Levulinic acid (LA) is a new versatile platform chemical derived from renewable non-food biomass. A major challenge in the purification of LA from biomass hydrolysate is the separation of LA and formic acid. A novel granular activated carbon (GAC) adsorption and separation of LA and formic acid were investigated in this work. Adsorption equilibria elucidated that LA preferentially adsorbed onto GAC than formic acid. Mixed solution of LA and formic acid was fed into the GAC packed-bed at 30°C, then formic acid was washed out from the column in a pure form with 60°C water and finally LA was effectively eluted with 95% (v/v) ethanol at 60°C. LA can be completely separated from formic acid by this simple GAC adsorption process with good yield and high purity.
β-chitosan preparation from squid pens was carried out using aqueous NaOH with the ultrasonic assistance. Single factor experiments and L9(34) orthogonal experiments were used to investigate the effect of three parameters (reaction time, concentration of NaOH and reaction temperature) on deacetylation of β-chitin. The optimal conditions for deacetylation of chitin were reaction temperature 80°C, reaction time 2 h and concentration of NaOH 50%. The optimal conditions allowed deacetylation degree of β-chitin from 71.32% to 92.91%. The β-chitosan from squid pens was confirmed by Fourier transform infrared spectroscopy. The antibacterial activities of the prepared β-chitosans againstaphylococcus aureus(S. aureus) andEscherchia coli(E.coli) were then determined and compared by the MIC (minimum inhibitory concentration). Results indicate that β-chitosans with different degrees of deacetylation (DD) possess different antibacterial activity. The growth ofS. aureuscan be easily inhibited by prepared β-chitosan thanE.coli.
The transformation conditions of the protoplasts from Trichoderma viride mediated by restriction enzyme were studied in this paper. The optimum generation conditions of protoplasts were as followed: 8 mg/ml glucanex was added into the phosphate buffer (pH 6.98), the mycelial that cultured for 24 hr was hydrolyzed for 4 hr at 30°C under 40 r/min shaking speed. The protoplast yield was 4.7×107 cfu/mg. The regeneneration rate of protoplast was 14.5% on CM medium contained 0.3 mol/L KCl and 0.3 mol/L Inositol. Transformants were obtained by transfering hygromycin B resistance gene into T. viride by restriction enzyme mediated integration (REMI), The preliminary identification of the transformants indicated that the exogenous gene had been integrated into T. viride genome.
Water-insoluble β - ( 1 - 3 ) – D - glucan isolated from the sclerotium of Poria cocos hardly exhibits biological activity. Therefore, it is advantageous to produce a value-added product from Poria cocos. We extracted the β - ( 1 - 3 ) – D - glucan from the sclerotium of Poria cocos and synthesized a carboxymethylated derivative, carboxymethyl-pachyman (CMP). The influences on the degrees of substitution ( DS ) of CMP, for example, volume ratio of ethanol to water, [NaOH]/[MCA] ratio, reaction temperature and reaction time have been examined, respectively. The most favorable conditions for pachyman carboxymethylation are obtained with a [NaOH]/[MCA] ratio of 1.5, at 45°C for 60 minutes with a reaction medium consisting of a ethanol/water 80:20 (v/v) mixture.
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