响应面法优化拟威尔嗜杀酵母Cyberlindnera mrakii WM1代谢产嗜杀因子的发酵条件

以保藏于本实验室的海洋酵母菌种资源库的酵母菌株Cyberlindnera mrakii WM1为研究对象,以人类条件致病菌白色假丝酵母Canidia albicans YTS-03为嗜杀毒素抑菌活性测试指示菌,以抑菌圈直径为考察指标,对拟威尔嗜杀酵母WM1代谢产嗜杀因子的发酵条件进行优化。首先以接种量、发酵液p H、发酵温度和时间为自变量,确定其四个因素对嗜杀活性的抑菌效果影响显著,再对这四个因素进行响应面实验优化。获得WM1生长代谢产嗜杀因子的最佳发酵条件为:接种量8%,发酵液p H4.0,发酵温度21℃,发酵时间2.5 d。优化后的WM1酵母发酵液的抑菌圈的直径达到21.00 mm,比优化前(16.5 mm)提高27.3%;菌液浓度也达2.58×10~8CFU/m L,比优化前(1.9×10~8CFU/m L)提高了35.8%。同时,最优发酵条件下获得的实验结果与模型预测值相吻合,说明建立的回归模型是切实可行的。     

野生嗜杀白假丝酵母LFA418的产毒条件优化及其毒素粗提物特性

对1株分离自新疆楼兰葡萄酒厂野生白假丝酵母(Candida albicans)LFA418的嗜杀特征及其粗毒素特性进行研究。结果显示,C.albicans LFA418具有致死克鲁维毕赤酵母(Pichia kluyveri)、贝酵母(Saccharomyces bayanus)、Lachancea thermotolerans和葡萄牙假丝酵母(Candida lusitaniae)的嗜杀性。接种体积分数7%C.albicans LFA418到YEPD液体培养基中,25℃培养32 h,可以获得最大产量的嗜杀毒素;利用截留分子质量为8 000 D的透析袋制备的粗毒素,在温度分别-20、4℃时pH 4.2~4.6和pH 4.2时温度4~20℃具有嗜杀活性的稳定性。     

野生嗜杀酿酒酵母的分离筛选

研究从水果中分离酵母菌约70株,经过筛选获得了5株嗜杀酵母,建立了切实有效的嗜杀酵母的筛选技术路线和方法.通过形态学特征观察、糖发酵、嗜杀酵母显微鉴定等实验,鉴定这5株嗜杀酵母均为酿酒酵母(Saccharomyces cerevisiae).通过发酵实验,筛选到1株适宜啤酒发酵、性能良好的嗜杀酵母菌株.     

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。     

接种不同嗜杀特性的酿酒酵母对赤霞珠发酵中酵母多样性的影响

以赤霞珠葡萄为原料,分别接种不同嗜杀特性的酿酒酵母(Saccharomyces cerevisiae)菌株NXU17-26(中性)、UCD522(敏感菌株)和UCD2610(嗜杀菌株),并以自然发酵为对照,研究各菌株对赤霞珠葡萄酒的发酵特征及发酵中酵母菌多样性的影响。结果表明,接种发酵在启酵和发酵速度上显著快于自然发酵。WLN培养基将分离到的480株酵母菌鉴定为7种类型,26S rDNA D1/D2序列分析进一步将其鉴定为4属5种:葡萄汁有孢汉逊酵母(Hanseniaspora uvarum)、克鲁维毕赤酵母(Pichia kluyveri)、伯顿丝孢毕赤酵母(Hyphopichia burtonii)、S.cerevisiae、库徳毕赤酵母(Pichia kudriavzevii)。这4属5种的酵母均存在于自然发酵中,而接种发酵中仅有H.uvarum和S.cerevisiae两种酵母,接种发酵中酵母菌多样性较低。Interdelta指纹图谱分析表明,所接种的酿酒酵母菌株是相应发酵中的优势菌株:接种中性酵母NXU17-26的发酵中,NXU17-26的基因型占比为63.46%;接种敏感菌株UCD522中,UCD522的基因型占比为44.68%,野生酿酒酵母NXU18-15表现出较强的竞争力,基因型占比为34.04%;接种嗜杀酵母UCD2610的发酵中,UCD2610的基因型占比为62.74%。非加权算术平均数法聚类分析表明,分离自同一发酵中的不同酿酒酵母菌株间的遗传差异性较小;分离自不同发酵中的酿酒酵母菌株间遗传差异性较大。     

天山冻土中嗜冷酵母菌生物多样性

采用麦芽浸膏富集平板涂布天山冻土中可培养酵母菌,通过麦芽浸膏分离培养基筛选菌株.采用酵母菌常规生理生化实验、最适生长温度、最适pH对分离菌株的生理学进行研究.以NL1和NL4为PCR扩增引物,通过26S rRNA基因D1/D2区序列同源性分析,初步确定酵母菌株的系统进化地位.分离筛选到4株嗜低温酵母菌,分属于隐球酵母(Cystofilobasidium infirmominiatum)、掷孢酵母(Sporobolomyces patagonicus)、棒孢酵母(Clavispora lusitaniae)和毕赤酵母(Pichia kluyveri).     

多粮浓香型白酒生产过程中可培养酵母菌多样性分析与优质功能菌筛选

分析多粮浓香型白酒生产过程中可培养酵母菌多样性,基于ITS rDNA序列构建其系统发育树对其进行鉴定,筛选优质酿酒功能酵母菌,并考察其发酵特性。结果表明,共分离出43株酵母菌,分为12种形态类型,编号为WY1～WY12,其中,菌株WY2、WY6、WY9为库德里阿兹威（氏）毕赤酵母（Pichia kudriavzevii）;菌株WY1、WY3为酿酒酵母（Saccharomyces cerevisiae）;菌株WY4为海洋嗜杀酵母（Wickerhamomyces anomalus）;菌株WY5为扣囊复膜酵母菌（Saccharomycopsis fibuligera）;菌株WY7为拜氏接合酵母（Zygosaccharomyces bailii）;菌株WY8为葡萄牙棒孢酵母（Clavispora lusitaniae）;菌株WY10为季也蒙毕赤酵母（Galactomyces geotrichum）;菌株WY11、WY12为罗伦隐球酵母（Cryptococcus laurentii）。功能酵母菌筛选结果表明,扣囊复膜酵母菌（S. fibuligera）WY5-1和酿酒酵母（S. cerevisiae）WY3-2具有良好的产乙醇特性;库德里阿兹威氏毕赤酵母（Pichia kudriavzevii）WY6-3和WY9-2具有良好的产酯特性、温度和pH耐受性,为浓香型白酒的工业生产中菌株的选择提供了更多可能。     

甘蔗内生酵母菌的分离鉴定及发酵性能

为研究甘蔗内生酵母菌的种类并筛选出发酵性能良好的酵母菌株,该文采用组织分离法对甘蔗中的内生酵母菌进行分离,通过形态学、生理生化以及26S rDNA D1/D2区序列分析法进行鉴定。利用杜氏管发酵法初筛产气性能较好的菌株,确定筛选菌株的最适生长条件,然后采用摇瓶发酵法对其进行耐糖、耐盐以及耐酒精等耐受性试验,复筛出发酵性能优良的菌株。结果表明,从甘蔗中共分离得到内生酵母菌63株,鉴定为8种：葡萄有孢汉逊酵母(Hanseniaspora uvarum)、季也蒙毕赤酵母(Meyerozyma guiliermondii)、汉逊德巴利酵母(Debaryomyces hansenii)、嗜油假丝酵母(Candida oleophila)、类筒假丝酵母(Candida zeylanoides)、异常威克汉姆酵母(Wickerhamomyces anomalus)、Cystobasidium minutum以及Papiliotrema terrestris。从63株酵母菌中,筛选一株生长性能和发酵性能优良的菌株J-6,在温度26℃、pH5.0的条件下,24 h时生长速率达到最大值,其最大值为1.99...     

嗜杀酵母的生物学特性及应用展望

嗜杀酵母能够分泌嗜杀毒素杀死特定的微生物。将嗜杀酵母作为工业生产用菌株,可以有效防止生产过程中的杂菌污染,净化发酵体系,保证发酵的正常进行;嗜杀毒素还可以制备成为抗真菌剂,用以抵制病原酵母及类酵母等微生物的侵染。综合论述了嗜杀酵母的分类学地位及生物学特性,嗜杀毒素产生和作用的机理,并阐述了环境因素对嗜杀酵母菌自身及其分泌嗜杀毒素的影响。     

硒浓度梯度驯化结合紫外诱变法选育富硒酵母菌研究

为获得高产富硒酵母,通过硒浓度梯度驯化啤酒酵母Sac.cerevisiae Fec205、戴氏酵母Sac.delbrueckii Fec209、热带假丝酵母Candida tropicalis Fec2011等3株酵母菌,结果显示啤酒酵母Sac.cerevisiae Fec205比其他2株酵母的耐硒性能更强。因此以啤酒酵母Sac.cerevisiae Fec205为原始菌株进行紫外诱变以提高其富硒能力。通过硒抗性筛选,挑取出6株生长快、菌落大的突变菌株单菌落。取发酵培养基中生物量大的3株酵母菌Sac.cerevisiae Y-3,Y-4,Y-1,接种于硒浓度为40μg/ml发酵培养基,结果显示选育出的3株诱变后的啤酒酵母Sac.cerevisiae Y-3,Y-4,Y-1的硒含量分别为932、832、915μg/g,其中最高的Y-3比原始菌株啤酒酵母Sac.cerevisiae Fec205的硒含量增长50.08%、生物量提高了50.97%。     

Determination of killer activity in yeasts isolated from the elaboration of seasoned green table olives

In this work 51 yeasts strains isolated from seasoned green table olives and belonging to the Candida, Debaryomyces, Kluyveromyces, Pichia, and Saccharomyces genera were characterized by their killer activity in different conditions. Killer activity of isolates was analyzed in a medium with different pH's (3.5 to 8.5) and NaCl concentrations (5, 8, and 10%). At every pH tested, all the genera studied had killer strains, although the smallest percentages of killer yeasts were found at the highest pH (8.5). The presence of 5 and 8% NaCl increased the detected killer percentage, but the highest salt concentration (10%) decreased it. The interaction between the reference killer yeasts and yeasts isolated from olives was analyzed. Most isolates were killer-sensitive to one or more killer reference strains. Only 2 of the 51 strains tested were considered killer-neutral. Cross-reaction trials between isolates and spoilage yeasts showed that, of the isolates, nine killer strains, belonging to Debaryomyces hansenii, Kluyveromyces marxianus, Pichia anomala, Pichia guilliermondii, and Saccharomyces cerevisiae, had the broadest spectra of action against yeasts that cause spoilage. These killer yeasts and the toxins that they produce are candidates for further investigation as suppressors of indigenous olive table yeast growth. The results confirmed the highly polymorphic expression of the killing activity, with each strain showing different killer activities. This method may thus be very useful for simple and rapid characterization of yeast strains of industrial interest.     

Rapid differentiation of Candida albicans from other Candida species using its unique germ tube formation at 39 degrees C

In this study, we found that no Candida species other than C. albicans is able to form germ tubes at 39 degrees C in serum-free YEPD (1% (w/v) yeast extract, 2% (w/v) peptone and 2% (w/v) dextrose) media, which makes it easy to identify C. albicans from other Candida species. When cultivated in rabbit serum for at least 2 h at 37 degrees C, more than 60% of C. albicans cells generated germ tubes. In YEPD, however, germ tubes began to appear from C. albicans cells within 30 min at 39 degrees C, and more than 60% of C. albicans cells formed the germ tubes after 1 h at 39 degrees C. Standard Candida strains (ATCC, CBS), three C. albicans and two C. dubliniensis strains were cultured in serum at 37 degrees C for 2 h and in YEPD at 39 degrees C for 1 h. All of the three C. albicans formed germ tubes at 39 degrees C. The two C. dubliniensis strains formed germ tubes in serum at 37 degrees C, but grew as a yeast form in YEPD at 39 degrees C. All of the clinically isolated C. albicans strains in our laboratory formed germ tubes in YEPD at 39 degrees C for 1 h, and none of the clinically isolated Candida species other than C. albicans generated germ tubes in YEPD at 39 degrees C. Thus, the unique germ tube formation of C. albicans induced by high temperature (39 degrees C) in YEPD could be applied to a protocol for the rapid and convenient identification of C. albicans in clinical laboratories.     

Molecular Identification of Yeasts Associated with Traditional Egyptian Dairy Products

ABSTRACT:  This study aimed to examine the diversity and ecology of yeasts associated with traditional Egyptian dairy products employing molecular techniques in yeast identification. A total of 120 samples of fresh and stored Domiati cheese, kariesh cheese, and "Matared" cream were collected from local markets and examined. Forty yeast isolates were cultured from these samples and identified using the restriction-fragment length polymorphism (RFLPs) of 5.8S-ITS rDNA region and sequencing of the domains D1 and D2 of the 26S rRNA gene. Yeasts were identified as  Issatchenkia orientalis  (13 isolates),  Candida albicans  (4 isolates),  Clavispora lusitaniae  ( Candida lusitaniae ) (9 isolates),  Kodamaea ohmeri  ( Pichia ohmeri ) (1 isolate),  Kluyveromyces marxianus  (6 isolates), and  Candida catenulata  (7 isolates). With the exception of  C. lusitaniae , the D1/D2 26S rRNA gene sequences were 100% identical for the yeast isolates within the same species. Phylogenetic reconstruction of  C. lusitaniae  isolates grouped them into 3 distinguished clusters. Kariesh cheese was found to be the most diverse in its yeast floras and contained the highest total yeast count compared with other examined dairy products. This was linked to the acidic pH and lower salt content of this cheese, which favor the growth and survival of yeasts in foodstuffs. Stored Domiati cheese also contained diverse yeast species involving isolates of the pathogenic yeast  C. albicans . This raises the possibility of dairy products being vehicles of transmission of pathogenic yeasts.     

传统自然发酵黏豆包关键酵母的筛选鉴定

目的 筛选适宜谷物黏豆包发酵的酵母菌菌株。方法 以采集自黑龙江省不同地区的传统自然发酵黏豆包谷物发酵液为研究对象,通过高通量测序技术,分析发酵液中微生物多样性,再利用传统培养法对发酵液中的酵母菌进行分离,筛选出耐低温、耐低pH、起酵时间快和酵香风味好的酵母菌株。结果 通过高通量测序结果显示,在真菌菌属水平上, 3个地区样品共包含5个门、30个属、30个种,微生物群落为酿酒酵母属(Saccharomyces)、威克汉姆酵母属(Wickerhamomyces)、毕赤酵母属(Pichia)等,其中酿酒酵母属为首要优势菌属,次级优势菌皆为威克汉姆酵母属。在此基础上,利用平板划线分离出21株酵母菌,通过分子生物学鉴定, TY5、TY9和AC6为酿酒酵母, TY8和SC4为威克汉姆酵母, AC3为热带假丝酵母, SC3为季也蒙毕赤酵母,SC5为胶红酵母;TY5、TY8、TY9、AC6、SC6在pH为3、15℃条件下具有较好的生长性能,其中菌株TY9和AC6具有较强的耐酸性及耐低温性,且起酵时间快,菌株TY9发酵风味最好,呈现较强的谷物发酵风味。结论 筛选出一株耐低温、耐低pH、起酵时间快和酵香风味...     

ASSESSMENT OF POTENTIAL PROBIOTIC PROPERTIES OF LACTIC ACID BACTERIA AND YEAST STRAINS

ABSTRACT

Four lactic acid bacteria (LAB) and three yeast strains isolated from a traditional Bulgarian cereal-based fermented beverage were assessed for potential probiotic properties. Acid and bile resistance, antipathogenic activity and antibiotic resistance of the strains were evaluated. Tolerance to low pH values (2.0–3.0) and high bile concentrations (0.2–2.0%) of the LAB and yeast strains varied, but all strains kept viable throughout the experiments. Antagonistic activity towards most of the eight test-pathogens was observed for one LAB (Lactobacillus plantarum B28) and two yeast strains (Candida rugosa Y28 and Candida lambica Y30). Antibiotic resistance (39 antibiotics) of the LAB strains was variable, but showed their potential for therapeutic application.     

腌鱼中耐盐酵母菌的分离鉴定及其生理生化特性

为了获得生产性能优良的菌株,采用PDA固体培养基平板涂布法从腌鱼中分离、纯化酵母菌,研究优势耐盐酵母菌株的生长温度、耐酸能力、耐亚硝酸盐能力等生理生化特性及ITS rDNA分子生物学鉴定。结果表明,15种不同种类腌制海鱼中共分离出436株酵母菌,经纯化后获得9株不同种属的酵母菌,通过不同NaCl含量的YPD液体培养基对9株酵母菌进行筛选,最终筛选出7#季也蒙毕赤酵母和9#奥默柯达酵母两株耐盐性较好的优势耐盐酵母菌菌株,耐盐能力分别达到9%和12%,最适生长温度均在28~32 ℃之间,最适pH在5~6之间,耐亚硝酸盐含量可达100 mg/kg。腌鱼中获得优势菌株具有良好的生长性能,可为腌鱼制品发酵剂的开发奠定基础。     

Technological and spoiling characteristics of the yeast microflora isolated from Bella Di Cerignola table olives

This study focused to investigate the technological significance and the spoiling impact of diverse yeast strains, isolated from 'Bella di Cerignola' Italian table olives. Sixty-four isolates (belonging mainly to the species Candida famata and C. guilliermondii ) were studied to assess their growth at different temperatures (15, 25 and 37 °C), pHs (4.0, 5.0 and 9.5) and NaCl concentrations (0–10.0%) in lab medium. Their pectolytic, xylanolytic, lipolytic and catalase activities were also evaluated. Most of the yeasts showed a moderate pectolytic activity and were able to grow at pH 9.5 after 120 h of incubation. Salt and temperature were the most important environmental variables affecting yeast growth, which could exert a strong selective pressure on yeast population. Candida guilliermondii appeared more resistant to high salt concentrations, whereas C. famata was able to grow at 15 °C.     

产地葡萄酒发酵菌种选育及工艺优化研究

该研究从三门峡产区采集的葡萄果粒中分离到酵母株,经过耐性试验和酒精模拟发酵试验,筛选出发酵性能优良的菌株SY1和SY2,相比普通酿酒酵母发酵产酒率分别提高3.3%和2.9%;并依托原有的葡萄酒生产工艺,选取SY1作为试验菌株,分别通过改变发酵温度、酵母接种量及葡萄汁糖度的单因素试验及三因素三水平的L9(33)正交试验,最终得出以酒精度为评定指标的最佳发酵条件为主发酵温度26℃,酵母接种量6%,葡萄汁起始糖度24 Brix;以感官评价为评定指标的最佳发酵条件为主发酵温度24℃,酵母接种量10%,葡萄汁起始糖度20 Brix。     

Improvement of soy-sauce flavour by genome shuffling in Candida versatilis to improve salt stress resistance

Genome shuffling of Candida versatilis was applied to improve the soy-sauce flavour by further increasing salt stress resistance. A mutant S3-5, with a stronger resistance to salt, was isolated after three rounds of genome shuffling. It is found that S3-5 improved stress tolerance to higher potassium chloride and lithium chloride. S3-5 not only grew well in the YPD (peptone, yeast extract and dextrose) medium containing high concentrations of sodium chloride with various pH values, but also exhibited improvement of growth ability in soy-sauce medium. The main aroma compounds in soy sauce were distinctly improved. Notably, S3-5 produced about 2.78 times as much ethanol as the control strain. Another important aroma compound, 4-hydroxy-2 (or 5)-ethyl-5 (or 2)-methyl-3 (2H)-furanone (HEMF) was enhanced by up to 80%. Meanwhile, S3-5 accelerated flavour formation of soy sauce thus decreasing the total time required for the aroma development.