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1.
Production of xylitol from D-xylose by Candida tropicalis: optimization of production rate 总被引:5,自引:0,他引:5
Horitsu H Yahashi Y Takamizawa K Kawai K Suzuki T Watanabe N 《Biotechnology and bioengineering》1992,40(9):1085-1091
The effect of culture conditions on xylitol production rate was investigated using Candida tropicalis IFO 0618. From the variance analysis of xylitol production rate, it was found that initial yeast extract concentration was highly significant (99%), while the interaction between D-xylose concentration and aeration rate was significant (95%). These results show the importance of initial yeast extract concentration and of the balance between D-xylose concentration and aeration in the production of xylitol. It was also clearly shown that C. tropicalis needed more yeast extract concentration for efficient xylitol production than for its growth. In order to enhance xylitol production rate, culture conditions were optimized by the Box-Wilson method. In this respect, initial D-xylose concentration, yeast extract concentration, and K(L)a were chosen as the independent factors in 2(3)-factorial experimental design. As the result of experiments, a maximum xylitol production rate of 2.67 g/L . h was obtained when initial D-xylose concentration and yeast extract concentration were 172.0 and 21.0 g/L, respectively, and K(L)a was 451.50 h(-1) by 90% oxygen gas. (c) 1992 John Wiley & Sons, Inc. 相似文献
2.
Kim JH Han KC Koh YH Ryu YW Seo JH 《Journal of industrial microbiology & biotechnology》2002,29(1):16-19
Xylitol, a functional sweetener, was produced from xylose by biological conversion using Candida tropicalis ATCC 13803. Based on a two-substrate fermentation using glucose for cell growth and xylose for xylitol production, fed-batch
fermentations were undertaken to increase the final xylitol concentration. The effects of xylose and xylitol on xylitol production
rate were studied to determine the optimum concentrations for fed-batch fermentation. Xylose concentration in the medium (100
g l−1) and less than 200 g l−1 total xylose plus xylitol concentration were determined as optimum for maximum xylitol production rate and xylitol yield.
Increasing the concentrations of xylose and xylitol decreased the rate and yield of xylitol production and the specific cell
growth rate, probably because of an increase in osmotic stress that would interfere with xylose transport, xylitol flux to
secretion to cell metabolism. The feeding rate of xylose solution during the fed-batch mode of operation was determined by
using the mass balance equations and kinetic parameters involved in the equations in order to increase final xylitol concentration
without affecting xylitol and productivity. The optimized fed-batch fermentation resulted in 187 g l−1 xylitol concentration, 0.75 g xylitol g xylose−1 xylitol yield and 3.9 g xylitol l−1 h−1 volumetric productivity. Journal of Industrial Microbiology & Biotechnology (2002) 29, 16–19 doi:10.1038/sj.jim.7000257
Received 15 October 2001/ Accepted in revised form 30 March 2002 相似文献
3.
Analysis and optimization of a two-substrate fermentation for xylitol production using Candida tropicalis 总被引:1,自引:0,他引:1
Xylitol, a functional sweetener, was produced from xylose using Candida tropicalisATCC 13803. A two-substrate fermentation was designed in order to increase xylitol yield and volumetric productivity. Glucose
was used initially for cell growth followed by conversion of xylose to xylitol without cell growth and by-product formation
after complete depletion of glucose. High glucose concentrations increased volumetric productivity by reducing conversion
time due to high cell mass, but also led to production of ethanol, which, in turn, inhibited cell growth and xylitol production.
Computer simulation was undertaken to optimize an initial glucose concentration using kinetic equations describing rates of
cell growth and xylose bioconversion as a function of ethanol concentration. Kinetic constants involved in the equations were
estimated from the experimental results. Glucose at 32 g L−1 was estimated to be an optimum initial glucose concentration with a final xylose concentration of 86 g L−1 and a volumetric productivity of 5.15 g-xylitol L−1 h−1. The two-substrate fermentation was performed under optimum conditions to verify the computer simulation results. The experimental
results were in good agreement with the predicted values of simulation with a xylitol yield of 0.81 g-xylitol g-xylose−1 and a volumetric productivity of 5.06 g-xylitol L−1 h−1.
Received 16 June 1998/ Accepted in revised form 28 February 1999 相似文献
4.
The effects of four aldehydes (furfural, 5‐hydroxymethylfurfural, vanillin and syringaldehyde), which were found in the corncob hemicellulose hydrolysate, on the growth and xylitol fermentation of Candida tropicalis were investigated. The results showed that vanillin was the most toxic aldehyde for the xylitol fermentation, followed by syringaldehyde, furfural and 5‐hydroxymethylfurfural. Moreover, the binary combination tests revealed that furfural amplified the toxicity of other aldehydes and the toxicities of other binary combinations without furfural were simply additive. Based on the fermentation experiments, it was demonstrated that the inhibition of aldehydes could be alleviated by prolonging the fermentation incubation, increasing the initial cell concentration, enhancing the initial pH value and minimizing the furfural levels in the hydrolysate evaporation process. The strategies that we proposed to suppress the inhibitory effects of the aldehydes successfully avoided the complicated and costly detoxifications. Our findings could be potentially adopted for the industrial xylitol fermentation from hydrolysates. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1181–1189, 2013 相似文献
5.
Xylitol production from aspenwood hemicellulose hydrolysate by Candida guilliermondii 总被引:3,自引:0,他引:3
The production of xylitol by the yeast Candida guilliermondii was investigated in batch fermentations with aspenwood hemicellulose hydrolysate and compared with results obtained in semi-defined media with a mixture of glucose and xylose. The hemicellulose hydrolysate had to be supplemented by yeast extract and the maximum xylitol yield (0.8 g g–1) and productivity (0.6 g l–1 h–1) were reached by controlling oxygen input. 相似文献
6.
Isolation of a petite mutant from a histidine auxotroph of Candida albicans and its characterization
Respiration-deficient (petite) mutations have been induced in various yeasts, which are categorized as petite-positive. Candida
albicans was classified among the petite-negative yeasts. Since then, a few reports have appeared, describing the isolation
of petite mutants in C. albicans.
We report in the present study on the isolation of a petite mutant of C. albicans-SAR1. This mutant was isolated from a histidine
auxotroph of C. albicans after mutagenesis with N-methyl-N′-nitro-N-nitrosoguanidine, thus our petite mutant carries a double
mutation. SAR1 was characterized morphologically, biochemically and ultrastructurally. The results revealed differences from
the wild type in respect to morphological, physiological and biochemical characteristics. Electron microscopy showed that
the cells of the petite mutant contain only very few mitochondria that looked ‘thread like’ without any cristae. The significance
of the mutation in the virulence of the mutant vs. that of the wild-type is being assessed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
利用克隆获得的具有双重辅酶依赖性的热带假丝酵母xyl1基因,通过表达载体pGAPZB转入巴斯德毕赤酵母X-33,采用海藻酸钙凝胶包埋法固定该重组菌,研究固定化条件下玉米芯水解液的发酵特性,实现对玉米芯等农业废弃物资源的利用。结果表明,转化xyl1基因的巴斯德毕赤酵母X-33的总酶活达到1.64U/mg。固定化细胞的最适发酵条件为pH 6.0、30℃、接种量20%、装液量28%、转速130r/min,木糖醇转化率为37.5%。为生物转化法大规模生产木糖醇以及乙醇提供新的选择途径。 相似文献
8.
全球范围内,随着抗肿瘤药物、免疫抑制剂和广谱抗菌药物的使用,真菌感染的发病率显著提高,其中念珠菌感染占到绝大多数。目前热带念珠菌已经成为非白念珠菌中最常见的病原菌。我国热带念珠菌的临床分离率及对氟康唑及伏立康唑的耐药率都明显高于世界平均水平。但是,相比于白念珠菌,关于热带念珠菌的研究及相关临床信息相对较少。该文就侵袭性热带念珠菌感染危险因素、流行病学以及药物敏感性进行全面的综述。 相似文献
9.
A xylitol-producer yeast isolated from corn silage and designated as ASM III was selected based on its outstanding biotechnological potential. When cultivated in batch culture mode and keeping the dissolved oxygen at 40% saturation, xylitol production was as high as 130 g l(-1) with a yield of 0.93 g xylitol g(-1) xylose consumed. A preliminary identification of the yeast was performed according to conventional fermentation and assimilation physiological tests. These studies were complemented by using molecular approaches based on PCR amplification, restriction-fragment length polymorphism analysis and sequencing of the rDNA segments: intergenic transcribed spacer (ITS) 1-5.8S rDNA-ITS 2, and D1/D2 domain of the 26S rRNA gene. Results from both the conventional protocols and the molecular characterization, and proper comparisons with the reference strains Candida tropicalis ATCC 20311 and NRRL Y-1367, led to the identification of the isolate as a new strain of C. tropicalis. 相似文献
10.
Long-term cell recycle fermentations of Candida tropicalis were performed over 14 rounds of fermentation. The average xylitol concentrations, fermentation times, volumetric productivities and product yields for 14 rounds were 105 g l–1, 333 h, 4.4 g l–1 h–1 and 78%, respectively, in complex medium; and 110 g l–1, 284 h, 5.4 g l–1 h–1 and 81%, respectively, in a chemically defined medium. These productivities were 1.7 and 2.4 times those with batch fermentation in the complex and chemically defined media, respectively. The xylitol yield from xylose with cell recycle fermentation using the chemically defined medium was 81% (w/w), which was 7% greater than the xylitol yield with batch fermentation (74%); both modes of fermentation gave the same yield using the complex medium. These results suggest that the chemically defined medium is more suitable for production of xylitol than complex medium. 相似文献
11.
To quantify the thigmotropism, we adapted the our previous method using a chemotaxifilter system in combination with a bioluminescent
adenosine triphosphate (ATP) assay based on firefly luciferase-luciferin system and analyzed the relationship between the
ability of germ tube formation and thigmotropism of C. albicans and C. tropicalis.
Both the ability to form germ tube and the amount of hyphae exhibiting thigmotropism varied depending upon both the species
and strains of Candida. C. albicans formed more germ tubes than C. tropicalis. A good correlation was observed between the
ability to form a germ tube and the capacity for thigmotropism, and the results gave a level of significance (p<0.05).
Further, SEM observation revealed that relatively long hyphae of C. tropicalis with penetrated through the pores of filter
membrane. This phenomenon may be of importance in the development of pathogenesis of C. tropicalis as well as C. albicans.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
The sequence cato encoding catechol 1,2-dioxygenase from Candida tropicalis JH8 was cloned, sequenced, and expressed in Escherichia coli. The sequence cato contained an ORF of 858?bp encoding a polypeptide of 285?amino acid residues. The recombinant catechol 1,2-dioxygenase exists as a homodimer structure with a subunit molecular mass of 32 KD. Recombinant catechol 1,2-dioxygenase was unstable below pH 5.0 and stable from pH 7.0 to 9.0; its optimum pH was at 7.5. The optimum temperature for the enzyme was 30°C, and it possessed a thermophilic activity within a broad temperature range. Under the optimal conditions with catechol as substrate, the Km and Vmax of recombinant catechol 1,2-dioxygenase were 9.2?µM and 0.987?µM/min, respectively. This is the first article presenting cloning and expressing in E. coli of catechol 1,2-dioxygenase from C. tropicalis and characterization of the recombinant catechol 1,2-dioxygenase. 相似文献
13.
Candida tropicalis cells were immobilized in calcium alginate. Gel beads were used to inoculate a medium containing concentrated rectified grape must as the sole carbohydrate source for both semi-continuous and continuous riboflavin production, in a 1litre glass stirred-tank fermenter. In semi-continuous mode, vitamin B2 concentrations in culture broth ranged from approximately 350 to 650mg.l-1 in successive runs. In continuous mode, concentrations of about 400–600mg.l-1 were observed in the effluent for more than 1monthwithout significant loss of flavinogenic activity. The highest value of both vitamin B2 production and sugar bioconversion occurred at the lowest dilution rate (0.008h-1). 相似文献
14.
15.
All cells of four Candida tropicalis strains IFO 0199 (Ct-0199), IFO 0587 (Ct-0587), IFO 1400 (Ct-1400), and IFO 1647 (Ct-1647), obtained by cultivation at 27 and 37 degrees C for 48 h in yeast extract-added Sabouraud liquid medium, showed the shapes of typical budding yeast and the same agglutination patterns against factor sera 1, 4, 5 and 6 in the commercially available kit 'Candida Check'. The cells of the C. tropicalis IFO 0589 strain display the same properties at 27 degrees C but formed hyphae at 37 degrees C. The cell wall mannan (Ct-0589-37-M) obtained from the strain cells cultured at 37 degrees C had lost most of its reactivity against factor sera 4, 5 and 6 in an enzyme-linked immunosorbent assay, in contrast to the mannan (Ct-0589-27-M) at 27 degrees C. The 1H-nuclear magnetic resonance patterns of the mannans obtained from the cells of the four C. tropicalis strains IFO 0199, IFO 0587, IFO 1400, and IFO 1647, obtained by cultivation at 37 degrees C, did not change compared to those at 27 degrees C. By contrast, the Ct-0589-37-M had significantly lost the beta-1,2-linked mannopyranose units, corresponding to the serum factors 5 and 6. These results show that the IFO 0589 strain is an unusual strain among the general C. tropicalis strains studied. 相似文献
16.
An on-line device, ORP (oxidation-reduction potential)-stat, was used to control glucose-feeding for enhancing xylitol conversion from D-xylose during an oxygen-limited fermentation by Candida tropicalis. The fermentation was carried out in a 5 l jar fermenter. After glucose in the medium was depleted, a switching to a limited aeration and feeding glucose controlled by ORP-stat was performed. The maximum xylitol yield was obtained under a condition at an ORP of -180 mV and at an aeration rate of 0.2 l min(-1). 相似文献
17.
Glucose repressed xylose utilization inCandida tropicalis pre-grown on xylose until glucose reached approximately 0–5 g l–1. In fermentations consisting of xylose (93 g l–1) and glucose (47 g l–1), xylitol was produced with a yield of 0.65 g g–1 and a specific rate of 0.09 g g–1 h–1, and high concentrations of ethanol were also produced (25 g l–1). If the initial glucose was decreased to 8 g l–1, the xylitol yield (0.79 g g–1) and specific rate (0.24 g g–1 h–1) increased with little ethanol formation (<5 g l–1). To minimize glucose repression, batch fermentations were performed using an aerobic, glucose growth phase followed by xylitol production. Xylitol was produced under O2 limited and anaerobic conditions, but the specific production rate was higher under O2 limited conditions (0.1–0.4 vs. 0.03 g g–1 h–1). On-line analysis of the respiratory quotient defined the time of xylose reductase induction. 相似文献
18.
一株高效利用木糖的酵母菌的分离及鉴定 总被引:3,自引:0,他引:3
从256个自然试样中筛选到1株高效转化D-木糖为木糖醇的酵母菌株441-28—1。初始木糖质量浓度为90g/L的条件下,24h内的木糖利用效率为3.0g/(L·h)。通过高效液相分析,菌株441-28—1的主要代谢产物为木糖醇。在初始木糖质量浓度为65g/L的条件下,摇瓶分批发酵,木糖醇生成速率达1.1g/(L·h),木糖醇转化率为70%。经过形态、生理生化特征测定,以及ITS序列分析(GenBank的登记号为EU121523),将441-28—1菌株鉴定为热带假丝酵母(Candida tropicalis)。Candida tropicalis(热带假丝酵母)已保存于中国高校工业微生物资源数据平台,保藏编号CICIM Y0092。 相似文献
19.
热带假丝酵母酰基辅酶A氧化酶的纯化及性质研究 总被引:3,自引:0,他引:3
利用热带假丝酵母由烷烃生产二元酸时,二元酸面临被β氧化降解的代谢途径。酰基辅酶A氧化酶是二元酸β氧化的限速酶。以热带假丝酵母1230菌株为材料,经硫酸铵分级沉淀、阴离子交换柱层析、BlueSepharose亲和柱层析,得到电泳均一的酰基辅酶A氧化酶。该酶有两种亚基,分子量分别为74kD和78kD。酶作用最适pH和最适温度分别为80和50℃。金属离子Ag+、Pb2+完全抑制酶活性,Ba2+、Mg2+、Ca2+对酶活性有明显抑制作用。丙烯酸是酶的反竞争性抑制剂,Ki为0633mmol/L,维生素C是竞争性抑制剂,Ki为2.01×10-3mmol/L。 相似文献
20.
Latifa Jamai Khalid Sendide Khalil Ettayebi Faouzi Errachidi Omar Hamdouni-Alami Mohamed Ali Tahri-Jouti Timothy McDermott Mohamed Ettayebi 《FEMS microbiology letters》2001,204(2):375-379
Calcium alginate-immobilized Candida tropicalis and Saccharomyces cerevisiae are compared for glucose fermentation. Immobilized C. tropicalis cells showed a slight morphological alteration during ethanol production at 40 degrees C, but their fermentation capacity was reduced by 25%. Under immobilization conditions, the two species demonstrated two different mathematical patterns when the relationship between growth rate, respiration rate, and ethanol tolerance was assessed. The interspecific difference in behavior of immobilized yeast cells is mainly due to their natural metabolic preference. The production of CO(2) by calcium alginate-immobilized C. tropicalis, as well as the lower supply of oxygen to the cells, are the major factors that reduce ethanol production. 相似文献