Production of struvite from beverage waste as phosphorus source

In this work was investigated the influence of pH on the synthesis of struvite using cola beverage waste as source of phosphorus. The process was operated in a batch reactor. The reaction time was 20 minutes, and the chemicals MgCl2.6H2O and NH4Cl were used in the experiment, with a molar ratio of Mg+2:NH4+:PO4(3-) = 1:1:1. The products were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), surface area (BET), thermogravimetric analysis (TGA) and infra-red (IR). From the results was verified the formation of a crystalline phase at pH 9.5, with a surface area of 6.59 m² g-1 and a particle size of about 0.25 µm

A rapid and accurate 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide colorimetric assay for quantification of bacteriocins with nisin as an example*

The objective of this study is to propose a more accurate and faster MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] colorimetric assay (MCA) for quantitative measurement of polypeptide bacteriocins in solutions with nisin as an example. After an initial incubation of nisin and indicator bacterium Micrococcus luteus NCIB 8166 in tubes, MTT was added for another incubation period. After that, nisin was quantified by estimating the number of viable bacteria based on measuring the amount of purple formazan produced by cleavage of yellow tetrazolium salt MTT. Then MCA was compared to a standard agar diffusion assay (ADA). The results suggested a high correlation coefficient (r 2=0.975±0.004) between optical density (OD) and the inhibitory effect of nisin on a bacterial strain Micrococcus luteus NCIB 8166 at a range of 0.125~32 IU/ml. The MCA described in this study was very quick. Quantification of nisin took only 7~8 h and the detection limit was at the level of 0.125 IU/ml when compared to 12 IU/ml and 24~28 h for ADA. The MCA provides an accurate and rapid method for quantification of nisin in solutions and is expected to be used for quantification of other antimicrobial substances

Effect of Cholesterol on the Properties of Spray-Dried Lysozyme-Loaded Liposomal Powders

The influence of cholesterol (Chol) in the liposomal bilayer on the properties of inhalable protein-loaded liposomal powders prepared by spray-drying technique was investigated. Lysozyme (LSZ) was used as a model protein. Feed solution for spray drying was prepared by direct mixing of aqueous solution of LSZ with mannitol solution and empty liposome dispersions composed of hydrogenated phosphatidylcholine and Chol at various molar ratios. The spray-dried powders were characterized with respect to morphology, thermal property, and crystallinity using scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction, respectively. Most formulations gave slightly aggregated, spherical particles, and percentage yields of the spray-dried powders decreased with increasing Chol content. Degree of particle aggregation depended on the powder composition. The powders spontaneously formed liposomes which efficiently entrapped LSZ after reconstitution with HEPES buffered saline (HBS) at 37°C. Lysozyme entrapment efficiency and size distribution of the reconstituted liposomes were evaluated after the powders were reconstituted with HBS. Increasing Chol content resulted in a decrease in size of the reconstituted liposomes and an increase in entrapment efficiency of LSZ. These results correlated with thermal behaviors of the reconstituted liposomes. Biological activity of LSZ was not affected by the spray-drying process. It was also demonstrated that LSZ-loaded liposomal powders could be produced without the need to preload the LSZ into liposomes prior to spray-drying process