Y1402 under the following optimal conditions: glucose concentration of 40 g/L, yeast extract concentration of 0.63 g/L, Tween 80 concentration of 2 g/L, L-methionine concentration of 5 g/L, liquid volume of 25 mL/250 mL, initial pH of 5.3, fermentation temperature of 32 °C, inoculum size of 0.8%, shaking speed of 210 rpm, and fermentation time of 54 h. The fermentation was scaled up to a 3 L fermenter under the optimized conditions, and the yield of 3-Met reached 0.71 g/L. Additionally, an aroma analysis revealed that the flavor substances produced by S. fibuligera Y1402 in sorghum hydrolysate medium was mainly composed of compounds with floral, sweet, creamy, roasted nut, and clove-like aromas. Therefore, S. fibuligera has great potential for application in the brewing of Baijiu and other fermented foods.

The Identification of a Strain for the Biological Purification of Soy Molasses to Produce Functional Soy Oligosaccharides and Optimize Purification Conditions.

Soy molasses is rich in oligosaccharides like sucrose, stachyose, and raffinose, with stachyose and raffinose being functional oligosaccharides. Harnessing soy molasses for the production of functional soy oligosaccharides (FSO) can significantly elevate its value. Biological purification, a method leveraging the selective utilization of different carbon sources by microorganisms, allows for the specific removal of sucrose from soy molasses while preserving stachyose and raffinose, thereby increasing the FSO content. This research identified a yeast named YT312 with strong purification capabilities for soy molasses and optimized the purification conditions. The study revealed that yeast YT312 was Wickerhamomyces anomalus, exhibiting a broad range of growth temperatures and pH levels alongside a high tolerance to glucose, sucrose, and NaCl. Through single-factor and orthogonal experiments, it was established that under specific conditions-0.375% inoculum size, 30 °C fermentation temperature, 150 rpm shaking speed, 10-fold dilution ratio, pH of 7, and 12 h of fermentation-sucrose was completely removed from soy molasses, while functional raffinose and stachyose were retained at rates of 96.1% and 90.2%, respectively. Consequently, W. anomalus YT312 displayed exceptional characteristics for the biological purification of soy molasses and the production of FSO.

Adverse childhood experiences predict internet gaming disorder in university students: the mediating role of resilience.

BACKGROUND: To investigate the relationship between adverse childhood experiences and internet gaming disorder (IGD) and the mediating role of resilience in the relationship between these two factors. METHODS: The adverse childhood experience scale, resilience scale and IGD Scale were administered to 9349 university students. Correlations and mediating effects were calculated among these scores. RESULTS: After controlling for sex and age, significant correlations among adverse childhood experiences, resilience and IGD were observed; resilience was a partial mediator variable in the relationship between adverse childhood experiences and IGD. CONCLUSIONS: The more adverse childhood experiences an individual has, the less their mental toughness and the greater their tendency to become addicted to internet games. Adverse childhood experiences can effectively predict IGD, and the risk of becoming addicted to the internet can be decreased by increasing one's mental toughness.

Microbiological Safety and Quality of Fermented Products.

Fermented foods, which have emerged fortuitously over the course of human development, have become an essential part of human history worldwide [...].

Screening of Yeasts Isolated from Baijiu Environments for Producing 3-Methylthio-1-propanol and Optimizing Production Conditions.

3-Methylthio-1-propanol (3-Met) is widely used as a flavoring substance and an essential aroma ingredient in many foods. Producing 3-Met by microbial transformation is green and eco-friendly. In the present study, one strain, YHM-G, which produced a high level of 3-Met, was isolated from the Baijiu-producing environment. Strain YHM-G was identified as Hyphopichia burtonii according to its morphological properties, physiological and biochemical characteristics, and ribosomal large subunit 26S rRNA gene D1/D2 domain sequence analysis. The optimal conditions for 3-Met production by YHM-G were obtained by single factor design, Plackett-Burman design, steepest ascent path design and response surface methodology as follows: 42.7 g/L glucose, pH 6, 0.9 g/L yeast extract, 6 g/L L-methionine (L-Met), culture temperature 28 °C, shaking speed 210 rpm, loading volume 50 mL/250 mL, inoculum size 0.5% (v/v), culturing period 48 h and 2.5 g/L Tween-80. Under these optimal conditions, the 3-Met production by strain YHM-G was 3.16 g/L, a value 88.1% higher than that before optimization. Strain YHM-G can also produce a variety of flavor compounds that are important for many foods. This strain thus has the potential to increase the abundance of 3-Met in some fermented foods and enhance their aroma profiles.

Production of Xylooligosaccharides from Jiuzao by Autohydrolysis Coupled with Enzymatic Hydrolysis Using a Thermostable Xylanase.

The production of xylooligosaccharides (XOS) from Jiuzao was studied using a two-stage process based on autohydrolysis pretreatment followed by enzymatic hydrolysis. Jiuzao was autohydrolyzed under conditions where temperature, time, particle size, and solid-liquid ratio were varied experimentally. Optimal XOS production was obtained from Jiuzao with a >20 mesh particle size treated at 181.5 °C for 20 min with a 1:13.6 solid-liquid ratio. Subsequently, optimal enzymatic hydrolysis conditions for xylanase XynAR were identified as 60 °C, pH 5, and xylanase XynAR loading of 15 U/mL. Using these conditions, a yield of 34.2% XOS was obtained from Jiuzao within 2 h. The process developed in the present study could enable effective and ecofriendly industrial production of XOS from Jiuzao.