Isolation of starch and protein degrading strain Bacillus subtilis FYZ1-3 from tobacco waste and genomic analysis of its tolerance to nicotine and inhibition of fungal growth.

Aerobic fermentation is an effective technique for the large-scale processing of tobacco waste. However, the specificity of the structure and composition of tobacco-derived organic matter and the toxic alkaloids in the material make it currently difficult to directly use microbial agents. In this study, a functional strain FYZ1-3 was isolated and screened from thermophilic phase samples of tobacco waste composting. This strain could withstand temperatures as high as 80°C and grow normally at 0.6% nicotine content. Furthermore, it had a strong decomposition capacity of tobacco-derived starch and protein, with amylase activity of 122.3 U/mL and protease activity and 52.3 U/mL, respectively. To further understand the mechanism of the metabolic transformation of the target, whole genome sequencing was used and the secondary metabolite gene cluster was predicted. The inhibitory effect of the strain on common tobacco fungi was verified using the plate confrontation and agar column methods. The results showed that the strain FYZ1-3 was Bacillus subtilis, with a genome size of 4.17 Mb and GC content of 43.68%; 4,338 coding genes were predicted. The genome was annotated and analyzed using multiple databases to determine its ability to efficiently degrade starch proteins at the molecular level. Moreover, 14 functional genes related to nicotine metabolism were identified, primarily located on the distinct genomic island of FYZ1-3, giving a speculation for its nicotine tolerance capability on the molecular mechanism. By mining the secondary metabolite gene cluster prediction, we found potential synthetic bacteriocin, antimicrobial peptide, and other gene clusters on its chromosome, which may have certain antibacterial properties. Further experiments confirmed that the FYZ1-3 strain was a potent growth inhibitor of Penicillium chrysogenum, Aspergillus sydowii, A. fumigatus, and Talaromyces funiculosus. The creation and industrial use of the functional strains obtained in this study provide a theoretical basis for its industrial use, where it would be of great significance to improve the utilization rate of tobacco waste.

Hatched Eggshell Membrane Can Be a Novel Source of Antioxidant Hydrolysates to Protect against H2O2-Induced Oxidative Stress in Human Chondrocytes.

Natural antioxidants derived from agricultural by-products have great promise and ecological advantages in the treatment of oxidative stress-related diseases. The eggshell membrane (ESM) from hatched eggs, i.e., the hatched ESM, is a globally abundant agricultural byproduct, and its high-value utilization has been rarely studied compared to the well-studied ESM from fresh eggs. In this research, we systematically characterized the hatched ESM as a novel source of antioxidant hydrolysates and explored their potential role in H2O2-induced human chondrocytes. The results showed that the hatched ESM is a protein-rich fibrous mesh material with a significantly different structure and composition from those of fresh ESM. Enzymatic hydrolysis of hatched ESM can produce antioxidant hydrolysates rich in low molecular weight (MW) peptides, which mainly derived from the Lysyl oxidase homolog by Nano-LC-MS/MS analysis. The peptide fraction with MW < 3 kDa (HEMH-I) exhibited the highest DPPH radical scavenging, Fe2+-chelating, and Fe3+-reducing abilities. In H2O2-induced human SW1353 chondrocytes, HEMH-I treatment significantly increased the cell viability and ameliorated oxidative stress, inflammatory response, and cartilage matrix degradation by reducing the level of ROS, matrix metalloprotease 3 (MMP3), MMP13, and IL-6, and by promoting the expression of SOD and type II collagen, potentially through activating the cellular Keap1/Nrf2/HO-1 pathway. This study provides a theoretical basis for the value-added application of hatched ESM waste to produce antioxidant hydrolysates and indicates their potential as functional food and pharmaceuticals.

Identification and molecular mechanisms of novel antioxidant peptides from two sources of eggshell membrane hydrolysates showing cytoprotection against oxidative stress: A combined in silico and in vitro study.

Eggshell membranes (ESM) from fresh and hatched chicken eggs are important agricultural byproducts. In this study, we investigated the antioxidant and cytoprotective activity of hydrolysates from fresh and hatched ESM, identified the antioxidant peptides and explored their potential molecular mechanism using a combined in silico and in vitro approach. The results showed that the hydrolysates fractions (MW < 3 kDa) of both ESM exhibited excellent antioxidant effects and could protect H2O2-induced RAW264.7 cells by reducing ROS and MDA levels involving the modulation of the Keap1-Nrf2 pathway. Six novel peptides identified by integrated approaches of peptidomics and in silico bioinformatic analysis were synthesized, exhibiting significantly higher ORAC values (629.41-1823.77 µmol TE/mmol) than GSH (397.21 µmol TE/mmol). Among these, KPLCPP, MDGWPR, and LWNPR possessed stronger ABTS scavenging and cytoprotective activities than GSH. All the six peptides could dock onto the Keap1-Kelch domain. Moreover, KPLCPP and LWNPR could regulate the Keap1-Nrf2 pathway and induced the overexpression of antioxidant enzymes including HO-1, SOD and GSH-Px. With the molecular docking and western blot analysis, the underlying molecular mechanism of the ESM antioxidant peptides might be related to the activation of Keap1-Nrf2 pathway by occupying the Nrf2-binding site on Keap1. This study provides a theoretical basis for the application of fresh and hatched ESM antioxidant peptides in functional foods, as well as insights for the identification and the mechanisms research of more food-derived antioxidant peptides.

An approach for compatibilization of the starch with poly(lactic acid) and ethylene-vinyl acetate-glycidyl-methacrylate.

In this study, we evaluated the possibility of dimethyldidodecylammonium bromide (DDAB)-modified graphene oxide quantum dots (DDAB-GOQDs) as a new compatibilizer to improve the compatibility of hydrophilic starch with hydrophobic polylactic acid (PLA) and ethylene-vinyl acetate-glycidylmethacrylate (EVA-GMA). The successful synthesis of DDAB-GOQDs was verified by Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and Zeta-Plus assay. The differential scanning calorimetry (DSC), polarized light optical microscopy (POM) and iso-thermal crystallization kinetics analysis showed that 0.25% DDAB-GOQDs could significantly increase the crystallization rate and nucleation density as well as reduce the spherulites size of the nanocomposites. Compared to pure composites, the nanocomposites containing 0.25% DDAB-GOQDs showed obvious enhancement in thermal stability and surface hydrophobicity, with an increase of ~22 °C and ~24.1° in the maximum decomposition temperature and contact angle, coupled with similar improvement in the storage modulus and UV-shielding capacity. Morphological analysis, FTIR and creep behavior experiments revealed that adding 0.25% DDAB-GOQDs enhanced the interface compatibility of the nanocomposites by promoting the formation of the interpenetrated network through strong polar hydrogen bond or electrostatic force within the polymeric components. Overall, (0.25%) DDAB-GOQDs can serve as an effective compatibilizer for the PLA/starch/EVA-GMA system due to improved crystallization, thermal stability, barrier properties and creep-resistance.

High-Performance Supercapacitor Electrode Materials from Cellulose-Derived Carbon Nanofibers.

Nitrogen-functionalized carbon nanofibers (N-CNFs) were prepared by carbonizing polypyrrole (PPy)-coated cellulose NFs, which were obtained by electrospinning, deacetylation of electrospun cellulose acetate NFs, and PPy polymerization. Supercapacitor electrodes prepared from N-CNFs and a mixture of N-CNFs and Ni(OH)2 showed specific capacitances of ∼236 and ∼1045 F g(-1), respectively. An asymmetric supercapacitor was further fabricated using N-CNFs/Ni(OH)2 and N-CNFs as positive and negative electrodes. The supercapacitor device had a working voltage of 1.6 V in aqueous KOH solution (6.0 M) with an energy density as high as ∼51 (W h) kg(-1) and a maximum power density of ∼117 kW kg(-1). The device had excellent cycle lifetime, which retained ∼84% specific capacitance after 5000 cycles of cyclic voltammetry scans. N-CNFs derived from electrospun cellulose may be useful as an electrode material for development of high-performance supercapacitors and other energy storage devices.