Activity of different ''killer'' yeasts on strains of yeast species undesirable in the food industry

Killer strains of the genera Saccharomyces, Hansenula and Kluyveromyces were tested for killing activity against yeasts that cause trouble in the food industry (in the genera Zygosaccharomyces, Kloeckera, Saccharomycodes and Schizosaccharomyces). Saccharomyces strains killed only Zygosaccharomyces rouxii strains, while non-Saccharomyces strains showed a wider anti-yeast spectrum. The Kluyveromyces phaffii killer strain was of particular interest because of its killer action against Kloeckera apiculata, Saccharomycodes ludwigii and Zygosaccharomyces rouxii.     

ATP production by sorbitol-treated cells of a methanol yeast, Candida boidinii (Kloeckera sp.) No. 2201

The phosphorylation system of AMP by sorbitol-treated cells of a methanolutilizing yeast, Candida boidinii (Kloeckera sp.) No. 2201, was investigated for the production of ATP. Firstly, reaction conditions for the ATP production were optimized. Under the optimal conditions, 20–30 g 1^?1 of ATP were produced in the conversion rate of 60–70% from AMP. Activities of reactions involved in the ATP-producing system were compared with cells from different cultures to prepare the cells having the higher activity and to know the essential reaction limiting the rate of the system. The energy efficiency of this system was also discussed.     

Effect of Milk Components on IgA Production in Peyer’s Patch Cell Cultures from Mouse

The lipid composition of some commercial bakers’ yeasts having different freeze-sensitivity in frozen dough was investigated to clarify the correlation between their lipid composition and freeze-tolerance. The total lipid content including neutral lipid, free fatty acid, sterol, and phospholipid ranged between 23.0 to 32.2 mg/100 mg protein of the yeasts tested. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were the main phospholipids found in all yeast strains, but no distinct difference in these components between freeze-tolerant and freeze-sensitive strains was observed. Palmitoleic (C16:l), oleic (C18:l), palmitic (16:0), and stearic (CI8:0) acids were the major fatty acids present in total lipid and phospholipid, and unsaturation indices of fatty acid in these lipid components were almost equal by the strains. The molar ratios of sterol to phospholipid of freeze-sensitive strains were higher than those of freeze-tolerant strains. The difference in the sterol-pho-spholipid ratio that influences the fluidity of plasma membranes in yeast cells was supposed to reflect the difference in freeze-sensitivity of bakers’ yeast.     

人LNα4LG4-5在毕赤酵母中的表达研究

为实现人层粘连蛋白α4链LG4-5组件(Human Laminin Alpha4Chain LG4-5Module,hLNα4LG4-5)蛋白的分泌表达,采用DNA重组技术将hLNα4LG4-5cDNA片段插入分泌型酵母表达载体pPICZαA中,构建了相应的重组表达质粒pPICZαA-LG45并在GS115毕赤酵母菌株中表达,纯化蛋白后进行细胞学实验证明,hLNα4LG4-5有明显促进肿瘤细胞粘附和扩展的作用,为深入研究LG4-5组件结构与功能奠定了基础。     

Production of Food and Fodder Yeasts

Abstract

A decade or so ago, there was considerable interest in developing single cell protein production from raw materials. Many factors have influenced the development of fodder yeast technology, notably the biochemistry and physiology of the yeast.

It is shown that those considerations have led to the choice of a continuous fermentation technology.     

Ogataea populialbae sp. nov., a yeast species from white poplar

During a survey of methylotrophic yeasts in natural habitats in Hungary, the yeast community associated with the exudates of white poplar ( Populus alba ) was found to be unique among the tree exudates hitherto investigated. Nineteen methanol-assimilating yeast strains representing an undescribed ascomycetous species were isolated from tree exudates of P. alba collected at different locations in Hungary. Analysis of the D1/D2 large subunit rRNA gene sequences placed the strains in the Ogataea clade and the new species is described as Ogataea populialbae . The type culture is NCAIM Y.01853^T (CBS 11363, NRRL Y-48632).     

Blastobotrys serpentis sp. nov., isolated from the intestine of a Trinket snake (Elaphe sp., Colubridae)

Asporogenus yeast strains W113AT and W113B were isolated from the intestine of a dead Trinket snake. The two isolates showed 100% sequence similarity in the D1/D2 domain of the large-subunit (LSU) rRNA gene, internal transcribed spacer (ITS) 1-5.8S rRNA gene-ITS2 region and mitochondrial small-subunit rRNA gene and the cytochrome oxidase II gene sequence and also showed similar phenotypic characteristics. The nearest phylogenetic neighbors of W113AT and W113B based on the sequence of the D1/D2 domain of the LSU rRNA gene were Blastobotrys chiropterorum NRRL Y-17017T and Blastobotrys terrestris NRRL Y-17704T with about 98% similarity. The close affiliation of W113AT and W113B with B. chiropterorum NRRL Y-17017T and B. terrestris NRRL Y-17704T was also evident from the high similarity observed in the nucleotide sequences of the mitochondrial small subunit rRNA (96-97.8%) and the cytochrome oxidase II (95.5-95.6%) genes. In the neighbor-joining phylogenetic trees constructed based on the D1/D2 domain or cytochrome oxidase gene, the isolates clustered with the above-mentioned species. However, the isolates showed a number of differences in their phenotypic properties with B. chiropterorum NRRL Y-17017T and B. terrestris NRRL Y-17704T and hence are regarded as representing a novel member of the genus Blastobotrys, for which the name Blastobotrys serpentis sp. nov. is proposed.     

红富士苹果园酵母多样性研究

从北京顺义和山东泰安红富士苹果园采集果实、叶片、树皮和土壤等不同基物,分离酵母菌,利用26S rDNA的D1/D2区域序列分析并结合形态学特征和SSCP分析对这些菌株进行了分类学研究,探讨了苹果园酵母的物种多样性及其分布。北京苹果园共分离酵母菌129株,鉴定为13属21种,优势属为Pichia（4个种）,Cryptococcus（3个种）,Pseudozyma（3个种）,子囊菌占较大优势,分布于8属12种,占总种数的57.1%。山东苹果园共分离酵母291株,鉴定为13属26种,优势属为假丝酵母Candida（6个种）,毕赤酵母Pichia（4个种）和隐球酵母Cryptococcus（3个种）,并且子囊菌占较大优势,分布于7属17种,占总种数的65.4%。     

Anticryptococcal activity by alveolar macrophages from rats treated with cortisone acetate during different periods of time

The interaction of the killer yeast Pichia anomala UP 25F with the killer toxin-sensitive clinical isolate Candida albicans UCSC 10S and its natural toxin-resistant mutant derivative C. albicans UCSC 10R were studied under various conditions. A differential inhibition was shown to occur in vitro at pH and temperature values, which are not encountered in vivo, only by using preformed killer toxin, since antagonism due to yeast growth proved to be predominant on the killer effect. Under adverse growth conditions, the P. anomala killer yeast proved to be able to produce an anatoxin antigenically related to the active or heat inactivated killer toxin. These findings suggest that killer toxins may not function as potential virulence factors in the competition between the opportunistic killer yeast P. anomala and sensitive microorganisms for colonization in the course of natural human infections.     

石河子不同树龄蟠桃土壤中可培养酵母多样性分析及功能酵母的筛选

为了探究新疆本土蟠桃园可培养酵母菌多样性,并挖掘功能酵母资源,本研究以新疆石河子蟠桃园3年、8年、15年树龄的根际和非根际土壤以及桃树叶片为材料,经过传统的分离培养方法获得可培养的酵母菌菌株,并进行形态学、生理生化以及26S r DNA的D1/D2区序列分析,共获得可培养酵母菌129株,从属于12个属17个种,其中子囊菌酵母为优势菌群,占分离属的88%,分布于威克汉姆酵母属(Wickerhamomyces),Vanrija属,Barnettozyma属和有孢圆酵母属(Torulaspora)等11个属的15个种。担子菌占分离属的12%,分布于隐球酵母属(Cryptococcus)的2个种。其中优势属威克汉姆酵母属,包括异常威克汉姆酵母(W. anomalus)和W. pijperi两个种,占总比例的33%,优势种异常威克汉姆酵母所占总株数比例为17%。从可培养酵母中共筛选出23株功能酵母,其中富硒酵母21株,优势种为白地霉(Galactomyces candidum),产蛋白酶酵母2株均属于隐球酵母属的Cryptococcus albidus。结果表明,新疆桃园中蕴含丰富的酵母菌资源,非根际土壤中的酵母多样性大于根际及叶片酵母多样性,且分离得到富硒酵母及产蛋白酶酵母。本研究挖掘了新疆本土可培养酵母菌资源,同时也为功能酵母的开发和利用提供理论指导。     

Discrepancy in glucose and fructose utilisation during fermentation by Saccharomyces cerevisiae wine yeast strains

While unfermented grape must contains approximately equal amounts of the two hexoses glucose and fructose, wine producers worldwide often have to contend with high residual fructose levels (>2 gl(-1)) that may account for undesirable sweetness in finished dry wine. Here, we investigate the fermentation kinetics of glucose and fructose and the influence of certain environmental parameters on hexose utilisation by wine yeast. Seventeen Saccharomyces cerevisiae strains, including commercial wine yeast strains, were evaluated in laboratory-scale wine fermentations using natural Colombard grape must that contained similar amounts of glucose and fructose (approximately 110 gl(-1) each). All strains showed preference for glucose, but to varying degrees. The discrepancy between glucose and fructose utilisation increased during the course of fermentation in a strain-dependent manner. We ranked the S. cerevisiae strains according to their rate of increase in GF discrepancy and we showed that this rate of increase is not correlated with the fermentation capacity of the strains. We also investigated the effect of ethanol and nitrogen addition on hexose utilisation during wine fermentation in both natural and synthetic grape must. Addition of ethanol had a stronger inhibitory effect on fructose than on glucose utilisation. Supplementation of must with assimilable nitrogen stimulated fructose utilisation more than glucose utilisation. These results show that the discrepancy between glucose and fructose utilisation during fermentation is not a fixed parameter but is dependent on the inherent properties of the yeast strain and on the external conditions.     

The genetic control of dark recombination in yeast

The post-UV effects of dark holding and photoreactivating light on survival and intragenic recombination in UV-sensitive strains of yeast have been studied. The results indicate that two liquid holding dark repair pathways exist in this organism: the excision pathway which does not lead to intragenic recombination (“silent” repair) and a dark recombination pathway which does lead to intragenic recombination. A third pathway also exists which is plating-dependent and leads to intragenic recombination via a postreplication pathway.     

酵母三杂交系统的应用研究进展

介绍了酵母三杂交系统的原理、应用、前景和存在的不足.在酵母双杂交基础上发展起来的酵母三杂交系统,将应用范围扩大到研究蛋白质-蛋白质、蛋白质-RNA、蛋白质-小分子药物间的相互作用.     

The propeptide of yeast cathepsin D inhibits programmed necrosis

The lysosomal endoprotease cathepsin D (CatD) is an essential player in general protein turnover and specific peptide processing. CatD-deficiency is associated with neurodegenerative diseases, whereas elevated CatD levels correlate with tumor malignancy and cancer cell survival. Here, we show that the CatD ortholog of the budding yeast Saccharomyces cerevisiae (Pep4p) harbors a dual cytoprotective function, composed of an anti-apoptotic part, conferred by its proteolytic capacity, and an anti-necrotic part, which resides in the protein''s proteolytically inactive propeptide. Thus, deletion of PEP4 resulted in both apoptotic and necrotic cell death during chronological aging. Conversely, prolonged overexpression of Pep4p extended chronological lifespan specifically through the protein''s anti-necrotic function. This function, which triggered histone hypoacetylation, was dependent on polyamine biosynthesis and was exerted via enhanced intracellular levels of putrescine, spermidine and its precursor S-adenosyl-methionine. Altogether, these data discriminate two pro-survival functions of yeast CatD and provide first insight into the physiological regulation of programmed necrosis in yeast.     

PEG／LiAc转化酵母细胞方法的改进

ＰＥＧ／ＬｉＡｃ法转化酵母适用于酵母双杂交系统的大量筛选,并能获得１０＾６转化子／μｇ质粒以上的转化率,但如果没有进口的ＰＥＧ３３５０而采用分子量接近的国产ＰＥＧ４０００进行转化的话,转化率仅为１０＾４,远低于文献报道的水平。我们报道了一个改进的ＰＥＧ／ＬｉＡｃ方法,采用国产ＰＥＧ６０００,转化率也能达到１０＾６,且能将的热激时间从２０ｍｉｎ缩短为２ｍｉｎ。     

葡萄酒中酵母菌高产甘油的研究进展

甘油是酵母菌酒精发酵过程中的副产物,甘油作为非挥发性物质,对葡萄酒的香气没有贡献,但是其黏性和甜味,可使葡萄酒具有圆润、柔滑、甘甜、肥硕、更易入口的特性,也可用于平衡酒中的酸感,增加口感复杂性,是高品质果酒的重要成分。近年来,国内外对高产甘油酵母的研究日益增多,着重于提高葡萄酒中酵母发酵生产甘油的能力。     

A Novel Synthesis of (±)-Munduserone via Acetylenic Intermediates

A riboflavin α-glucoside-synthesizing enzyme from the acetone powder of pig liver was purified by a procedure including fractionation with ammonium sulfate, heat treatment, fractionation with acetone, gel filtration on a Sephadex G-150 column, calcium phosphate gel treatment, and isoelectric focusing. A final enzyme preparation was homogeneous on polyacrylamide disc gel electrophoresis and in the ultracentrifuge. The enzyme had a sedimentation coefficient of 9.90 S and an isoelectric point of pH 3.7. The enzyme had a pH optimum at 6.0 with maltose as substrate. The enzyme catalyzed the hydrolysis of diverse kinds of α-glucosidic substrates, and the transfer of α-glucosyl residue from these substrates to riboflavin. The Km value for maltose was 1.20×10^?3m. The enzyme hydrolyzed phenyl α-maltoside to glucose and phenyl α-glucoside. Amylose was almost completely hydrolyzed to glucose by the enzyme. Maltotriose was obtained as the main transfer product after the treatment of maltose with the enzyme. The enzyme also catalyzed the transfer of α-glucosyl residue from maltose to pyridoxine, esculin, rutin, and adenosine. It was recognized that a single enzyme catalyzed not only the hydrolysis of maltose and α-glucosidic substrates but also the transfer of the α-glucosyl residue of these substrates to suitable acceptors.     

Comprehensive phenotypic analysis for identification of genes affecting growth under ethanol stress in Saccharomyces cerevisiae

We quantified the growth behavior of all available single gene deletion strains of budding yeast under ethanol stress. Genome-wide analyses enabled the extraction of the genes and determination of the functional categories required for growth under this condition. Statistical analyses revealed that the growth of 446 deletion strains under stress induced by 8% ethanol was defective. We classified these deleted genes into known functional categories, and found that many were important for growth under ethanol stress including several categories that have not been characterized, such as peroxisome. We also performed genome-wide screening under osmotic stress and identified 329 osmotic-sensitive strains. We excluded these strains from the 446 ethanol-sensitive strains to extract the genes whose deletion caused sensitivity to ethanol-specific (359 genes), osmotic-specific (242 genes), and both stresses (87 genes). We also extracted the functional categories that are specifically important for growth under ethanol stress. The genes and functional categories identified in the analysis might provide clues to improving ethanol stress tolerance among yeast cells.     

α-Mannosidase from Pineapple Fruit: Partial Purification and Action on Glycopeptides

α-Mannosidase [EC 3.2.1.24, α-D-mannoside mannohydrolase] from the acetone powder of pineapple fruit juice was purified 190-fold by column chromatographic procedures. The partially purified a-mannosidase was detected to be contaminated with little other glycosidases, using p-nitrophenyl derivatives of glycosides. The enzyme released mannose from both the carbohydrate moiety of stem bromelain and glycopeptide prepared from the parent protein. The enzyme split about 70% of the total mannose of ovalbumin glycopeptide.     

酵母菌体在食品中开发与应用

介绍以酵母菌体为原料制取食用蛋白、酵母精及增鲜剂，并对各制品在食品中的应用进行了阐述，旨在推动酵母菌体开发与利用的进程。