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The pulp and paper industry is highly dependent on forest and water resources. It has more concerns on fair utilization of these resources and their conservation for its further expansion. Present study emphasizes on the use of rice straw (agro waste) in papermaking to protect wood based resources. It further deals with ozone bleaching (Z) prior to elemental chlorine free bleaching that proved to be significant in terms of reducing the effluent load specially the reduction in toxic, recalcitrant and carcinogenic compounds. Z based sequences resulted in pulp brightness of â¼85% that was 3.6% higher than the elemental chlorine free bleaching. Bleached pulps of Z based sequences were found to be having better strength properties than elemental chlorine based sequence and thus may be adopted as improved bleaching technology. The analysis of handsheets prepared after pulp bleaching was performed using X-Ray diffraction, ATR-FTIR and SEM. Incorporating ozone stage resulted in marked reduction of 58% and 63% in total solids in bleaching wastewater. Reduction of more than 80% in BOD, COD and adsorbable organic halides was achieved in Z based bleaching in comparison to chlorine bleaching. The amount of chlorophenols, guaiacols, catechols, vanillins and syringols became negligible (approx. 90% reduction) in effluents of Z based bleaching sequences. The chlorine dioxide followed by peroxide bleaching after Z stage was found to be the most promising to reduce the effluent load.
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Clorofenoles , Ozono , Cloro , Residuos Industriales , Papel , Aguas ResidualesRESUMEN
A gram positive, rod shaped, bacterium was isolated from pulp and paper mill sludge and characterized as Brevibacillus parabrevis (MTCC 12105) by biochemical tests and 16S rRNA gene sequencing. CD and EOP stage wastewater, collected from a leading pulp and paper mill situated in North India, was used for degradation study. Wastewater degradation efficiency of the bacterial isolate was evaluated by Flask study in batch mode and Reactor study in semi continuous mode. The isolated bacterium showed a considerable reduction of the colour (59%), chemical oxygen demand (62%) and lignin (53.8%) content of Kraft paper mill effluent at 37 °C after 5 days. During reactor study it reduced 42.6% Lignin, 51.6% Colour and 60.3% COD (chemical oxygen demand) of the wastewater at 48 h RT (retention time). The isolate was deposited at MTCC Chandigarh, India with an accession no. MTCC 12105.
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Biodegradación Ambiental , Brevibacillus/clasificación , Brevibacillus/aislamiento & purificación , Brevibacillus/metabolismo , Papel , Aguas del Alcantarillado/microbiología , Análisis de la Demanda Biológica de Oxígeno , Reactores Biológicos/microbiología , Brevibacillus/genética , ADN Bacteriano , ADN Ribosómico/genética , India , Residuos Industriales , Lignina/metabolismo , Filogenia , ARN Ribosómico 16S/genética , Eliminación de Residuos Líquidos , Aguas Residuales/microbiologíaRESUMEN
Bacterial nanocellulose was produced here using static, static intermittent-fed batch (SIFB) and rotary disc bioreactor (RDB) mode. Economical black tea broth media with symbiotic consortia of bacteria and yeast (SCOBY) was used towards feasible BNC production (instead of commercial NCIM 2526 strain and conventional HS media). The physicochemical characterization of BNC produced in all three modes via FE-SEM, ATR-FTIR, XRD and TGA results showed a highly porous morphology, mostly Iα form, good crystallinity and thermal stability, respectively. BNC crystallinity lies in the range of 68 % (RDB) to 79.4 % (static and SIFB). Water retention value (86 to 93 %) and moisture content (85 to 93 %) are high for BNC produced in all three modes. Commendable difference in the BNC yield, sugar consumption, conversion yield and residual sugar was observed using different methods. Highest BNC yield 29.4 ± 0.66 gL-1 was obtained under SIFB method as compared to static mode (13.6 ± 0.32 g L-1). Under RDB, a negligible amount of BNC i.e., 1.0 ± 0.2 g L-1 was produced. SCOBY with BTB medium was found unsuitable for BNC production under RDB and needs further investigation. Thus, this comparative study offers a way to produce a commendable amount of low-priced BNC for various techno-industrial usage.
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The present study reports the combined enzymatic production efficiency of thermophilic fungus Thermomyces lanuginosus VAPS25 using a combinatory artificial intelligence-based tool, resulting in 2.7 IU/ml, 5.2 IU/ml, and 18.85 U/ml activity of endoglucanase, amylase, and lipase, respectively with good thermostability at 90 °C (pH 8-10). Interestingly, the metal ions viz. Cu2+ and Mg2+ increased the endoglucanase activity to 5 folds, i.e.,5.6 IU/ml compared to control. Further, the amylase and lipase activity was also enhanced by Fe2+ and Co2+ to 5.4 IU/ml and 19.57 U/ml, respectively. Additionally, the deinking efficiency was improved by 68.9%, 42.7%, and 52.8% by endoglucanase, amylase, and lipase, respectively, while the consortium increased the deinking efficiency to 72.7%. The bio-bleached paper strength parameters such as burst index, breaking length, tear index, and tensile index of sheets were significantly improved by 1.38%, 13.54%, 7.54%, and 20.88%, respectively. These enzymes at an industrial scale would help develop an economical paper recycling process.
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Celulasa , Eurotiales , Inteligencia Artificial , Redes Neurales de la ComputaciónRESUMEN
OBJECTIVES: Previous studies showed that angiopoietin-1(Ang-1) expression was increased in the synovium in early rheumatoid arthritis (RA) patients. The present study was therefore designed to examine whether determination of serum Ang-1 might be effective in diagnosis of early RA. METHODS: One hundred and five serum samples of RA (21 males, 84 females) were studied for serum Ang-1 level. Serum samples were also collected from other collagen diseases, including 35 cases of SLE, 29 cases of systemic sclerosis, 16 cases of polymyositis/dermatomyositis. Serum samples were additionally obtained from 34 patients who visited our clinic for evaluation of symmetrical polyarthritis with morning stiffness. After one year of follow-up, those patients who satisfied the ACR 1987 classification criteria for RA were defined as 'early RA'. Serum Ang-1 levels were measured by sandwich ELISA using anti-angiopoietin-1 antibodies (both monoclonal and polyclonal antibodies). Serum anti-CCP antibody and rheumatoid factor (RF) were measured by ELISA and by laser nepherometry, respectively. RESULTS: Serum Ang-1 in RA patients was significantly higher than those in other collagen diseases. Serum Ang-1 levels in 50 normal healthy individuals were 5.8 ± 0.31 pg/ml (mean ± SEM). There was no significant difference in CRP and serum RF at the first visit between early RA patients and non-RA patients, whereas serum Ang-1 levels at the first visit were significantly higher in early RA (58.7 ± 17.9 pg/ml [mean ± SEM]) than those in non-RA (8.2 ± 4.5 pg/ml). ROC analysis revealed that serum Ang-1 (cut-off 23.91 pg/ml) could diagnose early RA at sensitivity 57.1% and specificity 84.6%, providing comparable area under the curve (0.71, 95% CI: 0.54-0.88) to that of serum anti-CCP antibody (0.72, 95% CI: 0.53-0.92). There was no significant correlation between anti-CCP antibody and Ang-1. CONCLUSIONS: These results indicate that serum Ang-1 is as useful a marker for the diagnosis of early RA as serum anti-CCP antibody.
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Angiopoyetina 1/sangre , Artritis Reumatoide/diagnóstico , Adolescente , Adulto , Anciano , Artritis Reumatoide/sangre , Artritis Reumatoide/tratamiento farmacológico , Artritis Reumatoide/inmunología , Autoanticuerpos/sangre , Biomarcadores/sangre , Estudios de Casos y Controles , Diagnóstico Precoz , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Inmunosupresores/uso terapéutico , Japón , Masculino , Persona de Mediana Edad , Nefelometría y Turbidimetría , Péptidos Cíclicos/inmunología , Valor Predictivo de las Pruebas , Pronóstico , Estudios Retrospectivos , Factor Reumatoide/sangre , Factores de Tiempo , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores , Regulación hacia Arriba , Adulto JovenRESUMEN
Bio-bleaching effect on bagasse pulp using xylano-pectinolytic enzymes produced by a bacterial species was studied in order to evaluate the potential of these enzymes in paper industry. In this study, action of enzymes was maximum with xylanase/pectinase dose 7/1.75 IU/g, pulp consistency 1:12.5 g/L, pH 8.5, temperature 50° C and 180 min of treatment time. Under the optimized bio-bleaching conditions, removal of reducing sugars (6.15±0.05 mg/L), brightness (16.08%), whiteness (25.54%) and release of chromophores (hydrophobic and phenolic compounds and lignin impurities) were maximum, along with decrease in kappa number (26.28%), and yellowness (27.88%) values were obtained. Improvement in the various physical properties like breaking length (10.28%), burst index (29.55%), tear index (5.02%), double fold (14.89%), Gurley porosity (15%) and viscosity (8.6%), along with the reduction of chlorine dioxide dose by 27%, was also observed. There is also reduction in COD and BOD values of bio-bleached effluents by 27.62% and 20.52%, respectively. This is the first report on bio-bleaching of bagasse pulp using xylano-pectinolytic enzymes.
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Poligalacturonasa , Saccharum , Celulosa , Endo-1,4-beta Xilanasas , PapelRESUMEN
Cellulose is the most abundant renewable resource which has found a diverse range of applications. Cellulose dissolution is a significant property for manufacturing man-made cellulosic fiber through viscose process. Crystalline microfibrillar structure and relatively high ordered packing of polymeric chains contribute to recalcitrance and poor reactivity of cellulose. One of the most common methods to improve cellulose dissolution is cellulase treatment. Herein, cellulase treatment at different doses was studied to explore the correlation of cellulose dissolution with crystallinity. Pulp showed improvement in Fock reactivity and other properties related to viscose application. But contrary to previous studies, cellulose crystallinity as determined by XRD and FTIR did not correlate with Fock reactivity at a higher dose of cellulase. The results indicated some complex mechanism to be involved between the cellulose dissolution and crystallinity than a simple negative correlation. Cellulase treatment at 150 HCU/g resulted in the upgraded pulp suitable for viscose application.
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The objective of this study was to check the potential of crude xylano-pectinolytic enzymes in bleaching of rice straw pulp, in order to reduce the toxic waste load for managing the environmental pollution. The xylano-pectinolytic enzymatic bleaching step for delignification was found to be most effective at pulp consistency 1:10 g/ml, xylanase:pectinase dose of 9:4 IU/ml, pH 8.5 and treatment time 180 min at temperature of 55 °C, and resulted in lowering of kappa number of the rice straw pulp by 15.29%. In subsequent bleaching stages, this enzymatic pre-bleaching treatment also resulted in 30% reduction of active chlorine dioxide dose without any loss of optical properties. Significant improvement in various physical properties of the enzymes treated pulp, tear index (15.43%), breaking length (11.11%), double fold number (25.92%), burst index (9.88%) and viscosity (13.63%), and Gurley porosity (39.86%) was also noticed. This approach resulted in reduction of BOD and COD values by 21.07% and 26.57%, respectively. This is the first study on the use of crude xylano-pectinolytic enzymes for bio-bleaching of rice straw pulp.
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Oryza , Papel , Poligalacturonasa , Compuestos de Sodio , TemperaturaRESUMEN
Ternary nano-biocomposite films of bacterial cellulose-chitosan-gelatin (BC-C-G) were fabricated by immersing the BC pellicles into chitosan and gelatin mixture and subsequently freeze-drying. Scanning electron microscopy (SEM) images of the nano-biocomposite films revealed the presence of interconnected pores, with fibre diameter 20-150 nm. The composite films have a porosity of 95.3%, and showed good hydrophilicity with swelling ratio of 19 ± 1.8 and in vitro degradability. X-ray diffraction, attenuated total reflectance Fourier transform infrared spectroscopy, and thermogravimetric (TG) analysis results showed some interactions among the molecules of BC, gelatin, and chitosan within the film. The composite film offered good matrix for adhesion and proliferation of L929 fibroblasts cells as indicated by the cell attachment study, FE-SEM of cell-film constructs and cytocompatibility assay. Thus, the nano-biocomposite films of BC-C-G could be of paramount importance as tissue engineering scaffold. The "all-natural" ternary polymer composite films of BC-C-G have not been evaluated before for biomedical applications.
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Quitosano , Gelatina , Celulosa , Espectroscopía Infrarroja por Transformada de Fourier , Ingeniería de Tejidos , Andamios del Tejido , Difracción de Rayos XRESUMEN
The potential of alkaline cellulo-xylanolytic enzymes from non-pathogenic Bacillus subtilis strain was tested for deinking of photocopier waste paper. Cellulase and xylanase play a crucial role in deinking of different types of waste paper. Partial purification of cellulo-xylanolytic enzymes was carried out using ultrafiltration followed by ammonium sulfate precipitation. The ultrafiltered enzyme was used for deinking the photocopier waste paper along with chemical deinking. An enzyme dose of 0.6 IU/g and reaction time of 60 min for ultrafiltered cellulo-xylanolytic enzyme significantly increased deinking efficiency, tear index (9.52%) and folding endurance (5±2%) as compared to chemical deinking. There was improvement in strength properties such as tear index and double-fold along with freeness of pulp (18%). There was slight decrease in tensile index (0.6%) and burst index (16%) while ISO brightness remained unaffected. Enzymatic deinking (74.3%) by ultrafiltered cellulo-xylanolytic from Bacillus subtilis was found significant over conventional chemical deinking.
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Celulasa , Tinta , Endo-1,4-beta Xilanasas , PapelRESUMEN
A 57-year old female civilian was suffocated by an intruder The victim (experienced severe dyspnoea) but violently resisted the assault. Two hours after this event, on admission to a Trauma Centre, she demonstrated left facial swelling with low percutaneous oxygen saturation. Chest X-ray and computed tomography demonstrated pulmonary oedema. This improved dramatically within a short time and she was discharged on the 5th hospital day. Pulmonary oedema induced by suffocation has been reported only rarely. The possible mechanisms by which pulmonary oedema might form after the relief of airway obstruction are discussed.
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Obstrucción de las Vías Aéreas/complicaciones , Edema Pulmonar/etiología , Catecolaminas/sangre , Víctimas de Crimen , Femenino , Humanos , Persona de Mediana Edad , Edema Pulmonar/diagnóstico por imagen , Tomografía Computarizada por Rayos XRESUMEN
This study explores the modification of bacterial nanocellulose (BNC), produced in fermented tea medium with bio-extracts from herbal plants, to produce entirely natural antibacterial nanocellulose films. The antibacterial property was imparted by impregnating the synthesized BNC into bio-extracts of Terminalia arjuna (arjuna), Azadirachta indica (neem), Withania somnifera (ashwagandha), Tinospora cordifolia (giloy), and Murraya koenigii (curry leaves). FE-SEM analysis of modified BNC films revealed the presence of cloudy layer of bio-extracts over the BNC nanofibrous network. The modified BNC production was confirmed by ATR-FTIR. The modified BNC showed tremendous antibacterial activity against Escherichia coli (E. coli) and Aerococcus viridians (A. viridans). T. arjuna modified BNC showed the highest antibacterial activity against E. coli and A. viridans with inhibition zone of 27.08 mm and 26.34 mm, respectively, while M. koeniggi modified BNC showed the lowest antibacterial activity for both E. coli and A. viridans with inhibition zone of 14 mm and 14.2 mm, respectively. The water retention, moisture content and porosity values reflect highly hydrophilic nature of BNC films and their well suitability for varied biomedical applications like antibacterial wound dressings, herbal biomasks, scaffoldings, etc. The modification of BNC films with the bio-extracts used in this study has not been reported previously.
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Antibacterianos/química , Factores Biológicos/química , Celulosa/química , Azadirachta/química , Vendajes , Factores Biológicos/farmacología , Escherichia coli/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/métodos , Murraya/química , Extractos Vegetales/química , Extractos Vegetales/farmacología , Hojas de la Planta/química , Withania/químicaRESUMEN
Micro-nanofibrillated cellulose was prepared using bleached mixed hardwood pulp by a low energy consuming chemo-refining approach having potential to be implemented easily in paper industry. Bleached mixed hardwood pulp was pretreated with sodium meta-periodate and sodium chlorite and micro-nanofibrillated by using refining in Valley beater. Scanning electron microscopy images of prepared micro-nanofibrillated cellulose showed 87 % fibre distribution in nano range, 4.47⯱â¯0.5â¯g/g water retention value and 2.13⯱â¯0.1â¯meq/100â¯g carboxyl content. Carboxylation effect of given chemical pretreatment was further confirmed by FTIR analysis. Paper handsheets, having bleached mixed hardwood pulp and prepared micro-nano-fibrillated cellulose, resulted in about 5% lower bulk with 27 %, 32 % and 87 % higher breaking length, burst factor and double fold, respectively than control (without nano-fibrillated cellulose). Prepared micro-nanofibrillated cellulose addition didn't show negative effect on pulp drainability (33⯰SR). This work showed that micro-nanofibrillated cellulose might also be prepared using conventional routes of paper industry to improve paper properties.
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Cellulosic fiber is hydrophilic in nature and making it hydrophobic represents a process called sizing in papermaking. Alkenyl succinic anhydride (ASA) sizing is dominating over other sizing processes due to its high reactivity and economy. The shelf life of conventionally used cationic starch (CS) stabilized ASA emulsion is 20-25â¯min. In our previous study, the ASA emulsion was found to be stable up to 4â¯h using anionic polyacrylamide (APAM) as stabilizer. Present communication was aimed to utilize, the APAM stabilized ASA emulsion with most commonly utilized cellulosic pulps (mixed hardwood, bagasse and recycled) and fillers to assist its commercial utilization in papermaking. APAM stabilized ASA emulsion facilitated back water utilization with improved sizing degree unlike CS based ASA emulsion. Lower amount of ASA sizing was required in bagasse pulp compared to other pulps which might be attributed to low crystallinity ratios and hydrogen bond energy.
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BACKGROUND AND PURPOSE: Detailed arterial anatomy of the sphenoid ridge and olfactory groove meningiomas is complicated due to the fine angioarchitecture and anastomoses between each feeder. Herein, we present details of the arterial anatomy and the relationships of feeders in these lesions. MATERIALS AND METHODS: This study included 20 patients admitted to our department between April 2015 and March 2020. Conditions of subjects consisted of 16 sphenoid ridge meningiomas and 4 olfactory groove meningiomas. We mainly analyzed arterial anatomy using 3D rotational angiography and slab MIP images of these lesions. We also analyzed the anastomoses of each feeder. RESULTS: We found that 19 (95%), 15 (75%), and 15 (75%) lesions had feeders from the ophthalmic, internal carotid, and external carotid arteries, respectively. As feeders from the ophthalmic artery, recurrent meningeal arteries were involved in 18 lesions (90%). Fifteen lesions (75%) had anastomoses between each feeder. CONCLUSIONS: Most of the meningiomas in the sphenoid ridge and olfactory groove had feeders from the ophthalmic and internal carotid arteries. There were various anastomoses between each feeder. This is the first report to demonstrate the detailed arterial anatomy and frequency of recurrent branches from the ophthalmic artery and their anastomoses using detailed imaging techniques.
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Neoplasias Meníngeas/irrigación sanguínea , Neoplasias Meníngeas/patología , Meningioma/irrigación sanguínea , Meningioma/patología , Adulto , Angiografía de Substracción Digital/métodos , Arteria Carótida Externa/diagnóstico por imagen , Arteria Carótida Externa/patología , Arteria Carótida Interna/diagnóstico por imagen , Arteria Carótida Interna/patología , Angiografía Cerebral/métodos , Femenino , Humanos , Masculino , Neoplasias Meníngeas/diagnóstico por imagen , Meningioma/diagnóstico por imagen , Persona de Mediana Edad , Arteria Oftálmica/diagnóstico por imagen , Arteria Oftálmica/patología , Hueso EsfenoidesRESUMEN
Pacinian corpuscles in the mesentery of adult cats were fixed with either glutaraldehyde, osmium tetroxide or permanganate solutions by close intra-arterial injection through the mesenteric artery, and were processed, after electron staining and Epon embedding, for electron microscopy. Better resolution of the corpuscle's ultrastructure was obtained than available heretofore. The myelinated segment of the corpuscle contains blood vessels separated from the axon by collagen fibers and 3 to 4 layers of lamellae. No blood vessels are found in the central core, though access from the vessels is afforded by diffusion through the "cleft" of the inner core. Two cell types are discernible in the inner core hemilamellae; the "clear cells" in which pinocytotic vesicles and organelles abound and reflect the greater metabolic activity of these cells, in contrast to the "dark cells." The ultraterminal is ellipsoidal in form with projections into the "cleft" which give this portion an irregular appearance in section. The terminal and ultraterminal are packed with mitochondria, and "synaptic" vesicles are seen in the ultraterminal. The innermost laminae of the inner core cells are in close apposition to the terminal and break their regular pattern of hemilamellation to surround the small ultraterminal projections at the apical part of the corpuscle.
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Mesenterio/inervación , Terminaciones Nerviosas/citología , Animales , Axones , Capilares , Gatos , Colágeno , Retículo Endoplásmico , Microscopía Electrónica , Mitocondrias , Vaina de MielinaRESUMEN
Bacterial nanocellulose (BNC) has emerged as a natural biopolymer of significant importance in diverse technological areas due to its incredible physicochemical and biological characteristics. However, the high capital investments, production cost and lack of well-organized scale-up processes resulting in low BNC production are the major impediments need to be resolved. This review enfolds the three different and important portions of BNC. Firstly, advancement in production technologies of BNC like cell-free extract technology, static intermittent fed batch technology and novel cost-effective substrates that might surmount the barriers associated with BNC production at industrial level. Secondly, as BNC and its composites (with other polymers/nanoparticles) represents the utmost material of preference in current regenerative and diagnostic medicine, therefore recently reported biomedical applications of BNC and functionalized BNC in drug delivery, tissue engineering, antimicrobial wound healing and biosensing are widely been focused here. The third and the most important aspect of this review is an in-depth discussion of various pitfalls associated with BNC production. Recent trends in BNC research to overcome the existing snags that might pave a way for industrial scale production of BNC thereby facilitating its feasible application in various fields are highlighted.
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Bacterias/química , Celulosa/química , Nanopartículas/química , Animales , Biopolímeros/química , Sistemas de Liberación de Medicamentos/métodos , HumanosRESUMEN
Bacterial nanocellulose (BNC), a natural origin biopolymer with multi-dimensional applications has captured a great deal of attention owing to its implausible properties. However, low yield of BNC accompanied with high production cost is challenging its usage in various technological applications. In this study, BNC production has been reported utilizing fermented black tea broth brewed from fresh tea leaves (FBTBF) as well as from used tea leaves (FBTBU) as a cost-effective and high-quality BNC yielding medium. The symbiotic combination of bacteria and yeasts (SCOBY) was exploited here to bring fermentation in tea broth. The production yields on dry weight basis were 13.3â¯gâ¯L-1 in FBTBF and 12.8â¯gâ¯L-1 in FBTBU, obtained with 60â¯gâ¯L-1 of glucose in 20â¯days. The conversion yields of 0.32 and 0.31â¯g BNC/g sugar were obtained with both the tea broths. The study of produced pellicle using ATR-FTIR, FE-SEM and XRD confirmed its structural, morphological and chemical nature similar to that of BNC. Thus, fermented black tea broth appears to be a potential medium for BNC production. The use of fermented tea broth for the industrial scale production of BNC might significantly reduce its production cost.
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Bacterias/metabolismo , Celulosa/química , Celulosa/metabolismo , Fermentación , Nanoestructuras/química , Simbiosis , Té/microbiología , Biotransformación , Concentración de Iones de Hidrógeno , Cinética , Azúcares/metabolismo , Té/química , Temperatura , Agua/químicaRESUMEN
To improve the process economy of reactivity improvement, crude cellulase from Bacillus subtilis was employed for the treatment and significant dissolving pulp properties were analyzed. With increase in enzyme dose from 0.25 to 2 U/g o.d. pulp, improvement in Fock reactivity and alkali solubilities (S10 and S18) were observed with simultaneous reduction in viscosity and yield. Fourier transform infrared spectroscopy and scanning electron microscopy were used to observe the molecular level effects on dissolving grade pulp. The most suitable cellulase dose for reactivity improvement with lowering of viscosity was 0.25 U/g o.d. pulp. With increases in enzyme dose, alkali solubilities (S10 and S18) of dissolving pulp showed continuous increment, while alpha-cellulose of pulp showed reduction due to chain scission of long cellulose fiber fraction.
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The GCR1 gene product is required for maximal transcription of yeast glycolytic genes and for growth of yeast strains in media containing glucose as a carbon source. Dominant mutations in two genes, SGC1 and SGC2, as well as recessive mutations in the SGC5 gene were identified as suppressors of the growth and transcriptional defects caused by a gcr1 null mutation. The wild-type and mutant alleles of SGC1 were cloned and sequenced. The predicted amino acid sequence of the SGC1 gene product includes a region with substantial similarity to the basic-helix-loop-helix domain of the Myc family of DNA-binding proteins. The SGC1-1 dominant mutant allele contained a substitution of glutamine for a highly conserved glutamic acid residue within the putative basic DNA binding domain. A second dominant mutant, SGC1-2, contained a valine-for-isoleucine substitution within the putative loop region. The SGC1-1 dominant mutant suppressed the GCR1 requirement for enolase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase, and pyruvate kinase gene expression. Expression of the yeast enolase genes was reduced three- to fivefold in strains carrying an sgc1 null mutation, demonstrating that SGC1 is required for maximal enolase gene expression. Expression of the enolase genes in strains carrying gcr1 and sgc1 double null mutations was substantially less than observed for strains carrying either null mutation alone, suggesting that GCR1 and SGC1 function on parallel pathways to activate yeast glycolytic gene expression.