Shih-Bin Lin

In situ modification of bacterial cellulose network structure by adding interfering substances during fermentation

In an attempt to obtain bacterial cellulose (BC) with improved rehydration ability, Tween 80, urea, fluorescent brightener, hydroxypropylmethyl cellulose (HPMC) and carboxymethyl cellulose (CMC) were introduced into BC fermentation medium. Measurements of the mechanical strength of the resulting BCs (TBC, UBC, FBC, HBC and CBC) showed a decline except for UBC. SEM images showed that, although the cellulose bundle widths of FBC, HBC and CBC increase, the cellulose network void in FBC grew, while those in HBC and CBC shrank. X-ray diffraction and FT-IR analysis demonstrated that the addition of HPMC and CMC reduced the degree of crystallinity in their corresponding MBCs from 70.54% to 52.23% and 45.38%, respectively. HBC and CBC also exhibited the highest rehydration ability among all MBCs as well as the lowest crystallinity. The in situ modification with HPMC and CMC during fermentation can effectively improve rehydration ability of BC by altering its network structure.

The bioactive composite film prepared from bacterial cellulose and modified by hydrolyzed gelatin peptide

The hydrolyzed gelatin peptides, obtained from the hydrolysis of Tilapia nilotica skin gelatin with alcalase and pronase E, were fractionated using an ultrafiltration system into hydrolyzed gelatin peptides-a (10 kDa membrane), hydrolyzed gelatin peptides-b1, and hydrolyzed gelatin peptides-b2 (5 kDa membrane) fractions. The highest oxygen radical absorbance capacity was observed in hydrolyzed gelatin peptides-b2, which contained more nonpolar amino acids than the other hydrolyzed gelatin peptides. Hydrolyzed gelatin peptides-b2 at a concentration of 12.5 mg/ml exhibited the highest proliferation ability and increased the expression of Type I procollagen mRNA, which indicated an enhanced collagen synthesis. Hydrolyzed gelatin peptides protected Detroit 551 cells from 2,2′-azobis(2-amidinopropane) dihydrochloride-induced oxidative damage and increased cell viability. Hydroxylpropylmethyl cellulose-modified bacterial cellulose and dried fabricated biofilm were less eligible for Detroit 551 cell proliferation than bacterial cellulose. The release of hydrolyzed gelatin peptides in bacterial cellulose film was slower than that in hydroxylpropylmethyl cellulose-modified bacterial cellulose and dried fabricated biofilm; thus, bacterial cellulose film and hydroxylpropylmethyl cellulose-modified bacterial cellulose and dried fabricated biofilm are suitable candidates for applications in delayed release type and rapid release type biofilms, respectively.

Hurdle Effect of Antimicrobial Activity Achieved by Time Differential Releasing of Nisin and Chitosan Hydrolysates from Bacterial Cellulose.

We investigated the combined antimicrobial effect of nisin and chitosan hydrolysates (CHs) by regulating the antimicrobial reaction order of substances due to differential releasing rate from hydroxypropylmethylcellulose-modified bacterial cellulose (HBC). The minimum inhibitory concentration of nisin against Staphylococcus aureus and that of CHs against Escherichia coli were 6 IU and 200 μg/mL, respectively. Hurdle and additive effects in antimicrobial tests were observed when nisin was used 6 h before CH treatment against S. aureus; similar effects were observed when CH was used before nisin treatment against E. coli. Simultaneously combined treatment of nisin and CHs exhibited the low antimicrobial effect. HBC was then selected as the carrier for the controlled release of nisin and CHs. A 90% inhibition in the growth of S. aureus and E. coli was achieved when 30 IU-nisin-containing HBC and 62.5 μg/mL-CH-containing HBC were used simultaneously. The controlled release of nisin and CHs by using HBC minimized the interaction between nisin and CHs as well as increased the number of microbial targets.