Evaluation of the Biogenic Amines and Microbial Contribution in Traditional Chinese Sausages

Biogenic amines (BAs) in sausages represent a health risk for consumers, and thus investigating the BAs accumulation mechanism is important to control the BAs. In this study, the BAs profiles of 16 typical Chinese sausage samples were evaluated, and 8 kinds of common BAs were detected from different samples. As a whole, the BAs contents of the majority of Chinese sausage samples were within the safe dosage range, except that the total BAs and histamine concentrations of sample HBBD were above the toxic dosage levels. Furthermore, the bacterial and fungal communities of the Chinese sausage samples were investigated by high-throughput sequencing analysis, and Staphylococcus, Bacillus, Lactococcus, Lactobacillus, Debaryomyces, and Aspergillus were identified as the predominant genera. Accordingly, 13 representative strains were selected from the dominant genera, and their BAs formation and degradation properties were evaluated. Finally, the results of fermented meats model experiment indicated that the Staphylococcus isolates including Staphylococcus pasteuri Sp, Staphylococcus epidermidis Se, Staphylococcus carnosus Sc1, Staphylococcus carnosus Sc2, and Staphylococcus simulans Ss could significantly reduce BAs, possessing the potential as the starter cultures to control the BAs in fermented meat products. The present study not only helped to explain the BAs accumulation mechanism in Chinese sausage, but also developed the candidates for potential BAs control in fermented meat products

Colloid Surf. B-Biointerfaces

The bifunctional coating with antithrombotic and antimicrobial activity was developed using nattokinase (NK) and nanosilver (AgNPs). Firstly, the adsorption interactions between NK and AgNPs were confirmed, and the composite particles of NK-AgNPs were prepared by adsorption of NK with AgNPs. At 5 FU/mL of NK concentration, the saturation adsorption capacity reached 24.35 FU/mg AgNPs with a high activity recovery of 97%, and adsorption by AgNPs also enhanced the heat stability and anticoagulant effect of NK. Based on the electrostatic force driven layer-by-layer self-assembly, the NK-AgNPs were further assembled with polyethylenimine (PEI) to form coating. UV-vis analysis showed that the self-assembly process was regular, and atom force microscopy analysis indicated that NK-AgNPs were uniformly embedded into the coating. The NK-AgNPs-PEI composite coating showed potent antithrombotic activity and antibacterial activity. This study developed a novel strategy to construct the bifunctional coating with antithrombotic and antimicrobial properties, and the coating material showed promising potential to be applied in the medical device. (C) 2014 Elsevier B.V. All rights reserved.The bifunctional coating with antithrombotic and antimicrobial activity was developed using nattokinase (NK) and nanosilver (AgNPs). Firstly, the adsorption interactions between NK and AgNPs were confirmed, and the composite particles of NK-AgNPs were prepared by adsorption of NK with AgNPs. At 5 FU/mL of NK concentration, the saturation adsorption capacity reached 24.35 FU/mg AgNPs with a high activity recovery of 97%, and adsorption by AgNPs also enhanced the heat stability and anticoagulant effect of NK. Based on the electrostatic force driven layer-by-layer self-assembly, the NK-AgNPs were further assembled with polyethylenimine (PEI) to form coating. UV-vis analysis showed that the self-assembly process was regular, and atom force microscopy analysis indicated that NK-AgNPs were uniformly embedded into the coating. The NK-AgNPs-PEI composite coating showed potent antithrombotic activity and antibacterial activity. This study developed a novel strategy to construct the bifunctional coating with antithrombotic and antimicrobial properties, and the coating material showed promising potential to be applied in the medical device. (C) 2014 Elsevier B.V. All rights reserved

Evaluation of the Biogenic Amines Formation and Degradation Abilities of Lactobacillus curvatus From Chinese Bacon

Control of biogenic amines (BAs) is critical to guarantee the safety of fermented meat products. The aim of this study is to evaluate the BAs formation and degradation abilities of lactic acid bacteria from Chinese bacon to obtain the beneficial candidate for BAs control. Seven lactic acid bacteria were selected from the typical Chinese bacon products, identified as Lactobacillus curvatus by 16S rDNA analysis. Then, genes analysis and high-performance liquid chromatography (HPLC) analysis were performed to evaluate the BAs formation and degradation abilities of as-selected strains. All L. curvatus strains were confirmed to harbor the genes encoding the tyrosine decarboxylase and ornithine decarboxylase, and they could produce tyramine, β-phenethylamine, putrescine, and cadaverine. In comparison, the lowest concentration of total BAs was obtained in L. curvatus G-1. Meanwhile, all L. curvatus strains were positive in amines oxidase gene analysis, and they could also degrade six common BAs, especially the L. curvatus G-1 with the highest degradation percentage (above 40%) for each BA. Furthermore, fermented meat model analysis verified that the L. curvatus G-1 could significantly reduce BAs. In conclusion, L. curvatus G-1 shows a low BAs-producing ability, as well as a high BAs-degrading ability, and this study provides a promising candidate for potential BAs control in fermented meat products

Immobilization of beta-glucosidase onto Magnetic Nanoparticles and Evaluation of the Enzymatic Properties

This paper reports on a novel and efficient beta-glucosidase immobilization method using magnetic Fe3O4 nanoparticles as a carrier. Based on response surface methodology, the optimal immobilization conditions obtained were: glutaraldehyde (GA) concentration, 0.20%; enzyme concentration, 50.25 mu g/mL; cross-linking time, 2.21 h; and the maximum activity recovery reached 89.35%. The magnetic immobilized enzyme was characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM). FTIR revealed that beta-glucosidase was successfully immobilized on the magnetic nanoparticles. TEM showed that enzyme-magnetic nanoparticles possessed nano-scale size distribution. VSM confirmed that the enzyme-magnetic nanoparticles were superparamagnetic. The properties of the immobilized beta-glucosidase were improved, and the immobilized beta-glucosidase exhibited wider pH and temperature ranges of activation, higher accessibility of the substrate, better thermal stability, and better storage stability than that of the free enzyme. The enzyme-magnetic nanoparticles could be separated magnetically for easy reuse. Immobilization of beta-glucosidase onto the magnetic nanoparticles has the potential for industrial application

J. Chem. Technol. Biotechnol.

BACKGROUNDBiosynthesis of silver nanoparticles (AgNPs) is considered a green method. Sunlight could induce the synthesis of AgNPs with bacteria and plant biomass, while animal and fungus biomass have not been investigated for synthesis of AgNPs under sunlight radiation. RESULTSUnder 80 000 lx sunlight intensity and 4 mg mL(-1) of tryptone solution, the maximum AgNPs yield was obtained after 60 min, and the Ag+ (1 mmol L-1) conversion rate reached 98 2%. Transmission electron microscopy revealed that T-Ag (tryptone-mediated) were circular and oval, with an average diameter of 11.63 +/- 4.17 nm, and Y-Ag (yeast extract-mediated) displayed similar shape and size to T-Ag. X-ray diffraction confirmed that T-Ag and Y-Ag were in the form of nanocrystals. As-prepared AgNPs showed obvious antimicrobial activity against B. subtilis and E. coli. Capping with peptides helped to maintain colloidal stability of AgNPs. Without sunlight, AgNPs showed high stability at pH 7-11 due to high -potential values, while the stability was destroyed at pH 4. Further exposure to sunlight for 48 h also resulted in sedimentation of AgNPs. CONCLUSION Sunlight could induce tryptone and yeast extract to synthesize AgNPs, and the stability of AgNPs could be regulated by capping peptides, pH, and sunlight exposure. (c) 2013 Society of Chemical IndustryBACKGROUNDBiosynthesis of silver nanoparticles (AgNPs) is considered a green method. Sunlight could induce the synthesis of AgNPs with bacteria and plant biomass, while animal and fungus biomass have not been investigated for synthesis of AgNPs under sunlight radiation

J. Chem. Technol. Biotechnol.

BACKGROUND: Adsorption is believed to be an effective and green technology for the removal and recovery of rare earths (III) from dilute solution. RESULTS: A novel hybrid gel, abbreviated as ALG-PGA, has been prepared through crosslinking calcium alginate (ALG) and. gamma-poly glutamic acid (PGA), and its adsorption behavior towards whole rare earths (III) has been examined. Taking Nd(III) as a representative element, the adsorption capacity, kinetics, reusability, selectivity and mechanism have been investigated. Cation exchange is proposed as a possible adsorption mechanism. Doping PGA molecules into calcium alginate beads can significantly enhance the adsorption capacity and the selectivity of rare earths from non-rare earths. The maximum adsorption capacity obtained for Nd(III) was 1.65 mmol g(-1). Reutilization of ALG-PGA gel was confirmed for up to eight consecutive sorption-desorption cycles with no damage to the gel. CONCLUSION: The prepared biosorbent, ALG-PGA, was biocompatible and cost effective with a good adsorption ability for Nd(III), and provides a new approach to the recovery of rare earths (III) from rare earths-containing wastewater. (C) 2013 Society of Chemical IndustryBACKGROUND: Adsorption is believed to be an effective and green technology for the removal and recovery of rare earths (III) from dilute solution

Magnetic nanoparticles (MNPs) covalently coated by PEO-PPO-PEO block copolymer for drug delivery

A stable drug carrier has been prepared by covalently coating magnetic nanoparticles (MNPs) with PEO-PPO-PEO block copolymer Pluronic P85. The particles were characterized by TEM, XRD, DLS, VSM, FTIR, and TGA. A typical product has a 15 nm magnetite core and a 100 nm hydrodynamic diameter with a narrow size distribution and is superparamagnetic with large saturation magnetization (57.102 emu/g) at room temperature. The covalently-coated Pluronic-MNPs (MagPluronics) were proven to be stable in different conditions, such as aqueous solution, 0.2 M PBS solution, and pH 13.5 solution, which would be significant for biological applications. Furthermore, MagPluronics also possess temperature-responsive property acquired from the Pluronic copolymer layer on their surface, which can cause conformational change of Pluronics and improve load and delivery efficiency of the particles. The temperature-controlled loading and releasing of hydrophobic model drug curcumin were tested with these particles. A loading efficiency of 81.3% and a sustained release of more than 4 days were achieved in simulated human body condition. It indicates that the covalently-coated MagPluronics are stable carriers with good drug-loading capacity and controlled-release property. (C) 2012 Elsevier Inc. All rights reserved

Encapsulation of Pannonibacter phragmitetus LSSE-09 in alginate-carboxymethyl cellulose capsules for reduction of hexavalent chromium under alkaline conditions

Cr(VI) was efficiently reduced to Cr(III) by Pannonibacter phragmitetus LSSE-09 encapsulated in liquid-core alginate-carboxymethyl cellulose capsules under alkaline conditions. Taking into account the physical properties of the capsules, the activity of encapsulated cells, and total Cr(III) concentration in the supernatant, optimal conditions (0.5% w/v sodium alginate; 2% w/v sodium carboxymethyl cellulose; 0.1 M CaCl(2); 30-min gelation time) for LSSE-09 encapsulation were determined. At optimal conditions, a relatively high reduction rate of 4.20 mg g ((dry weight)) (-1) min(-1) was obtained. Total Cr(III) concentration in the supernatant was significantly decreased after reduction, because 63.7% of the formed soluble organo-Cr(III) compounds compared with those of free cells were captured by the relatively smaller porous structure of alginate capsules. The optimal pH value (9.0) for Cr(VI) reduction was not changed after encapsulation. In addition, encapsulated LSSE-09 showed no appreciable loss in activity after eight repeated cycles at 37A degrees C, and 85.7% of its initial activity remained after 35-day storage at 4A degrees C. The results suggest that encapsulated LSSE-09 in alginate-carboxymethyl cellulose capsules has potential biotechnological applications for the detoxification of Cr(VI)-contaminated wastewater

Enhancement of biodesulfurization by Pseudomonas delafieldii in a ceramic microsparging aeration system

A 700 ml membrane-aerated, stirred glass reactor equipped with four vertical baffles was constructed. Biodesulfurization of model oil (n-dodecane containing dibenzothiophene-DBT) and hydrodesulfurized diesel was carried out using Pseudomonas delafieldii strain R-8. Microbubble aeration gave an activity of 1.3 mg DBT removed g(-1) h(-1) and 277 mu g sulfur g(-1) h(-1) for model oil and hydrodesulfurized diesel, respectively. These values were 1.9- and 1.6-times higher than using a traditional bubble aeration process. This is a promising method for the biodesulfurization of petroleum feedstocks