Amylase Production by the Marine Yeast Aureobasidium pullulans N13d

The marine yeast strain N13d, producing an extracellular amylase, was isolated from the deep sea sediments of the Pa-cific Ocean. This strain was identified to be Aureobasidium pullulans by 18S rRNA gene sequence analysis and routine yeast identi-fication methods. The optimal sea water medium for amylase production by this yeast strain was 1.0% peptone and 1.0% soluble starch with pH 4.0. The optimal conditions for amylase production by this yeast strain were with temperature 28 ℃, aeration rate 6 Lmin-1 and agitation speed 250 rmin-1. Under these conditions, 58.5 units of amylase activity per mg protein were produced within 56 h of fermentation.

Herbicidal activity of Aureobasidium pullulans PA-2 on weeds and optimization of its solid-state fermentation conditions

Fungal strain PA-2 was isolated from infected poplar leaves from the Ping’an District, Haidong City of Qinghai Province, China. Based on the culture characteristics and the internal transcribed spacer(ITS) sequence of its 16S r DNA, the strain was identified as Aureobasidium pullulans. The culture and metabolites of strain PA-2 showed high herbicidal potential to five tested weeds Galium aparine var. tenerum, Chenopodium album, Malva crispa, Polygonum lapathifolium and Avena fatua. For the in vitro test, 5 days after the detached leaves were inoculated with PA-2 culture, all leaves infected by the hyphae and became black and rotten. For the in vivo test, a metabolite filtrate of PA-2 culture was sprayed over the living weed plants, and five days after inoculation, the weed plants became withered and necrotic. Seven days after inoculation, the fresh weight reductions of G. aparine var. tenerum, C. album, M. crispa, P. lapathifolium and A. fatua were 87.25, 78.46, 82.25, 62.11, and 80.27%, respectively. Galium aparine var. tenerum and M. crispa exhibited significant reductions in fresh weight. The bio-safety test on the five crops showed no significant plant height reductions, which was also observed for wheat(Triticum aestivum), faba bean(Vicia faba), and barley(Hordeum vulgare). By contrast, oilseed rape(Brassica napus) and pea(Pisum sativum) exhibited light spots but no significant reductions in plant height. These results indicated that A. pullulans could be a potential microbial herbicide for the control of the target weeds in crops. Optimization of the carbon and nitrogen sources for cultural media and substances for solid-state fermentation indicated that PA-2 had better colony growth and spore production with the optimal carbon source of glucose(C4), nitrogen source of soybean flour(N2), and the optimal substance was wheat bran. The results in this study provide useful information for the development ofA. pulluans PA-2 as an herbicide for bio-control of the weed.

Studies on the optimal culture conditions of <i>Aureobasidium pullulans</i>to produce exopolysaccharides

In the current study, in order to change the permeability of cell membrane and solve the problem of linked group of fungi mycelium, the method of adjusting osmotic pressure of medium and adding tween-80 was established. The utilized strain with relatively high exopolysaccharide (EPS) yield and low pigment level was obtained after the rejuvenation and sifting of long-preserved Aureobasidium pullulans strain. The optimal proportion of substrate was determined by means of orthogonal test. The transformation ratio of EPS was increased by 10% - 20% and the pigment content was greatly reduced. The fermenting liquor is between creamy white and pale yellow, and the white primary product can be gained without decolourization step. Furthermore, to magnify to 5 L bioreactor can get the similar result.

The ornithine-urea cycle involves fumaric acid biosynthesis in Aureobasidium pullulans var.aubasidani,a green and eco-friendly process for fumaric acid production

The current petroleum chemical methods for fumaric acid production can cause heavy pollution and global warming.In this study,the engineered strains of A.pullulans var.aubasidani were found to be suitable for green fumaric acid producer.Removal and complementation of the relevant genes showed only the ornithine-urea cycle(OUC)was involved in high level fumarate biosynthesis which was controlled by the Ca^(2+)signaling pathway.Removal of both the GOX gene encoding glucose oxidase and the PKS1 gene encoding the polyketide synthase for 3,5-dihydroxydecanoic acid biosynthesis and overexpression of the PYC gene encoding pyruvate carboxylase made the strain e-PYC produce 88.1±4.3 g/L of fumarate at flask level and 93.9±0.8 g/L of fumarate during the fed-batch fermentation.As a yeast-like fungal strain,it was very easy to cultivate A.pullulans var.aubasidani DH177 and their mutants in the bioreactor and to edit its genomic DNAs to enhance fumarate production.It was found that 2 mol of CO_(2) could be fixed during a maximal theoretical yield of 2 mol of fumarate per mole of glucose consumed in the OUC.Therefore,the OUC-mediated fumarate biosynthesis pathway in A.pullulans var.aubasidani was a green and eco-friendly process for the global sustainable development and carbon neutrality.

Dual pH and microbial-sensitive galactosylated polymeric nanocargoes for multi-level targeting to combat ulcerative colitis

Ulcerative colitis(UC)is a type of inflammatory bowel disease characterized by inflammation,ulcers and irritation of the mucosal lining.Oral drug delivery in UC encounters challenges because of multifaceted barriers.Dexamethasone-loaded galactosylated-PLGA/Eudragit S100/pullulan nanocargoes(Dexa-GP/ES/Pu NCs)have been developed with a dual stimuli-sensitive coating responsive to both colonic pH and microbiota,and an underneath galactosylated-PLGA core(GP).The galactose ligand of the GP preferentially binds to the macrophage galactose type-lectin-C(MGL-2)surface receptor.Therefore,both stimuli and ligand-mediated targeting facilitate nanocargoes to deliver Dexa specifically to the colon with enhanced macrophage uptake.Modified emulsion method coupled with a solvent evaporation coating technique was employed to prepare Dexa-GP/ES/Pu NCs.The nanocargoes were tested using in vitro,ex vivo techniques and dextran sodium sulfate(DSS)induced UC model.Prepared nanocargoes had desired physicochemical properties,drug release,cell uptake and cellular viability.Investigations using a DSS-colitis model showed high localization and mitigation of colitis with downregulation of NF-ĸB and COX-2,and restoration of clinical,histopathological,biochemical indices,antioxidant balance,microbial alterations,FTIR spectra,and epithelial junctions’integrity.Thus,Dexa-GP/ES/Pu NCs found to be biocompatible nanocargoes capable of delivering drugs to the inflamed colon with unique targeting properties for prolonged duration.

Pullulan分子结构的研究

利用 GC- MS、IR和 13 C- NMR对 Pullulan的连接碳位和键型进行了研究 ,结果表明 ,Pullulan分子的主链由 β(1→ 3)糖苷链相连 ,主链上每 2～ 3个葡萄糖带有一个葡萄糖残基分枝 ,与主链以 β(1→ 6 )链相连 。

胞外多糖pullulan处理养猪场污水效果分析

用pullulan处理养猪场污水 ,结果表明 :污水的稀释倍数与pullulan的添加量对处理效果有极显著的影响。当Pullulan在 2倍稀释污水中的添加量达到 3mg/kg时 ,污水的生物需氧量 (BOD)、化学耗氧量 (COD)、总P、N的去除率达到 90 %以上 ;大肠杆菌的去除率达到 95 %以上 ,透过率也从 8%上升到 92 %。

胞外多糖Pullulan处理养猪场污水的研究

对 Pullulan处理养猪场污水进行了研究 .结果表明 :污水的稀释倍数与 Pullulan的添加量对处理效果有极显著的影响 ,当 Pullulan在 2倍稀释污水中的添加量达到 3mg/ kg时 ,污水的 BOD、COD、总 P、N的去除率达到 90 %以上 ;大肠杆菌的去除率达到 95 %以上 ,透过率也从 8%上升到 92 % .

动力学原理在芒果涂膜保鲜中的应用

通过对采后芒果果实经Pullulan涂膜处理后的芒果果实呼吸作用的变化的研究,利用芒果呼吸作用产生的CO2浓度(分压)建立芒果呼吸强度的动力学方程。研究结果表明:芒果经3%Pullulan溶液涂膜后的呼吸强度的动力学方程式为:RCO2=6.15×10-2/y2.2723;未经处理的呼吸强度的动力学方程式:RCO2=0.331/y1.9112。建立此方程式为探讨最佳的涂膜材料、涂膜厚度提供依据。

麦芽三糖的制备与分析

目的 :以普鲁兰多糖为底物 ,制备麦芽三糖。方法 :在 46℃ ,p H5 .6时以普鲁兰酶特异性水解普鲁兰多糖的 α- 1,6糖苷键 ,酶解反应 8小时 ,经分级沉淀、浓缩、干燥 ,得到麦芽三糖干粉。以进口试剂为对照 ,通过纸层析及高效液相色谱对产物做定性、定量分析。结果 :以本法制备麦芽三糖 ,产物收率为 6 3.1% ,纸层析定性为麦芽三糖 ,HPL C测定其纯度为 92 .3%。结论 :以本法制备麦芽三糖工艺简单 ,经 HPL

麦芽四糖生产工艺试验

麦芽四糖是一种新型麦芽低聚糖．试验中采用麦芽四糖淀粉酶和普鲁兰酶协同水解预处理过的淀粉，通过单因素试验和响应面曲线（ＲＳＡ）法确定了较好的酶解工艺条件．所得产品中麦芽四糖占总糖比例达８４％以上。

胞外多糖Pullulan分子的结构研究

本试验利用CC-MS、IR和^13C-NMR对Pullulan的连接碳位和键型进行了研究，结果表明，Pullulan分子的主链由β(1→3)糖苷链相连，主链上每2～3个葡萄糖带有一个葡萄糖残基分枝，与主链以β(1→6)链相连，Pullulan分子上还含有羧基。

Pullulan的抗肿瘤活性研究

本文对Ｐｕｌｌｕｌａｎ抗小鼠移植性Ｍｅｔｈｙｌｃｈｏｌａｎｔｈｒｅｎｅ－Ｉ Ｏｉｌｇｏｃｅｌｌｕｌｅｒ和Ｓｏｌｉｄ Ｓａｒｃｏｍａ－１８０肿瘤的活性进行了研究，结果表明，Ｐｕｌｌｕｌａｎ的给与剂量和给与方式不同，其抗肿瘤效果也不同，从抗Ｍｅｔｈｙｌｃｈｏｌａｎｔｈｒｅｎｅ－Ｉ Ｏｉｌｇｏｃｅｌｌｕｌｅｒ来说，腹腔给与的抗肿瘤效果显著高于口投给与之效果，当腹腔给与的剂量为０．

Electrospun Food-Grade Ultrafine Fibers from Pectin and Pullulan Blends

Electrospinning was used to produce ultrafine fibers and fibrous mats from aqueous solutions containing two edible polysaccharides: pectin (PEC) and pullulan (PUL). The process excluded the use of a synthetic carrier polymer or non-aqueous solvents thus maintaining the food-grade status of the components. The inclusion of PUL reduced the surface tension and electric conductivity of pectin solution, and promoted molecular entanglement between PEC and PUL as confirmed by rheological analysis. The spinnability of either polysaccharide was promoted by inclusion of the other. Cross-linking PEC networks were obtained by soaking the fibrous mats in successive Ca2+ solution. The fibrous mats can be used to carry bioactive compounds as demonstrated using probiotic bacteria Lactobacillus rhamnosus GG (LGG) as a model bioactive compound. The research is significant for the development of food products with unique textures and functionalities.

响应面优化普鲁兰酶酶解玉米淀粉工艺研究

研究普鲁兰酶对蜡质玉米淀粉脱支工艺的影响.以还原力(DE)为考察指标,探讨pH、温度、加酶量和酶解时间对玉米淀粉脱支的影响,采用响应面法对酶解过程中的工艺参数进行优化.研究结果表明,在玉米淀粉脱支工艺单因素试验中最适的酶解条件是:pH 5.0,温度50℃,加酶量7.2 U/g,酶解时间12 h;最佳酶解条件为:pH 5.3,加酶量8.1 U/g,温度50℃.最佳条件下得到的DE为0.57,较单因素试验的DE高,证明此优化条件能较好地提高蜡质玉米淀粉的脱支程度.

Effect of Pullulan and Hydrocolloids on Rheological Properties and Quality Parameters of Wheat-Soy Baladi Bread

Baladi bread is a staple food in Egypt and high nutritive value however, stales rapidly. The aim of the study was to conduct a comparative evaluation of pullulan and hydrocolloid combinations on rheological properties and quality parameters of wheat-soy baladi bread. Pullulan polysaccharides (Pu) and hydrocolloids as Arabic gum (AG), K-carrageenan (KC), pectin (P), and xanthan gum (XG) were applied. Rheological properties of samples included Pu and hydrocolloids were analyzed through extensiograph and farinograph. The crust color, staling, and sensory attributes of bread were evaluated. Results revealed that wheat flour (WF) has lower water absorption capacity, dough development time, mixing tolerance index, and resistance to extension however, has higher dough stability, extensibility, and dough energy compared to wheat-soy flour (WSF). Pu and/or hydrocolloids addition to WSF dough evidently improved bread quality. Pu was significantly enhanced crust color and yielded fresher bread relative to control. Additionally, Pu showed the highest Alkaline Water Retention Capacity (AWRC) value after 5 days at 25°C ± 2°C. Results demonstrated that hydrocolloids especially pullulan can significantly improve dough properties, baking quality, sensory acceptability, and delay staling of wheat-soy baladi bread.

Pullulan Acetate Coated Magnetite Nanoparticles for Hyper-Thermia:Preparation,Characterization and In Vitro Experiments

Amphipathic polymer pullulan acetate (PA)-coated magnetic nanoparticles were prepared and characterized by various physicochemical means. The cytotoxicity and cellular uptake of the magnetic nanoparticles were examined. The hyperthermic effect of the magnetic nanoparticles on tumor cells was evaluated. Transmission electron microscopy (TEM) showed that the PA coated magnetic nanoparticles (PAMNs) had spherical morphology. Dynamic light scattering (DLS) showed that the size distribution of PAMNs was unimodal,with an average diameter of 25.8 nm ± 6.1 nm. The presence of the adsorbed layer of PA on the magnetite surface was confirmed by Fourier transform infrared (FTIR) spectroscopy. Magnetic measurements revealed that the saturation magnetization of the PAMNs reached 51.9 emu/g and the nanoparticles were superparamagnetic. Thermogravimetric analysis (TGA) showed that the Fe_(3)O_(4) particles constituted 75 wt% of the PAMNs. The PAMNs had good heating properties in an alternating magnetic field. Cytotoxicity assay showed that PAMNs exhibited no significant cytotoxicity against L929 cells. TEM results showed that a large number of PAMNs were internalized into KB cells. PAMNs have good hyperthermia effect on KB cells in vitro by magnetic field induced hyperthermia. These novel magnetic nanoparticles have great potential as magnetic hyperthermia mediators.

Succinate-bonded pullulan: An efficient and reusable super-sorbent for cadmium-uptake from spiked high-hardness groundwater

Chemically modified pullulan was evaluated for its sorption efficiency and selectivity to remove cadmium（Cd） from spiked high-hardness groundwater（GW）. Pullulan esterified with succinic anhydride using dimethylaminopyridine showed a fairly high degree of substitution value as confirmed by1 H NMR spectroscopy. Pullulan succinate（Pull-Suc） was converted into the sodium salt（Pull-Suc-Na）. The effect of contact time（5–200 min） and p H（2–8） on Cd-uptake by the sorbent（Pull-Suc-Na） was investigated. The sorbent showed more than 90% Cd-removal in first 15 min from distilled water（DW） and GW solution,respectively. Comparison of Pull-Suc-Na with other polysaccharidal sorbents suggested its high efficiency（DW 476.2 mg/g and GW 454.5 mg/g） and selectivity for the removal of Cd by an ion exchange mechanism, which is further supported by the negative Gibbs free energy values calculated from Langmuir isotherms. A Langmuir isotherm kinetic model provided the best fit for the sorption of Cd using Pull-Suc-Na. The sorbent showed a negligible decrease in Cd-uptake over three regeneration cycles. The thermal stability testing of the sorbents indicated that Pull-Suc-Na（sorbent） is more stable than Pull-Suc.

Survival of some food-borne bacteria in kefir produced by microbial levan and pullulan

Kefir is a fermented milk product produced by kefir grains traditionally or lyophilized starter culture.Some quality characteristics of kefir produced at 22℃ and 30℃ using kefir grains after addition of microbial levan and pullulan were investigated for 14 days.Additionally,the survival of different Gram-positive and Gram-negative bacteria strains which were inoculated before and after fermentation were investigated during storage.The pH and titratable acidity were in the ranges of 4.67–4.39 and 1.10–0.87%,respectively.The highest exopolysaccharide values(458.3–465.3 mg/kg)were found in the samples produced with the addition of 1%(w/v)of microbial levan at 30℃.Yeast counts were in the ranges of 6.73–5.11 log CFU/mL while the lactobacilli and lactic streptococci counts were in the ranges of 9.64–7.91 and 9.64–8.69 log CFU/mL,respectively.The microbial polysaccharide addition did not show any significant differences in the enumeration of lactic acid bacteria in kefir(p>0.05).All Gram-positive and Gram-negative bacteria grew/survived during fermentation however Listeria monocytogenes was the most susceptible test bacterium to metabolites during storage.The highest reduction in the counts of L.monocytogenes was determined as 2.39 log units after 24 h of fermentation at 30℃ in the samples which were inoculated before fermentation and produced with the addition of pullulan.Kefir samples produced at 30℃ without polysaccharide addition were considered as the best with respect to appearance,taste,consistency and overall acceptability.