| The y-PGA fermented by strain Bacillus licheniformis CGMCC3336 was used as the original in this article,the fermentation were used to do the downstream extraction work on?-PGA,including sterilization,decolorizing,concentrated by ultrafiltration and drying steps.The decolorizing include active carbon and resin decolorizing,finally get the white and high purity y-PGA sample.Using the y-PGA sample in two applications,one for the?-PGA and pullulan nanofiber membrane,optimize the preparation conditions and then adopted glutaraldehyde cross linking nanofiber membrane to improve surface hydrophilic,optimization glutaraldehyde crosslinking conditions,then attachment erythromycin drugs,finally preparation of the y-PGA/pullulan nanofiber membrane dressings has an antibacterial effect.On the other hand is y-PGA with chitosan gel adsorbent material,depend on the response surface optimization experiments,then using y-PGA/chitosan gel adsorbent material absorbing heavy metals such as Cu2+ and Fe3+,finally preparation of the material for absorbing heavy metals such as Cu2+ and Fe3+.Here are main conclusions of this article:Taking the y-PGA fermentation broth,selection plate and frame filter sterilization process,choosing 1200 mesh filter cloth,clay:diatomite=1:2,the total addition amount of filter aid is 1.5%(w/v),under these conditions,the bacteria removal rate was 96.89%,the loss of y-PGA was 12.16%.The powdered activated carbon was used to bleach firstly,selecting 17#of activated carbon 3 the addition amount was 2.5%(w/v),the decolorization conditions:20?,40min,pH 5.0,the decolorization rate was 89.21%,the loss of y-PGA was 13.95%.The resin was used to decolorzing secondly,selecting D941#of resin,the addition amount was 18mL,the decolorization conditions:6r/min,pH 5.0,the decolorization rate was 79.89%,the loss of y-PGA was 21.39%.Small molecular impurities in the fermentation supernatant were removed by ultrafiltration,choosing 10 kDa membrane package and conducted 5 times of ultrafiltration to elute and remove the impurities,the ion removal was 90.42%.Finally,we selected the method of freeze drying to dispose the samples at last and determined its purity is 90.55%,molecular weight is 3.92×105 Da,ash is 3.7%,moisture is 5.2%,total sugar is 0.023%and hybrid protein is 0.037%.The y-PGA mixed with pullulan prepared nanofiber membrane by electrospinning.The optimum conditions obtained with blend spinning method,40%polyglutamate and 20%pullulan,polyglutamic acid and pullulan addition ratio was 1:12,14 kV voltage,15 cm spinning distance to prepare nanofibers with small diameter and narrow size distribution without beads.The nanofiber fibers had a smaller diameter of 99.19nm.In order to improve the stability of polyglutamate-pullulan nanofiber membrane in an aqueous environment,to investigate the performance of different glutaraldehyde crosslinking conditions:glutaraldehyde crosslinking by the ratio of the glutaraldehyde and ethanol was 1:86,glutaraldehyde crosslinking 15h,glutaraldehyde crosslinking by adding 0.15mL H2SO4,fiber diameter increased from 164nm to 195nm,contact angle increased from 38.55°to 67.36°,46.23%improved at 0s,contact angle increased from 21.35°to 50.27°,57.53%improved at 5s.Attachment erythromycin drugs in fiber membrane,observe antibacterial effect:we can identify with the fiber membrane has antibacterial effect when erythromycin add 0.05g,inhibition zone size is 10.37mm±1.05mm.The y-PGA mixed with chitosan prepared gel adsorbent material.Depend on the response surface optimization experiments:the ratio of poly-glutamic acid and chitosan 15:85,total volume added 5.56%,the amount of acetic acid 22.75mL,the concentration of acetic acid 0.5M,the compressive strength of the gel samples was 16.2MPa,the swelling ratio was 7.02.The gel adsorbent material applied to adsorption of heavy metals Cu2+ and Fe3+:the optimum adsorption pH was 6.0,the optimum adsorption temperature is 20?,at this time of Cu2+ maximum adsorption rate of 98.53%,Fe3+ maximum adsorption rate of 9136%.so it has application value. |
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