Effect of hydrolyzed soybean on the volatile flavors and microbial community in the traditional brewing process of chi-flavor Baijiu.

Addition of soybean in raw materials could improve the flavor of chi-flavor Baijiu (CFB) in production. For investigating the mechanism of flavor improvement during fermentation, the changes of volatile flavors and their relationship with microbial community were analyzed. The results showed that the average contents of lactic and acetic acid in EG (added with hydrolyzed soybean) samples were higher those of CK (without hydrolyzed soybean) samples. The contents of main volatile esters, including ethyl acetate, ethyl palmitate, and ethyl benzoate, in EG samples were higher than those in CK samples at the end of fermentation. The content of alcohols in EG sample was 140.55 mg/L, higher than that in CK sample at the end of fermentation. Especially, the average content of characteristic flavor ß-phenylethanol in EG samples increased 17.6% in comparison with that in CK samples during fermentation. Lactobacillus and Pediococcus were the dominant bacterial genera, whereas Saccharomyces, Mortierella, and Trichosporon were dominant fungal genera in both CK and EG samples. Lactobacillus and Weissella confusa showed strong positive correlation with ß-phenylethanol, ethyl acetate, and ethyl benzoate. This study provides an in-depth analysis of the effects of hydrolyzed soybeans on the volatile flavor compounds and microbial communities of CFB and theoretical guidance for improving the quality of CFB.

Study on the Influence of CaO on the Electrochemical Reduction of Fe2O3 in NaCl-CaCl2 Molten Salt.

The presence of calcium-containing molten salts in the electrolysis of oxides for metal production can lead to the formation of CaO and, subsequently, the generation of intermediate products, affecting the reduction of metals. To investigate the impact of CaO on the reduction process, experiments were conducted using a Fe2O3-CaO cathode and a graphite anode in a NaCl-CaCl2 molten salt electrolyte at 800 °C. The electrochemical reduction kinetics of the intermediate product Ca2Fe2O5 were studied using cyclic voltammetry and I-t curve analysis. The phase composition and morphology of the electrolysis products were analyzed using XRD, SEM-EDS, and XPS. The experimental results demonstrate that upon addition of CaO to the Fe2O3 cathode, Ca2Fe2O5 is formed instantly in the molten salt upon the application of an electrical current. Research conducted at different voltages, combined with electrochemical analysis, indicates that the reduction steps of Ca2Fe2O5 in the NaCl-CaCl2 molten salt are as follows: Ca2Fe2O5 ⟶ Fe3O4 ⟶ FeO ⟶ Fe. The presence of CaO accelerates the electrochemical reduction rate, promoting the formation of Fe. At 0.6 V and after 600 min of electrolysis, all of the Ca2Fe2O5 is converted into Fe, coexisting with CaCO3. With an increase in the electrolysis voltage, the electrolysis product Fe particles visibly grow larger, exhibiting pronounced agglomeration effects. Under the conditions of a 1 V voltage, a study was conducted to investigate the influence of time on the reduction process of Ca2Fe2O5. Gradually, it resulted in the formation of CaFe3O5, CaFe5O7, FeO, and metallic Fe. With an increased driving force, one gram of Fe2O3-CaO mixed oxide can completely turn into metal Fe by electrolysis for 300 min.

Screening ester-producing yeasts to fortify the brewing of rice-flavor Baijiu for enhanced aromas.

To enhance the aromas in Guangdong rice-flavor Baijiu, ester-producing yeast was selected to fortify Baijiu brewing. Among eight kinds of ester-producing yeasts selected, Saccharomyces cerevisiae CM15 (CM15) that showed both the stronger ability to utilize substrates to produce esters and the excellent tolerance to industrially relevant stress factors was chosen. When CM15 was synergistically fermented with six kinds of Kojis from distilleries of rice-flavor liquor in Guangdong, the enhanced total esters had happened to the liquors brewing with the fortified four kinds of Kojis, especially with Koji F. When Koji F was fortified with CM15, the resultant Baijiu showed a higher esters proportion and a lower higher alcohol ratio than that of Baijiu brewed only with Koji F, with the content of ethyl acetate and ethyl lactate increasing by 25% and 214%, respectively. This study suggested that CM15 can be used as a functional microorganism to fortify Baijiu brewing, which might also be suitable for other traditional fermented foods.

Germicidal effect of intense pulsed light on Pseudomonas aeruginosa in food processing.

Background: Pseudomonas aeruginosa (P. aeruginosa) can cause serious infections in many parts of the body and is also an underestimated foodborne pathogen. Intense pulsed light sterilization is recognized for its high sterilization efficiency, flexible and safe operation and ease of installation on production lines, which makes up for the shortcomings of several other physical sterilization technologies. Methods: This experiment studied the killing efficiency of different capacitances (650 µF, 470 µF, and 220 µF) of intense pulsed light on foodborne pathogenic microorganisms P. aeruginosa in the models of liquid food models, 96-well cell plates, and polycarbonate membrane models at room temperature (25°C) and refrigerated (4°C) environments to provide data to support the application of IPL sterilization devices in food processing. Results: The IPL was very effective in killing P. aeruginosa in the planktonic state as well as in the early and mature biofilm states, meeting target kill rates of 100%, 99.99%, and 94.33% for a given number of exposures. The biofilms formed in the polycarbonate membrane model and the 96-well plate model were more resistant to killing compared to the planktonic state. To achieve the same bactericidal effect, the number of flashes increased with decreasing capacitance. Conclusion: The bactericidal effect of IPL on P. aeruginosa was significantly influenced by the state of the bacterium. The larger the capacitance the higher the number of pulses and the better the sterilization effect on P. aeruginosa.

Enhanced ion-electron mixing interface for high energy solid-state lithium metal batteries.

Solid-state Li metal batteries (SSLMBs) are famous for superior security and excellent energy density. Nevertheless, the poor interfacial contact between solid lithium and electrode is one key problem in the development of SSLMBs, resulting in high impedance and growth of lithium dendrites along the grain boundaries. Herein, an innovative and accessible approach has been applied to SSLMBs, which introduces an ion-electron mixing (IEM) interface on the surface of Li1.3Al0.3Ti1.7(PO4)3 (LATP). The IEM interlayer generates LixSn/LiI of fast lithium-ion conductor through an in-situ reaction. The existence of LiI would promote the quick transmission of Li+ at the interface and inhibit the electronic conduction, thus restraining the growth of lithium dendrites. The batteries with IEM@LATP electrolyte could stably cycle more than 1000 h at high current density of 0.1 mA cm-2. Even increasing the current density to 3.0 mA cm-2, the batteries still could work normally. This novel and viable approach offers a robust basis for the practical application of SSLMBs and has some general applicability to other solid-state batteries.

Characterization and Correlation of Microbiota and Higher Alcohols Based on Metagenomic and Metabolite Profiling during Rice-Flavor Baijiu Fermentation.

Higher alcohol, as an inevitable product of fermentation, plays an important role in the flavor and quality of Baijiu. However, the relationship between the complex microbial metabolism and the formation of higher alcohols in rice-flavor Baijiu was not clear. To investigate the relationship between microorganisms and higher alcohol production, two fermentation mashes inoculated with starters from Heyuan Jinhuangtian Liquor Co., Ltd. (Heyuan, China) as JM and Guangdong Changleshao Co., Ltd. (Meizhou, China) as CM, respectively, with significant differences in higher alcohol profiles during rice-flavor Baijiu fermentation were selected. In general, higher alcohols presented a rapid accumulation during the early fermentation stages, especially in JM, with higher and faster increases than those in CM. As for their precursors including amino acids, pyruvic acid and ketoacids, complex variations were observed during the fermentation. Metagenomic results indicated that Saccharomyces cerevisiae and Rhizopus microsporus were the microorganisms present throughout the brewing process in JM and CM, and the relative abundance of R. microsporus in JM was significantly higher than that in CM. The results of higher alcohol metabolism in JM may contribute to the regulation of higher alcohols in rice-flavor Baijiu.

Cattail-Grass-Derived Porous Carbon as High-Capacity Anode Material for Li-Ion Batteries.

Cattail-grass-derived porous carbon as high-capacity anode materials were prepared via high-temperature carbonization and activation with KOH. The samples exhibited different structures and morphologies with increasing treatment time. It was found that the cattail grass with activation treatment-1 (CGA-1) sample obtained at 800 °C for 1 h presented excellent electrochemical performance. As an anode material for lithium-ion batteries, CGA-1 showed a high charge-discharge capacity of 814.7 mAh g-1 at the current density of 0.1 A g-1 after 400 cycles, which suggests that it has a great potential for energy storage.

Biofilm formation of two genetically diverse Staphylococcus aureus isolates under beta-lactam antibiotics.

Purpose: Our aim was to evaluate the biofilm formation of 2 genetically diverse Staphylococcus aureus isolates, 10379 and 121940, under different concentrations of beta-lactam antibiotics on biomass content and biofilm viability. Methods: Biofilm formation and methicillin resistance genes were tested using PCR and multiplex PCR. PCR was combined with bioinformatics analysis to detect multilocal sequence typing (MLST) and SCCmec types, to study the genetical correlation between the tested strains. Then, the crystal violet (CV) test and XTT were used to detect biomass content and biofilm activity. Antibiotic susceptibility was tested using a broth dilution method. According to their specific MIC, different concentrations of beta-lactam antibiotics were used to study its effect on biomass content and biofilm viability. Results: Strain 10379 carried the icaD, icaBC, and MRSA genes, not the icaA, atl, app, and agr genes, and MLST and SCCmec typing was ST45 and IV, respectively. Strain 121940 carried the icaA, icaD, icaBC, atl, and agr genes, not the aap gene, and MLST and SCCmec typed as ST546 and IV, respectively. This suggested that strains 10379 and 121940 were genotypically very different. Two S. aureus isolates, 10379 and 121940, showed resistance to beta-lactam antibiotics, penicillin, ampicillin, meropenem, streptomycin and kanamycin, some of which promoted the formation of biofilm and biofilm viability at low concentrations. Conclusion: Despite the large differences in the genetic background of S. aureus 10379 and 121940, some sub-inhibitory concentrations of beta-lactam antibiotics are able to promote biomass and biofilm viability of both two isolates.

Effect of Ti on Characterization and Properties of CoCrFeNiTix High Entropy Alloy Prepared Via Electro-Deoxidization of the Metal Oxides and Vacuum Hot Pressing Sintering Process.

The CoCrFeNi system is one of the most important high entropy alloys (HEAs) systems. By adding and adjusting the alloy element components and using different synthesis methods, different phases, organization and microstructure can be obtained, thus improving their properties. In this study, CoCrFeNiTix HEAs with various Ti contents (x in molar ratio, x = 0, 0.5, 1.0, 1.5) were fabricated by an electrochemical process by virtue of different oxides. The impacts of different Ti contents on the structure, distribution of elements, mechanical properties and corrosion behavior were researched using XRD, EDX and other testing methods. The bulk CoCrFeNiTix (x = 0, 0.5, 1.0, 1.5) HEAs could be obtained through vacuum hot pressing sintering process (VHPS), which had a single-phase FCC structure. The results of the study showed that the bulk CoCrFeNiTix exhibited superior ultimate tensile strength (UTS) and hardness, with the UTS of CoCrFeNiTi as high as 783 MPa and the hardness of CoCrFeNiTi1.5 reaching 669 HV. The corrosion behavior of CoCrFeNiTix (x = 0, 0.5, 1.0, 1.5) HEAs in 0.5 M H2SO4, 1 M KOH and 3.5 wt% NaCl was improved with addition of Ti. CoCrFeNiTix (x = 0, 0.5, 1.0, 1.5) HEAs have great potential for application in the fields of biomedical coating and aerospace, as well as extreme military industry, etc.

Effect of Cathode Physical Properties on the Preparation of Fe3Si0.7Al0.3 Intermetallic Compounds by Molten Salt Electrode Deoxidation.

As a new process, molten salt electrolysis is widely used in the preparation of metal materials by in situ reduction in solid cathodes. Therefore, it is meaningful to study the influence of the physical properties of solid cathodes on electrolysis products. In this paper, mixed oxides of Fe2O3-Al2O3-SiO2 were selected as raw materials, and their particle size distribution, pore size distribution, specific surface area, and other physical properties were investigated by mechanical ball milling at different times. The CaCl2-NaCl molten salt system was selected to electrolyze the sintered cathode solid at 800 °C and a voltage of 3.2 V. The experimental results show that with the prolongation of ball-milling time, the particle size of mixed oxide raw materials gradually decreases, the specific surface area gradually increases, the distribution of micropores increases, and the distribution of mesopores decreases. After sintering at 800 °C for 4 h, the volume and particle size of the solid cathode increased, the impedance value gradually decreased, and the pores first increased and then decreased. The electrolysis results showed that the prolongation of the ball-milling time hindered the electrolysis process.

Electrochemical Mechanism of Molten Salt Electrolysis from TiO2 to Titanium.

Electrochemical mechanisms of molten salt electrolysis from TiO2 to titanium were investigated by Potentiostatic electrolysis, cyclic voltammetry, and square wave voltammetry in NaCl-CaCl2 at 800 °C. The composition and morphology of the product obtained at different electrolysis times were characterized by XRD and SEM. CaTiO3 phase was found in the TiO2 electrochemical reduction process. Electrochemical reduction of TiO2 to titanium is a four-step reduction process, which can be summarized as TiO2→Ti4O7→Ti2O3→TiO→Ti. Spontaneous and electrochemical reactions take place simultaneously in the reduction process. The electrochemical reduction of TiO2→Ti4O7→Ti2O3→TiO affected by diffusion was irreversible.

Adaptive mechanism of Lactobacillus amylolyticus L6 in soymilk environment based on metabolism of nutrients and related gene-expression profiles.

Lactobacillus amylolyticus L6 isolated from naturally fermented tofu-whey was characterized as potential probiotics. To give insight into the adaptive mechanism of L. amylolyticus L6 in soymilk, the gene-expression profiles of this strain and changes of chemical components in fermented soymilk were investigated. The viable counts of L. amylolyticus L6 in soymilk reached 1012 CFU/mL in the stationary phase (10 hr). The main sugars reduced gradually while the acidity value significantly increased from 45.33° to 95.88° during fermentation. About 50 genes involved in sugar metabolization and lactic acid production were highly induced during soymilk fermentation. The concentration of total amino acid increased to 668.38 mg/L in the logarithmic phase, and 45 differentially expressed genes (DEGs) in terms of nitrogen metabolism and biosynthesis of amino acid were detected. Other genes related to lipid metabolism, inorganic ion transport, and stress response were also highly induced. Besides, the concentration of isoflavone aglycones with high bioactivity increased from 14.51 mg/L to 36.09 mg/L during the fermentation, and the expression of 6-phospho-ß-glucosidase gene was also synchronously induced. This study revealed the adaptive mechanism of L. amylolyticus L6 in the soymilk-based ecosystem, which gives the theoretical guidance for the application of this strain in other soybean-derived products.

Electrochemical Mechanism of Recovery of Nickel Metal from Waste Lithium Ion Batteries by Molten Salt Electrolysis.

With the widespread use of lithium-ion batteries, the cumulative amount of used lithium-ion batteries is also increasing year by year. Since waste lithium-ion batteries contain a large amount of valuable metals, the recovery of valuable metals has become one of the current research hotspots. The research uses electrometallurgical technology, and the main methods used are cyclic voltammetry, square wave voltammetry, chronoamperometry and open circuit potential. The electrochemical reduction behavior of Ni3+ in NaCl-CaCl2 molten salt was studied, and the electrochemical reduction behavior was further verified by using a Mo cavity electrode. It is determined that the reduction process of Ni3+ in LiNiO2 is mainly divided into two steps: LiNiO2 → NiO → Ni. Through the analysis of electrolysis products under different conditions, when the current value of LiNiO2 is not less than 0.03 A, the electrolysis product after 10 h is metallic Ni. When the current reaches 0.07 A, the current efficiency is 77.9%, while the Li+ in LiNiO2 is enriched in NaCl-CaCl2 molten salt. The method realizes the separation and extraction of the valuable metal Ni in the waste lithium-ion battery.

Enhanced Production of Pterostilbene in Escherichia coli Through Directed Evolution and Host Strain Engineering.

Pterostilbene is a derivative of resveratrol with a higher bioavailability and biological activity, which shows antioxidant, anti-inflammatory, antitumor, and antiaging activities. Here, directed evolution and host strain engineering were used to improve the production of pterostilbene in Escherichia coli. First, the heterologous biosynthetic pathway enzymes of pterostilbene, including tyrosine ammonia lyase, p-coumarate: CoA ligase, stilbene synthase, and resveratrol O-methyltransferase, were successively directly evolved through error-prone polymerase chain reaction (PCR). Four mutant enzymes with higher activities of in vivo and in vitro were obtained. The directed evolution of the pathway enzymes increased the pterostilbene production by 13.7-fold. Then, a biosensor-guided genome shuffling strategy was used to improve the availability of the precursor L-tyrosine of the host strain E. coli TYR-30 used for the production of pterostilbene. A shuffled E. coli strain with higher L-tyrosine production was obtained. The shuffled strain harboring the evolved pathway produced 80.04 ± 5.58 mg/l pterostilbene, which is about 2.3-fold the highest titer reported in literatures.

Study on the Behavior of Electrochemical Extraction of Cobalt from Spent Lithium Cobalt Oxide Cathode Materials.

The molten salt electrochemical method was used to reduce the Co in spent LiCoO2. The reduction mechanism of Co (III) in LiCoO2 was analyzed by cyclic voltammetry, square wave voltammetry, and open circuit potential. The reduction process of Co (III) on Fe electrode was studied in NaCl-CaCl2-LiCoO2 molten salt system at 750 °C. The results show that the reduction process of Co (III) is a two-step reduction: Co (III) → Co (II) → Co (0) and they are all quasi-reversible processes controlled by diffusion. Phase analysis (XRD) shows that Li+ and Cl2- in the molten salt form LiCl electrolysis experiments with different voltages were carried out, which proved the stepwise reduction of Co in LiCoO2.

Cloning and expression of a novel α-galactosidase from Lactobacillus amylolyticus L6 with hydrolytic and transgalactosyl properties.

Lactobacillus amylolyticus L6, a gram-positive amylolytic bacterium isolated from naturally fermented tofu whey (NFTW), was able to hydrolyze raffinose and stachyose for the production of α-galactosidase. The cell-free extract of L. amylolyticus L6 was found to exhibit glycosyltransferase activity to synthesize α-galacto-oligosaccharides (GOS) with melibiose as substrate. The coding genes of α-galactosidase were identified in the genome of L. amylolyticus L6. The α-galactosidase (AglB) was placed into GH36 family by amino acid sequence alignments with other α-galactosidases from lactobacilli. The optimal reaction conditions of pH and temperature for AglB were pH 6.0 and 37°C, respectively. Besides, potassium ion was found to improve the activity of AglB while divalent mercury ion, copper ion and zinc ion displayed different degrees of inhibition effect. Under the optimum reaction condition, AglB could catalyze the synthesis of GOS with degree of polymerization (DP) ≥5 by using 300 mM melibiose concentration as substrate. The maximum yield of GOS with (DP) ≥3 could reach 31.56% (w/w). Transgalactosyl properties made AglB a potential candidate for application in the production of GOS.

A novel process for obtaining pinosylvin using combinatorial bioengineering in Escherichia coli.

Pinosylvin as a bioactive stilbene is of great interest for food supplements and pharmaceuticals development. In comparison to conventional extraction of pinosylvin from plant sources, biosynthesis engineering of microbial cell factories is a sustainable and flexible alternative method. Current synthetic strategies often require expensive phenylpropanoic precursor and inducer, which are not available for large-scale fermentation process. In this study, three bioengineering strategies were described to the development of a simple and economical process for pinosylvin biosynthesis in Escherichia coli. Firstly, we evaluated different construct environments to give a highly efficient constitutive system for enzymes of pinosylvin pathway expression: 4-coumarate: coenzyme A ligase (4CL) and stilbene synthase (STS). Secondly, malonyl coenzyme A (malonyl-CoA) is a key precursor of pinosylvin bioproduction and at low level in E. coli cell. Thus clustered regularly interspaced short palindromic repeats interference (CRISPRi) was explored to inactivate malonyl-CoA consumption pathway to increase its availability. The resulting pinosylvin content in engineered E. coli was obtained a 1.9-fold increase depending on the repression of fabD (encoding malonyl-CoA-ACP transacylase) gene. Eventually, a phenylalanine over-producing E. coli consisting phenylalanine ammonia lyase was introduced to produce the precursor of pinosylvin, trans-cinnamic acid, the crude extraction of cultural medium was used as supplementation for pinosylvin bioproduction. Using these combinatorial processes, 47.49 mg/L pinosylvin was produced from glycerol.

A novel process for obtaining phenylpropanoic acid precursor using Escherichia coli with a constitutive expression system.

Phenylpropanoids are widely used in food supplements, pharmaceuticals, and cosmetics with diverse benefits to human health. Trans-cinnamic acid or p-coumaric acid is usually used as the starting precursor to produce phenylpropanoids. Synthetic bioengineering of microbial cell factories offers a sustainable and flexible alternative method for obtaining these compounds. In this study, a constitutive expression system consisting of Rhodotorula glutinis phenylalanine/tyrosine ammonia lyase was developed to produce a phenylpropanoic acid precursor in Escherichia coli. To improve trans-cinnamic acid and p-coumaric acid production, BioBrick optimization was investigated, causing a 7.2- and 14.2-fold increase in the yield of these compounds, respectively. The optimum strain was capable of de novo producing 78.81 mg/L of trans-cinnamic acid and 34.67 mg/L of p-coumaric acid in a shake flask culture. The work presented here paves the way for the development of a sustainable and economical process for microbial production of a phenylpropanoic acid precursor.

Increased resveratrol production in wines using engineered wine strains Saccharomyces cerevisiae EC1118 and relaxed antibiotic or auxotrophic selection.

Resveratrol is a polyphenolic compound with diverse beneficial effects on human health. Red wine is the major dietary source of resveratrol but the amount that people can obtain from wines is limited. To increase the resveratrol production in wines, two expression vectors carrying 4-coumarate: coenzyme A ligase gene (4CL) from Arabidopsis thaliana and resveratrol synthase gene (RS) from Vitis vinifera were transformed into industrial wine strain Saccharomyces cerevisiae EC1118. When cultured with 1 mM p-coumaric acid, the engineered strains grown with and without the addition of antibiotics produced 8.249 and 3.317 mg/L of trans-resveratrol in the culture broth, respectively. Resveratrol content of the wine fermented with engineered strains was twice higher than that of the control, indicating that our engineered strains could increase the production of resveratrol during wine fermentation.