德宏水牛乳饼中乳酸菌的分离鉴定及发酵性能研究

德宏水牛奶乳饼是云南特有的乳制品,微生物资源丰富,是乳酸菌的重要来源,也是分离筛选优良发酵剂的天然基础。本文采用16S rRNA基因序列分析法和纯培养法对15份水牛奶乳饼中乳酸菌种属进行分离鉴定,通过对菌株产酸、产香、发酵乳活菌计数等比较,以筛选出具有优良发酵特性的乳酸菌。结果表明:15份水牛奶乳饼样品中共分离鉴定出57株乳酸菌(3个属,6个种和1个亚种),其中Lactobacillus fermentum和Lactobacillus oris为优势菌属,占总菌属的36.84%和24.56%。57株乳酸菌发酵特性比较后得到两株优势菌株MGR3-1和MBR1-1。此研究为后续开发和应用优良发酵剂提供理论基础。     

水牛乳中可培养乳酸菌多样性分析

采用传统分离培养方法,从三品杂交生水牛奶混合样品中,分离出105株乳酸菌,通过形态、生理生化、API细菌鉴定系统及16S rDNA基因序列分析方法对各菌株属种进行鉴定。16S rRNA序列分析结果显示,105株菌共分为5个属8个种,呈现较为丰富的乳酸菌多样性,具体数量分布为乳酸乳球菌21株,植物乳杆菌19株,格氏乳球菌17株,乳明串珠菌13株,食窦魏斯氏菌11株,肠膜明串珠菌8株,类肠膜魏斯氏菌6株,嗜热链球菌5株,糊精乳杆菌5株。由此可知,水牛乳中可培养乳酸菌优势菌群的主次关系为：乳酸乳球菌（Lactococcus lactis）＞植物乳杆菌（Lactobacillus plantaru）＞格氏乳球菌（Lactococcus garvieae）＞乳明串珠菌（Leuconostoc lactis）＞食窦魏斯氏菌（Weissella cibaria）,此为后续开发水牛乳中优势乳酸菌资源提供了良好的理论基础。     

新疆乳品中乳酸菌的多样性及耐药性分析

从新疆北部地区采集的样品中分离出103株乳酸菌并进行生理生化表型鉴定,对这些乳酸菌进行16S rRNA基因序列测序,构建系统发育树发现分离的乳酸菌主要为5个属分别为乳杆菌属、肠球菌属、乳球菌属、魏斯式菌属、明串珠菌属。采用纸片扩散法（K-B）研究不同属中不同乳酸菌对8种常见抗生素的耐药性分析。耐药性研究表明,分别有6株对链霉素、新霉素有耐药性,5株对红霉素有耐药性,7株对卡那霉素有耐药性,8株全部对萘啶酸具有耐药性,4株对万古霉素、四环素具有耐药性,2株对头孢唑肟存在耐药性。     

新疆不同地域发酵乳品中Lactobacillus多样性的研究

利用MRS,M17等5种不同培养基从12份采自新疆北部伊犁、博乐、塔城、阿勒泰地区牧民家庭传统方法制作的乳品中分离乳酸菌,并进行了生理生化表型特征鉴定。对这些乳酸菌进行16Sr RNA基因序列的测序,构建系统发育树,初步建立其属水平的进化地位,再利用乳杆菌种间特异性引物对其进行种水平的鉴定和分类。共分离164株疑似乳酸菌,大部分菌株对温度适应性较强。以杆菌为主,系统发育表明:样品中乳酸菌主要有7个属,其中Lactobacillus(78株)、Carrobacterium(3株)、Weissella(1株)、Lactococcus(22株)、Enterococcus(47株)、Streptococcus(8株)、Vagococcus(5株)。种特性扩增显示乳杆菌存在种水平的差异。主要有4个种。利用牛津杯从样品中筛选出了10株对大肠杆菌(Escherichia coli)、枯草芽孢杆菌(Bacillus subtilis)、李斯特氏菌(Listeria monocytogenes)金黄色葡萄球菌(Staphylococcus aureus)均具有明显抑制作用的乳杆菌,为乳酸菌作为生物型防腐剂应用到食品工业中奠定基础。     

南疆传统发酵酸奶中可产生生物膜乳酸菌的筛选及鉴定

为了探索新疆长寿地区传统发酵酸奶中优势乳酸菌的生物膜形成能力,采用纯培养法、96孔微量板定量检测法、扫描电子显微镜观察法及16S rRNA基因序列分析法,对3份阿图什和1份乌什传统发酵酸奶中可产生生物膜的乳酸菌进行了筛选、分子鉴定及生物膜结构图片观察。最终从4份样品中分离出57株乳酸菌,其中38株(73.68%)乳酸菌均有不同程度的生物膜形成能力,16株(28.07%)乳酸菌为强黏附成生物膜菌株、22株(38.59%)为中等黏附成生物膜菌株。分子鉴定实验结果显示,可形成生物膜的乳酸菌共有3个属、6个种,其中16株为Enterococcus durans、1株为Enterococcus faecium、7株为Enterococcus thailandicus、3株为Enterococcus lactis、6株为Lactobacillus plantarum、5株为Streptococcus thermophilus。可产生生物膜乳酸菌中肠球菌(Enterococcus)为优势菌属,其次为乳杆菌属(Lactobacillus)和链球菌属(Streptococcus)。     

1株产细菌素植物乳杆菌的筛选及其细菌素抑菌性质研究

从广西巴马地区取样的米粉中共分离出31株乳酸菌,以单核细胞增生李斯特菌为指示菌,采用牛津杯平板扩散法检测抑菌物质,筛选得到1株产细菌素的乳酸菌M23。通过微生物形态学与16S rRNA基因序列分析,鉴定该菌株为植物乳杆菌。植物乳杆菌M23代谢产生的乳酸菌细菌素在p H 2.0~10.0范围内具有良好的抑菌活性,121℃处理15 min的条件下依然具有抑菌活性,表明其具有良好的酸碱稳定性和热稳定性。发酵试验表明,该乳酸菌素的最佳收获时间为乳酸菌培养14 h。抑菌谱试验表明,该乳酸菌素能够有效抑制部分食源性革兰氏阳性、阴性致病菌。     

黄粉虫内生菌的分离鉴定及其对淀粉、纤维素和木质素的降解活性的测定

目的 分离培养黄粉虫体内细菌, 并测定这些菌对淀粉、纤维素及木质素的降解活性。方法 对黄粉虫表面消毒, 以LB和高氏一号培养基分离虫体内部细菌并进行16S rRNA基因序列分析。变色圈法测定降解活性。结果 共分离到8株细菌, 16S rRNA基因序列分析表明, 1株属于肠球菌属, 3株属于乳酸球菌属, 2株属于芽胞杆菌属, 另2株属肠杆菌属。水解酶测定结果表明, 菌株FJAT-18107具有淀粉和木质素水解作用, 其16S rRNA基因序列与解淀粉芽胞杆菌Bacillus amyloliquefaciens (NR_075005)最相似。结论 本研究为了解昆虫内生菌功能提供了参考。     

埃塞俄比亚发酵食品中乳酸菌的分离鉴定

采用传统纯培养方法对采集自非洲埃塞俄比亚地区的蜂蜜酒,咖啡,面引子等4份发酵食品中的乳酸菌进行分离纯化,运用16S rDNA序列分析和系统发育进化关系研究方法进行种属鉴定。结果表明,经16S rRNA基因序列分析,共分离到55株乳酸菌,分属于3个属,11个种或亚种,包括乳杆菌属(Lactobacillus)51株,肠球菌属(Enterococcus)3株,链球菌属(Streptococcus)1株,其中Lactobacillus paracasei为埃塞俄比亚地区蜂蜜酒中的优势菌株,占该样品总分离株的75%,Lactobacillus pontis为该地区面引子中的优势菌种,占该样品总分离株的41%。     

哈萨克斯坦传统发酵乳制品中乳酸菌的多样性

为了阐明哈萨克斯坦传统发酵乳制品中乳酸菌生物多样性,采用传统纯培养方法对采集的5份传统发酵乳制品中的乳酸菌进行分离纯化,运用16S rRNA基因序列分析方法和系统发育树研究进行属种鉴定。结果表明,从5份传统乳制品中分离鉴定了49株乳酸菌分属于4个属8个种或亚种,乳杆菌属(Lactobacillus)44株,片球菌属(Pediococcus)1株、肠球菌属(Enterococcus)3株,链球菌属(Streptococcus)1株。其中乳杆菌属、片球菌属、肠球菌属、链球菌属是哈萨克斯坦地区传统发酵乳制品中的主要乳酸菌,其中Pediococcus pentosaceus为优势菌种,占总分离株的22%。     

南海海域动物肠道中抗菌活性乳酸菌的分离及多样性分析

以湛江南海海域常见的10种海洋动物为研究对象,采用倾注平板法分离肠道乳酸菌,以单核细胞增生李斯特氏菌(Listeria monocytogenes)等5株有害菌为指示菌,采用双层牛津杯扩散法测定其抗菌活性,通过建立16S r RNA基因序列的系统发育树对具有抗菌活性的乳酸菌进行多样性分析。结果表明:根据形态观察和部分生理生化实验去重复后,共分离出43株有溶钙圈、革兰氏染色呈阳性、过氧化氢酶反应为阴性的乳酸菌,并且均不同程度地具有抗菌活性。对其中的13株抗菌能力强、抗菌谱广的乳酸菌进行16S r RNA分子生物学鉴定与分析,发现它们分属于厚壁菌门(Firmicutes)的4个科6个属,且除菌株LY-87与模式菌株Lactococcus lactis subsp.lactis的16S r RNA基因序列相似性为100%外,其他菌株与其系统发育关系最密切的典型菌株之间都存在着一定的遗传差异(相似性为95.7%~99.9%),其中菌株PQ-26与模式菌株Pediococcus pentosaceus的相似性仅为95.7%,可能是Pediococcus属中潜在的新种。研究表明湛江南海海域动物肠道中存在较为丰富的抗菌活性乳酸菌,并可能蕴藏着乳酸菌新种,其抗菌物质资源有待进一步研究与开发。     

竞争中寻求差异差异中寻求认同如何提升珠宝首饰品牌竞争力

伴随着珠宝首饰业的迅猛发展，行业竞争不断激烈，首饰业中的批发，加盟连锁，加工等业务均不同程度地在发生转变，企业中传统的“商标”意识逐渐向“品牌”意识转型已成为市场发展的规律。     

Bifidobacterium species isolated from animal feces and from beef and pork meat

Bifidobacteria were isolated from 122 of 145 samples of animal feces (from cattle, swine, sheep, goats, horses, rabbits, chickens, geese, and pigeons) from farms in France and Austria and from 92 of 955 production and processing chain samples of beef and pork (obtained at slaughter, cutting, and retail). Bacterial strains were identified to species by phenotypic numerical classification based on API 50CH and ID 32A tests and DNA-DNA hybridization. Bifidobacterium pseudolongum was present in 81% (99 of 122 samples) of all Bifidobacterium-positive fecal samples and predominated in samples from all animal species except those from swine from Austria. In these Austrian swine samples, the majority of strains were identified as Bifidobacterium thermophilum (78%), followed by B. pseudolongum (48%). The distribution of B. thermophilum and B. pseudolongum differed significantly between Austrian swine and cattle samples such as those collected along beef and pork production and processing chains. Bifidobacterium animalis was isolated from swine feces, and Bifidobacterium ruminantium was isolated from cow dung. Six fecal isolates (from cattle, swine, rabbits, goats, and horses) were identified as belonging to Bifidobacterium species of predominantly human origin: B. adolescentis, B. bifidum, and B. catenulatum. Only one other species, Bifidobacterium choerinum, was detected with low frequency in a pork processing chain. B. pseudolongum subsp. pseudolongum was predominant in pig feces, whereas B. pseudolongum subsp. globosum was predominant in feces from other animal species. Four strains closely related to both subspecies (58 to 61% DNA reassociation) formed a distinct genomic group. PCR techniques, which are more rapid and sensitive than culture-based methods, could be used to detect directly B. pseudolongum and B. thermophilum as indicators of fecal contamination along the meat processing chain.     

Purification and characterization of X-prolyl-dipeptidyl-aminopeptidase from Lactobacillus lactis and from Streptococcus thermophilus

X-Prolyl-dipeptidyl-aminopeptidase recently was found in several lactic acid bacteria. This article describes the purification of the enzymes from Lactobacillus lactis and Streptococcus thermophilus and compares their characteristics. Enzymes from both strains are serine-peptidases. They both have a molecular weight of about 165,000 daltons, an isoelectric point near 4.5, and are constituted of two subunits. The pH optimum of the enzyme isolated from L. lactis is 7.0, whereas the enzyme from S. thermophilus possesses a broad pH optimum between 6.5 and 8.2 with glycyl-L-prolyl-aminomethylcoumarin as substrate. Below pH 5, both enzymes are unstable; however, that from S. thermophilus is more rapidly denatured. The enzyme from S. thermophilus is more sensitive to heat than the corresponding enzyme from L. lactis. Enzymes from the both strains have different specificities towards various substrates and are differently effected by metals, chelators, and other inhibitors. The importance of this enzyme for the metabolism of lactic acid bacteria is discussed.     

Malnutrition and dietary protein: evidence from China and from international comparisons

Malnutrition, as measured by anthropometric status, is a powerful risk factor for illness and elevated death rates throughout life. Understanding the relative importance of disease, dietary quantity, and dietary quality in causing malnutrition is therefore of major importance in the design of public policy. This paper contributes to the understanding of the relative importance of quantity and quality of diet by utilizing aggregate data to complement previously reported individual-level studies. Three compilations of anthropometric data--one involving subjects from 13 provinces in China, another involving subjects from 64 counties in China, and a third involving 41 populations in 40 countries--are used to examine the relative importance for human growth of inadequacies of dietary energy and protein. The analysis involves regressing average adult heights and weights against estimates of average energy and protein availability (by province, county, or country) and per capita incomes. We use protein availability in part as a marker for overall quality of the diet, while recognizing that protein is far from perfectly correlated with dietary fat or micronutrient availability. The paper discusses issues of both data quality and statistical methodology, and points to relevant resulting caveats to our conclusions. Subject to these limitations, all three analyses suggest that, at the levels of dietary intake in these populations, lower protein intake is related to growth failure whereas lower levels of energy availability are not. The protein effect appears stronger for males than for females.     

Isolation and Properties of Starch from Wild Yam from Zimbabwe

Wild Yam (Dioscorea dumetorum) was collected during the wet as well as dry season in the bush of Zimbabwe. Starch from its tubers was isolated in behavioral conditions and properties were determined such as size of granules, content of water, amylose, phosphorus, proteins and lipids, characteristics of gelation of its gels and thermal properties (TG, DTG, DTA).     

Prevalence and antibiotic-resistance of Salmonella isolated from beef sampled from the slaughterhouse and from retailers in Dakar (Senegal)

A study was made of Salmonella contamination in beef sampled from a slaughterhouse and from retailers in Dakar, Senegal. The serotypes as well as antibiotic-resistance patterns of the Salmonella isolates were determined. A total of 435 meat samples (236 from the slaughterhouse, 199 from retailers) were tested. Among them, 275 (63%) were positive for Salmonella, 43% (101/236) from the slaughterhouse and 87% (174/199) from the retailers. Furthermore, 97% of the investigated retailers had at least one beef sample contaminated by Salmonella. The 286 Salmonella isolates were divided into 51 serotypes. The most prevalent serotypes were Salmonella bredeney (25%), S. muenster (8%), S. waycross (7%), S. corvallis (4%) and S. kentucky (4%). About 62% of the isolates were resistant to nitrofurans. Resistance rates were lower to streptomycin (22%), sulfamethoxazole (15%), spectinomycin (1%), chloramphenicol (1%), and tetracycline (0,4%) while low-level resistance to quinolones was detected. About 16% of the Salmonella strains were multiresistant to two or more antibiotic families. Finally, ten resistance profiles have been identified. This study shows the huge spread of Salmonella in the beef production chain in Dakar, Senegal. Finally, this study provides the very first data about Salmonella prevalence in sub-saharian Africa.     

由杏仁壳及其他农产品废弃物制备生物纺织纤维

绿色产品是否存在其他价值?能否将废弃物转化为具有额外价值的原材料?来自大学实验室和工业公司的研究者们正尝试采用木屑、杏仁壳或其他农产品废弃物作为原料制备纺织品。Ecolastane项目主要致力于研究可再生产业用纺织纤维的生产。     

从信用和规则做起

何谓信用，辞海解释为：信用就是诚实、不欺、遵守诺言。信用就是一种信守承诺的责任感，是对自己行为后果负责的道德感，说白了就是不蒙人，守规矩，说话算数，表里如一。信用作为一种文化传统和理念，是人类不断发展而修炼出来的一种美德，也是一种待人处事的经验积累。因为不管你身在何方，不管你处在什么年代，只有讲信用、守规矩，你才能得到别人的接纳和尊重，才能很容易与别人交流，也才能找到忠诚的朋友，更重要的是你可以通过诚信和努力到达理想的彼岸。俗话说，没有规矩，就不能成方圆。做任何事情包括做游戏都要有规则。守纪律，…     

Antiradical and functional properties of subcritical water extracts from edible mushrooms and from commercial counterparts

This study deals with the antioxidant and functional potential of subcritical water extracts from edible mushrooms, in comparison to commercial products. Pleurotus citrinopileatus extracts showed the highest phenolic content and antioxidant properties. Similar results were determined in commercial extracts of Coriolus versicolor. The highest growth inhibition in selected human carcinogenic cells was identified for the P. citrinopileatus extract obtained during heating up to 160 °C. Rheological studies confirmed that glucan-based hydrogels prepared with mushroom extracts exhibited enhanced viscoelastic properties compared to those formulated with commercial products. The extracts providing the strongest gels were obtained from Pleurotus eryngii, followed by Hericium erinaceus and Pleurotus citrinopileatus. No water syneresis for the proposed hydrogels was observed. The formulated hydrogels could be interesting for their application in the food sector.     

Purification and comparison of triosephosphate isomerases from ammonia-oxidizing bacteria isolated from terrestrial and marine environments

Triosephosphate isomerases [TIMs, EC 5.3.1.1] were purified from two ammonia-oxidizing bacteria: Nitrosomonas sp. K1 (K1), Nitrosomonas sp. TNO632 (TNO). The molecular masses of the native enzymes were estimated to be about 53.6 (K1-TIM) and 51.9 kDa (TNO-TIM) by gel filtration, whereas SDS-PAGE produced one band for each enzyme with M(r) values of 27.1 (K1-TIM) and 26.4 kDa (TNO-TIM), respectively, suggesting that the enzymes consist of identical subunits. The apparent K(m) for d-glyceraldehyde-3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP) were about 1.19 and 4.78 mM (K1-TIM), and 0.41 and 6.01 mM (TNO-TIM), respectively. The two TIMs had different pH-activity curves with an optimum pH range of 6.5 (K1-TIM) and 8.0 (TNO-TIM). The temperature optima of K1-TIM and TNO-TIM were 50-60 and 60-65 degrees C, respectively. Both enzymes were strongly inhibited by 5,5'-ditiobis at 1.0 mM. The N-terminal amino acid sequences of K1-TIM and TNO-TIM were MRAGFVAGNWKMHG (K1-TIM) and MVRTGLVAGNWKMNG (TNO-TIM). A homology of 74.1% was observed between K1-TIM and TNO-TIM.