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1.
A mutant strain of the deuteromycete Aureobasidium pullulans deficient in melanin synthesis was used to investigate the production of the exopolysaccharide pullulan and biomass, respectively. Shake-flask experiments with different carbon sources showed significant differences in pullulan elaboration. Sucrose was most suitable for pullulan synthesis among the carbon sources examined. Fermentations were carried out both batch-wise and continuously in a stirred vessel fermentator. In batch fermentations about 45% of the glucose offered was converted into pullulan at maximum formation rates of 0.16 g/l per hour using standard medium. The yield of polysaccharide could be maintained at 45% in continuous fermentations. At a dilution rate of 0.05 l/h, the formation rate of polysaccharide increased up to 0.35 g/l per hour. Alterations in the nitrogen content of the feed significantly affected the consumption rate of glucose and the production rate of polysaccharide, but final concentrations of biomass were hardly affected.
Correspondence to: R. Schuster 相似文献
2.
Robert Dufresne Jules Thibault Anh Leduy Robert Lencki 《Applied microbiology and biotechnology》1990,32(5):526-532
Summary The feasibility of pressurized culture was explored for the growth of Aureobasidium pullulans and the synthesis of pullulan. For all volumetric flow rates of air, the production of biomass increased with pressure up to a critical value ranging from 0.50 to 0.75 MPa, at which point a drastic decrease in biomass production and a change in cellular morphology was observed. For pullulan synthesis, the same dramatic decrease was observed at approximately the same critical pressure. In the pressure range 0.1–0.65 MPa, the synthesis of pullulan was subject to what is believed to be the competing effects of oxygen availability and pressure inhibition.Offprint requests to: J. Thibault 相似文献
3.
Effects of different sugars on pullulan production, UDP-glucose level, and activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glucosyltransferase in Aureobasidium pullulans Y68 were examined. It was found that more pullulan was produced when the yeast strain was grown in the medium containing glucose than when it was cultivated in the medium supplementing other sugars. Our results demonstrate that when more pullulan was synthesized, less UDP-glucose was left in the cells of A. pullulans Y68. However, it was observed that more pullulan was synthesized, the cells had higher activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glycosyltransferase. Therefore, high pullulan yield is related to high activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glucosyltransferase in A. pullulans Y68 grown on different sugars. A pathway of pullulan biosynthesis in A. pullulan Y68 was proposed based on the results of this study and those from other researchers. This study will be helpful to metabolism-engineer the yeast strain to further enhance pullulan yield. 相似文献
4.
Cell growth and extracellular pullulanase production ofBacillus stearothermophilus G-82 were investigated in batch culture using a defined medium with glucose, maltose, pullulan or amylopectin as carbon source. Maximum enzyme activity was with pullulan or amylopectin. Cell growth in batch culture was better under oxygen unlimited conditions, while higher total and specific enzyme activities, using pullulan or amylopectin, were obtained in oxygen-limited conditions. Enzyme accumulation took place in the late growth phase. The highest enzyme production of 300 U/I was reached when pullulan was used as carbon source in conditions of oxygen limitation. 相似文献
5.
Aureobasidium pullulans produced pullulan and melanin when grown in medium containing low nitrate levels. With high nitrate concentrations, however, this fungus produced a mixture of exopolysaccharides (EPS) without melanin synthesis. At 0.78 g l(-1) N as nitrate, where no melanin synthesis occurred, maximum EPS yields reached 6.92 g l(-1) and then decreased to the final yield of 2.36 g l(-1). Following melanin addition (0.1 g l(-1)), yields reached 7.02 g l(-1) at 48 h and fell to a final yield of 5.21 g l(-1). The EPS produced in high nitrate medium contained both pullulan and (1-->3)-beta-glucan, but only pullulan was produced with melanin-supplementation. With melanin addition a doubling of (1-->3)-beta-glucanase activity was observed in high nitrate medium compared to that without supplementation. On the other hand amylolytic activities disappeared in medium with melanin production or addition. Culture filtrates sustained a higher reducing capacity (RC) when melanin was present. Low RC appeared to reduce (1-->3)-beta-glucanase activity and increase amylolytic activities. Thus, higher RC appears to inhibit production/activity of amylose-degrading enzymes capable of degrading pullulan, and stimulates (1-->3)-beta-glucanase synthesis/activity, leading to a preferential accumulation of pullulan. 相似文献
6.
Ji-Hyun Lee Jeong-Hwa Kim Il-Hui Zhu Xiao-Bei Zhan Jin-Woo Lee Dong-Hoon Shin Sung-Koo Kim 《Biotechnology letters》2001,23(10):817-820
Aureobasidium pullulans had a maximum yield coefficient of pullulan (Y
p/s=0.24) with an initial pH of the culture broth of 6.5 in a shake-flask culture. In a batch culture, the maximum pullulan yield coefficient of 0.30 was obtained at the aeration rate of 0.5 vvm. A yeast-like form and mycelial form of cells were found at the culture broth with pH controlled at 4.5 with a maximum yield coefficient of pullulan of 0.27. However, a high portion (35%) of high molecular weight pullulan (M
w>2 000 000) was produced at pH 6.5 with a yeast-like morphology of the cells. 相似文献
7.
Effects of different pH and carbon sources on pullulan production, UDP-glucose level and pullulan-related synthases activity inAureobasidium pullulans Y68 were examined. It was found that more pullulan was produced when the yeast strain was grown in the medium with initial pH 7.0 than when it was grown in the same medium with constant pH 6.0. The results also show that higher pullulan yield was obtained when the cells were grown in the medium containing glucose than when they were cultivated in the medium supplementing other carbon sources. Our results demonstrate that the more pullulan was synthesized, the less UDP-glucose was left in the cells ofA. pullulans Y68. However, it was observed that more pullulan was synthesized; the cells had higher pullulan-related synthase activity. Therefore, high pullulan yield was related to low UDP-glucose level and high pullulan-related synthases activity inAureobasidium pullulans Y68. 相似文献
8.
Summary Experiments were carried out withA. pullulans (ATCC 9348) at constant dissolved oxygen concentration (DO=100 and 50% related to air saturation at 1 bar) and at constant stirrer speeds (n=500 and 150 [min–1]). The highest pullulan yield was achieved at decreased constant DO in connection with decreased shear rate. Biomass production was not affected. 相似文献
9.
R. Gaur R. Singh S. Tiwari S.K. Yadav N.S. Daramwal 《Journal of applied microbiology》2010,109(3):1035-1043
Aims: To isolate the novel nonmelanin pullulan‐producing fungi from soil and to optimize the physico‐chemical and nutritional parameters for pullulan production. Methods and Results: A selective enrichment method was followed for the isolation, along with development of a suitable medium for pullulan production, using shake flask experiments. Pullulan content was confirmed using pure pullulan and pullulanase hydrolysate. Eurotium chevalieri was able to produce maximum pullulan (38 ± 1·0 g l?1) at 35°C, pH 5·5, 2·5% sucrose, 0·3% ammonium sulfate and 0·2% yeast extract in a shake flash culture medium with an agitation rate of 30 rev min?1 for 65 h. Conclusions: The novel pullulan‐producing fungus was identified as E. chevalieri (MTCC no. 9614), which was able to produce nonmelanin pullulan at from poorer carbon and nitrogen sources than Aureobasidium pullulans and may therefore be useful for the commercial production of pullulan. Significance and Impact of the Study: Eurotium chevalieri could produce pullulan in similar amounts to A. pullulans. Therefore, in future, this fungus could also be used for commercial pullulan production, because it is neither polymorphic nor melanin producing, hence its handling during pullulan fermentation will be easier and more economical. 相似文献
10.
11.
Biofilm is a natural form of cell immobilization in which microorganisms attach onto solid support. In this study, a pigment-reduced
pullulan-producing strain, Aureobasidium pullulans (ATCC 201253), was used for continuous pullulan fermentation in a plastic composite support (PCS) biofilm reactor. Optimal
conditions for the continuous pullulan production were determined by evaluating the effects of the feeding medium with various
concentrations of ammonium sulfate and sucrose and dilution rate. Pullulan concentration and production rate reached maximum
(8.3 g/l and 1.33 g/l/h) when 15 g/l of sucrose, 0.9 g/l of ammonium sulfate, and 0.4 g/l of yeast extract were applied in
the medium, and the dilution rate was at 0.16 h−1. The purity of produced pullulan was 93.0%. The ratio of hyphal cells of A. pullulans increased when it was grown on the PCS shaft. Overall, the increased pullulan productivity can be achieved through biomass
retention by using PCS biofilm reactor. 相似文献
12.
The production of the polysaccharide pullulan by the yeast-like fungi, Aureobasidium pullulans, is accompained by cellular morphogenetic changes. High productivity and yield of the process have been found to correlate with high concentration of yeast-like cells in the culture. The morphogenetic changes of A. pullulans cells depend on the culture conditions, e.g., dissolved oxygen, shear rate and medium composition. In order to improve the productivity of the process, a novel control law was formulated. A feeding strategy dependent on the culture cellular composition was designed and aimed to keep the yeast-like cell concentration high. The culture morphogenetic composition during the process was monitored by a recently developed vision sensor. Feeding was actuated when the yeast-like cell concentration decreased below a threshold. The proposed control strategy improved pullulan production by increasing both productivity and yield of the cells by 67% and 80%, correspondingly. The results point to the advantage and the potential of using the monitoring and control system and algorithm to increase productivity and yield in cellular bioprocesses. 相似文献
13.
D M Updegraff 《Biotechnology and bioengineering》1971,13(1):77-97
Extensive screening studies on cellulolytic bacteria and fungi led to the selection of Myrothecium verrucaria as the organism producing the maximum rate of protein biosynthesis from ball-milled newspaper. Studies in aerated stirred-jar fermentors were carried out to determine the conditions for maximum protein synthesis rate and maximum final protein concentration. The optimum aeration rate was 250 to 374 mM of oxygen at 300 to 400 rpm stirring rate. The pH optimum was broad, from 3.9 to 6.5. Urea at 0.03% and yeast autolysate at 0.1% stimulated growth rate and protein production. The maximum rate of protein biosynthesis and the maximum protein yield were 0.3 g/liter/day and 1.42 g/liter, respectively, from medium G3 with 4% ball-milled newspaper. The final product, obtained by evaporation of the total culture, was 33.7 g from one liter of medium which originally contained 40 g of ball-milled newspaper and 11.3 g of other dissolved materials. The protein content of this final product was 3.3 g, calculated from total organic N × 6.25 or 1.42 g calculated from the biuret method. Both the synthesis rate and the final cell yield are below those obtainable by growing Fungi Imperfecti, yeasts or bacteria on soluble materials such as glucose. 相似文献
14.
A strain Aureobasidium pullulans AP329, was used for the production of pullulan by employing hydrolysed sweet potato as cultivation media. Hydrolysis with α-amylase alone resulted in the lowest yields of pullulan. In contrast continuous hydrolysis with pullulanase and the β-amylase in sweet potato itself gave higher yields, but prolonged hydrolysis with amyloglucosidase decreased the yield. The maximum pullulan yield (29.43 g/l) was achieved at the dextrose equivalent value of 45 and pH of 5.5 for 96 h. As a substitute of sucrose, hydrolysed sweet potato was found to be hopeful and the yield of pullulan was higher than that of glucose and sucrose. The molecular weight of pullulan obtained from hydrolysed sweet potato media was much higher than that of sucrose and glucose media. Results of this work indicated that sweet potato was a promising substrate for the economical production of pullulan. 相似文献
15.
Yefu Chen Jian Guo Feng Li Mingming Liu Xinxin Zhang Xuewu Guo Dongguang Xiao 《Biotechnology and Bioprocess Engineering》2014,19(2):282-288
Xylose, the second most abundant sugar in lignocellulosic materials, is not efficiently utilized in current lignocellulose biotransformation processes, such as cellulosic ethanol production. The bioconversion of xylose to value-added products, such as pullulan, is an alternative strategy for efficient lignocellulose biotransformation. This paper reports the production of pullulan from xylose and hemicellulose hydrolysate by Aureobasidium pullulans AY82. The effects of DL-dithiothreitol (DTT) and pH on pullulan production from xylose were also intensively investigated. A maximal increase of 17.55% of pullulan production was observed in flasks added with 1.0 mM DTT. Batch fermentations with controlled pH were also conducted, and the optimal pH for cell growth and pullulan synthesis was 3.0 and 5.0, respectively. Based on these findings, two-stage pH control fermentations were performed, in which the pH of the medium was first adjusted to 3.0 for cell growth, and then changed to 5.0 for pullulan synthesis. However, the earlier the pH was changed to 5.0, the more pullulan was produced. Fermentation with controlled pH of 5.0 acquired the highest pullulan production. Under the optimized conditions (with the addition of 1.0 mM DTT and controlled pH of 5.0), the maximal pullulan production obtained from xylose was 17.63 g/L. A. pullulans AY82 also readily fermented hemicellulose hydrolysate under these optimized conditions, but with lower pullulan production (12.65 g/L). Fourier transform infrared spectroscopy and high-performance liquid chromatography showed that the structure of the pullulan obtained in this study was identical to that of the pullulan standard. 相似文献
16.
Prasongsuk S Berhow MA Dunlap CA Weisleder D Leathers TD Eveleigh DE Punnapayak H 《Journal of industrial microbiology & biotechnology》2007,34(1):55-61
Tropical isolates of Aureobasidium pullulans previously isolated from distinct habitats in Thailand were characterized for their capacities to produce the valuable polysaccharide, pullulan. A. pullulans strain NRM2, the so-called “color variant” strain, was the best producer, yielding 25.1 g pullulan l−1 after 7 days in sucrose medium with peptone as the nitrogen source. Pullulan from strain NRM2 was less pigmented than those from the other strains and was remarkably pure after a simple ethanol precipitation. The molecular weight of pullulan from all cultures dramatically decreased after 3 days growth, as analyzed by high performance size exclusion chromatography. Alpha-amylase with apparent activity against pullulan was expressed constitutively in sucrose-grown cultures and induced in starch-grown cultures. When the alpha-amylase inhibitor acarbose was added to the culture medium, pullulan of slightly higher molecular weight was obtained from late cultures, supporting the notion that alpha-amylase plays a role in the reduction of the molecular weight of pullulan during the production phase.Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. 相似文献
17.
Guoqiang Chen Jiming Wang Yulong Su Youshuang Zhu Ge Zhang Hongwei Zhao 《Preparative biochemistry & biotechnology》2017,47(10):963-969
Pullulan with different molecular-weight could be applied in various fields. A UV-induced mutagenesis Aureobasidium pullulans UVMU6-1 was obtained from the strain A. pullulans CGMCC3.933 for the production of low-molecular-weight pullulan. First, the obtained polysaccharide from A. pullulans UVMU6-1 was purified and identified to be pullulan with thin-layer chromatography, Fourier transform infrared, and nuclear magnetic resonance. Then, culture medium and conditions for this strain were optimized by flask fermentation. Based on the optimized medium and culture conditions (pH 4, addition of 4?g/L Tween 80 for 96?hr of cultivation), continuously fermentation was performed. The highest pullulan production and dry biomass was 109 and 125?g/L after fermentation for 114?hr, respectively. The average productivity was about 1?g/L/hr, which was intensively higher than the previous reported. This study would lay foundations for the industrial production of pullulan. 相似文献
18.
19.
Kuan-Chen Cheng Ali Demirci Jeffrey M. Catchmark 《Journal of industrial microbiology & biotechnology》2010,37(6):587-594
Pullulan is a linear homopolysaccharide that is composed of glucose units and often described as α-1, 6-linked maltotriose.
In this study, response surface methodology using Box–Behnken design was employed to study the effects of sucrose and nitrogen
concentrations on pullulan production. A total of 15 experimental runs were carried out in a plastic composite support biofilm
reactor. Three-dimensional response surface was generated to evaluate the effects of the factors and to obtain the optimum
condition of each factor for maximum pullulan production. After 7-day fermentation with optimum condition, the pullulan production
reached 60.7 g/l, which was 1.8 times higher than the result from initial medium, and was the highest yield reported to date.
The quality analysis demonstrated that the purity of produced pullulan was 95.2%, and its viscosity was 2.5 centipoise (cP),
which is higher than the commercial pullulan and related to its molecular weight. Fourier transform infrared spectroscopy
(FTIR) also suggested that the produced exopolysaccharide was pullulan. 相似文献
20.
Byung-Kwan Kang Hee-Jong Yang Nack-Shick Choi Keug-Hyun Ahn Chan-Sun Park Byung-Dae Yoon Min-Soo Kim 《Biotechnology letters》2010,32(1):137-142
By disruption of the pullulan synthetase gene (pul) of Aureobasidium pullulans IMS822 KCTC11179BP, we constructed a mutant strain, A. pullulans NP1221, which produced a pure β-glucan exopolysaccharide. The mutant NP1221 was white, whereas the wild-type strain produced
a black dye. When we compared fermentation kinetics between wide-type and mutant strains, the mutant NP1221 did not produce
pullulan. Substrate uptake rate and β-glucan production were similar in both strains. However, the biomass yield of mutant
NP1221 was 2.3-fold (9.2 g l−1) greater than that of wild-type. 相似文献