This work presents a green and chemical free sequential process consisting of autohydrolysis, enzymatic treatment, and membrane assisted refining for the valorization of almond shell into the low ...degree of polymerisation xylooligosaccharides. For autohydrolysis, the temperatures (180, 200, and 220 °C) with different reaction times were evaluated. Further, enzymatic treatment of the autohydrolysate was performed to increase the concentration of low degree of polymerisation xylooligosaccharides. For enzymatic treatment, three different doses (5, 10, and 15 U) was used, and the optimum dose estimated using statistical analysis. Finally, the XOS rich enzyme liquor was subjected to membrane assisted refining using 1 kDa and 250 Da membranes to obtain XOS concentrate. Under the optimal condition (200 °C, 5 min) of autohydrolysis, about 54.5% of xylan could be obtained as oligosaccharides. However, the autohydrolysate was composed of 3.5% (w/w of biomass) of low degree of polymerisation xylooligosaccharides (xylobiose and xylotriose). The enzymatic treatment using 10 U of the enzyme could increase the concentration of low degree of polymerisation xylooligosaccharides to 8.2% (w/w of biomass). Finally, the membrane-assisted refining could recover 69.1 ± 0.1% (w/w) of produced xylooligosaccharides.
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•Autohydrolysis solubilize 54.5% hemicellulose from almond shell.•Enzymatic hydrolysis increases concentration of low degree of polymerisation XOS.•Sequential membrane separation gives concentrated XOS liquor.•Final concentrate is rich is xylobiose (44.6%) and xylotriose (12.4%).
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•Alkali pretreatment of milled shell recovers above 90% hemicellulose.•Particle size less than 120 μm was found to be critical.•Magnetic nanoparticle acts as potential support for ...endoxylanase.•Immobilized enzyme at par with free enzyme and produces xylooligosaccharides.
In this work, the effect of particle size on alkali pretreatment of the almond shell was evaluated for recovery of hemicellulose. Further, endoxylanase from Thermomyces lanuginosus was immobilized on Fe-based magnetic nanoparticles to enable reuse of enzyme. Reduction in particle size significantly influences the recovery of hemicellulose as particle size below 120 μm enable recovery of 97% available hemicellulose in 1 h at 121 °C with 2 M alkali. The enzyme could retain 93.3% of enzymatic activity upon immobilization onto magnetic support using glutaraldehyde (25 mM) and was at par with the free enzyme in terms of pH and temperature profile. The measurement of reaction kinetics (Km and Vmax) indicates similar values for free and immobilized enzyme. The structural and morphological analysis indicates presence near spherical magnetic core and successful cross-linking of the enzyme without alteration of the magnetic core. The immobilized enzyme was able to hydrolyze hemicellulose to produce XOS, the yield equivalent to 67.4% of that obtained using free enzyme at 50 °C. The comparison of XOS production ability at 50 and 60 °C, suggests that the immobilized enzyme retains activity as similar yield was obtained at both temperatures, whereas, the yield for free enzyme decreases significantly. The XOS yield on recycling of immobilized enzyme for three successive cycles was found to reduce to 41% of the initial cycle. However, in all cycles of enzymatic hydrolysis, the percentage of xylobiose was found to be above 90%.
Xylan is available abundantly in nature as a major constituent of hemicellulose, a component of lignocellulosic biomass. Agricultural wastes such as straw, stalk, cob, hull, husk, bagasse and pulp of ...hardwood represent a major source of xylan. Xylooligosaccharides (XOS), the hydrolysis product of xylan is substrate for colonic commensal bacterial population, acting as potential prebiotic. Its fermentation produces short chain fatty acids, improves gut epithelial health and regulates metabolic process. These oligosaccharides possess bound phenolics including ferulic acid, coumaric acid, thus imparting additional antioxidant effect and immunomodulatory activity. This paper deals with xylan based oligosaccharides with an emphasis placed on the need of oligosaccharides and discusses in detail the health benefits of xylooligosaccharides.
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•Particle size <120 µ enables above 95% hemicellulose recovery.•Lower substrate concentration gives higher xylooligosaccharides yield.•Produced XOS comparable to commercial XOS in terms of gas and ...acid levels.•Short chain oligosaccharides produce higher level of acetate.
Almond shell, a by-product obtained from the nut industry, was valorised into low degree of polymerisation xylooligosaccharides using alkaline pretreatment and enzymatic hydrolysis. The effect of particle size on hemicellulose recovery upon pretreatment was studied using 1 and 2 M NaOH. It was observed that particle size significantly influences hemicellulose recovery, as particles below 120 µm resulted in near complete recovery at 2 M NaOH. Enzymatic hydrolysis of hemicellulose was optimised using response surface methodology, to obtain efficient xylooligosaccharides production at low enzyme dose and high substrate concentration. For higher XOS yield, an enzyme dose of 10 U and substrate concentration <2% was optimal. The in-vitro human faecal fermentation study revealed no significant difference in gas and short chain fatty acid level among substrates evaluated. It was observed that short chain oligosaccharides produce higher level of acetate than medium chain oligosaccharides.
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•Temperature-induced pH change affects the crystal habit of potassium acid phthalate (KAP).•Comprehensive experimental investigation allows screening of operating conditions leading ...to desired crystal habit.•Experimental investigation coupled with computational approach allows predictive control on KAP habit and morphology.
Achieving greater control on crystallization to obtain desired crystal structure and morphology is a significant challenge in material synthesis. The highly stochastic nature of crystallization makes it necessary to conduct thorough experimental and computational investigations of crystalline materials. Polymorphic transformation, including hydrate formation during crystallization of potassium acid phthalate (KAP) is one such example. The hydrated form of crystals can appear during crystallization when water interacts strongly with functional groups of solute molecules, leading to its inclusion into the crystal lattice. Here, we show the temperature-dependent transformation of anhydrous KAP (form-I) to monohydrate KAP (form-II) crystal. Such polymorphic and associated morphological changes as a function of temperature and supersaturation are studied using in-situ hot-stage optical microscopy and validated with morphology domain analysis. While the measured growth rates and morphologies do not vary significantly with supersaturation, they show a stronger temperature dependence due to the formation of hydrated forms. The computational results uncover the previously unknown effect of temperature-dependent pH increase, which causes deprotonation of the carboxylic group leading to destabilization of 110 facets. The appearance of hydrated form seems to be due to temperature-induced pH changes. These results provide fundamental insights into the mechanism of hydrate transformations during cooling crystallization.
One of the major technological challenges in developing a microalgal biorefinery is to minimize the fossil energy inputs, particularly in two important downstream unit operations, cell harvesting and ...disruption. Hence, this study involved synthesizing and applying biopolymer nanocomposite to achieve concomitant biomass harvesting, cell disruption, and nanocomposite recovery by exploiting its cationic, photocatalytic, and magnetic properties respectively, in an integrated and optimized process chain. Accordingly, dual-functionalized chitosan-TiO2 conjugated particles (CTC) and trifunctionalized magnetic nanocomposites (MNCs) namely, chitosan coated core–shell structures of Fe3O4–TiO2, were prepared and characterized. The harvesting efficiency of >98% was achieved at the optimal dosages of chitosan, CTC and MNCs of 0.11, 0.09, and 0.07 g g–1 Chlorella minutissima biomass, respectively. TiO2 driven photocatalysis could effectively disrupt harvested wet-biomass, when exposed to UV irradiation in the presence of either CTC or MNCs for 2 h, and when subjected to visible light with only MNCs for 3 h. Photocatalytic cell disruption helped recover 96–97% of the intracellular lutein and lipid, when compared to ultrasonication as control. Subsequently, the MNCs were separated from residual biomass by physicochemical treatment, resulting in over 98% detachment efficiency for reuse in the downstream process chain. To the best of our knowledge, this integrated green process is novel, in terms of meeting a contemporary technological challenge in downstream processing of microalgal biomass, and this research outcome may inspire the development of sustainable microalgal biorefinery for the production of lutein and biodiesel.
Herein, we demonstrate the design and synthesis of a single-component prodrug β-carboline-benzothiazole-norfloxacin (CB-NFX) for the cocktail release of therapeutics that enables spatiotemporal ...control over bacterial growth. With the help of in silico studies, the prodrug was designed based on the β-carboline photoremovable protecting group, caging the acid functionality of norfloxacin (NFX) antibiotic. We have formulated nanoparticles of CB-NFX to obtain nanophotocage CB-NFX NPs. These nanoparticles adhere to the bacterial cell wall, followed by the release of NFX and singlet oxygen (1O2) upon visible-light irradiation. The combined effect of the therapeutics shows excellent spatiotemporal control in bacterial inhibition. This concept can be applied to develop other advanced antibacterial biomaterials for combination therapy (drug and 1O2) and find wide applications in antibacterial research.
To study the prevalence of β-thalassemia mutations in two North Indian states.
Mutation(s) were analyzed in 62 patients using 10 sets of allele-specific primers.
Four mutations IVS1 nt5 (G → C), F.S ...8/9 (+G), F.S 41/42 (−TCTT) and del 619 bp were found to constitute 94.1% of the total alleles studied. Prevalence of IVS1 nt5 (G → C) was the highest, closely followed by F.S 8/9 (+G). The latter was thus unusually high and not consistent with earlier reports. Two mutations in
cis were detected in one carrier of the thalassemia trait and in his father, thus signifying the possibility of vertical transmission of mutations in a single β-globin allele.
F.S 8/9 (+G), as well as IVS1 nt5 (G → C), are the major mutations in Indian states; however, the possibility of multiple mutations in
cis in a fetus with the thalassemia trait has to be considered in a prenatal screening program.
