产抗氧化胞外多糖海洋细菌Bacillus subtilis OST23a的诱变育种

利用产生抗氧化活性胞外多糖的海洋细菌Bacillus subtilis OST23a为出发菌株进行高产菌株的诱变选育。采用紫外、硫酸二乙酯复合诱变处理后筛选得到一株高产胞外多糖的优良突变菌株UD292,发酵产胞外多糖水平达到43.92mg/L,较出发菌株提高了6.26倍,且多糖的抗氧化活性没有显著变化。对突变菌株进行连续传代实验结果表明突变菌株遗传性状稳定。     

紫外与亚硝基胍复合诱变选育高产多糖罗耳阿太菌

以实验室保存的罗耳阿太菌(Athelia rolfsii)为出发菌株,分别采用紫外线(UV)和亚硝基胍(NTG)诱变方法选育高产多糖菌株。与出发菌株相比,紫外诱变菌株多糖产量增加了10.70%,亚硝基胍诱变菌株多糖产量增加了15.78%。通过响应面设计紫外线和亚硝基胍复合诱变,得到正向突变株,其中X2突变株遗传性状稳定,多糖产量达19.868g/L,相比出发菌株增长了23.85%。     

灵芝紫外诱变育种研究

应用原生质体紫外诱变技术,对灵芝真菌进行了紫外诱变处理.从30株诱变株中选出1株菌体产率和多糖产量明显优于原始菌株的突变株Hs-26,经遗传稳定性试验、10 L发酵罐发酵培养,Hs-26高产突变株发酵周期、菌体及胞外多糖产量都明显超过原始菌株,菌体产量相对提高38.71%,多糖产量相对提高79.16%,表明所得突变株是比原始菌株更优秀的稳定高产的新菌株.     

蛹虫草高产胞外虫草素和虫草多糖的诱变育种

通过诱变获得高产胞外虫草素和虫草多糖的蛹虫草菌株.采用紫外线诱变(UV)、化学诱变(LiCl)、复合诱变(UV-LiCl) 3种方式对蛹虫草孢子进行诱变;发酵检测存活菌株的胞外虫草素和虫草多糖的含量.结果:以胞外虫草素为指标,3种诱变方式的最大正突变率分别为化学突变(29.2％)＞紫外突变(28.6％)＞复合诱变(26.5％);以胞外多糖为指标,最大正突变率分别为紫外诱变(35.7％)＞复合诱变(33.3％)＞化学诱变(27.0％).紫外诱变突变株Z-5-1胞外虫草素产量达0.842g/L,比出发菌株高311％;紫外诱变突变株Z-4-7胞外虫草多糖产量达5.250g/L,比出发菌株高148％.在连续培养5代后,仍具有较好的遗传稳定性.紫外诱变能获得较高的蛹虫草正突变率,同时能获得高产虫草素、虫草多糖的突变株.     

脉冲强光诱变选育高产乳酸植物乳杆菌及其益生特性研究

该研究采用脉冲强光对植物乳杆菌（Lactobacillus plantarum）CICC 6240进行诱变，并以乳酸产量为响应值，通过响应面法优化脉冲强光诱变条件。采用最佳脉冲强光对植物乳杆菌CICC 6240进行诱变后，通过溶钙圈法和乳酸产量测定选育高产乳酸的突变株，并对其耐酸、耐胆盐、人工胃肠液耐受性、疏水性、自聚集能力进行研究。结果表明，最佳脉冲强光诱变条件为脉冲电压1 700 V，脉冲次数18次，脉冲距离9 cm。采用此条件进行诱变后，筛选出两株高产乳酸的突变株G10、G16，其乳酸产量较原始菌株分别提高58.96%和56.53%。突变株G10、G16在pH值2.0条件下培养3 h后，存活率分别为77.72%、72.55%；在人工模拟胃肠液中培养后，存活率分别为71.40%、78.16%；在1.0%胆盐条件下培养3 h后存活率分别为75.32%、62.96%；培养24 h时自凝集率分别为76.49%、74.80%；对二甲苯、氯仿和乙酸乙酯的疏水性分别为83.33%、75.26%;78.00%、80.36%及53.16%、50.36%。综上，突变株G10为高产乳酸的优良菌株。     

高产胞外多糖干酪乳杆菌的太空诱变选育

为了提高干酪乳杆菌G5的胞外多糖产生能力,采用太空诱变技术对其进行选育,从中筛选出高产胞外多糖菌株。通过富集培养、平板筛选、脱脂乳发酵和遗传稳定性实验,最终得到两株高产胞外多糖且遗传稳定性较好的突变株EPS-33和EPS-43。突变株EPS-33和EPS-43在25℃发酵脱脂乳,发酵结束时胞外多糖的产量分别220.42和198.49mg/L,为出发菌株的1.9倍和1.7倍。2个突变菌株与出发菌株产胞外多糖的变化趋势基本相同,但产量大幅增加。     

产CLA嗜酸乳杆菌的筛选诱变与鉴定

从传统泡菜中选育高产共轭亚油酸(Conjugated Linoleic Acid,CLA)的菌株L28,利用人工诱变方法,以L28为出发菌株,采用紫外线、亚硝基胍(NTG)依次诱变及紫外、亚硝基胍复合诱变处理,经进一步液体发酵复筛获得多株突变菌株,CLA的最优产量为95.1425μg/mL.其中L44突变菌株为CLA生成能力最高菌株.经16S rDNA全序列分析法和生理生化试验确定菌株的种属,然后经过Gene Bank基因比对确定同源基因,最后经鉴定为嗜酸乳杆菌(Lactobacillus acidophilus).     

紫外线与氯化锂诱变选育高产乳糖酶米曲霉

以产乳糖酶米曲霉(ATCC20423)为出发菌株,通过紫外线和紫外复合氯化锂诱变处理选育高产乳糖酶菌株.利用紫外线辐照诱变得到突变株UV-15-20的乳糖酶活力为114.08U/mL,比出发菌株提高了49.22％;以紫外线复合氯化锂选育得到突变株UV-LiCl-38乳糖酶活力为121.42U/mL,比出发菌株提高了58.82％.传代实验表明两个突变株均具有稳定的遗传性.     

纳塔尔链霉菌的脉冲强光诱变育种研究

采用电脉冲强光对纳塔尔链霉菌(Streptomyces natalensis)进行诱变处理,以添加了硫酸链霉素的平板进行筛选.选育出一株正突变株SNll4,在同等发酵条件下,纳他霉素产量达到1.098g/L,比出发菌株提高了1.6倍,连续5次传代,其产量性状无大突变,表明该菌株遗传性状稳定.     

等离子体注入诱变选育细菌纤维素高产菌株

为了选育高产细菌纤维素的木葡糖酸醋杆菌(Gluconacetobacter xylinum)突变株,通过等离子体注入诱变,筛选得到一株产细菌纤维素能力最高的突变株GX-5,其细菌纤维素产量为4.162 g/L,比出发菌株提高了83.19%。     

氮源对嗜热链球菌胞外多糖表型特征的影响

乳酸菌胞外多糖(EPS)具有增加发酵乳黏度,防止乳清析出,增强凝乳强度等特性,是目前食品科学领域的研究热点之一.本研究以基础培养基M17为对照,以大豆蛋白胨、胰蛋白胨和酪蛋白胨替代M17液体培养基的复合氮源,探究不同氮源对嗜热链球菌IMAU20561胞外多糖的产量、分子质量及结构的影响.结果表明:嗜热链球菌IMAU20...     

干巴菌菌丝体多糖的制备及其水解特性

培养基优化实验表明,马铃薯葡萄糖培养基是干巴菌的最适产糖培养基,菌丝体产量和菌丝体多糖产量分别可达7.56 g/L和0.42 g/L。采用Plackett-Burman试验及响应面试验优化干巴菌多糖的提取工艺,结果表明,极显著影响因素及其最优条件为超声功率400 W、超声时间10 min、醇沉倍数3 倍,优化后多糖得率可达6.98%。体外抗氧化实验证明,干巴菌多糖具有良好的抗氧化活性,并且酶水解（纤维素酶、蜗牛酶）和酸水解（硫酸）均可使多糖的抗氧化能力显著增强。采用逐级酸水解结合柱前衍生高效液相色谱法分析多糖结构,其单糖残基分布规律为：支链末端残基由半乳糖和少量甘露糖构成;半乳糖大多分布于支链外侧及支链末端;葡萄糖是主要单糖组分,主要分布于主链及支链内侧;甘露糖主要分布于支链内侧。本研究为酶水解及酸水解方法在多糖领域中的应用及干巴菌多糖的资源开发提供理论基础。     

Antioxidant activity of prebiotic ginseng polysaccharides combined with potential probiotic Lactobacillus plantarum C88

The potential prebiotic properties of Panax ginseng polysaccharides were studied using ten strains of Lactobacillus plantarum isolated from traditional Chinese fermented foods. These probiotics showed different growth characteristics depending on the extract and strain specificity. L. plantarum C88 showed higher cell densities and growth rate when cultured on P. ginseng polysaccharides. In the in vitro antioxidant assay, P. ginseng polysaccharides combined with L. plantarum C88 were found to possess significant DPPH, ABTS and superoxide anion radicals scavenging activities, and acidic polysaccharides showed better antioxidant activity than neutral polysaccharides. Furthermore, we evaluated the antioxidant effect of acidic P. ginseng polysaccharide combined with L. plantarum C88 strain in natural ageing mice in vivo. Acidic P. ginseng polysaccharide and L. plantarum C88 together inhibited the formation of malondialdehyde (MDA) and increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), catalase (CAT) and total antioxidant capacities (T‐AOC) in a dose‐dependent manner.     

新疆芜菁酸性多糖分离纯化、抗氧化活性研究及红外表征

目的 检测分离纯化的芜菁酸性多糖(Brassica rapaL.acidic polysaccharide,BRAP)的含量和纯度,并对其进行抗氧化能力检测和红外表征。方法 (1)经阴离子交换柱DEAE-650M、HW-55F色谱柱以及Sephacryl S-300色谱柱洗脱分离纯化芜菁多糖;(2)采取紫外-可见分光光度法及苯酚-硫酸法测定芜菁酸性多糖的含量;(3)经由测定芜菁酸性多糖羟基自由基(·OH)清除能力,1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基(·DPPH)清除能力、金属Cu²⁺还原能力来评价其抗氧化活性,并与VC抗氧化能力进行对比;(4)应用红外光谱分析芜菁酸性多糖的化学键或官能团信息,通过高效凝胶渗透色谱法对芜菁酸性多糖的均一性分析。结果 芜菁酸性多糖的含量为55.47%;芜菁酸性多糖对·DPPH和·OH有一定清除能力,对金属Cu²⁺也有还原能力,但均比VC弱,红外光谱分析显示,芜菁酸性多糖中有多羟基醛糖的特征吸收峰以及与抗氧化活性相关的羟基。高效凝胶渗透色谱图显示芜菁酸性多糖为高纯度多糖。结论 新疆芜菁中有含量较为丰富且纯度较高的酸性多糖组分,且该成分具有较好的抗氧化活性。     

Characterization of the angiotensin-converting enzyme inhibitory activity of fermented milks produced with Lactobacillus casei

Our study assayed angiotensin-converting enzyme (ACE) inhibitory activity and fermentation characteristics of 41 food-originated Lactobacillus casei strains in fermented milk production. Twenty-two of the tested strains produced fermented milks with a high ACE inhibitory activity of over 60%. Two strains (IMAU10408 and IMAU20411) expressing the highest ACE inhibitory activity were selected for further characterization. The heat stability (pasteurization at 63°C for 30 min, 75°C for 25 s, and 85°C for 20 s) and resistance to gastrointestinal proteases (pepsin, trypsinase, and sequential pepsin/trypsinase treatments) of the ACE inhibitory activity in the fermented milks produced with IMAU10408 and IMAU20411 were determined. Interestingly, such activity increased significantly after the heat or protease treatment. Because of the shorter milk coagulation time of L. casei IMAU20411 (vs. IMAU10408), it was selected for optimization experiments for ACE inhibitory activity production. Our results show that fermentation temperature of 37°C, inoculum density of 1 × 10⁶ cfu/g, and fermentation time of 12 h were optimal for maximizing ACE inhibitory activity. Finally, the metabolite profiles of L. casei IMAU20411 after 2 and 42 h of milk fermentation were analyzed by ultra-HPLC electron spray ionization coupled with time-of-flight mass spectrometry. Nine differential abundant metabolites were identified, and 2 of them showed a strong and positive correlation with fermented milk ACE inhibitory activity. To conclude, we have identified a novel ACE inhibitory L. casei strain, which has potential for use as a probiotic in fermented milk production.     

油莎豆发芽前后营养成分及多糖生物活性的变化

为考察发芽对油莎豆营养成分及油莎豆多糖体外抗氧化、降糖活性的影响，采用近红外光谱分析仪、氨基酸分析仪分析了发芽前后油莎豆淀粉、脂肪、蛋白质、纤维、灰分、氨基酸的含量，蒽酮硫酸法分析多糖含量；利用DPPH·、ABTS+·及总抗氧化能力评价油莎豆多糖抗氧化活性；采用PNPG法，以阿卡波糖作对照，分析油莎豆多糖体外降糖活性。结果表明，发芽对油莎豆各营养成分影响有一定差异，发芽后油莎豆的脂肪提高了8.22%，淀粉、蛋白质、纤维、灰分含量分别降低了11.75%、11.09%、10.31%和7.69%，氨基酸总量增加了8%；发芽后油莎豆多糖的得率增加了9.23%，同时发芽提高了油莎豆多糖的抗氧化、降糖作用等生物活性。高效阴离子交换色谱（HPAEC-PAD）技术分析结果表明，发芽改变了油莎豆多糖的单糖组成比例，产生了更多的抗氧化活性较强的单糖（鼠李糖）。相关性分析表明，油莎豆发芽后强的抗氧化能力、降糖作用与高的多糖含量呈极显著相关性（P<0.01，r=0.985~0.997），研究为油莎豆的深加工和功能化产品的开发提供重要的科学参考。     

马齿苋多糖提取工艺优选及活性初筛

以多糖提取得率为指标,采用正交试验对加酶超声辅助法提取马齿苋多糖的工艺条件进行了优化。方法:以未经酶解和未采用超声处理的传统水提醇沉法得到的多糖做对照,通过近红外光谱分析加酶超声处理对马齿苋多糖结构的影响并对马齿苋多糖的抗氧化活性进行分析。结果表明:在纤维素酶2.5%,超声温度60℃,超声功率70 W,超声时间20 min,多糖提取得率达到18.40%。结论:近红外光谱分析表明,加酶超声对多糖的结构没有显著影响,提高了多糖提取率。体外抗氧化性实验表明,所提取马齿苋多糖具有较强的总抗氧化能力,对.OH和DPPH均有较好的清除能力,活性大小与多糖的浓度呈明显的线性关系。     

金花葵多糖提取工艺优化及结构表征和抗氧化性研究

优化金花葵干花苞中多糖的提取工艺,并对其结构和抗氧化活性进行研究。本研究在单因素实验的基础上,通过正交试验优化水提醇沉法提取多糖的工艺,利用高效液相色谱(HPLC)法分析多糖的单糖组成,应用傅里叶红外光谱(FTIR)法和扫描电镜(SEM)观察对多糖官能团和外貌进行分析,并检测了多糖清除自由基的能力和还原力。结果表明,金花葵的干花苞多糖最佳提取工艺为：提取温度100℃、提取时间3 h和料液比1:50 g/mL。在此工艺条件下,多糖得率为17.23%±0.19%,多糖含量为27.87%±0.60%。其单糖组成及摩尔比为阿拉伯糖:半乳糖:鼠李糖:甘露糖:葡萄糖=0.97:1:0.23:0.05:0.43。表面呈不规则片状,并且证明具有糖醛酸、吡喃糖环官能团。此外,提取的多糖具有一定的清除DPPH自由基、ABTS⁺自由基能力,对自由基半数抑制对应浓度(IC₅₀)分别为1.22、4.43 mg/mL,表明具有良好的抗氧化活性。研究结果为金花葵花苞中多糖的化学结构解析和功能研究提供了研究基础与理论依据。     

Factors influencing autoaggregation and aggregation of Lactobacillus delbrueckii subsp. bulgaricus isolated from handmade yogurt

Of 26 Lactobacillus delbrueckii subsp. bulgaricus strains isolated from yogurt, strains B2 and 22, which produce low levels (28 and 21 mg liter(-1), respectively) of extracellular polysaccharides (EPSs), and strains B3 and G12, which produce high EPS levels (211 and 175 mg liter(-1), respectively), were selected for further study. The two high EPS-producing strains showed a significant autoaggregation and coaggregation ability with Escherichia coli ATCC 11230 (P < 0.05). Moreover, the effect of bile was evaluated on autoaggregation and hydrophobicity. Autoaggregation and hydrophobicity of these L. delbrueckii subsp. bulgaricus strains decreased after treatment with bile. Only the high EPS-producing L. delbrueckii subsp. bulgaricus strain B3 showed greater autoaggregation (80%) and hydrophobicity (86%) than the other strains after bile treatment. When these strains were assessed for the inhibition of E. coli ATCC 11230 in coculture, L. delbrueckii subsp. bulgaricus B3 completely inhibited E. coli during 24 and 48 h of incubation. This investigation showed that a high EPS production and coaggregation ability may be important in the selection of probiotic strains.