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。     

几株出芽短梗霉在不同发酵条件下产生多糖的比较

将已有的４株出芽短梗霉在摇瓶中于不同发酵条件下进行比较,考察了它们的生长情况,不同的碳源、氮源、磷酸盐、初始ｐＨ和通气量等对短梗霉多糖合成的影响,获得一株产短梗霉多糖的高产菌株,为以后工作打下良好基础。     

二价阳离子短梗霉多糖发酵的影响

就二价阳离子对短梗霉多糖和黑色素的影响进行了分析和研究。结果表明,二价阳离子对短梗霉多糖的合成和黑色素的形成均有较大的影响。通过对培养基中二价阳离子含量和种类的控制不仅可以抑制细胞黑色素的形成,而且还保持了很高的多糖发酵水平,在３０Ｌ生物反应器中短梗霉多糖的产量和转化率分别达到了５９．８ｇ／Ｌ和６１．５％。     

短梗霉胞外多糖发酵及其发酵动力学

对短梗霉（Aureobasidiumpullulans)胞外多糖（EPS）的发酵及其发酵动力学进行了研究。短梗霉菌体前期生长速度较快,到48b生长趋于稳定期,其胞外多糖合成随菌体生长的不断上升,到84b多糖的产量达到最高,为14.24(g/L)发酵实验基于Logitic方程和Luedeking-Piret方程,得到了描述发酵过程的动力学数学模型和模型参数,同时对实验数据与模型进行了验证比较。     

出芽短梗霉发酵生普罗蓝糖的研究

对一株野生型的出芽短梗霉（Ａｕｒｅｏｂａｓｉｄｉｕｍｐｕｌｌｕｌａｎｓ）Ｆｔｌ和从Ｆｔｌ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Ｆｔｌ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。     

发酵条件对短梗霉多糖产量的影响

对短梗霉发酵培养基的初始pH,初始蔗糖浓度,酵母膏浓度,NH4^ 浓度,接种量和装液量等发酵条件对短梗霉多糖发酵影响进行了研究。结果表明,发酵条件对多糖发酵有显著的影响,当初始pH,初始蔗糖浓度,NH4^ 浓度,酵母膏浓度和装液量分别为6.5,5.0%,0.5g/L,0.2%和25ml时多糖的产量达到最大值;但接种量在2.0%-7.0%之间对多糖的产量影响不大,可见,通过对培养条件的调整,有助于短梗霉多糖的产量的提高。     

出芽短梗霉的研究进展

出芽短梗霉是一类类酵母真菌,具有酵母样和真菌菌丝体两种形态,影响其形态的因素有碳源,氮源,离子种类及浓度和pH值等,出芽短梗霉的发酵产物多种多样,如多聚糖,酶,抗真菌素等,通过选育优良菌株可提高发酵产物的产量。     

短梗霉多糖超滤器的计算

超滤浓缩是短梗霉多糖分离纯化过程中的重要工序。本文研究了短梗霉多糖溶液的浓度每超滤速率的关系,推导出新的超滤器计算公式。根据预定的生产规模及工艺条件,可以对超滤器进行设计计算。实验结果表明用这种方法计算的结果是可靠的。     

二价阳离子对短梗霉多糖发酵的影响

就二价阳离子对短梗霉多糖和黑色素的影响进行了分析和研究。结果表明 ,二价阳离子对短梗霉多糖的合成和黑色素的形成均有较大的影响。通过对培养基中二价阳离子含量和种类的控制不仅可以抑制细胞黑色素的形成 ,而且还保持了很高的多糖发酵水平 ,在 30L生物反应器中短梗霉多糖的产量和转化率分别达到了 59 8g/L和 61 5%。     

Polysaccharide production by sponge-immobilized cells of the fungus Aureobasidium pullulans

T.P. WEST AND B.R.-H. STROHFUS. 1996. Cells of the fungus Aureobasidium pullulans ATCC 42023 were immobilized in sponge cubes and examined for their ability to elaborate the polysaccharide pullulan in relation to carbon source. It was found that fungal cells grown on corn syrup, sucrose or glucose as a carbon source could be immobilized in sponge cubes and that comparable cell weights and viable cell concentrations were immobilized. Independent of the carbon source tested, the immobilized fungal cells could be used at least three times for the production of polysaccharide. The immobilized A. pullulans cells elaborated the highest polysaccharide levels in the culture medium after 5–7 d of growth at 30°C.     

Polysaccharide production by Aureobasidium pullulans: factors affecting polysaccharide formation

Aureobasidium pullulans NRRL 6220 synthesized polysaccharide most actively in media containing sucrose, fructose or maltose with (NH₄)₂SO₄ (0.6 g/l) or ammonium acetate giving greatest yields of the polysaccharide. With (NH₄)₂SO₄ at 1.2 g/l, production of polysaccharide was decreased considerably. Polysaccharide production was highest with an initial pH of 6.5 while biomass formation was better below an initial pH of 5.5. Optimum phosphate concentration for polysaccharide production was 0.03 m.S.M. Badr-Eldin, H.G. El-Masry and O.A. Abd El-Rahman are with the Microbial Chemistry Department, National Research Center, Dokki, Cairo, Egypt; F.H.A. Mohamad is with the Chemical Engineering and Pilot Plant Department, National Research Center, Dokki, Cairo, Egypt. O.M. El-Tayeb is with the Microbiology Department, Faculty of Pharmacy, Cairo University, Egypt.     

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.     

Polysaccharide production by a reduced pigmentation mutant of Aureobasidium pullulans NYS-1

AIMS: To isolate a reduced pigmentation mutant of Aureobasidium pullulans NYS-1 and characterize its cellular pigmentation plus its polysaccharide and biomass production relative to carbon source. METHODS AND RESULTS: Cellular pigmentation, polysaccharide levels and biomass production by the isolated mutant NYSRP-1 were analysed relative to carbon source. Cellular pigmentation of the mutant was lower than its parent strain using either carbon source. The mutant elaborated higher polysaccharide levels on sucrose than on corn syrup. The pullulan content of the polysaccharide synthesized and biomass production by the mutant rose as the carbon source concentration was increased. CONCLUSION: It is feasible to isolate a reduced pigmentation mutant from strain NYS-1 that exhibits elevated polysaccharide production using corn syrup as a carbon source. SIGNIFICANCE AND IMPACT OF THE STUDY: The mutant provides an advantage for commercial pullulan production because of its reduced pigmentation and enhanced polysaccharide synthesis.     

Polysaccharide production by a reduced pigmentation mutant of the fungus Aureobasidium pullulans

Abstract A reduced pigmentation mutant was isolated from Aureobasidium pullulans ATCC 42023 by chemical mutagenesis and was subsequently characterized. The pigment melanin was present not only in A. pullulans cells but also contaminated the elaborated polysaccharide and thus, was measured in both fractions. Cellular and polysaccharide melanin levels of the mutant strain were at least 11-fold and 18-fold reduced, respectivelu, compared toits parent strain after 7 days of growth at 30°C whether sucrose or glucose served as the carbon source in the culture medium. Polysaccharide and cell dry weight levels of the mutant were very similar to those observed for the parent after growth on sucrose or glucose as the source of carbon over a period of 7 days at 30°C. The pullulan content of the polysaccharide produced by the parent or mutant strain was lower for sucrose-grown cells than for glucose-grown cells. It was also noted that the pullulan content of the polysaccharide elaborated by the mutant strain was slightly higher than that of the polysaccharide produced by the parent strain after growth on either sucrose or glucose.     

Beta-galactosidase from Aureobasidium pullulans

A red-pigmented, radiation-resistant, Gram-negative, rod-shaped bacterium isolated from irradiated pork is described. The D₁₀ values in buffer solution and on pork mince are 3·45 and 5·05kGy respectively. The strain has been identified as a Deinobacter species.     

Inorganic Sulfur Oxidation by Aureobasidium pullulans

Aureobasidium pullulans (de Bary) Arnaud isolated from the phylloplane of sycamore exposed to heavy atmospheric pollution oxidized S⁰ to S₂O₃²⁻, S₄O₆²⁻, and SO₄²⁻ in vitro. The intermediates S₂O₃²⁻ and S₄O₆²⁻ were also oxidized to SO₄²⁻. Cell-free extracts of A. pullulans also oxidized reduced forms of S, the oxidation increasing linearly with increasing protein concentration, showing that the process is enzymatic. The possible role of fungi in S oxidation in soils is discussed.     

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.