西藏牦牛发酵乳中乳酸菌及酵母菌的特性与相互作用

研究了西藏牦牛发酵乳中的优势菌株:发酵乳杆菌166A、乳酒假丝酵母37、酿酒酵母100、郎比克假丝酵母58在牛乳中的生长特性。探讨了发酵乳杆菌与酵母菌间的相互作用,在发酵过程中3株酵母菌均对发酵乳杆菌166A的生长有促进作用,发酵乳杆菌166A能抑制乳酒假丝酵母37的生长。酵母菌与发酵乳杆菌166A共同接种有利于保持产品冷藏期间活菌数的稳定,菌株之间可能存在共生作用。     

传统发酵牦牛酸乳中酵母菌的分子生物学鉴定

通过提取羊八井地区传统发酵牦牛酸乳中分离到的36 株酵母菌的基因组DNA,经聚合酶链式反应（polymerase chain reaction,PCR）扩增其26S rDNA并测定序列,将序列输入GenBank中通过基本局部序列检索工具（Basic Local Alignment Search Tool,BLAST）检索确定种属（同源性≥99%）。结果表明：传统发酵牦牛酸乳中酵母菌主要为马克斯克鲁维酵母17 株（47.2%）、酿酒酵母6 株（16.7%）、平常假丝酵母5 株（13.9%）、喜仙人掌毕赤酵母4 株（11.1%）、发酵毕赤酵母3 株（8.3%）,1 株鉴定失败。并构建系统发育进化树结合分子鉴定结果分析酵母菌的遗传多样性。     

川西北牧区传统发酵牦牛酸奶中发酵毕赤酵母菌的分离鉴定

对川西北部分牧区的10份传统发酵牦牛酸奶样品进行酵母菌的分离,通过常规形态特征和26S rRNA基因测序分析鉴定出6株发酵毕赤酵母菌(Pichia fermentans)。同源性分析显示6株分离菌与已知发酵毕赤酵母菌的同源性高达99.7%~100%。实验结果为该地区传统发酵牦牛酸奶中微生物组成多样性研究以及发酵毕赤酵母菌遗传多样性研究提供参考。     

传统发酵牦牛酸奶中马克斯克鲁维酵母菌的分离鉴定及系统发育分析

对川西北部分牧区的10 份传统发酵牦牛酸奶样品进行酵母菌的分离,通过常规形态特征和26S rRNA基因测序分析鉴定出16 株马克斯克鲁维酵母菌（Kluyveromyces marxianus）。同源性分析显示16 株分离菌与已知马克斯克鲁维酵母的同源性高达99.3%～100%。16 株分离菌中形成明显的两种序列类型,其中10 株分离菌与另外6 株分离菌相比在扩增片段的第537位点上发生碱基缺失、第554位点上碱基由G突变为A、第564位点上碱基由A突变为T。系统进化分析显示两种序列类型的分离株也形成两个独立进化分支。     

新疆酸驼乳中酵母菌的生理生化鉴定及初步应用

分别从新疆南山、水西沟采集的2份酸驼乳中,分离得到酵母菌30株。采用传统形态学、生理生化特性方法对酵母菌进行鉴定,鉴定结果为5株克勒克酵母属Kloeckera,为林德纳克勒克酵母Kloeckera lindner;4株假丝酵母属Candida,为乳酒假丝酵母Candida kefyr;7株克鲁维酵母属Kluyveromyces,为马克斯克鲁维酵母Kluyveromycesmarxianus;9株酵母属Saccharomyces,为酿酒酵母Saccharomyces cerevisiae;5株酒香酵母属（Brettanomyces）,为异酒香酵母Brettanomyces anomalus。自选分离于酸驼乳中酵母菌菌株S19,通过响应面分析法研究初始糖度、发酵温度、接种量对自选酵母菌菌株酿造哈密瓜果酒品质的影响,得出哈密瓜果酒品质与影响因素间的回归模型,根据模型进行工艺参数优化。结果表明,接种量对哈密瓜果酒品质影响显著。利用自选酵母菌酿造哈密瓜果酒的最佳工艺参数是：初始糖度为12.0%、发酵温度为25.0℃、接种量为1.5%。     

新疆传统发酵酸奶中酵母菌的分离鉴定及系统发育分析

从新疆塔城地区哈萨克族不同牧场家庭中自然发酵牛乳采集18份样品,从中分离筛选得到47株酵母菌,并进行形态鉴定、生理生化鉴定、聚合酶链式反应-变性梯度凝胶电泳（PCR-DGGE）,26S rDNA分子生物学鉴定,构建系统发育树。结果表明,47株菌中包括库德毕赤酵母（Pichia kudriavzevii）18株,阿萨希丝孢酵母菌（Trichosporon asahii）10株,酿酒酵母（Saccharomyces cerevisiae）7株,丝孢酵母（Trichosporon coremiiforme）4株,马克斯克鲁维酵母（Kluyveromyces marxianus）4株,东方伊萨酵母（Issatchenkia orientalis）2株,发酵毕赤酵母（Pichia fermentans）1株,近平滑假丝酵母（Candida parapsilosis）1株。鉴定结果对进一步认识并利用哈萨克族传统发酵酸奶中酵母菌资源具有重要意义。     

西藏灵菇来源酵母菌发酵面团菌株筛选与培养条件优化

从西藏灵菇中分离得到16株酵母菌,测定这16株酵母菌发酵面团的性能,结果表明,菌株Y15发酵力较好,即发酵力17.6mL/(g.h)。菌株Y15发酵的面包色泽呈金黄色,外形饱满,不塌陷,口感酥软,咀嚼时有弹性。对菌株Y15的发酵培养条件进行优化,其最佳发酵条件是:温度20℃,转速180r/min,培养时间16～18h;生理生化鉴定结果表明Y15与木篮假丝酵母相似度为80.2%。     

一株发酵木薯酒糟的热带假丝酵母菌株的分离及营养分析

采用富集培养方法分离到一株对木薯酒糟具有良好发酵性能的耐高温酵母菌株WHCZ.经形态、生理生化及分子分类鉴定为热带假丝酵母.氨基酸分析结果表明,该菌株的总氨基酸和必需氨基酸含量均高于产朊假丝酵母1807.对木薯酒糟的发酵试验结果表明,该菌株对木薯酒糟液的COD去除率比产朊假丝酵母更高;接种酵母菌株WHCZ后,经33℃摇床培养24h,木薯酒糟固形物的粗蛋白含量由原糟的12.48％升至19.6％,粗蛋白含量提高了57.77％.     

胀包酸奶有害酵母菌的分离鉴定

从吉林省收集到12份胀包酸奶样品中分离得到23株产气微生物。通过对分离菌株的表型、生理生化特征和26S rDNA序列进行分析,确定所有菌株都是酵母菌,其中东方伊萨酵母11株,马克思克鲁维酵母7株,阿萨希丝孢酵母3株,胶红酵母1株,季也蒙假丝酵母1株。本研究结果证实引起酸奶胀包的微生物菌群主要是酵母菌。     

ITS序列在酵母批量分子鉴定中的适用性

内部转录间隔区(internal transcribed spacer,ITS)序列是目前最常用的酵母分子鉴定标识之一。该文利用ITS序列同源性分析法对保藏于中国高校工业微生物资源与信息中心的623株酵母分离物进行了鉴定。实验结果显示:581株酵母分离物(93.3%)可通过ITS序列直接鉴定到种一级,40株分离物(6.4%)可鉴定至属一级,仅有2株酵母分离物无法通过ITS序列获得有效鉴定。上述结果表明,ITS序列在大多数酵母种属鉴定中具有很高的敏感性和特异性,可以作为第一分子标识用于大批量酵母分离物的分子鉴定。     

Growth characteristics of Candida kefyr and two strains of Lactococcus lactis subsp. lactis isolated from Zimbabwean naturally fermented milk.

Lactic acid bacteria (LAB) and yeasts constitute part of the microflora in Zimbabwean traditional fermented cows' milk, amasi. The present study was carried out to investigate the growth characteristics of Candida kefyr 23, Lactococcus lactis subsp. lactis biovar. diacetylactis C1 and L. lactis subsp. lactis Lc261, previously isolated from amasi, in ultrahigh temperature (UHT)-treated cows' milk. The strains were inoculated into the UHT milk as both single and yeast     

The role of interaction between yeasts and lactic acid bacteria in African fermented milks: a review

Yeasts are present in indigenous African fermented milks in numbers up to log 8 cfu g(-1), together with a varied lactic acid bacteria (LAB) flora, and therefore potentially contribute to product characteristics. However, interaction between yeasts and LAB in these products has received little notice. In studies of indigenous fermented milk in Zimbabwe and Uganda, many samples contained more than one species of yeast, but Saccharomyces cerevisiae was most commonly isolated. Other frequent isolates were other species of Saccharomyces and several species of Candida. Most yeast isolates were lactose-negative but usually galactose-positive. Some strains assimilated lactate and citrate. The growth in milk of strains of yeasts and LAB, isolated from naturally soured milk in Zimbabwe, and their interaction when selected pairs of strains were grown together has been studied. Interactions were shown by the significantly different amounts of certain metabolites produced, such as acetaldehyde and malty aldehydes, when co-cultures were compared to pure cultures. Preliminary sensory acceptance tests did not show, however, that milks made from a co-culture with Candida kefyr and LAB were preferable to the pure LAB culture. Further work is still needed to elucidate the reactions that may be taking place in fermented milk between varying LAB and yeast populations. The potential for use as starter cultures depends on various aspects, including the final product being prepared. The role of other microorganisms in naturally fermented milk also needs to be studied.     

The growth and interaction of yeasts and lactic acid bacteria isolated from Zimbabwean naturally fermented milk in UHT milk.

Nine yeast and four lactic acid bacterial strains, previously isolated from Zimbabwean traditionally fermented milk, were inoculated into ultra-high temperature treated (UHT) milk in both single and yeast-lactic acid bacteria co-culture. The lactic acid bacteria (LAB) strains consisted of Lactococcus lactis subsp. lactis biovar. diacetylactis C1, L. lactis subsp. lactis Lc39, L. lactis subsp. lactis Lc261 and Lactobacillus paracasei subsp. paracasei Lb11. The yeast strains used were Candida kefyr 23, C. lipolytica 57, C. lusitaniae 63, C. lusitaniae 68, C. tropicalis 78, Saccharomyces cerevisiae 71, S. dairenensis 32, C. colliculosa 41 and Dekkera bruxellensis 43. After 48-h fermentation at 25 degrees C, the samples were analysed for pH, viable yeast and bacterial counts, organic acids, volatile organic compounds (VOC) and carbon dioxide. The Lactococcus strains reduced the pH from about 6.6 to between 4.0 and 4.2, while Lb. paracasei subsp. paracasei Lb11 reduced the pH to about 5.4. Most of the yeasts, however, did not affect the final pH of the milk except for C. kefyr 23, which reduced the pH from 6.6 to 5.8. All the Lactococcus strains grew two log cycles during the 48-h fermentation period, while Lb. paracasei subsp. paracasei Lb11 grew about one log cycle. S. cerevisiae 71, C. colliculosa 41 and D. bruxellensis 43 showed poor growth in the milk in both single and co-culture. The other species of yeast grew about two log cycles. Candida colliculosa 41, S. dairenensis 32 and D. bruxellensis 43 showed reduced viability when in co-culture with Lb. paracasei subsp. paracasei Lb11. The samples in which C. kefyr 23 was used were distinct and characterised by large amounts of acetaldehyde, carbon dioxide and ethanol. However, in the samples where S. dairenensis, C. colliculosa, D. bruxellensis, C. lusitaniae, C. tropicalis, C. lipolytica and S. cerevisiae were used in co-culture, the final pH and metabolite content were mainly determined by the correspondin     

三种传统发酵食品中酵母菌的分离鉴定与特性分析

从红茶菌、藏灵菇及酸菜3种传统发酵食品中分离、鉴定酵母菌,并测定其产乙醇能力及生长性能。结果表明,从3种传统发酵食品中分离出9株酵母菌,包括3株马克斯克鲁维酵母（Kluyveromyces marxianus）、1株Starmerella davenportii、3株异常假丝酵母（Candida incommunis）及2株瑟氏哈萨克斯坦酵母（Kazachstania servazzii）。马克斯克鲁维酵母X1-1和X3-3可发酵葡萄糖、蔗糖和乳糖,其他酵母菌株只发酵葡萄糖。3株马克斯克鲁维酵母产乙醇力较弱,分别为29.8%vol、42.6%vol及29.6%vol,但生长速率快且活菌数高,其中菌株X1-2约6 h时进入对数期,约30 h时达到最大生物量（OD600 nm=6.152）,而其他3种酵母则生长缓慢。异常假丝酵母R5-2和瑟氏哈萨克斯坦酵母M2-2产乙醇能力较强,分别为75.8%vol和71.0%vol。     

山西老陈醋酿造过程中产酯酵母的筛选及产香特性分析

为选育山西老陈醋用微生物发酵剂,从传统发酵工艺的酒醅中分离筛选到3 株产酯酵母菌。结合形态学和酵母菌26S rDNA Dl/D2区序列分析,初步鉴定2 株菌为乙醇假丝酵母,1 株菌为毕赤酵母。将这3 株酵母应用于山西老陈醋生产,采用顶空固相微萃取和气相色谱-质谱联用技术分析醋中的酯类成分,并综合感官评价,结果表明,本研究筛选出的Pichia manshurica Y14与大曲混合发酵,酿制的山西老陈醋中的总酯含量比对照组提高40.5%,乙酸乙酯含量提高1.3 倍。添加Y14的成品醋中酯类物质更为丰富,香味更浓郁,有望将其开发成为山西老陈醋新型发酵剂。     

酵母菌与乳酸菌共培养发酵马铃薯渣的研究

选用4株酵母菌和2株乳酸菌固态发酵马铃薯渣,通过测定发酵产物粗蛋白和真蛋白含量变化情况,确定酵母菌与乳酸菌的共生关系,最终筛选生产SCP(单细胞蛋白)的适宜菌种组合。实验结果表明,适宜的菌株配伍为酿酒酵母+白地霉+热带假丝酵母+植物乳杆菌,经过发酵,马铃薯渣粗蛋白含量为35.63%,真蛋白含量为14.05%。     

乳扇中高产胞外多糖酵母菌的筛选及其抗氧化活性

为获得高产胞外多糖的酵母菌株,以云南地区发酵食品乳扇为原料,采用平板分离结合硫酸-苯酚测定法筛选目标酵母菌,并通过形态学、生理生化及分子生物学方法进行菌株鉴定,最终从乳扇中初步分离筛选出9 株产胞外多糖酵母菌,包括3 株胶红酵母（Rhodotorula mucilaginosa）、1 株白假丝酵母（Candida albicans）、4 株涎沫假丝酵母（Candida zeylanoides）及1 株金黄蝶形担孢酵母（Papiliotrema aurea）。其中筛选得到的金黄蝶形担孢酵母DF-12能较好利用葡萄糖、蔗糖及糖蜜等碳源高效合成胞外多糖,在发酵168 h后胞外多糖产量可达3 510 mg/L,具有较好的工业生产潜力。体外抗氧化能力实验表明DF-12菌株所产胞外多糖有一定清除1,1-二苯基-2-三硝基苯肼自由基和超氧阴离子自由基的能力。本研究为酵母菌胞外多糖在食品、药品领域的应用研究提供了一定的基础。