高光谱技术融合平板菌落法同步计数酸奶中益生菌

采用高光谱技术结合平板菌落法快速表征益生菌酸奶中常见的发酵菌种（保加利亚乳杆菌、嗜热链球菌）和益生菌种（干酪乳杆菌、嗜酸乳杆菌、植物乳杆菌）的光谱差异,并结合不同模式识别方法对混合菌种发酵酸奶中每种益生菌的数量进行同步计数,最后与传统计数法得到的菌落数量结果进行对比,通过2 种计数结果的差异性分析验证高光谱菌落计数的可行性。结果表明,当主成分数为9时,最小二乘支持向量机模型对不同种类菌落识别效果均优于K-最近邻法和误差反向传播神经网络模型,其中校正集识别率为99.20%,预测集识别率为93.33%,为最佳计数模型,与传统计数法并无显著差异（P＞0.05）,验证高光谱技术应用在混合菌种发酵酸奶中对每种益生菌同步计数的可行性,解决传统计数法无法同步计数混合菌种酸奶中各益生菌数量的缺陷问题,为快速无损检测酸奶品质与保健活性提供检测依据。     

巴马长寿老人源乳酸杆菌的筛选及其益生特性

为获得巴马长寿老人肠道乳杆菌并研究其益生特性,采用改良MRS+Ca CO3固体培养基与改良MRS+X-gal固体培养基从10位广西巴马百岁老人粪便中筛选出19株乳杆菌,再通过生理生化实验、糖发酵实验、模拟胃肠转运实验、疏水性实验和自凝集实验,筛选出消化道逆环境耐受性强和粘附力好的菌株3株(GU-L3、GU-P132和GU-G23),进一步对三株菌进行了16Sr DNA序列鉴定,结果发现GU-L3为干酪乳杆菌(Lactobacillus casei);GU-P132为发酵乳杆菌(Lactobacillus fermentum);GU-G23为格氏乳杆菌(Lactobacillus gasseri)。三个菌株经模拟胃肠液转运实验后,存活率皆达到107 CFU/m L以上,自凝集率分别为12.43±0.03%、78.88±0.01%和35.92±0.02%,疏水率分别为6.38±0.02%、81.77±0.02%和10.58±0.05%,粘附性也高于其他菌株。经与国内外有关报道相比,综合认为这三株来自巴马老人肠道的乳酸杆菌益生特性明显,具有较好的开发潜力。     

Screening of potential aquatic probiotics from the major microflora of guppies (Poecilia reticulata)

The fish (Poecilia reticulata) was used as the source for probiotics. 46 bacterial isolates were obtained from the skin, gills, guts and intestines of the guppy, Poecilia reticulata (collected from a government model fish farm in Kottayam, India). Of the above isolated strains, four isolates were selected based on their inhibitory spectrum against five indicator strains, Aeromonas hydrophila 1739, Vibrio cholerae 3906, Flavobacterium 2495, Acinetobacter 1271 and Alcaligenes 1424 (standard cultures collected from Microbial Type Culture Collection (MTCC) Chandigarh, India). Among the resulting isolates, two were gram-positive cocci, namely MBTU-PB2 and MBTU-PB3 and belong to the genus Staphylococcus. The other two were gram-negative rods, namely MBTU-PB1 and MBTU-PB4, of the genera Enterobacter and Acinetobacter, respectively. The basic probiotic characteristics of these isolates such as the production of bacteriocin like inhibitory substances (BLIS), antibiotic sensitivities and growth profiles were also determined. The above four isolated strains exhibited different antagonisms than the five indicator strains. During incubation, the antibacterial activity gradually increased in the inhibition zone and was influenced by the lag period (λ) and doubling time. The lag periods for most of the four selected strains were shorter than those of the indicator strains and the isolates had different growth rates (μ) than the indicator strains. All four isolates produced BLIS, however, the strains had different BLIS activities against the indicator strains. Treatment of the neutralized cell free supernatants of the selected isolates with proteases eliminated or reduced the BLIS activity, suggesting a proteinaceous nature of the inhibitory compounds. Further, the optimum BLIS activity was observed at neutral pH after 18 h of incubation. The antibiotic sensitivity assay revealed that the isolates were susceptible to routinely used antibiotics, whereas the plasmid profiles showed that the plasmids had no role in the antagonistic properties of the four isolated strains. The results showed that the isolates could be a promising source for biocontrol agents in aquacultures.     

全谷物脱脂酸牛奶的理化性质及流变学特性研究

为了获得富含益生菌和益生元的健康酸牛奶产品,该文应用益生菌发酵剂XPL-1和068发酵添加了全谷物粉的脱脂牛奶,并研究其理化性质和流变学特性,同时分析保质期内酸牛奶中乳酸菌数的变化情况。结果表明,全谷物粉的添加可提高脱脂酸牛奶的持水力以及产品的柔软性、光滑细腻程度和流动性,总体可接受性明显提升;此外,在保质期内全谷物酸牛奶样品中的活菌数均稳定在108 CFU/g以上。研究结果为全谷物脱脂酸牛奶的开发应用奠定了理论基础。     

乳酸菌合成共轭亚油酸及其应用研究进展

共轭亚油酸(conjugated linoleic acid,CLA)是一种具有多种生理活性的功能性脂肪酸,在食品、保健品中具有广阔的应用前景。然而,天然来源的CLA含量很低,不能满足人类需求。乳酸菌可以合成CLA,且广泛用于食品加工领域,利用乳酸菌开发富含CLA的功能食品是当今的研究热点。为推动CLA功能食品的研究开发,该文对合成共轭亚油酸乳酸菌的研究进展、合成共轭亚油酸乳酸菌的益生性研究以及将产CLA乳酸菌应用到食品和饲料中的研究现状进行综述,并对利用乳酸菌合成CLA进而应用于功能食品进行展望。     

桑叶多酚、多糖及其复配物的体外模拟消化特性、降糖降脂和促益生菌增殖活性研究

目的 考察桑叶多酚(mulberry leaf polyphenol, MLPP)、桑叶多糖(mulberry leaf polysaccharide, MLPS)相互作用对其体外消化特性、降糖降脂和促益生菌增殖活性的影响。方法 以MLPP、MLPS和桑叶多酚多糖复配物(mulberry leaf polyphenol-polysaccharide complex, PPPS)为研究对象, 通过高效液相色谱法和傅里叶变换红外光谱法分析MLPP、MLPS和PPPS在模拟消化口腔、胃和肠阶段的变化, 采用微孔法分析三者糖消化酶和脂肪消化酶抑制活性, 采用稀释平板法考察三者促益生菌增殖作用。结果 MLPP在口腔、胃、肠阶段的消化率分别为5.26%、20.91%、59.48%；PPPS在口腔、胃、肠阶段的消化率增长为20.75%、39.01%、79.95%, 表明桑叶多酚多糖复配后可提高多酚的消化率。MLPS、PPPS在口腔、胃、肠阶段消化中均未检出游离单糖，表明多酚的加入对多糖的消化无影响。PPPS对淀粉的消化和α-淀粉酶均有良好的抑制作用, 且效果显著优于MLPP、MLPS (P<0.05); MLPP、PPPS对α-葡萄糖苷酶、麦芽糖酶、蔗糖酶和脂肪酶的抑制作用显著优于MLPS (P<0.05), 但MLPP、PPPS间无显著差异。MLPP、MLPS、PPPS在适当的浓度范围均对鼠李糖乳杆菌(ATCC53103)有促增殖作用, PPPS对肠膜明串珠菌(GIM1.774)的增殖率显著高于鼠李糖乳杆菌(ATCC53103)、植物乳杆菌(GIM1.191)、干酪乳杆菌(GIM1.411)、嗜酸乳杆菌(GIM1.321)。结论 MLPP和多糖复配后可提高多酚的消化率, 也表现出优于单一组分的降糖降脂活性和促益生菌增殖作用。