Genome Analysis and Optimization of Caproic Acid Production of Clostridium butyricum GD1-1 Isolated from the Pit Mud of Nongxiangxing Baijiu.

Caproic acid is a precursor substance for the synthesis of ethyl caproate, the main flavor substance of nongxiangxing baijiu liquor. In this study, Clostridium butyricum GD1-1, a strain with high caproic acid concentration (3.86 g/l), was isolated from the storage pit mud of nongxiangxing baijiu for sequencing and analysis. The strain's genome was 3,840,048 bp in length with 4,050 open reading frames. In addition, virulence factor annotation analysis showed C. butyricum GD1-1 to be safe at the genetic level. However, the annotation results using the Kyoto Encyclopedia of Genes and Genomes Automatic Annotation Server predicted a deficiency in the strain's synthesis of alanine, methionine, and biotin. These results were confirmed by essential nutrient factor validation experiments. Furthermore, the optimized medium conditions for caproic acid concentration by strain GD1-1 were (g/l): glucose 30, NaCl 5, yeast extract 10, peptone 10, beef paste 10, sodium acetate 11, L-cysteine 0.6, biotin 0.004, starch 2, and 2.0% ethanol. The optimized fermentation conditions for caproic acid production by C. butyricum GD1-1 on a single-factor basis were: 5% inoculum volume, 35°C, pH 7, and 90% loading volume. Under optimal conditions, the caproic acid concentration of strain GD1-1 reached 5.42 g/l, which was 1.40 times higher than the initial concentration. C. butyricum GD1-1 could be further used in caproic acid production, NXXB pit mud strengthening and maintenance, and artificial pit mud preparation.

Typing of cancer cells by microswimmer based on Co-Fe-MOF for one-step simultaneously detect multiple biomarkers.

Capturing, identifying, and counting CTCs cancer cells that have escaped from the tumor and wandered into the bloodstream is a major challenge. We proposed a noval microswimmer dual-mode aptamer (electrochemical and fluorescent)-(Mapt-EF) homogeneous sensor with active capture/controlled release double signaling molecule/separation and release cell based on the Co-Fe-MOF nanomaterial for simultaneous one-step detection of multiple biomarkers protein tyrosine kinase-7 (PTK7), Epithelial cell adhesion molecule (EpCAM), and mucin-1 (MUC1) for diagnosis of multiple cancer cell types. The Co-Fe-MOF is a nano-enzyme capable of catalyzing the decomposition of hydrogen peroxide to release bubbles of oxygen, producing a driving force to conduct hydrogen peroxide through the liquid, and has the capacity to self-decompose during the catalytic process. Phosphoric acid is present in the aptamer chains of PTK7, EpCAM, and MUC1, and the aptamer chains are adsorbed to the surface of the Mapt-EF homogeneous sensor in the form of a gated switch to inhibit the catalytic decomposition activity of hydrogen peroxide. The Mapt-EF homogeneous sensor has the capability to actively target biomarkers that can be entrained by oxygen bubbles without being degraded. The detection time of the sensor was 20 min, the detection limits were 9.6 fg/mL, 8.4 fg/mL and 7.7 fg/mL with the linear range was 0-20 pg/mL, respectively. The Mapt-EF homogeneous sensor has high detection sensitivity, and its detection limit can reach the level of single cell at the lowest. The Mapt-EF homogeneous sensor has great application potential in clinical detection and analysis of tumor cells.

Discrimination of Chinese green tea according to tea polyphenols using fluorescence sensor array based on Tb (III) and Eu (III) doped Zr (IV) metal-organic frameworks.

A facile and rapid fluorescence sensor array based on Tb (III) and Eu (III) doped Zr (IV) metal-organic frameworks was proposed for Chinese green tea discrimination. According to large porosity of Tb@UiO-66-(COOH)2 and Eu@UiO-66-(COOH)2, phenolic hydroxyl groups of tea polyphenols could coordinate with free carboxylic acid groups and was captured into the pores, which led to the disturbance of electronic structure of ligand and inhibited the energy transfer efficiency from ligand to Tb (III) and Eu (III) center, causing the fluorescence quenching effect. Based on Hierarchy Cluster Analysis and Linear Discrimination Analysis, the fluorescence sensor array was employed for successful tea polyphenols classification through the analysis of different fluorescence quenching effect to tea polyphenols. Green tea samples within different categories and grades were also successfully discriminated using this assay according to tea polyphenols, providing a new method for Chinese green tea identification.

A novel electrochemical biosensor based on AMNFs@ZIF-67 nano composite material for ultrasensitive detection of HER2.

Antimonene (AMNFs) is a new kind of sp2-bonded honeycomb lattice two-dimensional material with strong rod-rail coupling, stability and hydrophilicity. Compared with graphene, antimonene has better sensitivity in DNA molecular sensing. We developed a suitable biosensor-Cd2+-aptamer@AMNFs@ZIF-67 nanocomposite for HER2 biomarker detection. Two-dimensional antimonene can be grown on the surface of ZIF-67 to enhance stability and biocompatibility. The aptamer chain can also be adsorbed on the surface of antimonene, and the complexes of the aptamer and the marker can be detached analytically after targeting the biomarker. The detection limit (LOD) was 4.853 fg/mL within 60 min, the detection range was 0-1000 pg/mL, and the LOD was lower than the existing HER2 aptamer biosensors. The results show that the biosensor has certain applicability and potential, and is expected to be a powerful tool for breast cancer diagnosis in the future.

Production of caproic acid by Rummeliibacillus suwonensis 3B-1 isolated from the pit mud of strong-flavor baijiu.

Caproic acid is the precursor of ethyl caproate, the main representative flavor substance of strong-flavor baijiu (SFB). Caproic acid-producing bacteria are considered to be the most important type of acid-producing microorganisms in the pit mud of the SFB ecosystem. In this study, the Rummeliibacillus suwonensis 3B-1 with a high yield of caproic acid (4.064 g/L) was screened from SFB pit mud. The genome of the R. suwonensis 3B-1 was sequenced, the total size was found to be 4117,671 bp and a calculated GC content of 35.86%. The caproic acid biosynthesis pathway was identified and analyzed, and it showed that 3B-1 could not only use ethanol, but it could also use glucose and other carbon sources as substrates to produce caproic acid. According to the genome analysis and with an optimized medium, the optimal conditions for caproic acid production were yeast powder at 3 g/L, sodium acetate at 15 g/L, and 1% biotin at 8 mL/100 mL. The yield of caproic acid reached 4.627 g/L, an increase of 13.9%, which was higher than that of general caproic acid bacteria. This is the first report of the synthesis of caproic acid by R. suwonensis. This strain could be used to produce caproic acid, an artificial pit mud preparation, and/or an enhanced inoculum in the production of SFB.

A novel multifunctional platform based on ITO/APTES/ErGO/AuNPs for long-term cell culture and real-time biomolecule monitoring.

Integrating long-term cell culture with real-time electrochemical monitoring is a promising strategy for future studies of physiological and pathological processes. However, great challenges still remain in fabricating such a platform with satisfactory electrochemical performance as well as desirable biocompatibility. Herein, we proposed a novel multifunctional platform based on gold nanoparticles/electrochemically reduced graphene oxide/3-aminopropyl-triethoxysilane modified indium tin oxide plate (ITO/APTES/ErGO/AuNPs). The unique biological and electrical properties of AuNPs and ErGO endow the platform with superior electrocatalytic activity and desirable biocompatibility. As a proof of concept, the present platform showed satisfactory electrochemical performance for sensitive and selective detection of hydrogen peroxide (H2O2) with a sensitivity about 0.25 µA µM-1 cm-2 and a detection limit of 0.38 µM in a linear range of 0.5-1461 µM. And the principle of catalytic reduction was clarified through density functional calculations (DFT). Furthermore, cells grew on the platform exhibited excellent proliferation ability and considerable viability after a long-term cultivation. Based on those desirable performances, in-situ and real-time monitoring of endogenously produced H2O2 released from cancer cells cultured on the platform has been successfully realized, which will be of great significance in pathophysiology research.

Colorimetric and fluorescent dual-identification of glutathione based on its inhibition on the 3D ball-flower shaped Cu-hemin-MOF's peroxidase-like activity.

Hemin as the organic linker ligand and Cu (II) as the metal center were applied to prepare a copper-metal-organic framework (Cu-hemin-MOF) via one-step hydrothermal method. Characterization using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD) demonstrate that the acquired Cu-hemin-MOF possesses the appearance of 3D ball-flower shape with the existence of C, N, O, Fe, and Cu on the surface. Further study found that this 3D ball-flower shaped Cu-hemin-MOF exhibits peroxidase-like activity, which can catalyze the peroxidase substrate of o-phenylenediamine (OPD) to generate 2,3-diaminophenazine (DAP) in the presence of H2O2. DAP has a yellow color and also emits a strong fluorescence when excited by ultraviolet light. Interestingly, Cu-hemin-MOF's peroxidase-like activity can be strongly inhibited by glutathione (GSH). In view of this, a dual readout (fluorescence and colorimetry) was proposed to detect GSH for the first time. Under optimal conditions, the proposed method exhibits good linear relationship between the signal response (fluorescence and colorimetry) and the concentration of GSH, and low limits of detection (LOD) of 2.3 and 26.6 nM, respectively.Graphical abstract.

Anthocyanin Encapsulated by Ferulic Acid-Grafted-Maltodextrin (FA-g-MD) Microcapsules Potentially Improved its Free Radical Scavenging Capabilities Against H2O2-Induced Oxidative Stress.

This study aimed to investigate the antioxidant activity and release behavior of anthocyanin (ANC) loaded within FA-g-MD wall (ANC-FA-g-MD microcapsule) in vitro. The microencapsulation of ANC was prepared by spray drying and displayed a biphasic release profile. The combination of ANC and FA-g-MD (0.0625-1 mg/mL) showed a higher antioxidant activity than that of both individuals. A possible intermolecular interaction between ANC and FA-g-MD was studied by UV-vis spectra. Intracellular reactive oxygen species (ROS), 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) test, and protein expression of quinone oxidoreductase 1(NQO1), glutathione reductase (GSR) and γ-glutamate cysteine ligase catalytic subunit (γ-GCLC) were measured through human colon cancer cells (HT-29). After a 24-hour incubation of the HT-29, the combinations (0-60 µg/mL) exhibited a high potential to diminish the ROS level. And the distinct upregulated expressions of GCLC and NQO1 of HT-29 were detected after treatment with combinations compared to those of single ones. These results suggested that the ANC-FA-g-MD microcapsules exerts enhanced antioxidant effect with capability of the modulation of GCLC and NQO1.