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•Whole slurry pretreated rice straw biomass was fermented with a thermophilic co-culture for the first time.•A modified consolidated bioprocessing approach was established to ...alleviate inhibition.•Polyethylene glycol and calcium carbonate resulted in enhanced buffering capacity of the medium.•The proposed bioconversion process yielded high ethanol concentration (142 mM) from an undetoxified whole slurry.•No solid/liquid separation, detoxification, and exogenous enzyme supplementation conducted for bioethanol production.
In this study, an innovative approach is proposed for the valorization of all sugars (cellulosic and hemicellulosic) contained in a lignocellulosic feedstock, as is rice straw biomass (RSB), for the production of second-generation bioethanol. For this purpose, the whole slurry obtained after dilute sulfuric acid pretreatment at a biomass loading of 5% (w/v) was subjected to consolidated bioprocessing without previous solid-liquid separation and/or detoxification and the concentrated solution of carbohydrates recovered was fermented to bioethanol by a co-culture of thermophilic anaerobic bacteria. To bypass the inhibitory effect of undetoxified whole slurry on the lower fermentability of the co-culture, the concentration of different additives was optimized for improved buffering capacity, enhanced substrate-microbe interaction, and by-product elimination. The individual supplementation of 3 selected additives at optimum concentration; 20 mM calcium carbonate, 0.4% (v/v) polyethylene glycol, and 1% (w/v) sodium acetate resulted in enhanced ethanol yield of 130.83 mM, 106.37 mM, and 99.10 mM, respectively, compared to 75.03 mM ethanol yield in control. The combined effect of optimal dosage of these additives was able to improve the ethanol concentration and yield to 142 mM and 48% of the theoretical maximum respectively, suggesting about 88.58% increase compared to control medium without additives supplementation. The combined supplementation of additives proved to be an advantageous strategy for bioethanol production using undetoxified whole slurry biomass.
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•Clostridium thermocellum ATCC 31924 was employed for consolidated bioprocessing.•Enhanced ethanol production was observed at alkaline pH.•95.32% conversion of crystalline cellulose ...was obtained.•Complete inhibition of lactate production in the presence of acetate.•High cellulase and xylanase activities were expressed by purified cellulosomes.
The production of bioethanol was studied by the cultivation of Clostridium thermocellum ATCC 31924 in MTC medium including crystalline cellulose as the sole substrate. The effects of key operational parameters that affect bioethanol production from microcrystalline cellulose were optimized. Under optimum conditions (pH 8.0, temperature 55 °C, inoculum size 4% (v/v) and 0.5% (w/v) substrate concentration), a maximum ethanol yield of 0.30 g ethanol/g cellulose consumed and 95.32% cellulose conversion was obtained. An inclusion of modest acetate concentration in the medium showed that carbon flux shifted away from lactate accompanied by 20% increase in ethanol production. It suggests that strain ATCC 31924 differed in its cellulose conversion efficacy and optimum pH requirements compared to the other reported strains of Clostridium thermocellum. The purified cellulosome of strain ATCC 31924 found to be rich in both cellulase and xylanase enzymes emphasizing the importance of this strain for the degradation of lignocellulosic biomass.
The treatment of disease in the future will be influenced by the ability to produce therapeutic formulations that have high availability at the disease site, sustained and long-term release, with ...minimal to no toxicity to healthy tissues. Biologically derived delivery systems offer promise in this regard owing to minimization of adverse effects while increasing the efficacy of the entrapped therapeutic. Silk fibroin nanoparticles overcome barriers set by synthetic nondegradable nanoparticles made of silicone, polyethylene glycol and degradable polylactic acid-polyglycolic acid polymers. Silk fibroin-mediated delivery has demonstrated high efficacy in breast cancer cells. While the targeting is associated with the specificity of entrapped therapeutic for the diseased cells, silk fibroin-derived particles enhance intracellular uptake and retention resulting in downmodulation of more than one pathway due to longer availability of the therapeutic. The mechanism of targeting for the nanoparticle is based on the silk fibroin composition, beta-sheet structure and self-assembly into beta-barrels.
•A new strain of Chlorella saccharophila was isolated from New Zealand marine waters.•This species can be grown heterotrophically using either glucose or glycerol.•This species produces both lipid ...and the carotenoids zeaxanthin and β-carotene.•This species has potential as a biofuel producer.
A fast growing strain of Chlorella saccharophila was isolated from the marine water of New Zealand and grown in heterotrophic conditions using glucose or glycerol as a carbon source. Biomass production was found to be higher in culture fed with glucose (2.14±0.08gL−1) as compared to glycerol (0.378±0.04gL−1). Lipid accumulation was similar for both carbon sources, at approximately 22% of dry cell weight. However, carotenoid yield was higher with glycerol (0.406±0.0125mgg−1) than with glucose (0.21±0.034mgg−1). Further optimization of the growth of the isolate gave maximal carotenoid production of 16.39±1.19mgg−1 total carotenoid, containing 11.32±0.64mgg−1 zeaxanthin and 5.07±0.55mgg−1 β-carotene. Comparison of various chemical and physical carotenoid extraction methods showed that ultrasonication was required for maximum extraction yields. The new strain has potential for biofuel, with carotenoid co-production.
Economic production of lignocellulose degrading enzymes for biofuel industries is of considerable interest to the biotechnology community. While these enzymes are widely distributed in fungi, their ...industrial production from other sources, particularly by thermophilic anaerobic bacteria (growth Topt ≥ 60 °C), is an emerging field. Thermophilic anaerobic bacteria produce a large number of lignocellulolytic enzymes having unique structural features and employ different schemes for biomass degradation, which can be classified into four systems namely; ‘free enzyme system’, ‘cell anchored enzymes’, ‘complex cellulosome system’, and ‘multifunctional multimodular enzyme system’. Such enzymes exhibit high specific activity and have a natural ability to withstand harsh bioprocessing conditions. However, achieving a higher production of these thermostable enzymes at current bioprocessing targets is challenging. In this review, the research opportunities for these distinct enzyme systems in the biofuel industry and the associated technological challenges are discussed. The current status of research findings is highlighted along with a detailed description of the categorization of the different enzyme production schemes. It is anticipated that high temperature-based bioprocessing will become an integral part of sustainable bioenergy production in the near future.
Metabolite production by filamentous fungi hampered because of high viscosity generated during growth. Low viscosity fermentation by mold is one of the preferred ways of large scale enzymes ...production. Cellulolytic enzymes play a key role during the process of lignocellulosic biomass conversion. In this study, a mutant RC‐23‐1 was isolated through mutagenesis (diethyl sulfate followed by UV) of Trichoderma reesei RUT‐C30. RCRC‐23‐1 not only gave higher cellulase production but also generated lower viscosity during enzyme production. Viscosity of mutant growth was more than three times lower than parent strain. RC‐23‐1 shows unique, yeast‐like colony morphology on solid media and small pellet‐like growth in liquid media. This mutant did not spread like mold on solid media. This mutant produces cellulases constitutively when grown in sugars. Using only glucose, the cellulase production was 4.1 FPU/ml. Among polysaccharides (avicel, xylan, and pectin), avicel gave maximum of 6.2 FPU/ml and pretreated biomass (rice straw, wheat straw and sugarcane bagasse) produced 5.1–5.8 FPU/ml. At 7 L scale reactor, fed‐batch process was designed for cellulase production using different carbon and nitrogen sources. Maximum yield of cellulases was 182 FPU/g of lactose consumed was observed in fed‐batch process. The produced enzyme used for hydrolysis of acid pretreated rice straw (20% solid loading) and maximum of 60% glucan conversion was observed. RC‐23‐1 mutant is good candidate for large scale cellulase production and could be a model strain to study mold to yeast‐like transformation.
In this study a mutant RC‐23‐1 was isolated through mutagenesis of T. reesei RUT‐C30, which not only gave higher cellulase production but also generated lower viscosity during enzyme production. RC‐23‐1 shows unique, yeast like colony morphology on solid media and small pellet like growth in liquid media. This mutant is good candidate for large scale cellulase production and could be a model strain to study mold to yeast‐like transformation.
A tracheal matrix scaffold decellularized by detergent-enzymatic treatment has been shown as a promising scaffold in tracheal tissue engineering. The objectives of this study were to evaluate the ...impact of this technique on tracheal extracellular matrix integrity and characterize the matrix environment for recellularization.
Brown Norway rat tracheae were decellularized using a modified detergent-enzymatic treatment. Antigenicity and cellularity were monitored during processing. Glycosaminoglycan content, histoarchitecture, and mechanical properties were also evaluated. Matrix compatibility was determined by cytotoxicity assay. Surface ultrastructure of the matrix and its interaction with seeded bone marrow stem cell-derived chondrocytes and tracheal epithelial cells were examined by scanning electron microscopy.
Rat trachea treated with five detergent-enzymatic treatment cycles demonstrated complete elimination of antigenicity. Although there was a significant loss of glycosaminoglycan (t test, p < 0.01), histoarchitecture of tracheal cartilage and basement membrane was retained after decellularization. Stiffness decreased, but sufficient compressive strength was preserved to maintain lumen patency. The decellularized matrix showed good cell compatibility and favored adhesion and growth of chondrocytes and respiratory epithelial cells, as demonstrated by scanning electron microscopy.
At the point of complete antigen removal, detergent-enzymatic treatment altered tracheal extracellular matrix composition but preserved the major structure and adequate mechanical strength. The matrix provided a compatible and supportive environment for recellularization.
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Aligned three-dimensional nanofibrous silk fibroin–chitosan (eSFCS) scaffolds were fabricated using dielectrophoresis (DEP) by investigating the effects of alternating current ...frequency, the presence of ions, the SF:CS ratio and the post-DEP freezing temperature. Scaffolds were characterized with polarized light microscopy to analyze SF polymer chain alignment, atomic force microscopy (AFM) to measure the apparent elastic modulus, and scanning electron microscopy and AFM to analyze scaffold topography. The interaction of human umbilical vein endothelial cells (HUVECs) with eSFCS scaffolds was assessed using immunostaining to assess cell patterning and AFM to measure the apparent elastic modulus of the cells. The eSFCS (50:50) samples prepared at 10MHz with NaCl had the highest percentage of aligned area as compared to other conditions. As DEP frequency increased from 100kHz to 10MHz, fibril sizes decreased significantly. eSFCS (50:50) scaffolds fabricated at 10MHz in the presence of 5mM NaCl had a fibril size of 77.96±4.69nm and an apparent elastic modulus of 39.9±22.4kPa. HUVECs on eSFCS scaffolds formed aligned and branched capillary-like vascular structures. The elastic modulus of HUVEC cultured on eSFCS was 6.36±2.37kPa. DEP is a potential tool for fabrication of SFCS scaffolds with aligned nanofibrous structures that can guide vasculature in tissue engineering and repair.
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