Cellulose fibers extracted from sesame hull using subcritical water as a pretreatment

Subcritical Water as a Pre-treatment of Mixed Microbial Biomass for the Extraction of Polyhydroxyalkanoates

Polyhydroxyalkanoate (PHA) recovery from microbial cells relies on either solvent extraction (usually using halogenated solvents) and/or digestion of the non-PHA cell mass (NPCM) by the action of chemicals (e.g., hypochlorite) that raise environmental and health hazards. A greener alternative for PHA recovery, subcritical water (SBW), was evaluated as a method for the dissolution of the NPCM of a mixed microbial culture (MMC) biomass. A temperature of 150 °C was found as a compromise to reach NPCM solubilization while mostly preventing the degradation of the biopolymer during the procedure. Such conditions yielded a polymer with a purity of 77%. PHA purity was further improved by combining the SBW treatment with hypochlorite digestion, in which a significantly lower hypochlorite concentration (0.1%, v/v) was sufficient to achieve an overall polymer purity of 80%. During the procedure, the biopolymer suffered some depolymerization, as evidenced by the lower molecular weight (M_w) and higher polydispersity of the extracted samples. Although such changes in the biopolymer’s molecular mass distribution impact its mechanical properties, impairing its utilization in most conventional plastic uses, the obtained PHA can find use in several applications, for example as additives or for the preparation of graft or block co-polymers, in which low-M_w oligomers are sought.

Characterization of Structure and Antioxidant Activity of Polysaccharides From Sesame Seed Hull

Sesame seed hull is the major by-product of sesame seed processing and is rich in polysaccharides. In this work, sesame hull polysaccharides (SHP) were extracted by ultrasound-assisted alkali extraction methods with a yield of 6.49%. Three purified polysaccharide fractions were obtained after decolorization, deproteinization, and column chromatography. Then, their main composition and antioxidant activity were investigated. The dominant fraction was SHP-2 with a yield of 3.78%. It was composed of galacturonic acid (51.3%), glucuronic acid (13.8%), rhamnose (8.9%), glucose (8.4%), and others. The linkage types of SHP-2 have the α-D-GalpA-(1,4)-linked, α-D-GlcpA-(1,2)-linked, β-T-D-Rhap-linked, β-D-Glcp-(1,6)-linked, β-T-D-Galp-linked, α-L-Xylp-(1,4)-linked, α-L-Araf-(1,3,5)-linked, and β-D-Manp-(1,4)-linked. This study might provide some useful basic data for developing applications for sesame seed hull polysaccharides in the food and pharmaceutical industries.

Combining biological and chemical methods to disassemble of cellulose from corn straw for the preparation of porous carbons with enhanced adsorption performance

In this study, we used a combination of chemical and biological pretreatment methods to extract cellulose from corn straw with a relative content of 92.40%. The adsorption performance and mechanism of the prepared porous carbon were investigated using synthetic dye malachite green (MG) and antibiotic tetracycline hydrochloride (TC) as adsorption models. The kinetic studies suggested that the adsorption followed the pseudo-second-order model and Bangham model. The Freundlich isotherm model fitted the adsorption data best for both MG and TC. The thermodynamic studies showed that the adsorption of MG and TC by adsorbents were spontaneous and endothermic in nature. In addition, the adsorption performance was maintained at 50% of the original value after five cycles. More importantly, this method not only improved the adsorption performance of prepared porous carbon materials but also provides a reference for the application of other lignocellulosic materials for cellulose extraction.

Structural Characteristics of Inulin and Microcrystalline Cellulose and Their Effect on Ameliorating Colitis and Altering Colonic Microbiota in Dextran Sodium Sulfate-Induced Colitic Mice

Several studies have reported that dietary fibers (DFs) from plants may exert beneficial effects on inflammatory bowel disease. In the present study, we investigated the structural differences of soluble DF (inulin) and insoluble DF (microcrystalline cellulose, MCC) and their effects on the intestinal barrier integrity, gut microbiota community, and inflammation response in mice with dextran sodium sulfate (DSS)-induced colitis. Mice were fed for 21 days with diets containing inulin or MCC (2.5 g/kg body weight), and colitis was induced by administration of DSS (4% w/v) in drinking water during the last 8 days of experimentation. The results showed that inulin and MCC differ in morphology and structure. MCC exhibited a smaller particle size, a larger specific surface area, and higher thermal stability than inulin. In addition, both inulin and MCC restored various physical signs (body weight, colon weight and length, disease activity index score, and infiltration of inflammatory cells), gut barrier function (as evidenced by the increased expression of claudin-3, claudin-7, ZO-2, occludin, JAM-2, and MUC-3 and the decreased activity of myeloperoxidase activity), downregulation of mRNA expression of proinflammatory cytokines (caspase-1, NLPR3, TLR4, TNF-α, and IL-1β), and modulation of colon microbiota community. Taken together, the present study demonstrates that DFs differ in morphology and structure and ameliorate DSS-induced colitis in mice by blocking proinflammatory cytokines, reinforcing gut barrier integrity, and modulating gut microbiota. Therefore, DFs, especially inulin, are promising dietary supplements to alleviate intestinal inflammation.