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This study investigated high-throughput screening of inhibitors for the key enzyme CitE in the synthesis of red yeast citrinin through computer simulation. First, Alphafold 2 was used to build the homology model of CitE. and it was aligned with similar sequences to predict the ligand binding region. Subsequently, a ligand library of 20 000 compounds was constructed by searching for natural ligands and flavonoid skeleton analogues in the Arthur database. Afterwards, molecular docking of the CitE protein to the library of small molecule compounds was performed using Maestro to select potential CitE ligands. Gromacs kinetic simulation was used to evaluate the binding stability, and the binding free energy was calculated using MM/PBSA. The protein-ligand binding mode was analyzed, confirming that six small molecule ligands including quercetin, luteolin, apigenin, genistein, 5,4’-dihydroxyflavone, and fisetin had strong CitE binding activities. The results from solid and liquid state fermentation showed that the above compounds exhibited significant inhibitory activity against Monascus citrinin production. Specifically, the addition of these compounds in solid state fermentation (20 mg/28 g of dry material) resulted in a reduction of Monascus citrinin production by 42.52%, 48.81%, 32.54%, 32.57%, 21.02%, and 13.67%, respectively, while their addition in liquid state fermentation (0.1 g/L) led to a reduction by 33.77%, 15.58%, 33.33%, 62.34%, 58.87%, and 50.22%, respectively. In summary, this study is of reference significance for establishing an efficient and safe Monasucs fermentation system.

In this study, Lactobacillus paracasei FP02, a strain isolated from pickled Chinese cabbage, was tested for its capability to reduce uric acid in vitro, and its physiological and biochemical characteristics were characterized. Furthermore, the effect of this strain on the serum uric acid level of a hyperuricemic (HUA) rat model was explored. The in vitro results showed that L. paracasei FP02 degraded uric acid and its precursor substances, inosine and guanosine, by 29.10%, 67.09%, and 70.48%, respectively, and inhibited xanthine oxidase (XOD) activity by 64.20%. Simultaneously, this strain could ferment various sugars (alcohols) and exhibited good tolerance to gastric acid and bile salts. The 14-day continuous intragastric administration of freeze-dried L. paracasei FP02 powder reduced the serum uric acid concentration by 49.96% compared to the hyperuricemia model group (P < 0.001), which was established by intragastric administration of potassium oxonate combined with high dietary uric acid. After the treatment, the serum uric acid concentration approached the levels observed in the blank control group. Additionally, in the FP02 treatment group, uric acid excretion in the urine increased, and serum XOD activity was significantly inhibited (P < 0.001). Renal sections showed that renal injury was partially restored in the FP02 treatment group. This study will lay the foundation for the development of L. paracasei FP02 as a potential drug or functional food for preventing HUA.

In this study, the genomes of 19 Latilactobacillus curvatus and 40 L. sakei strains were comparatively analyzed. Average nucleic acid identity (ANI) and genome-wide colinearity indicated that the genomes of L. curvatus and L. sakei had weak nucleotide sequence homology, allowing them to be used as indicators to distinguish the two species. Pangenomes for these species were constructed, whose core gene functions were annotated. The results showed that the core genomes of L. curvatus and L. sakei were mainly involved in their basic metabolism. Analysis of individual genomes of the strains revealed that 1) both L. curvatus and L. sakei contained a wide range of genes encoding glycoside hydrolases, which are abundant genetic resources for catabolizing and metabolizing dietary fiber such as polysaccharides, lactose utilization, and lignocellulose; 2) antibiotic resistance genes were annotated in the genomes of three strains, which originate from horizontal gene transfer; 3) the unique arginine deiminase pathway of L. sakei, the serine dehydratase and guanine deaminase pathways of L. curvatus, and the glutamate decarboxylase pathway of several strains were identified, revealing that the acid tolerance mechanisms of these two species are different; and 4) genes encoding cold stress proteins were discovered, which endow the two species with good cold processing properties. Moreover, the genomes of some L. sakei strains contained gene clusters related to the biosynthesis of lactocin S and condensin. In conclusion, this study established taxonomic criteria for the two species and information on individual differences between their strains, which will provide a basis for the study of the physiological, biochemical, molecular genetic mechanisms of L. curvatus and L. sakei and their industrial applications.

Purpose: To compare the structure and antioxidant activity of arabinoxylan (AX) extracted from wheat bran of different varieties by different methods. Methods: AX was extracted from wheat bran from the cultivars ‘Bainong 207’, ‘Baihan 207’, ‘Guanmai 1’, ‘Huayu 198’ and ‘Huayu 166’ by alkali extraction, ultrasonic-assisted xylanase extraction or ultrasonic-assisted cellulase extraction, and its chemical composition, relative molecular mass, molecular structure, thermal stability and antioxidant activity were determined. Results: Among the three extraction methods, alkali extraction gave higher levels of AX yield and total sugar content, while enzymatic extraction retained polyphenols to a greater extent, which may contribute to the better antioxidant capacity of the AX-rich extract, but reduced the relative molecular mass of AX to a certain extent. The monosaccharide composition of enzymatically extracted AX was significantly different from that of alkali extracted AX, and the glycosidic linkage types in enzymatically extracted AX were more complex. Compared with ultrasonic-assisted cellulase extraction, higher AX yield and total sugar content were obtained using ultrasound-assisted xylanase, while the polyphenol content of AX obtained by ultrasound-assisted cellulase extraction was higher, and monosaccharide composition and glycosidic linkage types were also different between AXs extracted by the two enzymatic methods. In addition, the relative molecular mass, the monosaccharide composition, and the types and proportions of glycosidic linkage of AX extracted from wheat bran of different varieties were different. Conclusion: The structure and activity of AX extracted from wheat bran by alkali extraction, ultrasonic-assisted xylanase extraction and ultrasonic-assisted cellulase extraction were obviously different. Compared with alkali extraction, AX obtained by enzymatic extraction had lower yield and molecular mass, but higher polyphenol content and better antioxidant performance. Compared with ultrasound-assisted cellulase extraction, AX obtained by ultrasound-assisted xylanase extraction had higher yield and total sugar content, but lower polyphenol content. The structure of wheat bran AX varied with different extraction methods and varieties.

This article reports on the successful downhole testing of the prototype permeability logging instrument, developed by the Li Ning Innovation Team of PetroChina. The test was carried out on 3 March 2024 in the Ren 91 standard well in Huabei (North China). In this article, we analysed the instrument characteristics of porosity logging measurement, saturation logging measurement, and permeability logging measurement in three stages of development, as well as the current research status of continuous depth-permeability measurement in the wellbore formations. We highlighted the basic principle of permeability logging measurement with Stoneley waves and pointed out the main challenges in the development of permeability logging measurement devices and on-site application research. [ABSTRACT FROM AUTHOR]

The Neurospora CYT-18 protein substitutes the RNA structural activity in a catalytic RNA and indicates the evolution of nuclear pre-messenger RNA introns from self-splicing introns. The CYT-18 protein exhibits similar functions to the peripheral RNA structure, P5abc, that strengthens the catalytic center of the Tetrahymena ribozyme intron. Both CYT-18 and P5abc RNA attach to overlapping locations in the intron center and initiate analogous conformational alterations related to splicing activity.