Bacterial cellulose (BC) is a fermentative product of Acetobacter xylinum characterized by high purity and crystallinity of up to 80%. Due to its excellent physical and mechanical properties, bacterial cellulose is increasingly interested in research, especially in the study of applying BC in different fields. Although it is a potential direction, the large-scale production of BC still has certain limitations, mainly the fermentation medium's high cost. Therefore, this study used pineapple waste as a carbon source for BC fermentation. After investigating the influence of fermentation factors on BC yield, this study focused on evaluating the crystallinity of BC under different fermentation conditions. The X-ray diffraction technique was used to determine the crystallinity, while Scanning Electron Microscopy was used to assess the differentiation of the BC structure. The study results showed that, at different fermentation conditions of temperature (25–35°C), time (5–10 days), and bacterial concentration (5–15%), the bacterial cellulose crystallinity was significantly different and in the range of 40.6 % to 83.4 %. The optimum crystallinity of BC was recorded when the experiment was set up at the fermentation temperature of 30°C, 13 days of fermentation time, and bacterial concentration of 14%, with the BC crystallinity being 82.2%.
Tuberculosis (TB) is one of the most dangerous infectious diseases and is caused by Mycobacterium bovis (Mb) and Mycobacterium tuberculosis (Mt). Branched‐chain amino acid aminotransferases (BCATs) were reported to be the key enzyme for methionine synthesis in Mycobacterium. Blocking the methionine synthesis in Mycobacterium can inhibit the growth of Mycobacterium. Therefore, in silico screening of inhibitors can be a good way to develop a potential drug for treating TB. A pyridoxal 5′‐phosphate (PLP)‐form of Mycobacterium bovis branched‐chain amino acid aminotransferases (MbBCAT), an active form of MbBCAT, was constructed manually for docking approximately 150 000 compounds and the free energy was calculated in Autodock Vina. The 10 compounds which had the highest affinity to MbBCAT were further evaluated for their inhibitory effects against MbBCAT. Within the selected compounds, compound 4 (ZINC12359007) was found to be the best inhibitor against MbBCAT with the inhibitory constant Ki of 0·45 μmol l−1 and IC50 of 2·37 μmol l−1. Our work provides potential candidates to develop effective drugs to prevent TB since the well‐known structural information would be beneficial in the structure‐based modification and design.
Magnetic composite fabricated from polyaniline and Fe3O4-hydrotalcite (Pan/MHT) was successfully applicated for removal of methyl orange (MO) from wastewater. The structure and properties of Pan/MHT were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, vibrating sample magnetometer, and Brunauer-Emmett-Teller adsorption isotherm. Adsorption kinetic results indicated that the adsorption process followed pseudosecond-order kinetic model ( R 2 = 0.999 ), MO adsorption onto Pan/MHT was well described by Freundlich isotherm ( R 2 = 0.994 ), and the MO adsorption capacity of 2 Pan/MHT obtained the highest with Q e = 156.25 mg / g . Batch adsorption experiments were carried out using magnetic composite with the effects of initial MO concentration, solution pH, and adsorbent dosage. The results revealed that the magnetic Pan/MHT exhibited efficient adsorption of MO in the aqueous solution as a result of the affinity for organic dyes, microporous structure, and suitable surface area for adsorption (15,460 m2/g). The superparamagnetic behavior of Pan/MHT (with H c = 18.56 Oe , M s = 23.38 × 10 − 3 emu / g , and M r = 0.91 × 10 − 3 emu / g ) helps that it could be separated from the solution and performs as an economical and alternative adsorbent to removal and degrade azo dye from wastewater. Pan/MHT was also investigated to reuse after desorption of MO in 0.1 M HCl, and the results show that 2 Pan/MHT can be reused for 4 cycles with Q e = 79.66 mg / g .
An overview of the basic technology to produce bioethanol from lignocellulosic biomass is presented in this context. The conventional process includes two main steps. First, lignocellulose must be pretreated in order to remove lignin and enhance the penetration of hydrolysis agents without chemically destruction of cellulose and hemicellulose. Second, the pretreated material is converted to bioethanol by hydrolysis and fermentation. Some typical published studies and popular processing methods in attempts to improve the biomass conversion to bioethanol and increase the cost-effectiveness are also introduced briefly. Herein, the refinery of the resulted raw bioethanol mixture to obtain higher concentrated solution is not regarded.
Alkaline pretreatment has been known as the most popular method to process lignocellulosic materials for bioethanol production due to its simplicity and high efficiency. However, the waste water of the process has a very high basicity, which requires neutralization with acids upon further disposal. In this study, rubber wood saw dust (Hevea brasiliensis) was employed as lignocellulosic material and its pretreatment was inspected with both diluted H2SO4 and NaOH in different combination ways. Hereby, acid was used not only for waste water neutralization but also to contribute to lignin removal. Analysis results showed that an aqueous solution of 2.0 - 2.5 wt.% H2SO4 can be used to treat the biomass followed by alkaline pretreatment. By this so-called combo-pretreatment technique, cellulose was well preserved without significant hydrolysis while the final pretreatment efficiency was up to 63.0%, compared to 48.2% of using only the alkaline solution and 13.7% of using only the acidic solution. Finally, alkaline waste water can be mixed to be neutralized with acidic waste water from the two previous steps. This innovated technique improved the pretreatment efficiency almost without increasing in chemical cost.
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