共查询到20条相似文献,搜索用时 31 毫秒
1.
Miguel A. Zamudio‐Jaramillo Adrian Hernandez‐Mendoza Victor J. Robles Patricia G. Mendoza‐Garcia José Joel Espinosa‐de‐los‐Monteros Hugo S. Garcia 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(1):100-105
BACKGROUND: Lactobacillus reuteri NRRL B‐14171 was immobilized in spherical calcium alginate beads to study reuterin production. RESULTS: In relation to free cells (82 mmol L?1), the immobilized cells showed a sharp increase in reaction rate and achieved similar conversions with a reduction in the required biomass. Tests for mass transfer limitations on the reaction rate indicated that neither intraparticle nor external constraints were present. Effectiveness factors near 1 were estimated. CONCLUSION: Immobilization induced increased production of reuterin in Lactobacillus reuteri and is a feasible option for increasing process productivity. Copyright © 2008 Society of Chemical Industry 相似文献
2.
Li Zhao Xingyuan Ma Yu Zheng Jianguo Zhang Guodong Wei Dongzhi Wei 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(4):626-632
BACKGROUND: Glycerol dehydrogenase [EC.1.1.1.6] and 1,3‐propanediol oxidoreductase [EC.1.1.1.202] were proved to be two of the key enzymes for glycerol conversion to 1,3‐propanediol in Klebsiella pneumoniae under anaerobic conditions. For insight into their significance on 1,3‐propanediol production under micro‐aerobic conditions, these two enzymes were over‐expressed in K. pneumoniae individually, and their effects on conversion of glycerol into 1,3‐propanediol in a resting cell system under micro‐aerobic conditions were investigated. RESULTS: In the resting cell system, over‐expression of 1,3‐propanediol oxidoreductase led to faster glycerol conversion and 1,3‐propanediol production. After a 12 h conversion process, it improved the yield of 1,3‐propanediol by 20.4% (222.1 mmol L−1 versus 184.4 mmol L−1) and enhanced the conversion ratio of glycerol into 1,3‐propanediol from 50.8% to 59.8% (mol mol−1). Over‐expression of glycerol dehydrogenase in K. pneumoniae had no significant influence both on 1,3‐propanediol yield and on the conversion ratio of glycerol into 1,3‐propanediol in the resting cell system. CONCLUSION: The results were important for an understanding of the significance of glycerol dehydrogenase and 1,3‐propanediol oxidoreductase in 1,3‐proanediol production under micro‐aerobic conditions, and for developing better strategies to improve 1,3‐propanediol yield. Copyright © 2008 Society of Chemical Industry 相似文献
3.
Xiaomei Zhang Yin Li Bin Zhuge Xueming Tang Wei Shen Zhiming Rao Huiying Fang Jian Zhuge 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(6):1075-1078
Response surface methodology was used to optimize 1,3-propanediol production by a novel recombinant Escherichia coli JM109 (pHsh-dhaB-yqhD). The optimal fermentation parameters for enhanced 1,3-propanediol yield were found to be: glycerol 61.8 g L−1, yeast extract 6.2 g L−1, Vitamin B12 0.049 g L−1 and fermentation time 30 h. Subsequent experimental trials confirmed the validity of the model. These optimal fermentation conditions in the cultivation flask culture led to a 1,3-propanediol concentration of 43.1 g L−1 and a conversion rate of 69.7% (g g−1). A maximum 1,3-propanediol concentration of 41.1 g L−1 was achieved in a 5 L fermenter using the optimized parameters. Copyright © 2006 Society of Chemical Industry 相似文献
4.
Asad‐ur‐Rehman Saman Wijesekara R.G Nakao Nomura Seigo Sato Masatoshi Matsumura 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(7):1072-1080
BACKGROUND: The objective of the present work is to report an efficient pre‐treatment process for sunflower oil biodiesel raw glycerol (SOB‐RG) and its fermentation to 1,3‐propanediol. RESULTS: The growth inhibition percentages of Clostridium butyricum DSM 5431 on grade A (pH 4.0) and grade B (pH 5.0) phosphoric acid‐treated SOB‐RG were similar to those of pure glycerol at 20 g glycerol L?1; i.e., 18.5 ± 0.707% to 20.5 ± 0.7% inhibition. In grade A, growth inhibition was reduced from 85.25 ± 0.35% to 32 ± 1.4% (a 53.25% reduction) at 40 g glycerol L?1 by washing grade A raw glycerol twice with n‐hexanol (grade A‐2). The kinetic parameters for product formation and substrate consumption in anaerobic batch cultures gave almost similar values at 20 g glycerol L?1, while at 50 g glycerol L?1 volumetric productivity (Qp) and specific rate of 1,3‐propanediol formation (qp) were improved from 1.13 to 1.85 g L?1 h?1 and 1.60 to 2.65 g g?1 h?1, respectively, by employing grade A‐2 raw glycerol, while the yields were similar (0.5–0.52 g g?1). CONCLUSION: The results are important as the pre‐treatment of SOB‐RG is necessary to develop bioprocess technologies for conversion of SOB‐RG to 1,3‐propanediol. Copyright © 2008 Society of Chemical Industry 相似文献
5.
Strain isolation and optimization of process parameters for bioconversion of glycerol to lactic acid
An‐An Hong Ke‐Ke Cheng Feng Peng Sheng Zhou Yan Sun Can‐Ming Liu De‐Hua Liu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(10):1576-1581
BACKGROUND: The crude glycerol from biodiesel production represents an abundant and inexpensive source which can be used as raw material for lactic acid production. The first aim of this investigation was to select a strain suitable for producing lactic acid from glycerol with a high concentration and productivity. The second aim was to obtain the optimum fermentation conditions, as a basis for large‐scale lactate production in the future. RESULTS: Eight bacterial strains, which could aerobically convert glycerol to lactic acid, were screened from soil samples. One of the strains, AC‐521, which synthesized lactic acid with a higher concentration, was identified based on its 16S rDNA sequences and physiological characteristics. These results indicated that this strain was a member of Escherichia coli. The optimal fermentation conditions for Escherichia coli AC‐521 were 42 °C, pH 6.5, 0.85 min?1 (KLa). CONCLUSION: Escherichia coli AC‐521 suitable for producing lactic acid from glycerol with high concentration and productivity was identified. After 88 h of fed‐batch fermentation, both the lactic acid concentration and glycerol consumption reached maximum, giving 85.8 g L?1 of lactic acid with a productivity of 0.97 g L?1 h?1 and a yield of 0.9 mol mol?1 glycerol. Copyright © 2009 Society of Chemical Industry 相似文献
6.
Kutlu Ozergin-Ulgen Ferda Mavituna 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1998,73(3):243-250
This paper provides quantitative information on oxygen transfer as well as the kinetic and metabolic parameters related to oxygen uptake in Streptomyces coelicolor A3(2) cultured in a 20 dm3 computer controlled bioreactor using both defined and complex media. It is evident from the literature that production of antibiotics is strongly affected by the dissolved oxygen concentration. Many processes of antibiotic fermentations have been developed to the point at which the microbial oxygen demand exceeds the oxygen transfer capability of the existing fermentation facilities. As a consequence, the oxygen transfer rate has become the rate limiting factor in such processes. It is necessary to know the oxygen kinetic and metabolic parameters of an aerobic fermentation for a successful scale-up and operational control of the process. In the literature, information concerning the oxygen uptake kinetics of the Streptomyces cultures is scarce despite their industrial importance. This paper, therefore, provides useful quantitative information on oxygen transfer and uptake rates in S. coelicolor cultures. In the defined medium, the total oxygen uptake rates were in the range of 5–6 mmol O2 dm−3 h−1 throughout the active growth phase, the maximum specific oxygen uptake rate was 7·44 mmol O2 g cell−1 h−1, the specific oxygen maintenance demand was 1·88 mmol O2 g cell−1 h−1, and the kLa values were in the range of 40–100 h−1. In the complex medium, however, the kLa values varied in the range of 18–70 h−1. © 1998 Society of Chemical Industry 相似文献
7.
The free‐radical polymerization behavior of 1‐vinyl,2‐pyrrolidone (NVP) was studied at low conversions, using capillary dilatometry. The aqueous media were kept at neutral pH and the studies were conducted isothermally, at 40 or 45°C. The azo‐type initiators used were 4,4′‐azobis‐4‐cyanopentanoic acid (ACPA), 2,2′‐azobisisobutyronitrile (AZBN), and 2,2′‐azobis[2‐(2‐imidazolin‐2‐yl)propane dihydrochloride] (ABDH). The monomer concentration and initiator concentration ranges were 1.17–2.34 mol L−1 and 1–8 mmol L−1, respectively. The rates of polymerization (Rp) and orders of reaction with respect to NVP and the initiator were evaluated and the kinetic equations were found to be Rp ∝ [NVP] [ACPA]1.2; Rp ∝ [NVP] [AZBN]1.1; and Rp ∝ [NVP]2.2 [ABDH]1.1. The polymers obtained were characterized by their viscosity numbers and correlation of the viscosity average molecular weights made with the type and amount of the azo initiator. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 239–246, 2000 相似文献
8.
J. C. Cizravi 《应用聚合物科学杂志》2001,79(2):337-341
N‐methyl N‐vinyl acetamide (NMNVA) monomer was polymerized at low conversions and its free radical kinetics were detailed using capillary dilatometry. The polymerizations were conducted isothermally, at 40°C using 2,2′‐azobis[2‐(2‐imidazolin‐2‐yl) propane dihydrochloride] (ABDH) as initiator. Monomer concentration and initiator concentration ranges were 1.10–1.70 mol · L−1 and 1–4 mmol · L−1, respectively. The aqueous polymerization media were kept at neutral pH. The rates of polymerization (Rp) and orders of reaction with respect to NMNVA and ABDH concentrations were evaluated and the kinetic expression was found to be ideal, with Rp ∝ [NMNVA]1.07 [ABDH]0.61. The polymers obtained were characterized by their viscosity numbers and correlation of viscosity average molecular weights was made with the amount of ABDH initiator. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 337–341, 2001 相似文献
9.
Chunjie Zhu Baishan Fang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(5):853-857
BACKGROUND: The purpose of the present work was to enhance 1,3‐propanediol productivity during the batch cultivation on a type of raw glycerol by application of a two‐stage temperature control strategy. RESULTS: First, the effect of the raw glycerol on microbial growth and 1,3‐propanediol production was investigated. The highest 1,3‐propanediol productivity, 1.93 g L?1 h?1, was achieved when the initial raw glycerol concentration was 6% (v/v). Second, the effect of temperature on microbial growth and 1,3‐propanediol production was investigated and kinetic analysis was carried out. The results indicated that 37 °C favored microbial growth while 35 °C was best for 1,3‐propanediol production. Finally, a two‐stage temperature control strategy was applied in 1,3‐propanediol production. The incubation temperature was kept at 37 °C from inoculation to 2 h and then switched to 35 °C. Compared with batch cultivations at 35 and 37 °C, the fermentation time was shortened from 10 to 9.2 h, resulting in an increase in 1,3‐propanediol productivity of around 11%. CONCLUSION: 1,3‐propanediol productivity was enhanced effectively by application of a two‐stage temperature control strategy. © 2012 Society of Chemical Industry 相似文献
10.
Ilgi Karapinar Kapdan Sebnem Aslan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(7):998-1005
BACKGROUND: The aim of this study was to evaluate the ammonium nitrogen removal performance of algae culture Chlorella vulgaris in a novel immobilized photobioreactor system under different operating conditions and to determine the biokinetic coefficients using the Stover–Kincannon model. RESULTS: The photobioreactor was continuously operated at different initial ammonium nitrogen concentrations (NH4‐N0 = 10–48 mg L−1), hydraulic retention times (HRT = 1.7–5.5 days) and nitrogen/phosphorus ratios (N/P = 4/1–13/1). Effluent NH4‐N concentrations varied between 2.1 ± 0.5 mg L−1 and 26 ± 1.2 mg L−1 with increasing initial NH4‐N concentrations from 10 ± 0.6 mg L−1 to 48 ± 1.8 mg L−1 at θH = 2.7 days. The maximum removal efficiency was obtained as 79 ± 4.5% at 10 mg L−1 NH4‐N concentration. Operating the system for longer HRT improved the effluent quality, and the percentage removal increased from 35 ± 2.4% to 93 ± 0.2% for 20 mg L−1 initial NH4‐N concentration. The N/P ratio had a substantial effect on removal and the optimum ratio was determined as N/P = 8/1. Saturation value constant, and maximum substrate utilization rate constant of the Stover–Kincannon model for ammonium nitrogen removal by C. vulgaris were determined as KB = 10.3 mg L−1 d−1, Umax = 13.0 mg L−1 day−1, respectively. CONCLUSION: Results indicated that the algae‐immobilized photobioreactor system had an effective nitrogen removal capacity when the operating conditions were optimized. The optimal conditions for the immobilized photobioreactor system used in this study can be summarized as HRT = 5.5 days, N/P = 8 and NH4‐N0 = 20 mg L−1 initial nitrogen concentration to obtain removal efficiency greater than 90%. Copyright © 2008 Society of Chemical Industry 相似文献
11.
Jian Hao Feng Xu Hongjuan Liu Dehua Liu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(1):102-108
The downstream processing of 1,3‐propanediol fermentation broth using flocculation, reactive extraction, and reactive distillation was studied. Cellular debris and soluble protein in the broth were flocculated by combined use of chitosan and polyacrylamide at optimal concentrations of 150 ppm and 70 ppm, respectively; the soluble protein in the broth decreased to 0.06 g L?1, and the recovery ratio of the supernatant liquor to broth was greater than 99%. 1,3‐Propanediol and other alcohols were extracted from the supernatant liquor by reacting with butyraldehyde. In a four‐stage countercurrent extraction with the volume ratio of the extraction solvent to the aqueous phase being 20:100, more than 99% 1,3‐propanediol acetal (2‐propyl‐1,3‐dioxane) and 2,3‐butanediol acetal (2‐propyl‐4,5‐dimethyl‐1,3‐dioxolane) were recovered from the aqueous phase; 35% of the glycerol acetals were recovered. The acetals produced were hydrolyzed in a reactive distillation column using the strongly acidic cation‐exchange resin as catalyst, the bottom product obtained was a mixture of 1,3‐propanediol (407 g L?1), 2,3‐butanediol (252 g L?1), glycerol (277 g L?1), and glycerol acetals (146 g L?1). Copyright © 2005 Society of Chemical Industry 相似文献
12.
Sarah Torkamani Jalal Shayegan Soheila Yaghmaei Iran Alemzadeh 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(12):1689-1693
BACKGROUND: To meet stringent emission standards stipulated by regulatory agencies, the oil industry is required to bring down the sulfur content in fuels. As some compounds cannot be desulfurized by existing desulfurizing processes (such as hydrodesulfurization, HDS) biodesulfurization has become an interesting topic for researchers. Most of the isolated biodesulfurizing microorganisms are capable of desulfurization of refined products whose predominant sulfur species are dibenzothiophenes so biocatalyst development is still needed to desulfurize the spectrum of sulfur‐bearing compounds present in whole crude. RESULTS: The first desulfurizing bacterium active at 60 °C has been isolated, which reduces DBT concentration from 2 mmol L?1 to 0.1 mmol L?1 after 95 h, following the 4S pathway. Its DBT desulfurization pattern was represented by the Michaelis‐Menten equation. Various parameters such as Vmax, Km, µm, Ks and maximum specific DBT desulfurization rate were calculated which are 0.092 mmol L?1 h?1, 3.554 mmol L?1, 0.157 h?1, 3.722 mmol L?1 and 0.192 mmol L?1 DBT g?1 DCW (dry cell weight) h?1, respectively. It can desulfurize 50% of the sulfur content of Kuhemond heavy crude oil (KHC oil) with an initial sulfur content of 7.6%wt in 6 days. Its maximum specific desulfurization rate for KHC oil is equivalent to 0.005 g sulfur g?1 DCW h?1. The bacterium was isolated during a heavy crude oil biodesulfurization project initiated by PEDEC, a subsidiary of National Iranian Oil Company. CONCLUSION: The KHC oil sulfur removal efficiency of the bacterium is approximately five times that of BBRC‐9016 bacterium. It removes sulfur selectively without using sulfur‐containing compounds as its carbon source. By applying various media during its isolation, the probability of screening the correct microorganism is increased. Copyright © 2008 Society of Chemical Industry 相似文献
13.
Vivek Rangarajan Gunaseelan Dhanarajan Ramya Kumar Ramkrishna Sen Mahitosh Mandal 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(12):1661-1669
BACKGROUND: Lipopeptide production is strongly influenced by trace metals. The availability of free Fe2+ in the media throughout the process of fermentation was found to be very critical. Since free Fe2+ was reported to be sequestered by the lipopeptide as it was produced, intermittent feeding of Fe2+ was strategized and optimized for enhanced lipopeptide production by marine Bacillus megaterium in glucose mineral salts medium (GMSM). RESULTS: Studies with the single‐dose Fe2+ (0.48 mmol L?1) supplementation after 8 h of fermentation resulted in lipopeptide concentration of 3.3 ± 0.1 g L?1. Lipopeptide production was further enhanced to 4.2 ± 0.15 g L?1 by adopting a multi‐dose Fe2+ feeding strategy. The maximum product yield (YP/S) of 0.24 ± 0.02 g g?1 with specific product formation rate (qp) of 0.124 ± 0.01 g g?1 h?1 was achieved when 0.48 mmol L?1 Fe2+ was fed intermittently at different times as per the designed strategy. CONCLUSION: Lipopeptide concentration was improved 4.7‐fold by single‐dosing and 5.8‐fold by multiple dosing of Fe2+, when compared with GMSM without Fe2+ supplementation. Copyright © 2012 Society of Chemical Industry 相似文献
14.
Silvana T Silveira Manuela K Jaeger Adriano Brandelli 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(3):361-366
BACKGROUND: Keratinases are important enzymes for biotechnological processes involving keratin hydrolysis. In this work substrate specificity and kinetic properties of a keratinase from Chryseobaterium sp. were investigated. RESULTS: The optimal conditions for activity of purified keratinase with respect to pH, temperature and sodium chloride concentration were established using factorial design and surface response techniques. The optimum conditions for keratinase activity were pH from 7.4 to 9.2, temperature from 35 °C to 50 °C and NaCl concentration from 50 to 340 mmol L?1, having azocasein as substrate. Subsequently, the kinetic parameters for this substrate were determined to be Km = 0.75 mg mL?1 and Vmax = 59.5 U min?1. The Ki value for 1,10‐phenanthroline was estimated at 0.78 mmol L?1. The enzyme specificity was evaluated over different synthetic and insoluble substrates. The protease exhibited specificity with selectivity for hydrophobic and positively charged residues. In relation to the insoluble substrates, the enzyme hydrolyzed preferably chicken nails. CONCLUSIONS: This enzyme effectively hydrolyzes insoluble keratin substrates. The knowledge of keratinase properties is an essential step in the development of biotechnological processes involving keratin hydrolysis. Copyright © 2008 Society of Chemical Industry 相似文献
15.
RaymondP.J. Bronger JochemP. Bermon Jürgen Herwig PaulC.J. Kamer PietW.N.M. vanLeeuwen 《Advanced Synthesis \u0026amp; Catalysis》2004,346(7):789-799
The solubility of the modifying ligand is an important parameter for the efficiency of a rhodium‐catalysed hydroformylation system. A facile synthetic procedure for the preparation of well‐defined xanthene‐type ligands was developed in order to study the influence of alkyl substituents at the 2‐, and 7‐positions of the 9,9‐dimethylxanthene backbone and at the 2‐, and 8‐positions of the phenoxaphosphino moiety of ligands 1 – 16 on solubility in toluene and the influence of these substituents on the performance of the ligands in the rhodium‐catalysed hydroformylation. An increase in solubility from 2.3 mmol⋅L−1 to >495 mmol⋅L−1 was observed from the least soluble to the most soluble ligand. A solubility of at least 58 mmol⋅L−1 was estimated to be sufficient for a large‐scale application of these ligands in hydroformylation. Highly active and selective catalysts for the rhodium‐catalysed hydroformylation of 1‐octene and trans‐2‐octene to nonanal, and for the hydroformylation of 2‐pentene to hexanal were obtained by employing these ligands. Average rates of >1600 (mol aldehyde) × (mol Rh)−1×h−1 {conditions: p(CO/H2) = 20 bar, T = 353 K, [Rh] = 1 mM, [alkene] = 637 mM} and excellent regio‐selectivities of up to 99% toward the linear product were obtained when 1‐octene was used as substrate. For internal olefins average rates of >145 (mol aldehyde)×(mol Rh)−1×h−1 {p(CO/H2) = 3.6–10 bar, T = 393 K, [Rh] = 1 mM, [alkene] = 640–928 mM} and high regio‐selectivities up to 91% toward the linear product were obtained. 相似文献
16.
Giandra Volpato Rafael Costa Rodrigues Júlio Xandro Heck Marco Antônio Záchia Ayub 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(6):821-828
BACKGROUND: In this work we used Plackett–Burman statistical design and central composite design in order to optimize culture conditions for lipase production by Staphylococcus caseolyticus strain EX17 growing on raw glycerol, which was obtained as a by‐product of the enzymatic synthesis of biodiesel. The stability of lipase was verified over several organic solvents, such as methanol, ethanol and n‐hexane. RESULTS: Optimal culture conditions for lipase production were found to be 36 °C, initial pH 8.12, glycerol 30 g L?1, olive oil 3.0 g L?1, and soybean oil 2.5 g L?1, with 145.8 U L?1 of enzyme activity. When commercial glycerol was substituted by the raw glycerol from biodiesel synthesis, lipolytic activity was 127.3 U L?1. Experimental validation of enzyme production matched values predicted by the mathematical model, which was 138.3 U L?1. Stability tests showed that lipase from S. caseolyticus EX17 was stable in methanol, ethanol, and n‐hexane. CONCLUSIONS: Results obtained in this work suggest that raw glycerol can be used for lipase production by S. caseolyticus EX17 and that this enzyme has a potential application in the synthesis of biodiesel. Copyright © 2008 Society of Chemical Industry 相似文献
17.
Tomoyuki Toyoda Kazuhisa Ohtaguchi 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(2):217-222
BACKGROUND: The pentitol D‐arabitol has been produced from D‐glucose utilizing osmophilic yeast strains, however, there are remarkably few reports available on the production of D‐arabitol from lactose. Previous studies in the laboratory have shown that the osmophilic yeast Kluyveromyces lactis NBRC 1903 can convert lactose to extracellular D‐arabitol without extracellular accumulation of D‐glucose or D‐galactose. The present study was undertaken to determine the participation of aeration on the D‐arabitol synthesis in K. lactis NBRC 1903. RESULTS: The highest D‐arabitol concentration of 91.7 mmol L?1 was achieved after 120 h cultivation in medium containing 555 mmol L?1 of lactose with initial volumetric liquid‐phase mass transfer coefficient of oxygen (kLa)0 of 85.5 h?1. The fractional yield of D‐arabitol was affected by not only aeration but also growth phase. The highest fractional yield of D‐arabitol in terms of lactose consumption was 0.255 that was obtained at stationary phase with (kLa)0 of 85.5 h?1. CONCLUSION: It was found that oxygen supply is a key factor in the production of D‐arabitol. Patterns of metabolism were classified according to the level of oxygen supply and the growth phase. Copyright © 2010 Society of Chemical Industry 相似文献
18.
Luis Caicedo Edelberto Silva Oscar Snchez 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(5):650-656
BACKGROUND: Fructooligosaccharides are important sweeteners produced by sucrose biotransformation. Although fructooligosccharides production has been reported widely, most studies have been carried out at laboratory level. This study evaluates semibatch and continuous fructooligosaccharides production by Aspergillus sp. N74 at bench scale in a mechanically agitated airlift. RESULTS: Sucrose biotransformation to fructooligosaccharides was carried out with biomass harvested after 24 or 48 h of culture. For 6.21 ± 0.33 or 9.66 ± 0.62 g biomass dry weight L−1, the highest FOS yields were obtained at batch operating 62.1 and 66.4% after 26 or 6 h of reaction, respectively. Reduction in fructooligosaccharides yield was observed for both biomass concentrations at semibatch operating, while a comparable yield was obtained during continuous operating (62.1% for 6.21 ± 0.33 g L−1 and a dilution rate 0.016 s−1, and 62.8% for 9.66 ± 0.62 g L−1 and a dilution rate 0.032 s−1). Nevertheless, 1‐kestose formation was favored with biomass harvested after 24 h under any operating mode. CONCLUSION: Biomass concentration, reaction time and operating mode have a notable effect on fructooligosaccharides yield and composition. 1‐kestose, the most valuable fructooligosaccharide, was obtained in greatest proportion at a biomass concentration 6.21 ± 0.33 g L−1. Under the different operating modes, Aspergillus sp. N74 mycelia and the reactor described are presented as a feasible alternative for scaling up fructooligosaccharides production. Copyright © 2008 Society of Chemical Industry 相似文献
19.
Teresa I. Cortiñas Humberto J. Silva Rodolfo J. Ertola 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1984,34(4):291-295
A Dunaliella strain has been isolated and grown in a medium containing saline lake water. Using 40% saline water and mixture of CO2-air (4% CO2) the algae grew with a specific growth rate of 0.073 h−1. The maximum cell concentration was 5.6 × 107 cells cm−3 which corresponded to 3.63 g dm−3 of dry biomass. Using 80% saline water, a glycerol concentration of 1.47 g glycerol g−1 of, protein was obtained which amounted to 44.3% of Dunaliella dry weight. Fermentor CO2 from a continuous yeast culture was also used as carbon source for photosynthetic growth. At 2.5% CO2 in the exit gas a decrease of the specific growth rate was observed but the final concentration attained was comparable to that obtained with CO2-air mixtures. 相似文献
20.
An organic–inorganic composite hydrogel was prepared based on hemicellulose and multi‐wall carbon nanotubes. The effects of hydrogel amount, initial concentration, contact time, and salt concentration on the adsorption performance of the prepared hydrogels were observed using methylene blue as a model hazardous material. The results indicated that the adsorption kinetic of methylene blue on the prepared adsorbent was well fitted to the pseudo‐second‐order kinetic model and the adsorption isotherm conformed to the Freundlich model. Removal percentage of methylene blue increased with increased adsorbent amount and kept higher than 98% when adsorbent amount was above 6 g L−1. Adsorption amount of methylene blue on the prepared adsorbent also increased when increasing initial concentration over the range from 50 to 500 mg L−1. Both of adsorption amount and removal percentage increased with an increase in the contact time, and removal efficiency obviously deteriorated as salt concentration increased. All obtained results reported that the prepared composite hydrogel would have an application prospect in water treatment. POLYM. COMPOS., 35:45–52, 2014. © 2013 Society of Plastics Engineers 相似文献