BACKGROUND:Talus cartilage injury is a common motor system disease.This type of injury will affect the patient's daily life and work ability,and may worsen the condition if left untreated.Surgical treatment is commonly used,but the selection of surgical methods and the evaluation of medium-and long-term follow-up results have always been difficult clinical problems. OBJECTIVE:To explore the influence of T1ρ technique on the range of quantitative evaluation of talus osteochondral injury on the choice of surgical method and the results of medium-and long-term follow-up. METHODS:A total of 154 patients with osteochondral injury of talus admitted to The Second Hospital of Tangshan from January 2019 to August 2022 were retrospectively selected as the study subjects.The lesion site of talus was examined by MRI before operation,and the T1ρ and T2 values of different types were compared.Different surgical methods were selected according to the different T1ρ values.Group A(n=73)was treated with microfracture surgery with T1ρ<45 ms;group B(n=81)was treated with autogenous bone and cartilage transplantation with T1ρ≥45 ms.The general clinical characteristics and curative effects of patients under different surgical methods were compared;the important factors of postoperative recurrence were analyzed by multivariate Logistic regression,and the relationship between T1ρ value and postoperative recurrence was analyzed by restricted cubic spline graph,y=1-1/(1+e-z)regression equation to build a prediction model.The stability of the model was verified by cross-checking method. RESULTS AND CONCLUSION:(1)Classification of talus osteochondral injury in 154 patients(type Ⅰ:36 cases;type Ⅱ:37 cases;type Ⅲ:40 cases;type Ⅳ:41 cases),T1ρ and T2 values of the four groups were statistically significant(P<0.05);pairwise comparison was also statistically significant(all P<0.05).(2)After treatment of 154 patients,7 cases(4.6％)had local swelling,3 cases(2.0％)had pain aggravation,and 5 cases(3.3％)had wound infection.There were 2 cases(1.3％)with poor cartilage healing.(3)After treatment,there were statistically significant differences between groups A and B in terms of American Orthopaedic Foot&Ankle Society score,visual analog scale score,plantar flexor motion range,dorsoextension motion range,subchondral bone marrow edema volume,interleukin-6,interleukin-8,C-reactive protein,procalcitonin,platelet-derived growth factor,transforming growth factor-β1,and efficacy(P<0.05).The total effective rate of group B(90％)was higher than that of group A(85％)(P<0.05).(4)Age(OR=1.589,95％CI:0.305-1.252,P=0.036),interleukin-6(OR=1.737,95％CI:0.974-5.254,P=0.049),interleukin-8(OR=1.385,95％CI:1.066-4.355,P=0.034),C-reactive protein(OR=1.957,95％CI:1.323-2.178,P=0.035),transforming growth factor-β1(OR=1.459,95％CI:0.897-2.455,P=0.038),T1-ρ(OR=1.687,95％CI:0.854-3.321,P=0.026),T2(OR=1.843,95％CI:0.657-2.454,P=0.036),complications(OR=1.719,95％CI:0.654-3.464,P=0.019),and classification of osteochondral injury of talus(OR=3.789,95％CI:1.023-5.897,P=0.028)were independent risk factors for postoperative recurrence.Microfracture surgery(OR=0.751,95％CI:0.321-1.264,P=0.012)and autogenous bone and cartilage grafting(OR=0.649,95％CI:0.246-1.356,P=0.023)were independent protective factors for recurrence after medium-and long-term follow-up.(5)When T1ρ value≤35 ms,the risk of postoperative recurrence decreased rapidly,and when T1ρ value>35 ms,the risk of postoperative recurrence increased rapidly.(6)Further stepwise regression analysis showed that these nine risk factors were most closely associated with postoperative recurrence,and the formula for postoperative recurrence was obtained.The probability of postoperative recurrence was calculated using the regression equation.When P=0.75,the maximum value of Jorden index was 77.728,indicating that the model has a better prediction effect.(7)It is indicated that the quantitative evaluation of T1ρ before operation can effectively guide the selection of surgical methods,improve the success rate of surgery and the quality of life of patients.

Functional membrane microdomains (FMMs) that are mainly composed of scaffold proteins and polyisoprenoids play important roles in diverse cellular physiological processes in bacteria. The aim of this study was to identify the correlation between MK-7 and FMMs and then regulate the MK-7 biosynthesis through FMMs. Firstly, the relationship between FMMs and MK-7 on the cell membrane was determined by fluorescent labeling. Secondly, we demonstrated that MK-7 is a key polyisoprenoid component of FMMs by analyzing the changes in the content of MK-7 on cell membrane and the changes in the membrane order before and after destroying the integrity of FMMs. Subsequently, the subcellular localization of some key enzymes in MK-7 synthesis was explored by visual analysis, and the intracellular free pathway enzymes Fni, IspA, HepT and YuxO were localized to FMMs through FloA to achieve the compartmentalization of MK-7 synthesis pathway. Finally, a high MK-7 production strain BS3AT was successfully obtained. The production of MK-7 reached 300.3 mg/L in shake flask and 464.2 mg/L in 3 L fermenter.
Bacillus subtilis/metabolism* ; Vitamin K 2/metabolism* ; Bioreactors/microbiology* ; Membrane Microdomains/metabolism*

Bacillus subtilis is recognized as a generally-regarded-as-safe strain, and has been widely used in the biosynthesis of high value-added products, including N-acetylneuraminic acid (NeuAc) which is widely used as a nutraceutical and a pharmaceutical intermediate. Biosensors responding to target products are widely used in dynamic regulation and high-throughput screening in metabolic engineering to improve the efficiency of biosynthesis. However, B. subtilis lacks biosensors that can efficiently respond to NeuAc. This study first tested and optimized the transport capacity of NeuAc transporters, and obtained a series of strains with different transport capacities for testing NeuAc-responsive biosensors. Subsequently, the binding site sequence of Bbr_NanR responding to NeuAc was inserted into different sites of the constitutive promoter of B. subtilis, and active hybrid promoters were obtained. Next, by introducing and optimizing the expression of Bbr_NanR in B. subtilis with NeuAc transport capacity, we obtained an NeuAc-responsive biosensor with wide dynamic range and higher activation fold. Among them, P535-N2 can sensitively respond to changes in intracellular NeuAc concentration, with the largest dynamic range (180-20 245) AU/OD. P566-N2 shows a 122-fold of activation, which is 2 times of the reported NeuAc-responsive biosensor in B. subtilis. The NeuAc-responsive biosensor developed in this study can be used to screen enzyme mutants and B. subtilis strains with high NeuAc production efficiency, providing an efficient and sensitive analysis and regulation tool for biosynthesis of NeuAc in B. subtilis.
N-Acetylneuraminic Acid/metabolism* ; Bacillus subtilis/metabolism* ; Promoter Regions, Genetic/genetics* ; Binding Sites ; Biosensing Techniques

Diacylglycerol (DAG) is an intermediate product in lipid metabolism and plays an important physiological role in human body. It is mainly prepared by hydrolyzing lipid with lipase. However, research on the detection method of 1, 2-diacylglycerol (1, 2-DAG) and 1, 3-diacylglycerol (1, 3-DAG) and catalytic specificity of lipase was not enough, which limits its wide application. To address these challenges, an efficient quantitative detection method was first established for 1, 2-DAG (0.025-0.200 g/L) and 1, 3-DAG (0.025-0.150 g/L) by combining supercritical fluid chromatography with evaporative light scattering detector and optimizing the detection and analysis parameters. Based on the molecular docking between Thermomyces lanuginosus lipase (TLL) and triolein, five potential substrate binding sites were selected for site-specific saturation mutation to construct a mutation library for enzyme activity and position specificity screening. The specificity of sn-1, 3 of the I202V mutant was the highest in the library, which was 11.7% higher than the specificity of the wild type TLL. In summary, the position specificity of TLL was modified based on a semi-rational design, and an efficient separation and detection method of DAG isomers was also established, which provided a reference for the study of the catalytic specificity of lipase.
Humans ; Diglycerides ; Molecular Docking Simulation ; Binding Sites ; Catalysis ; Lipase/genetics*

Ergothioneine (ERG) is a natural antioxidant that has been widely used in the fields of food, medicine and cosmetics. Compared with traditional plant extraction and chemical synthesis approaches, microbial synthesis of ergothioneine has many advantages, such as the short production cycle and low cost, and thus has attracted intensive attention. In order to engineer an ergothioneine high-yielding Escherichia coli strain, the ergothioneine synthesis gene cluster egtABCDE from Mycobacterium smegmatis and egt1 from Schizosaccharomyces pombe were introduced into E. coli BL21(DE3) to generate a strain E1-A1 harboring the ergothioneine biosynthesis pathway. As a result, (95.58±3.2) mg/L ergothioneine was produced in flask cultures. To further increase ergothioneine yield, the relevant enzymes for biosynthesis of histidine, methionine, and cysteine, the three precursor amino acids of ergothioneine, were overexpressed. Individual overexpression of serA^T410STOP and thrA resulted in an ergothioneine titer of (134.83±4.22) mg/L and (130.26±3.34) mg/L, respectively, while co-overexpression of serA^T410STOP and thrA increased the production of ergothioneine to (144.97±5.40) mg/L. Eventually, by adopting a fed-batch fermentation strategy in 3 L fermenter, the optimized strain E1-A1-thrA-serA^* produced 548.75 mg/L and 710.53 mg/L ergothioneine in glucose inorganic salt medium and rich medium, respectively.
Culture Media ; Ergothioneine/metabolism* ; Escherichia coli/metabolism* ; Fermentation ; Histidine/metabolism* ; Metabolic Engineering

Fermentation engineering is an industrial process that uses the transformation of microorganisms or other cells to produce a specific product in a specific bioreactor. Fermentation engineering has developed from an ancient food fermentation relying solely on experience accumulation to an important production mode of food, agriculture, medicine, chemical industry and other means of production and life. It has become a key technology to support the sustainable development of human beings, and is inseparable from the continuous progress of interdisciplinary technology. The interdisciplinary integration and the continuous upward movement of China's global industrial chain will inevitably put forward higher requirements for the cultivation of fermentation engineering composite talents in the new situation. In order to constantly improve the interdisciplinary fermentation engineering compound talent training system, in recent years, the research lab has been refining and improving the concept of talent training, and actively deepening the reform of talent training system. Systematic research and practice have been carried out around the aspects of training program, enrollment system, teacher background, subject setting, scientific research practice, evaluation system, etc., which has promoted the technological progress of fermentation engineering and related supporting industries, and contributed an important force to the transformation of China from a big fermentation country to a powerful fermentation country.
Agriculture ; China ; Fermentation ; Humans ; Industry

Genome-scale metabolic network model (GSMM) is an extremely important guiding tool in the targeted modification of industrial microbial strains, which helps researchers to quickly obtain industrial microbes with specific traits and has attracted increasing attention. Here we reviewe the development history of GSMM and summarized the construction method of GSMM. Furthermore, the development and application of GSMM in industrial microorganisms are elaborated by using four typical industrial microorganisms (Bacillus subtilis, Escherichia coli, Corynebacterium glutamicum, and Saccharomyces cerevisiae) as examples. In addition, prospects in the development trend of GSMM are proposed.
Corynebacterium glutamicum/genetics* ; Escherichia coli/genetics* ; Metabolic Engineering ; Metabolic Networks and Pathways/genetics*

As a typical food safety industrial model strain, Bacillus subtilis has been widely used in the field of metabolic engineering due to its non-pathogenicity, strong ability of extracellular protein secretion and no obvious codon preference. In recent years, with the rapid development of molecular biology and genetic engineering technology, a variety of research strategies and tools have been used to construct B. subtilis chassis cells for efficient synthesis of biological products. This review introduces the research progress of B. subtilis from the aspects of promoter engineering, gene editing, genetic circuit, cofactor engineering and pathway enzyme assembly. Then, we also summarized the application of B. subtilis in the production of biological products. Finally, the future research directions of B. subtilis are prospected.
Bacillus subtilis/genetics* ; Bacterial Proteins/genetics* ; Gene Editing ; Metabolic Engineering ; Promoter Regions, Genetic

Chitinase has a wide industrial application prospect. For example, it can degrade shrimp shells, crab shells and other crustacean waste into high value-added chitooligosaccharides. However, the low catalytic efficiency of chitinase greatly limits the production of chitooligosaccharides. In previous study, the we expressed a chitinase Chisb with high catalytic efficiency and studied its enzymatic properties. In order to further improve the catalytic efficiency of Chisb, with R13NprB-C-SP-H as the parent, here error-prone PCR was used to construct random mutant library to conduct directed evolution of chitinase Chisb. Two mutants C43D and E336R were obtained with 96-well plate primary screening and shaker-screening, and their enzymatic properties were also studied. The optimum temperature of C43D and E336R was 55 °C, and the optimum pH of C43D was 5.0, while that of E336R was 9.0. The catalytic efficiency of C43D and E336R was 1.35 times and 1.57 times higher than that of control. The chitooligosaccharide concentration of E336R and C43D was 2.53 g/L and 2.06 g/L, improved by 2.84 times and 2.31 times compared with the control (0.89 g/L), respectively. In addition, the substrate conversion rate of mutants E336R and C43D was 84.3% and 68.7%, improved by 54.6% and 39% compared with the control (29.7%), respectively. In summary, the study indicates that random mutation introduced by error-prone PCR can effectively improve the catalytic efficiency of chitinase Chisb. The positive mutants with higher catalytic efficiency obtained in the above study and their enzymatic property analysis have important research significance and application value for the biosynthesis of chitooligosaccharides.
Biocatalysis ; Chitin ; analogs & derivatives ; Chitinases ; Hydrogen-Ion Concentration ; Polymerase Chain Reaction

Objective To investigate the value of standardized iodine concentration and energy spectrum curve of dual-source CT in diagnosis of metastatic lymph nodes of gastric cancer.Methods The clinical data of 60 patients diagnosed as gastric cancer were collected in our hospital.All patients underwent dual-source CT routine abdominal scanning and dual-phase energy spectrum enhancement.According to the pathologic results,the lymph nodes were divided into metastatic and non-metastatic groups.Then the enhanced degree,dual-phase normalized iodine concentration (NIC)were measured and compared between metastatic lymph nodes and non-metastatic lymph nodes.The slope of the energy spectrum curve of metastatic lymph nodes and non-metastatic lymph nodes were calculated by dual-energy software.Results When the enhanced degree was higher than 80 HU,the sensitivity (82.4%)and specificity (78.6%)were higher. The artery-phase NIC values of metastatic lymph node and non-metastatic lymph node were(0.546±0.086)and(0.144±0.077),respectively. The difference was statistically significant (P<0.05).The venous-phase NIC values of metastatic lymph node and non-metastatic lymph nodes were (0.479±0.013)and (0.307±0.082),respectively.The difference was statistically significant (P<0.05).The dual-phase energy spectrum curves of metastatic and non-metastatic lymph nodes were all descending patterns.The difference was obvious at 40-80 keV and minimal at 80-140 keV.The sensitivity of diagnosing metastatic lymph nodes was 83.5%,and the specificity was 85.6%when the arterial curve slope was 6.87.The sensitivity of diagnosing metastatic lymph nodes was 63.6% and the specificity was 96.7%when the venous curve slope was 6.67.Conclusion The multiple parameters provided by dual-source CT dual-energy imaging are helpful to the qualitative and quantitative diagnosis of metastatic lymph nodes in gastric cancer.