摘要：
Cellulophaga algicola DSM 14237, isolated from the Eastern Antarctic coastal zone, was found to be able to hydrolyze several types of polysaccharide materials. In this study, a predicted beta-agarase (CaAga1) from C. algicola was heterologously expressed in Escherichia coli. The purified recombinant CaAga1 showed specific activities of 29.39, 20.20, 14.12, and 8.99 U/mg toward agarose, pure agar, and crude agars from Gracilaria lemaneiformis and Porphyra haitanensis, respectively. CaAga1 exhibited an optimal temperature and pH of 40 (o)C and 7, respectively. CaAga1 was stable over a wide pH range from 4 to 11. The recombinant enzyme showed an unusual thermostability, that is, it was stable at temperature below or equal to 40(o)C and around 70 (o)C, but was thermolabile at about 50 (o)C. With the agarose as the substrate, the Km and Vmax values for CaAga1 were 1.19 mg/mL and 36.21 U/mg, respectively. The reducing reagent (dithiothreitol) enhanced the activity of CaAga1 by more than one fold. In addition, CaAga1 was salt-tolerant given that it retained approximately 70% of the maximum activity in the presence of 2 M NaCl. The thin layer chromatography results indicated that CaAga1 is an endo-type beta-agarase and efficiently hydrolyzed agarose into neoagarotetraose (NA4) and neoagarohexaose (NA6). A structural model of CaAga1 in complex with neoagarooctaose (NA8) was built by homology modeling and explained the hydrolysis pattern of CaAga1.
摘要：
The effect on the intracellular reactive oxygen species (ROS) generation, and the antioxidant and cytotoxicity properties of rice bran polysaccharides (RBP) and RBP-metal complexes RBP-Fe(III), RBP-Cu, RBP-Zn and RBP-Ca, were evaluated using atomic absorption spectroscopy (AAS), scavenging activity assays, cell viability assay and fluorescence microscopy. The RBP-metal complexes were prepared using the hydrothermal method. The RBP-Fe(III) complexes were found to be potent scavengers for superoxide (O2-center dot) free radicals. The RBP alone and RBP-Ca complex showed high scavenging activity for 2,2-diphenyl-l-picrylhydrazyl (DPPH center dot) free radicals. In addition, the RBP-Fe(III) complex also showed good biocompatibility and lowered the intracellular ROS levels, while RBP alone, RBP-Zn and RBP-Ca complexes were observed to increase the intracellular ROS level. Our findings suggest that among the tested RBP-metal complexes, RBP-Fe(III) complex is a strong candidate as an antioxidant therapeutic. (C) 2018 Elsevier B.V. All rights reserved.
摘要：
To investigate the structure, in vitro digestibility and activity of polysaccharides from lotus root, their main fractions named LRPs were isolated and purified by gel filtration chromatography. Structural analyses indicated that: LRPs were alpha-(1 -> 6)-D-heteroglucans mainly composed of Glc-(1 ->, -> 6)-Glc(1 ->, -> 6)-Gal (1 ->, -> 4,6)-Gal- (1 -> and -> 3,6)-Glc-(1 ->, at a molar ratio of 1.00: 4.33: 0.83: 0.13: 1.14; the total molar percentage of other monosaccharides in LRPs, including Man, Rha, GalA and Ara, was 8.10%; the molecular weights of LRPs was in the range of 1.33 kDa to 5.30 kDa. According to the change of molecular weight and the productions of reducing sugar and free monosaccharide, the simulated experiments of salivary, gastric and intestinal digestion confirmed that LRPs were almost undigestible. Moreover, LRPs showed the scavenging ability against DPPH and hydroxyl radicals, the growth inhibition ability against SGC7901 and HepG2 cancer cells in vitro, and the immunostimulating effect on the NO and TNF-alpha productions of macrophages in vitro. LRPs nearly remain their initial structure and activities in upper gastrointestinal tract and have health-improving potentials. (C) 2019 Published by Elsevier B.V.
通讯机构：
[Zhang, Jibin] H;Huazhong Agr Univ, Coll Life Sci & Technol, Natl Engn Res Ctr Microbial Pesticides, State Key Lab Agr Microbiol, Wuhan 430070, Hubei, Peoples R China.
关键词：
Black soldier fly;Environment;Pollution;Soybean curd residues;Waste management
摘要：
Black soldier fly larvae (BSFL), Hermetia illucens (Diptera: Stratiomyidae) can reduce environmental pollution and convert organic wastes into biomass that is rich in protein and fat. The influence of the nutritional characteristics of organic waste on BSFL characteristics relevant for food and feed safety remains poorly understood. To evaluate the conversion of soybean curd residues (SCR) into high-quality animal-derived proteins and fats for human and livestock consumption, this study assessed the co-conversion efficacy, nutrient composition, safety, and anti-nutritional factor concentrations in BSFL after the development on SCR with Lactobacillus buchneri (L3-9). SCR was pretreated with L. buchneri (10(8) cfu/ml), and then BSFL was employed for conversion. BSFL fed with SCR and L. buchneri had a significantly higher dry mass reduction (55.7+/-0.9%), bioconversion rate (6.9+/-0.3%), crude protein content (55.3+/-0.6%), and fat content (30.0+/-0.6%) than SCR (49.0+/-0.7%, 5.0+/-0.3%, 52.8+/-0.3%, and 26.1+/-0.8%, respectively) and artificial feed (43.9+/-0.8%, 3.9+/-0.1%, 50.3+/-0.4%, and 24.3+/-0.4%, respectively). However, the feed conversion ratio (8.0+/-0.3), of BSFL fed with SCR and L. buchneri was lower than that of the BSFL fed with SCR (9.8+/-0.1) and artificial feed (11.1+/-0.5). In addition, BSFL had satisfactory concentrations of all essential amino acids and fatty acids required for human consumption as recommended by WHO/FAO/UNU. The heavy metals and anti-nutritional factor concentrations were within the safety intake levels for food and feedstock. Therefore, the addition of L. buchneri with BSFL on SCR did not only increase co-conversion performance but also enhanced the nutritional value of BSFL.
摘要：
The effects of amino acid-involved Maillard reactions (MRs) on the structure and activities of longan pulp polysaccharides (LPs), which were heteropolysaccharides mainly composed of glucose, galactose, mannose, rhamnose, glucuronic acid, ribose, and galacturonic acid, were investigated. The changes of browning degree and molecular weight (M-w) distribution in the MR systems containing LPs and amino acids (lysine, proline, or glycine) indicated that lysine was more active in conjugating with LPs. The MR-modified LPs (MLPs) obtained via a 4 h MR between LPs and lysine showed obvious structural differences from LPs. Specifically, particle-like LPs contained 94% fractions with a M-w less than 7.07 kDa, by contrast, network-like MLPs contained 45% fractions with a M-w larger than 264.1 kDa. Moreover, MLPs showed stronger radical scavenging abilities and macrophage immunostimulating effects, but weaker cancer cell growth-inhibitory abilities. The results indicate that the amino acid-involved MR is a promising method to modify native polysaccharides for better biological properties.
摘要：
AIMS: A thermostable endo-mannanase from the fungus Talaromyces cellulolyticus was identified to facilitate manno-oligosaccharide preparation from Konjac (Amorphophallus konjac) flour. METHODS AND RESULTS: A putative endo-1,4-beta-mannanase from the T. cellulolyticus was obtained and efficiently expressed by improving its gene dosage in the genome of the host. After cultivation in a bench-top bioreactor for about 120 h, the protein content and enzyme activity of mannanase increased to 3.4 g l(-1) and 17 500 U ml(-1) respectively. Enzymatic characterization showed that this enzyme has an optimal temperature of 80 degrees C, optimal pH of 5.0. Under the optimized hydrolysis conditions of pH 5.0, 70 degrees C, and an enzyme concentration of 200 U l(-1) solution, this enzyme could efficiently hydrolyse 0.5% konjac flour into manno-oligosaccharides (MOSs) with the degree of polymerization range from 3 to 7. The possible mechanism by which the enzyme produced MOSs was also discussed. CONCLUSION: Talaromyces cellulolyticus endo-mannanase is thermostable and has a broad pH range adaptability. Method of improving the dosage of mannanase gene in the genome could realized its high-level impression. This enzyme could efficiently hydrolyse konjac flour into manno-oligosaccharide products. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has enriched endo-mannanase resources, facilitated its bulk production and provided a strong reference for its application in manno-oligosaccharide preparation from the natural glucomannan of konjac flour.
摘要：
Colletotrichum higginsianum causes anthracnose disease in a wide range of cruciferous crops and has been used as a model system to study plant-pathogen interactions and pathogenicity of hemibiotrophic plant pathogens. Conidiation, hyphae growth, appressorial development and appressorial penetration are significant steps during the infection process of C. higginsianum. However, the mechanisms of these important steps during infection remain incompletely understood. To further investigate the mechanisms of the plant-C. higginsianum interactions during infection progress, we characterized Cyclase-Associated Protein (ChCAP) gene. Deletion of the ChCAP gene resulted in reduction in conidiation and hyphal growth rate. The pathogenicity of DeltaChCAP mutants was significantly reduced with much smaller lesion on the infected leaves compared to that of wild type strain with typically water-soaked and dark necrotic lesions on Arabidopsis leaves. Further study demonstrated that the appressorial formation rate, turgor pressure, penetration ability and switch from biotrophic to necrotrophic phases decreased obviously in DeltaChCAP mutants, indicating that the attenuated pathogenicity of DeltaChCAP mutants was due to these defective phenotypes. In addition, the DeltaChCAP mutants sectored on PDA with abnormal, dark color, vesicle-like colony morphology and hyphae tip. Moreover, the DeltaChCAP mutants had a reduced intracellular cAMP levels and exogenous cAMP can partially rescue the defects of DeltaChCAP mutants in appressorial formation and penetration rate, but not in colony morphology, conidial shape and virulence, indicating that ChCAP is a key component in cAMP signaling pathway and likely play other roles in biology of C. higginsianum. In summary, our findings support the role of ChCAP in regulating conidiation, intracellular cAMP level, hyphal growth, appressorial formation, penetration ability and pathogenicity of this hemibiotrophic fungus.
摘要：
Flavonoids are a group of metabolites in Ginkgo biloba thought to provide health benefits. R2R3-MYB transcription factors (TFs) play key roles in the transcriptional regulation of the flavonoid biosynthesis in plants. In this study, an R2R3-MYB transcription factor gene, GbMYBFL, was isolated from G. biloba and characterized. Results of bioinformatic analysis indicated that GbMYBFL is more closely related to the R2R3-MYB involved in flavonoid biosynthesis and displayed high similarity to MYB from other plants. The genmomic sequence of GbMYBFL had three exons and two introns, with its upstream sequence containing cis-acting regulatory elements Myb binding site, Myc recognition sites, and light, SA, MeJA responsive elements. Subcellular localization analysis indicates that GbMYBFL was located in the nucleus. Quantitative real-time PCR revealed that GbMYBFL was expressed in leaves, stems, roots, young fruits, male flower and female flower, and the level of transcription in male flower and leaves were higher than that in female flower, stems, roots, and young fruits. During G. biloba leaf growth, the transcription of GbMYBFL is positively correlated with the flavonoid content, suggesting that the GbMYBFL is involved in the flavonoid biosynthesis. Overexpression of GbMYBFL under the control of the CaMV35S promoter in Ginkgo callus notably enhanced the accumulation of flavonoids and anthocyanin compared with non-transformed callus. This finding suggested that GbMYBFL positively related to flavonoid biosynthesis, and the overexpression of GbMYBFL was sufficient to induce flavonoids and anthocyanin accumulation.
关键词：
High performance liquid chromatography;Oral administration;Pharmacokinetics;Acetonitrile;Herbicides;Pesticides;Quality control;Liver
摘要：
2,4-Dichlorophenoxyacetic acid (2,4-D) is a chlorophenoxy herbicide used worldwide. We describe a high-performance liquid chromatography (HPLC) method with UV detection for the determination of 2,4-D in female and male rat serum. This allows to observe the change of serum 2,4-D concentration in rats with time and its pharmacokinetics characteristics with a simple, rapid, optimized and validated method. The serum samples are pretreated and introduced into the HPLC system. The analytes are separated in a XDB-C18 column with a mobile phase of acetonitrile (solvent A) and 0.02 M ammonium acetate (containing 0.1% formic acid) (solvent B) using a gradient elution at a flow rate of 1.0 mL/min. The wavelength for UV detection was set at 230 nm. Calibration curve for 2,4-D was constructed over a range of 0.1-400 mg/L. The method was successfully applied to study the pharmacokinetics of 2,4-D in rats in this study. After oral administration of 300 mg/kg and 60 mg/kg 2,4-D, the mean Cmax values were 601.9 and 218.4 mg/L, the AUC0-->infinity values were 23,722 and 4,127 mgxh/L and the clearance (Cl) were 1.10 and 0.02 L/(hxkg), respectively. The developed method was found to be specific, precise, reproducible and rapid.
摘要：
Wolfiporia cocos is an important medicinal and edible fungus that grows in association with pine trees, and its dried sclerotium has been used as a traditional medicine in China for centuries. However, the commercial production of W. cocos sclerotia is currently limited by shortages in pine wood resources. Since protein phosphatases (PPs) play significant roles in growth, signal transduction, development, metabolism, sexual reproduction, cell cycle, and environmental stress responses in fungi, the phosphatome of W. cocos was analyzed in this study by identifying PP genes, studying transcript profiles and assigning PPs to orthologous groups. Fifty-four putative PP genes were putatively identified in W. cocos genome based on homologous sequences searching using BLASTx program against the Saccharomyces cerevisiae, Fusarium graminearum, and Sclerotinia sclerotiorum databases. Based on known and presumed functions of orthologues of these PP genes found in other fungi, the putative roles of these W. cocos PPs in colonization, hyphal growth, sclerotial formation, secondary metabolism, and stress tolerance to environment were discussed in this study. And the level of transcripts from PP genes in the mycelium and sclerotium stages was also analyzed by qRT-PCR. Our study firstly identified and functional discussed the phosphatome in the medicinal and edible fungus W. cocos. The data from our study contribute to a better understanding of PPs potential roles in various cellar processes of W. cocos, and systematically provide comprehensive and novel insights into W. cocos economically important traits that could be extended to other fungi.
摘要：
Acinetobacter sp. YT-02, a Gram-negative bacterium isolated from the activated sludge from a sodium N-cyclohexylsulfamate production plant, has the ability to degrade cyclohexylamine. It was classified as a member of Acinetobacter sp., a Gram-negative bacterium, sharing a 16S rRNA gene sequence identity of 99% with Acinetobacter guangdongensis strain 1NM-4. It could degrade 10 mmol/L cyclohexylamine within 22 h. Based on the identified metabolite, the metabolic pathway of cyclohexylamine could be postulated as it was degraded via cyclohexanone. Draft genome sequence of this strain (2,993, 647 bp of chromosome length) is presented here. We further identified the genes encoding the enzymes involved in cyclohexylamine oxidation to cyclohexanone and the subsequent downstream metabolic pathway of cyclohexanone oxidation. Strain YT-02 has the potentiality to be applied in the treatment of the pollutant cyclohexylamine, and it could also be treated as a research material to study the degradation mechanism of cyclohexylamine.
摘要：
The largely semi-deserted and deserted Dzungharian Basin sites in the northwest of China geologically represent an extension of the Paleozoic Kazakhstan Block and were once part of an independent continent. For reasons of overdevelopment and unreasonable operations during the process of exploitation and transportation, oil pollutants that were discharged into the soil environment caused serious pollution in this weak ecosystem. To explore the bacterial community composition in detail and their possible origination and potential during the natural attenuation of petroleum contaminants in this type of ecologic niche, GC-MS and high-throughput sequencing techniques were used to resolve the organic compounds and bacterial communities in vertical soil layers. The degradation of petroleum contaminants in semi-deserted and deserted soils mainly occurred in the layer at a depth of 45–55 cm. During this process, aromatic and heterocyclic compounds were significantly enriched in soils. The bacterial communities in this basin exhibited a distinct vertical stratification from the surface layer down to the bottom soil layer. Considering the interaction between the community composition and the geochemical properties, we speculate that the degradation of petroleum contaminants in this semi-deserted and deserted soil might represent a microorganism-mediated process and mainly occur in the deeper soil layer.
