Papers by Keyword: Poly-γ-Glutamic Acid

Abstract: The present paper describes the preparation and characterization of novel biodegradable nanoparticles based on self-assembly of poly-γ-glutamic acid (γ-PGA). The nanosystems were stable inaqueous media at low pH conditions. Solubility of the systems was determined by turbidity measurements. Surface charge and mobility were measured electrophoretically. It was found that the size and size distribution of the nanosystems depends on the concentrations of γ-PGA solutions and their ratio as well as on the pH of the mixture and the order of addition. The average hydrodynamic diameters were between 150 and 330 nm. These biodegradable,self-assembling stable nanocomplexes might be useful for several biomedical applications.

Abstract: In order to improvedβ-TCP biocompatibility and cell growth, was chosen to modify β-TCP matrices to produce a γ-PGA/β-TCP composite biomaterial. Then, the morphology, water uptake and retention abilities, in vitro degradation property in the simulated medium, cytotoxicity of this novel γ-PGA/β-TCP composite is investigated. SEM shows that the γ-PGA/β-TCP composite has a porous structure. By increasing the percentage ofγ-PGA from 0% to 50%, the swelling ratio of the composite s was enhanced from 9.0%to 297%. These data suggested that the surface hydrophilicity, water absorption rate, and swelling ratio were improved by adding γ-PGA to the composite. In the cytocompatibility test, the density of MC3T3-E1 preosteoblasts cells on the PTCP1:1 leachates was almost 110% higher than that on the controls on day 3. Therefore, the γ-PGA/β-TCP composite scaffolds, due to their better hydrophilicity, cytocompatibility, and porous structure, are very promising biomaterials for tissure engineering applications.

Abstract: Experiments were made to investigate the technology and conditions for producing chicken manure regenerative feed containing poly-γ-glutamic acid (γ-PGA) under solid-state fermentations (SSF) from Bacillus subtilis CCTCC202048. The maximum γ-PGA production (5.4%) was obtained in the mixed substrates of chicken manure, soybean cake and wheat bran (1:1:0.2 w/w) supplemented with 0.5% glutamic acid and 0.5% citric acid, with initial moisture content 65% and initial pH 8.5 in 250 ml flasks, inoculation at mid-log phase with a 4% inoculum level and cultivation for 48 h at 37°C. Scale-up experiments on the scale of 130 kg also showed that the yield of γ-PGA reached 4.2% and fermentation increased protein content of the solid substrates from 17.5% to 32.8%. These would lay a foundation for lessening the pollution of chicken manure, increasing chicken manure feed efficiency and exploring a late-model feed additive.

Abstract: Poly-γ-glutamic acid (γ-PGA) is a kind of water-soluble and biodegradable polymer, as a potential targeted biopolymer that can be refined from biomass directly. In this work, the effect of environmental parameters on γ-PGA formation by Bacillus licheniformis is investigated . The influence of culture temperature, pH and culture time on cell growth, γ-PGA production and molecular weight, polymer stereochemistry are determined. The γ-PGA yield is higher(30.13g/L) at culture temperature 37 , pH 7.0. Alteration of the medium pH, temperature, culture time and aeration had little to no significant effects on the product quality as measured by stereochemical composition. But alteration of the medium pH, temperature, culture time and aeration have obvious effects on the γ-PGA yield and molecular weight, increasing the biomass and γ-PGA yields. Under the optimal environmental conditions yields of γ-PGA in excess of 36g/L is obtained in submerged culture. Finally, the large-scale fermentation of γ-PGA production was successfully scaled up to a 100-l fermentor, with the highest γ-PGA productivity for over 57.5 g/l.