地毯草黄单胞菌分泌黄原胶的电镜观察

为了研究地毯草黄单胞菌(Xanthomonas axonopodis)FJAT-10151产黄原胶的分泌行为,采用比浊法测定地毯草黄单胞菌的生长曲线,干重法测定黄原胶产量,2,4-二硝基苯肼显色法测定黄原胶中丙酮酸含量变化,通过扫描电子显微镜镜(SEM)和透射电子显微镜镜(TEM)观察地毯草黄单胞菌产黄原胶的分泌行为。FJAT-10151在发酵时间0～26 h为对数期,26～72 h为稳定期。菌株FJAT-10151为短杆状(约2μm),端生鞭毛(约7.9μm),菌体外面形成了一层较厚的荚膜,且许多菌体通过黄原胶连在一起,分泌的黄原胶呈棒状和网状2种形态,聚集或缠绕在细胞表面,其含量随发酵时间的延长而增加。菌株FJAT-10151发酵72 h可获得高品质黄原胶,其产量及丙酮酸含量最高。     

地毯草黄单胞菌发酵生产黄原胶工艺条件优化

为了获得更高品质的黄原胶,优化黄原胶高产菌株地毯草黄单胞菌FJAT-10151的发酵工艺,通过单因素及正交设计对培养基(碳源、氮源和无机盐离子)和发酵条件(发酵时间、pH、装液量和接种量)进行优化,试验获得最佳发酵培养基为葡萄糖30g·L~(-1)、豆饼粉30g·L~(-1)、KH2PO42g·L~(-1)、pH值9.0。在装液量50mL/250mL、接种量8%培养条件下发酵72h,黄原胶产量达到21.0g·L~(-1),是初始培养条件产量8.65g·L~(-1)的2.43倍。优化发酵工艺后,黄原胶品质提高,丙酮酸含量从8.9%升高到16.3%,而蛋白质含量从15.27%降低到4.8%。     

药用资源沙枣产胶影响因素分析

【目的】研究种源、产地和环境因子对尖果沙枣、沙枣和东方沙枣的产胶率和胶多糖含量的影响。【方法】对新疆不同居群药用资源沙枣实地考察,收集沙枣胶,测算产胶率,提取沙枣胶中多糖并计算含量。【结果】不同基源的沙枣其产胶率和多糖含量统计上无显著差异(P>0.05,P=0.173);产地与产胶率相关性显著(尖果沙枣P=0.003、东方沙枣P=0.019、沙枣P=0.011),即低纬度地区产胶率高于高纬度地区,而产地与胶多糖含量差异不显著(P=0.051);生态因子海拔、无霜期、年均温和年积温与产胶率相关性显著,即海拔越低,无霜期越长,年均温和年积温越高,产胶率越高(P<0.05),而多糖含量与生态因子无显著相关(P值均>0.05)。【结论】在海拔较低的平原和天山以东、以南地区种植沙枣以推广沙枣胶产业。     

Replacing the substitute—Guar meal as an alternative for non‐genetically modified soybean meal in the nutrition of rainbow trout (Oncorhynchus mykiss,Walbaum, 1792)

Soybean meal (SBM) is widely used in aqua feed products. In the European Union, only non‐genetically modified (non‐GM) SBM is accepted. However, global production of non‐GM soybeans is declining and is limiting its utilization in aqua feeds. Therefore, non‐GM SBM alternatives are required. In this study, guar meal was evaluated as a substitute for non‐GM SBM in test feeds for rainbow trout (Oncorhynchus mykiss). Fish (initial weight of 57 ± 10.1 g) were stocked to 12 experimental tanks of a freshwater recirculation system with a stocking density of 6 kg/tank (500 L). Fish were organized in triplicate groups and received isonitrogenous and isocaloric experimental feeds designated as control and test feeds 1–3, where 0, 50, 100 and 150 g/kg feed of non‐GM SBM was replaced by guar meal. During the experimental test period of 56 days, fish were fed twice a day until apparent satiation. Compared to the control group, daily feed intake of test feeds 1–3 was significantly increased by guar meal inclusion. No significant differences in feed conversion ratio and specific growth rate were detected among all the treatments. Furthermore, guar meal inclusion did not affect protein efficiency ratio. However, protein productive value was significantly impaired when guar meal incorporation was above 100 g/kg feed. In accordance with the affected protein productive value, the crude protein content of the proximate whole fish body declined significantly. In contrast, condition factor, hepatosomatic index, slaughter yield and fillet yield provided no significant differences between the experimental groups. In conclusion, this study demonstrated that non‐GM SBM could be entirely replaced by guar meal without affecting the general performance of fish and suggests guar meal as an appropriate alternative for non‐GM SBM in the nutrition of rainbow trout.     

刺云实胶对魔芋葡甘聚糖分子链拓扑缠结的分析

将魔芋葡甘聚糖(KGM)与刺云实胶(TG)以一定的比例复配,通过旋转流变仪测定KGM-TG复配体系的相关流变特性,结合分子动力学和拓扑分析学研究KGM和TG分子的作用方式,探讨刺云实胶对魔芋葡甘聚糖分子链拓扑缠结的作用机理。结果表明,刺云实胶与KGM分子间存在协同增效作用,分子链间的主要作用是氢键作用力,刺云实胶的添加使得KGM分子链间的拓扑缠结强度与密度的增强,复配体系的力学性能得到加强。从分子作用本质上验证了刺云实胶与KGM之间流变性能的理化实验结果。     

Bioadhesive Controlled Metronidazole Release Matrix Based on Chitosan and Xanthan Gum

Metronidazole, a common antibacterial drug, was incorporated into a hydrophilic polymer matrix composed of chitosan xanthan gum mixture. Hydrogel formation of this binary chitosan-xanthan gum combination was tested for its ability to control the release of metronidazole as a drug model. This preparation (MZ-CR) was characterized by in vitro, ex vivo bioadhesion and in vivo bioavailability study. For comparison purposes a commercial extended release formulation of metronidazole (CMZ) was used as a reference. The in vitro drug-release profiles of metronidazole preparation and CMZ were similar in 0.1 M HCl and phosphate buffer pH 6.8. Moreover, metronidazole preparation and CMZ showed a similar detachment force to sheep stomach mucosa, while the bioadhesion of the metronidazole preparation was higher three times than CMZ to sheep duodenum. The results of in vivo study indicated that the absorption of metronidazole from the preparation was faster than that of CMZ. Also, MZ-CR leads to higher metronidazole C_max and AUC relative to that of the CMZ. This increase in bioavailability might be explained by the bioadhesion of the preparation at the upper part of the small intestine that could result in an increase in the overall intestinal transit time. As a conclusion, formulating chitosan-xanthan gum mixture as a hydrophilic polymer matrix resulted in a superior pharmacokinetic parameters translated by better rate and extent of absorption of metronidazole.     

地毯草黄单胞菌产黄原胶与魔芋胶复配胶的流变性

改善地毯草黄单胞菌FJAT-10151产的黄原胶的力学性能,研究黄原胶/魔芋胶复配胶的流变性,为该复配胶的开发应用提供基础数据及参考。通过分析复配比、质量浓度、pH值、加热温度、加热时间、氯化钾浓度等对黄原胶/魔芋胶复配胶黏度的影响研究其流变性。结果表明:黄原胶/魔芋胶复配胶为"非牛顿流体",最佳复配比为4∶6;复配胶的黏度随pH的增大先增大后减小,在pH 8.0时黏度最大;复配胶的黏度随加热温度的增大而先增大后减小,在60℃达到最大值;复配胶的黏度随加热时间的延长而减小;氯化钾浓度和冻融处理对复配胶的黏度都有一定程度的影响。0.5%复配胶在60℃加热30min条件下黏度为454.337Pa·s,其稠度系数为9 117。     

复合膳食纤维致大鼠降脂功效研究*

 探讨复合膳食纤维与3种单一膳食纤维对高脂血症大鼠体内脂类含量的影响。建立大鼠高脂血症模型后,在髙脂饲料中分别添加10％的膳食纤维：大豆纤维素(C组)、果胶(D组)、瓜儿豆胶(E组)以及大豆纤维素-果胶-瓜儿豆胶复合物(F组),同时设正常对照组(A组)和单纯高脂饲料对照组(B组)。8周后观察各种膳食纤维对大鼠的生长发育及脂类代谢的影响。结果显示,与B组比,各种膳食纤维皆可不同程度降低大鼠体内脂质水平(P>0.05,P<0.05,P<0.01 ),且以复合物组效果为佳(P<0.01)。研究表明,各种膳食纤维皆可不同程度地降低大鼠体内脂质含量,但复合膳食纤维的效果优于单一膳食纤维。     

高产脂马尾松扦插繁殖技术研究

从1999年起进行了高产脂马尾松扦插育苗试验,结果表明：通过修剪诱发母株促萌技术,幼树插穗繁殖系数可达5～10倍;选用开始木质化或半木质化的枝条作插穗,以黄心土垫底,面层铺粉状细沙作扦插基质,于秋季扦插,且穗条经生根促进剂处理和合理的管理,插条扦插生根率可达92％以上。高产脂马尾松扦插繁殖技术可有效地应用于生产。     

野油菜黄单胞菌重组克隆pIXU9278对黄原胶生物合成的影响

用ＰＩＪ３２００作为载体,构建了包含１５６２个重组克隆野生型野油菜黄单胞菌的粘粒文库,通过三亲交配法,基因文库中的重组克隆可以在ＰＲＫ２０１３的帮助下,从Ｅ．ｃｏｄｉ中以ＸＣＣＮＡＵ－９２中,绝大多数重线克隆对黄原胶合成无影响,但导致菌株生长缓慢,工程菌株ＸＣＣＮＡＵ－９２７８（ＰＩＸＵ９２７８）在２８℃、１２０ｔ／ｍｉｎ条件下发酵７２ｈ,产量达３７．５０ｇ／ｋｇ,发酵液度力为１４６００ｍＰａ．ｓ