[Effects of Wastewater Discharge on Antibiotic Resistance Genes and Microbial Community in a Coastal Area].

Wastewater treatment plants (WWTPs) are important sources of antibiotic resistance genes (ARGs) in aquatic environments. Mobile genetic elements (MGEs) and microbial communities are key factors that affect the proliferation of ARGs. To reveal the effects of WWTPs effluent discharge on the ARGs and microbial community in a coastal area, the structure and distribution of ARGs, MGEs, and microbial community in Shangyu (SY) and Jiaxing (JX) effluent receiving areas (ERAs) and the offshore area of Hangzhou Bay (HB) were investigated via high-throughput quantitative PCR and 16S rRNA high-throughput sequencing. The results showed that multidrug resistance genes were the most abundant ARGs across all the sampling sites. The diversity and abundance of ARGs and MGEs in the ERAs were much higher than those in the HB. Additionally, the diversities of the microbial community in the JX-ERA were higher than those in the SY-ERA and HB. PCoA showed that the distribution of ARGs, MGEs, and microbial communities in the ERAs and HB were significantly different, indicating that the long-term wastewater discharge could alter the distribution of ARGs, MGEs, and microbial communities in the coastal area. The co-occurrence pattern among ARGs, MGEs, and microbial communities revealed that 12 bacterial genera, such as Psychrobacter, Pseudomonas, Sulfitobacter, Pseudoalteromonas, and Bacillus, showed strong positive correlations with ARGs and MGEs. Most potential hosts carried multidrug and ß-lactamase resistance genes.

Simultaneous solid-liquid separation and primary purification of clavulanic acid from fermentation broth of Streptomyces clavuligerus using salting-out extraction system.

Clavulanic acid (CA) is usually used together with other ß-lactam antibiotics as combination drugs to inhibit bacterial ß-lactamases, which is mainly produced from the fermentation of microorganism such as Streptomyces clavuligerus. Recently, it is still a challenge for downstream processing of low concentration and unstable CA from fermentation broth with high solid content, high viscosity, and small cell size. In this study, an integrated process was developed for simultaneous solid-liquid separation and primary purification of CA from real fermentation broth of S. clavuligerus using salting-out extraction system (SOES). First, different SOESs were investigated, and a suitable SOES composed of ethanol/phosphate was chosen and further optimized using the pretreated fermentation broth. Then, the optimal system composed of 20% ethanol/15% K2HPO4 and 10% KH2PO4 w/w was used to direct separation of CA from untreated fermentation broth. The result showed that the partition coefficient (K) and recovery yield (Y) of CA from untreated fermentation broth were 29.13 and 96.8%, respectively. Simultaneously, the removal rates of the cells and proteins were 99.8% and 63.3%, respectively. Compared with the traditional method of membrane filtration or liquid-liquid extraction system, this developed SOES showed the advantages of simple operation, shorter operation time, lower process cost and higher recovery yield of CA. These results demonstrated that the developed SOES could be used as an attractive alternative for the downstream processing of CA from real fermentation broth.

Three-liquid-phase salting-out extraction of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)-rich oils from Euphausia superba.

The TLPSOES parameters were optimized by response surface methodology using Box-Behnken design, which were 16.5% w/w of ammonium citrate, 17.5% w/w of ethanol, and 46% w/w of n-hexane at 70 min of stirring time. Under optimized conditions the extraction efficiency attained was 90.91 ± 0.97% of EPA, 90.02 ± 1.04% of DHA, and 91.85 ± 1.11% of KO in the top n-hexane phase. The highest extraction efficiency of proteins and flavonoids, i.e. 88.34 ± 1.35% and 79.67 ± 1.13%, was recorded in the solid interface and ethanol phase, respectively. The KO extracted by TLPSOES system consisted of lowest fluoride level compared to the conventional method and whole wet krill biomass. The TLPSOES is a potential candidate for nutraceutical industry of KO extraction from wet krill biomass.

Fabrication of rigid and macroporous agarose microspheres by pre-cross-linking and surfactant micelles swelling method.

A novel combined method of pre-cross-linking and surfactant micelles swelling was proposed in this study to fabricate highly cross-linked and macroporous agarose (HMA) microspheres. Agarose was chemically modified by allylglycidyl ether (AGE) as heterobifunctional cross-linker via its active glycidyl moieties before gel formation and pre-cross-linking was achieved. By this means, the effective concentration of cross-linker presented in agarose gel increased significantly, and thus cross-linking with a high-efficiency was achieved. Further to enhance the intraparticle mass transfer of agarose microspheres, the surfactant micelles swelling method was utilized to create interconnected macropores. Under the optimal condition, HMA microspheres with homogeneous reticular structure and pore size of hundreds nanometers were successfully prepared. They exhibited a low backpressure with a flow velocity as high as 1987 cm/h, which was much higher than that of commercial Sepharose 4 F F. HMA microspheres were then derivatized with carboxymethyl (CM) groups and applied in ion-exchange chromatography. As expected, CM-HMA column separated model proteins effectively even at a flow velocity three times higher than that of commercial CM-4 F F. Visualization of dynamic protein adsorption by confocal laser scanning microscope (CLSM) revealed that the intraparticle mass transfer of CM-HMA microspheres was intensified due to its macroporous structure. All of the results indicated the newly developed agarose microspheres were a promising medium for high-speed chromatography.

Improving adjuvanticity of quaternized chitosan-based microgels for H5N1 split vaccine by tailoring the particle properties to achieve antigen dose sparing effect.

In this study, we developed the quaternized chitosan microgels without chemical crosslinking as an adjuvant of H5N1 split vaccine. The microgels with pH-sensitivity, positive surface charge and good biocompatibility, have been demonstrated in favor of enhancing both humoral and cellular immune response. However, the detailed mechanism of the chitosan-based microgels to enhance antigen specific immune responses remains unclear. Therefore, we prepared the quaternized chitosan microgels with well defined quaternization degrees (QDs, 20-80%) and particle sizes (800nm-5µm) by the premix membrane emulsification technique, and investigated the effect of quaternization degree (QD) and size on the adjuvanticity of microgels. Results suggested that microgels with relatively smaller size (807nm) and moderate quaternization degree (QD 41% and 60%) were favorable for a maximum immune response. The mechanism was studied and explained by examining the characteristics of microgels and investigating the stimulation of bone-marrow derived dendritic cells (BMDCs). Moreover, they induced significantly stronger immune responses at lower antigen doses (known as antigen sparing effect) compared to aluminum adjuvant. These data indicated that a maximum immune response can be achieved by controlling properties of chitosan microgels, which also could serve as a significant guidance for rational design of chitosan-based particle adjuvant.

The potential adjuvanticity of quaternized chitosan hydrogel based microparticles for porcine reproductive and respiratory syndrome virus inactivated vaccine.

Infectious diseases possess a big threat to the livestock industry worldwide. Currently, inactivated veterinary vaccines have attracted much attention to prevent infection due to their safer profile compared to live attenuated vaccine. However, its intrinsic poor immunogenicity demands the incorporation of an adjuvant. Mineral oil based adjuvant (Montanide™ ISA206) was usually used to potentiate the efficacy of veterinary vaccines. However, ISA206 could not induce robust cellular immune responses, which was very important in controlling virus replication and clearing the infected cells. Moreover, mineral oil would result in severe side effects. To improve both the humoral and cellular immune responses of porcine reproductive and respiratory syndrome virus (PRRSV) inactivated vaccine, we developed pH-sensitive and size-controllable quaternized chitosan hydrogel microparticles (Gel MPs) without using chemical cross linking agent. Gel MPs, ionic cross-linked with glycerophosphate (GP), were biocompatible and could efficiently adsorb the inactivated PRRSV vaccine with a loading capacity of 579.05µg/mg. After intramuscular immunization in mice, results suggested that Gel MPs elicited significantly higher cell-mediated immune responses and comparable humoral immune responses compared to ISA 206. Regarding the biocompatibility, safety and effectiveness, Gel MPs would be a promising candidate to enhance the efficacy of veterinary vaccine.

Chitosan-mediated formation of biomimetic silica nanoparticles: an effective method for manganese peroxidase immobilization and stabilization.

Our work here, for the first time, reported the use of chitosan-mediated biomimetic silica nanoparticles in enzyme immobilization. In order to make clear the relationship among silicification process, silica nanoparticle structure and immobilized enzyme activity, a mechanism of chitosan-mediated silicification using sodium silicate as the silica source was primarily evaluated. Chitosan was demonstrated effectively to promote the silicification not only in accelerating the aggregation rate of sodium silicate, but also in templating the formation of silica nanoparticles. Although the whole biomimetic silicification process contained polycondensation-aggregation-precipitation three stages, the elemental unit in precipitated silica was confirmed to be nanoparticles with 100 nm diameter regardless of the chitosan and silicate concentration used. Furthermore, the effect of enzyme on silicification process was also investigated. The introducing of manganese peroxidase (MnP) to silica precursor solution had no obvious effect on the silicification rate and nanoparticle morphology. The residual activity and embedding rate of immobilized MnP were 64.2% and 36.4% respectively under the optimum conditions. In addition, compared to native MnP, the MnP embedded in chitosan/silica nanoparticles exhibited improved stability against organic solvent and ultrasonic wave. After ultrasonic treatment for 20 min, 77% of the initial activity was remained due to the protective effect of chitosan/silica nanoparticles, while native MnP lost almost all of its original activity.

Hybrid magnetic cross-linked enzyme aggregates of phenylalanine ammonia lyase from Rhodotorula glutinis.

Novel hybrid magnetic cross-linked enzyme aggregates of phenylalanine ammonia lyase (HM-PAL-CLEAs) were developed by co-aggregation of enzyme aggregates with magnetite nanoparticles and subsequent crosslinking with glutaraldehyde. The HM-PAL-CLEAs can be easily separated from the reaction mixture by using an external magnetic field. Analysis by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) indicated that PAL-CLEAs were inlayed in nanoparticle aggregates. The HM-PAL-CLEAs revealed a broader limit in optimal pH compared to free enzyme and PAL-CLEAs. Although there is no big difference in Km of enzyme in CLEAs and HM-PAL-CLEAs, Vmax of HM-PAL-CLEAs is about 1.75 times higher than that of CLEAs. Compared with free enzyme and PAL-CLEAs, the HM-PAL-CLEAs also exhibited the highest thermal stability, denaturant stability and storage stability. The HM-PAL-CLEAs retained 30% initial activity even after 11 cycles of reuse, whereas PAL-CLEAs retained 35% of its initial activity only after 7 cycles. These results indicated that hybrid magnetic CLEAs technology might be used as a feasible and efficient solution for improving properties of immobilized enzyme in industrial application.

Novel vaccine delivery system induces robust humoral and cellular immune responses based on multiple mechanisms.

Aiming to enhance the immunogenicity of H5N1 split vaccine, the development of a novel antigen delivery system based on quaternized chitosan hydrogel microparticles (Gel MPs) with multiple mechanisms of immunity enhancement is attempted. Gel MPs based on ionic cross-linking are prepared in a simple and mild way. Gel MPs are superior as a vaccine delivery system due to their ability to: 1) enhance cellular uptake and endosomal escape of antigens in dendritic cells (DCs); 2) significantly activate DCs; 3) form an antigen depot and recruit immunity cells to improve antigen capture. Further in vivo investigation shows that Gel MPs, in comparison to aluminum salts (Alum), LPS, and covalent cross-linking quaternized chitosan MPs (GC MPs), induce higher humoral and cellular immune responses with a mixed Th1/Th2 immunity. In conclusion, these results demonstrate that Gel MPs are efficient antigen delivery vehicles based on multiple mechanisms to enhance both humoral and cellular immune responses against H5N1 split antigen.

Multiscale evaluation of pore curvature effects on protein structure in nanopores.

Protein structure in nanopores is an important determinant in porous substrate utilization in biotechnology and materials science. To date, accurate residue details of pore curvature induced protein binding and unfolding were still unknown. Here, a multiscale ensemble of chromatography, NMR hydrogen and deuterium (H/D) exchange, confocal scanning and molecular docking simulations was combined to obtain the protein adsorption information induced by pore size and curvature. Lysozyme and polystyrene microspheres within pores in the 14-120 nm range were utilized as models. With pore size increasing, the bound lysozyme presented a tendency of significantly decreased retention, less unfolding and fewer interacted sites. However, such a significant dependence between pore curvature and protein size only existed in a limited micro-pore range comparable to protein sizes. The mechanism behind the above events could be attributed to the diverse protein interaction area determined by pore curvature and size change, by models calculating the binding of lysozyme onto surfaces. Another surface of opposite curvature for nanoparticles was also calculated and compared, the rules were similar but with opposite direction and such a critical size also existed. These studies of proteins on curved interfaces may ultimately help to guide the design of novel porous materials and assist in the discrimination of the target protein from molecular banks.

Nanoparticles-based multi-adjuvant whole cell tumor vaccine for cancer immunotherapy.

Whole cell tumor vaccine (WCTV), as a potential treatment modality, elicits limited immune responses because of the poor immunogenicity. To address this issue, researchers have attempted to transduce a cytokine adjuvant into tumor cells, but these single-adjuvant WCTVs curtail the high expectations. In present study, we constructed a multi-adjuvant WCTV based on the nanoparticles modified with cell penetrating peptide, which could facilitate the transportation of granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin 2 (IL-2) into tumor cells. After inactivation, as-designed multi-adjuvant WCTV exhibited programmed promotions on DC recruitment, antigen presentation, and T-cell activation. In vivo evaluations demonstrated the satisfactory effects on tumor growth suppression, metastasis inhibition, and recurrence prevention. Therefore, the nanoparticles-based multi-adjuvant WCTV may serve as a high-performance treatment for anti-tumor immunotherapy.

[Peptides analysis in digested edible bird's nest by HPLC-MS].

Edible bird's nest contains lots of glycoproteins. The glycosylation inhomogeneity for glycoprotein often results in wide range of molecular weight and the difficulty for protein separation and charaterization. In this paper, proteins in the edible bird's nest were extracted using multiple extractions, and then digested by PNgase F and trypsin. The digest mixture was separated with HPLC, and peptides were identified based on MS/MS data searching. The results indicated that the extracted proteins were amount to 79.7% of total protein in the edible bird's nest. More than 20 species of peptides in the digested mixture were identified. The sequences of these peptides showed similarity with some proteins from Swiss-prot. The research indicated that deglycosylation, tryptic digestion coupled with HPLC-MS/MS is a proper strategy for characterization of proteins in the edible bird's nest.

Microcosmic mechanisms for protein incomplete release and stability of various amphiphilic mPEG-PLA microspheres.

The microcosmic mechanisms of protein (recombinant human growth hormone, rhGH) incomplete release and stability from amphiphilic poly(monomethoxypolyethylene glycol-co-D,L-lactide) (mPEG-PLA, PELA) microspheres were investigated. PELA with different hydrophilicities (PELA-1, PELA-2, and PELA-3) based on various ratios of mPEG to PLA were employed to prepare microspheres exhibiting a narrow size distribution using a combined double emulsion and premix membrane emulsification method. The morphology, rhGH encapsulation efficiency, in vitro release profile, and rhGH stability of PELA microspheres during the release were characterized and compared in detail. It was found that increasing amounts of PLA enhanced the encapsulation efficiency of PELA microspheres but reduced both the release rate of rhGH and its stability. Contact angle, atomic force microscope (AFM), and quartz crystal microbalance with dissipation (QCM-D) techniques were first combined to elucidate the microcosmic mechanism of incomplete release by measuring the hydrophilicity of the PELA film and its interaction with rhGH. In addition, the pH change within the microsphere microenvironment was monitored by confocal laser scanning microscopy (CLSM) employing a pH-sensitive dye, which clarified the stability of rhGH during the release. These results suggested that PELA hydrophilicity played an important role in rhGH incomplete release and stability. Thus, the selection of suitable hydrophilic polymers with adequate PEG lengths is critical in the preparation of optimum protein drug sustained release systems. This present work is a first report elucidating the microcosmic mechanisms responsible for rhGH stability and its interaction with the microspheres. Importantly, this research demonstrated the application of promising new experimental methods in investigating the interaction between biomaterials and biomacromolecules, thus opening up a range of exciting potential applications in the biomedical field including drug delivery and tissue regeneration.

[Inhibitory effect of folic acid/polyamide-amine as a miR-7 vector on the growth of glioma in mice].

OBJECTIVE: To explore if folic acid/polyamide-amine (FA/PAMAM) enhances the therapeutic effect of miR-7gene therapy for glioma in vivo. METHODS: The miR-7 gene was transfected into U251 glioma cells by FA/PAMAM. The efficiency of gene transfection was assessed by fluorescence microscopy. The miR-7 level was detect by quantitative RT-PCR. Intracranial glioma models were established in thymectomized mice, and FA/PAMAM nanoparticles were transplanted into the tumors in situ 3 days later. The animal survival was recorded and the gross tumor volume and degree of edema were observed by MRI. Apoptosis in the glioma cells and expression of proliferating cell nuclear antigen (PCNA), matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) were assessed by immunohistochemistry, and EGFR and AKT-2 protein expression was detected by Western blot assay. RESULTS: Compared with the liposomes, the FA/PAMAM nanoparticles were more efficient to transfer miR-7 gene into U251 glioma cells, MRI showed that the tumor growth was much slower in the FA/PAMAM/miR-7 group, and the animal survival time was longer. The apoptosis rate was (5.3 ± 0.9)% in the control group, (11.4 ± 2.4)% in the liposome/miR-7 group, and (17.7 ± 3.7)% in the FA/PAMAM/miR-7 group. The immunohistochemical assay showed that the levels of PCNA, MMP-2 and MMP-9 protein in the FA/PAMAM/miR-7 group were (34.6 ± 5.4)%, (24.5 ± 4.1)%, (25.4 ± 5.1)%, respectively, significantly lower than those in the liposome/miR-7 group (49.3 ± 5.9)%, (31.7 ± 7.1)% and (39.4 ± 6.4)%, respectively, and those in the control group (57.3 ± 7.4)%, (45.4 ± 6.9)% and (55.1 ± 7.3)%, respectively (all P < 0.05). The expressions of EGFR and AKT-2 proteins were 1.09 ± 0.12 and 0.62 ± 0.10 in the control group, 0.63 ± 0.11 and 0.43 ± 0.07 in the liposome/miR-7 group, and significantly deceased (0.47 ± 0.09 and 0.31 ± 0.04, respectively) in the FA/PAMAM/miR-7 group (all P < 0.05). CONCLUSION: Compared with the liposomes, FA/PAMAM can transfect miR-7 into glioma cells with a higher efficiency in vivo, makes a longer time of the drug action, and shows a certain inhibitory effect on the growth of glioma, therefore, might become a new drug targeting agent in gene therapy forglioma.

LiCl-induced improvement of multilayer nanofibrous lipase for biodiesel synthesis.

A unique method that applied a multilayer-immobilization strategy was developed to prepare nanofibrous enzymes for biosynthesis. LiCl co-electrospun with polyurethane nanofibers enabled strong physical adsorption of bovine serum albumin (BSA), forming the first layer of protein on the nanofibers; lipase AK was subsequently crosslinked to BSA as an outer layer of enzyme. The content of LiCl in nanofibers was found to be a sensitive factor affecting the activity and stability of the immobilized lipase. For biodiesel synthesis from soybean oil and methanol in isooctane, the reaction rate catalyzed by nanofibrious lipase carrying 5 wt% LiCl was 6.6-fold higher than fibers without LiCl, with a conversion of 91% was achieved within 2 h. LiCl also induced much improved enzyme stability. The nanofibrous lipase with 5% LiCl could be repeatedly used for 42 cycles without apparent activity loss, while the immobilized lipase without LiCl lost over 90% activity within 13 reuse cycles.

Biodegradable Microcapsules Prepared by Self-Healing of Porous Microspheres.

A method is herein proposed to produce biodegradable microcapsules by a self-healing of porous microspheres, which were prepared from water-in-oil-in-water (W1/O/W2) double-emulsion templates. Methoxypoly(ethylene glycol)-b-poly-dl-lactide (PELA) was dissolved in ethyl acetate (EA) as the oil phase (O) of double emulsion, NaCl and poly(vinyl acetate) aqueous solutions serving as internal and external water phases (W1 and W2), respectively. Porous PELA microspheres were prepared by a two-step emulsification and solvent extraction method. Core materials, such as proteins or latex particles, could then be loaded by diffusion from the external water phase. Eventually, the pores in the surface could heal up triggered by a solvent swelling or infrared irradiation to form closed microcapsules. Compared with traditional encapsulations which are based on the two-step emulsification, the proposed posthealing approach could overcome some drawbacks, such as the shear destruction, solvent erosion to delicate core materials, or even their unexpected release during the emulsification. Besides PELA, poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) microcapsules were also proved feasible to fulfill such an approach.

Surface charge affects cellular uptake and intracellular trafficking of chitosan-based nanoparticles.

Chitosan-based nanoparticles (NPs) are widely used in drug delivery, device-based therapy, tissue engineering, and medical imaging. In this aspect, a clear understanding of how physicochemical properties of these NPs affect the cytological response is in high demand. The objective of this study is to evaluate the effect of surface charge on cellular uptake profiles (rate and amount) and intracellular trafficking. We fabricate three kinds of NPs (∼ 215 nm) with different surface charge via SPG membrane emulsification technique and deposition method. They possess uniform size as well as identical other physicochemical properties, minimizing any differences between the NPs except for surface charge. Moreover, we extend our research to eight cell lines, which could help to obtain a representative conclusion. Results show that the cellular uptake rate and amount are both positively correlated with the surface charge in all cell line. Subsequent intracellular trafficking indicates that some of positively charged NPs could escape from lysosome after being internalized and exhibit perinuclear localization, whereas the negatively and neutrally charged NPs prefer to colocalize with lysosome. These results are critical in building the knowledge base required to design chitosan-based NPs to be used efficiently and specifically.

Simultaneous production of 1,3-dihydroxyacetone and xylitol from glycerol and xylose using a nanoparticle-supported multi-enzyme system with in situ cofactor regeneration.

Cofactor-dependent biotransformations often require consumption of a secondary substrate for cofactor regeneration. Alternatively, two synthetic reactions may be coupled together through cofactor regeneration cycles. Simultaneous production of value-added products from glycerol and xylose was realized in this work through an enzymatic NAD(H) regeneration cycle involving two enzymes. Glycerol dehydrogenase (GDH) catalyzed the production of 1,3-dihydroxyacetone (DHA) from glycerol, while xylose reductase (XR) enabled the reduction of xylose to xylitol using the protons released from glycerol. Both enzymes were immobilized with P(MMA-EDMA-MAA) nanoparticles. Interestingly, the immobilized multi-enzyme system showed much improved productivity and stability as compared to native enzymes, such that the total turnover number (TTN) reached 82 for cofactor regeneration while the yield reached 160g/g-immobilized GDH for DHA production.

Salt induced irreversible protein adsorption with extremely high loadings on electrospun nanofibers.

LiCl is a kosmotrope that generally promotes protein salvation in aqueous solutions. Herein we report that LiCl embedded in electrospun polymeric nanofibers interestingly induced an abnormal protein adsorption and substantially augmented the adsorption capacity of the fibers. As a result, equilibrium protein loadings reached over 64% (w/w) of the dry mass of fibers, 9-fold higher than that observed in the absence of the salt. The adsorption appeared to be irreversible such that little protein loss was observed even after washing the fibers vigorously with fresh buffer solutions. We further examined the application of such intensified protein adsorption for enzyme immobilization. Proteins including bovine serum albumin (BSA) and protamine were first adsorbed, followed by covalent attachment of an outer layer of an enzyme, α-chymotrypsin. Such a multilayer-structured nanofibrous enzyme exhibited extremely high stability with no obvious activity loss even after being incubated for 8 months at 4 °C in aqueous buffer solution. The LiCl induced irreversible protein adsorption, which has been largely ignored in previous studies with electrospun materials, rendering an interesting scenario of interfacial protein-material interactions. It also reveals a new mechanism in controlling and fabricating molecular interactions at interfaces for development of a broad range of biomaterials.