Pullulan production from deproteinized whey by Aureobasidium pullulans

Aureobasidium pullulans P56 was investigated using an adaptation technique and a mixed culture system. The adaptation of A. pullulans and the mixed cultures of A. pullulans and/or Lactobacillus brevisX20, Debaryomyces hansenii 194 and Aspergillus niger did not increase the production of polysaccharide. Enzymic hydrolysis of lactose in deproteinized whey gave a higher polysaccharide concentration and polysaccharide yield than acidic hydrolysed lactose. Maximum polysaccharide concentration (11.0 ± 0.5 g L⁻¹), biomass dry weight (10.5 ± 0.4 g L⁻¹), polysaccharide yield (47.2 ± 1.8%) and sugar utilization (93.2 ± 2.8%) were achieved using enzyme-hydrolysed whey (pH 6.5) containing 25 g L⁻¹ lactose and supplemented with K₂HPO₄ 0.5%, L-glutamic acid 1%, olive oil 2.5%, and Tween 80 0.5%. In this case the pullulan content of the crude polysaccharide was 40%. Received 16 December 1997/ Accepted in revised form 12 March 1999     

Pullulan production from brewery wastes by Aureobasidium pullulans

The production of pullulan from brewery wastes by Aureobasidium pullulans in shake flask culture was investigated. The maximum pullulan concentration (6.0g/l) was obtained after 72h of fermentation. The external addition of nutrients into the spent grain liquor improved significantly the production of pullulan. In this case, the highest values of pullulan concentration (11.0±0.5g/l), pullulan yield (48.2±1.5%), and sugar utilization (99.0±0.5%) were obtained in the medium (pH 6.5–7.5) supplemented with K₂HPO₄ 0.5%, l-glutamic acid 1%, olive oil 2.5%, and Tween 800.5%.     

出芽短梗霉发酵产生普罗蓝糖的研究

对一株野生型的出芽短梗霉(Aureobasidium pullulans)Ft1和从Ft1出发经原生质体再生筛选出的菌株R45进行了摇瓶发酵产普罗蓝糖的比较研究,结果表明R45无论从形态,菌体生长情况,还是从普罗蓝糖的产量,黑色素的产生等方面都与亲株Ft1有明显的区别,说明R45是一株具有一定生产价值的变异菌株.     

Pullulan Elaboration by Aureobasidium pullulans Protoplasts

Protoplasts of Aureobasidium pullulans are capable of producing pullulan. Biosynthesis of the polymer pullulan required induction with kinetics similar to those of whole cells. The protoplasts also produced a heteropolysaccharide component containing mannose, glucose, and galactose. The relative proportions of the pullulan and heteropolysaccharide fractions were a function of glucose concentration, with the pullulan content of the total polysaccharide rising from 20% at 2.5 mM glucose to 45% at 20 mM glucose. Elaboration of pullulan by both cells and protoplasts was sensitive to 0.6 M KCl, which was present as the osmotic stabilizer in protoplast experiments. The presence of KCl resulted in a shift in the pH optimum to a more acidic value. The molecular weight of the protoplast-derived pullulan was sharply reduced from the molecular weight of the whole-cell-derived product. Exposure of the protoplasts to proteolytic enzymes had no effect on polysaccharide elaboration.     

Modelling of cyclic fed-batch plus batch polygalacturonase production by Aureobasidium pullulans on raw orange peel

Summary Cyclic fed-batch plus batch polygalacturonase production by Aureobasidium pullulans in slurry fermentation systems using raw orange peel as substrate was studied in a 3-dm³ stirred fermentor by setting the main operating variables (T=297°K; pH₀=3.2; OP₀=3% w/v; n=700 rpm) to optimal values determined previously. In this way, it was possible to stabilize enzyme excretion at 130–140 VU cm^–3. The time course of this fermentation process in terms of cell growth, substrate consumption and enzyme synthesis was reconstructed with a mean standard error less than 10%, by applying an unstructured model set up in a batch run and further refined in a series of cyclic fed-batch plus batch operations. In particular, the enzyme formation rate was related to the effect of reducing sugars as inhibitors at higher concentrations and as activators at lower levels by using an exponential equation. Moreover, the consumption rate of reducing sugars was found to be linearly related to the cell growth rate, its specific date being of pseudo-first order with respect to the reducing sugar concentration.Offprint requests to: M. Moresi     

Pullulan production from synthetic medium by a new mutant of Aureobasidium pullulans

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.     

Influence of varying nitrogen sources on polysaccharide production by Aureobasidium pullulans in batch culture

Summary Polysaccharide formation by Aureobasidium pullulans was affected by the nitrogen source in the medium, and its yield fell when excess ammonium ions were present, even under conditions which otherwise supported its synthesis. Experiments carried out with pH control gave results which question some of the earlier published data, so it is possible to obtain high polysaccharide yields at low pH (2.5), and mycelial growth at high pH (6.5) with certain nitrogen sources. There appeared to be no causal relationship between morphology and polysaccharide-producing capacity of the cultures.Offprint requests to: R. J. Seviour     

Pullulan production and physiological characteristics of Aureobasidium pullulans under acid stress

In this study, batch processes of pullulan production by Aureobasidium pullulans CCTCC M 2012259 under different pH environments were evaluated. The pH of the medium decreased quickly to an acid stress condition under batch fermentation without pH control. A higher pullulan production was always obtained with a lower biomass under a given glucose concentration with constant pH control, and vice versa. Based on the nonlinear regression analysis of the results obtained from diverse pH control modes, a constant controlled pH of 3.8 was predicted as an optimum pH for efficient pullulan production using a one-element cubic equation. A maximum pullulan concentration of 26.8 g/L and a minimum biomass of 8.1 g/L were achieved under the optimal pH of 3.8, which were in good agreement with the results predicted by the mathematical model. Further information on the physiological characteristics of A. pullulans CCTCC M 2012259 such as intracellular pH, NADH/NAD⁺, ATP/ADP, and glutathione generation under moderate or severe acidic conditions were investigated, and the results presented more evidence on why pullulan biosynthesized with high efficiency under moderate acid stress (e.g., pH 3.8), which would also help us to better understand the response of the cells to acid stress.     

Polysaccharide production by immobilized Aureobasidium pullulans cells in batch bioreactors.

Cells of the fungus Aureobasidium pullulans ATCC 201253 were entrapped within 4% agar cubes or 5% calcium alginate beads and were examined for their production of the polysaccharide pullulan in batch bioreactors. The batch bioreactors were utilized twice for 168 hours of polysaccharide production in medium containing corn syrup as a carbon source. The agar-entrapped cells produced nearly equivalent pullulan concentrations during both production cycles. The alginate-entrapped cells produced higher polysaccharide levels during the second cycle compared to the levels observed during the initial cycle. The agar-entrapped cells elaborated a polysaccharide with a higher pullulan content than did the alginate-entrapped cells during both production cycles.     

出芽短梗霉A5产胞外多糖发酵条件的优化及产物结构鉴定

基于筛选获得能够生产分子量较高且无色素的普鲁兰多糖酵母菌株,对其进行菌株鉴定、产多糖发酵条件优化和多糖产物鉴定,旨在为工业上普鲁兰多糖发酵提供新的菌株来源。以YPD固体培养基为筛选培养基,氯霉素为筛选压力,曲利苯蓝为筛选指示剂;通过形态学,ITS间隔序列分析对筛选出的A5菌株进行鉴定。采用单因子优化A5菌株的最佳发酵条件;利用普鲁兰酶酶解并结合薄层层析法、红外光谱以及凝胶渗透色谱进行结构鉴定和分子量的测定。A5菌株鉴定为出芽短梗霉属,并被命名为出芽短梗霉A5。最优的发酵条件8%(w/v)麦芽糖,1%(w/v)酵母粉,2%(w/v)蛋白胨,0.5%(w/v)K_2HPO_4,0.06%(w/v)(NH_4)_2SO_4,0.03%(w/v)CaCl_2,pH6,7%(v/v)接种量;经过结构鉴定得知:该菌株的胞外产物是普鲁兰多糖,分子量为63.84 kDa。由此获得了一株生产普鲁兰多糖的出芽短梗霉菌株A5,产物无色素且分子量较高。经过初步的发酵条件优化,在最佳发酵条件下发酵培养后,获得普鲁兰多糖的产量为22.9 g/L。综合上述结果可知,菌株A5能够作为工业上生产普鲁兰多糖的重要候选菌株。     

短梗霉多糖发酵条件的研究

在摇瓶发酵条件研究的基础上。于16L自控发酵罐上进行了罐上发酵条件优化研究。发现以10％淀粉水解物为碳源时,淀粉水解物的最适DE值为40－50,发酵培养基中的硫酸铵最适用量不同于摇瓶发酵时的量,种龄和接种量、通气量、罐压、搅拌速度和搅拌叶轮挡数等均对多糖的产生有较大的影响。另外还进行了发酵过程的动力学的研究。     

Exopolysaccharide biosynthesis by a fast-producing strain of Aureobasidium pullulans

Summary The mutant strain Aureobasidium pullulans ICCF-68 was able to produce in batch fermentation on a glucose medium of 80 g/l, exopolysaccharide at high volumetric productivity and final concentration (1.05 g/l.h and 50.2 g/l, respectively). A specific pH pattern and very high oxygen requirement were shown.     

应用FTIR和NMR研究短梗霉多糖分子结构

短梗霉多糖是出芽短梗霉产生的一种胞外多糖,具有极好的成膜、成纤维、阻气、粘接、易加工、无毒性等特性,是微生物多糖中最令人瞩目的多糖之一．本研究应用ＦＴＩＲ和ＮＭＲ技术对由出芽短梗霉胞外产生的短梗霉多糖进行了分析．短梗霉多糖的红外光谱（４０００～４００ｃｍ－１）,具有明显的多糖特征吸收峰,证明多糖是由α－Ｄ－吡喃葡萄糖残基组成．应用先进的一维和二维核磁共振技术,在绝对温度３４３Ｋ下获得短梗霉多糖１Ｈ－ＮＭＲ谱和１３Ｃ－ＮＭＲ谱,确证短梗霉多糖的结构单元是α－１,４麦芽三糖,归属了短梗霉多糖的１Ｈ和１３Ｃ的全部化学位移     

Effect of nitrogen source on pullulan production by Aureobasidium pullulans grown in a batch bioreactor

Pullulan production by Aureobasidium pullulans ATCC 201253 using selected nitrogen sources was studied in a medium using corn syrup as a carbon source. Independent of the corn syrup concentration present, the use of corn steep liquor or hydrolysed soy protein as a nitrogen source instead of ammonium sulphate did not elevate polysaccharide production by ATCC 201253 cells grown in an aerated, batch bioreactor containing 4 litres of medium. Pullulan production on corn steep liquor or hydrolysed soy protein as a nitrogen source became more comparable as the concentration of corn syrup was increased. Cell weights after 7 days of growth on any of the nitrogen sources were similar. The viscosity of the polysaccharide on day 7 was highest for cells grown on ammonium sulphate and 12.5% corn syrup. The pullulan content of the polysaccharide elaborated by ammonium sulphate-grown cells on day 7 decreased as the corn syrup level rose in the medium while the pullulan content of polysaccharide produced by cells grown on corn steep liquor or soytone generally increased.     

Optimization of high molecular weight pullulan production by Aureobasidium pullulans in batch fermentations

Of five strains of Aureobasidium pullulans studied, NRRL Y-2311-1 yielded the highest titer (26.2 g/L) of pullulan and formed the lowest amount of melanin-like pigment. Sucrose was superior to glucose as the carbon and energy source on the basis of yield and titer of pullulan produced. Pullulan titer was higher (26.2 vs 5.1 g/L), biomass concentration was lower (6.9 vs 12.7 g/L), and DO was lower (0 vs 60% of saturation) when the fermenter was agitated by a marine propeller compared to Rushton impellers. Pullulan produced by strain NRRL Y-2311-1 ranged in weight-average molar mass (M(w)) from 486 KDa and number-average molar mass (M(n)) from 220 Da on day 1 of growth to 390 KDa and 690 Da on day 6; M(w) declined by about 35% from day 1 to day 3, the day of maximum pullulan titer. For the other strains, the ranges of molar mass on the day of maximum pullulan titer were 338-614 KDa (M(w)) and 100-6820 Da (M(n)).     

Improved exopolysaccharide production in fed-batch fermentation of Aureobasidium pullulans, with increased impeller speed

Summary Aureobasidium pullulans — when grown in fed-batch fermentation on 190 g glucose/l produced 68 g exopolysaccharide/l with a productivity of 0.42 g/l-h. When the impeller speed was increased from 280 rpm to 340 rpm, the exopolysaccharide increased to 101 g/l, the productivity was 0.90 g/l-h and the conversion ratio was 63 % (w/w).     

出芽短梗霉新菌株RM1603产普鲁兰多糖条件优化及多糖分析

目的:出芽短梗霉RM1603是一株高产胞外多糖新菌株,通过优化其产糖条件,鉴定其多糖结构,为进一步开发利用RM1603产胞外多糖奠定理论基础。方法:以RM1603为出发菌株,在单因素分析确定最佳氮源与无机盐的基础上,利用正交试验探究RM1603最佳发酵产糖条件;薄层层析及红外光谱分析确定胞外多糖产物结构。结果:出芽短梗霉菌RM1603的初始多糖产量为28.91g/L,发酵条件优化后产糖量达到65.213g/L,提高了约2.3倍;结构分析表明RM1603的多糖产物为普鲁兰多糖。结论:出芽短梗霉RM1603是一株具有较大产糖优势,极具开发潜力的高产普鲁兰糖新菌株;奠定了开发利用RM1603生产普鲁兰多糖的理论基础。     

Pullulan production by color variant strains ofAureobasidium pullulans

Summary Naturally occurring color variant strains ofAureobasidium pullulans are distinguished from typical strains by their brilliant pigmentation, overproduction of secreted enzymes (xylanase), and low DNA relatedness. Color variants have not previously been examined for pullulan secretion. Among five independently isolated color variants, strains NRRL Y-12,974 and YB-4026 made the greatest amounts of pullulan from cornstarch, with conversion efficiencies of about 10%. Neither color variant nor typical strains made significant amounts of pullulan from the unconventional lactose or xylan substrates. Pullulan yields were inversely correlated with biomass production. Pullulan production thus appears to be a variable characteristic of both color variant and typically pigmented strains ofA. pullulans, regulated by specific inducers during growth limitation.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.