Cell Toxicity Effect of Cadmium on Yeast Cells by Detecting NADH Autofluorescence

The cytotoxic effect of cadmium is studied by detecting intracellular nicotinamide adenine dinucleotidea（NADH） autofluorescence in this work. NADH autofluorescence in processes of cadmium-induced apoptosis, necrosis and reversible injury are recorded timely. The relativity between time course of NADH autofluorescence and cadmium toxicity is established. The cell toxicity effect of Cadmium on yeast cells is studied by detecting the time courses of intracellular reduced NADH autofluorescence in this work. The relativity between time courses of NADH autofluorescence and Cadmium toxicity is established.

Mediated Electrochemical Measurements of Intracellular Catabolic Activities of Yeast Cells

Coupling with the dual mediator system menadione/ferricyanide, microelectrode voltammetric measurements were undertaken to detect the ferrocyanide accumulations arising from the mediated reduction of ferricyanide by yeast cells. The results indicate that the dual mediator system menadione/ferricyanide could be used as a probe to detect cellular catabolic activities in yeast cells and the electrochemical response has a positive relationship with the specific growth rate of yeast cells.

Effects of Dietary Yeast Cell Wall Polysaccharides Supplementation to Late Gestation and Lactation Diets on Reproductive Performance and Blood Profiles of Sows and Their Offspring

This study was conducted to determine the effects of yeast cell wall polysaccharides（YCWP） on reproductive performance, serum profiles and milk composition during late gestation and lactation. A total of 96 sows（Landrace × Yorkshire） were blocked on a basis of breed, parity（2-3）and their respective d 85 of gestation, and then randomly allotted to the following three dietary treatments： CON（basal diet, treatment 1）, YCWP1（CON＋0.2% YCWP, treatment 2） and YCWP2（CON＋0.4% YCWP, treatment 3）. The experiment lasted from d 85 of gestation to weaning（d 21 of lactation）. Sows fed YCWP diets had lower backfat thickness reduction from postpartum to weaning（ P〈0.05）. The supplementation of YCWP tended to increase litter weight at weaning（P=0.08） compared with CON. The non-lipid and total milk solids in colostrum was improved by YCWP2（P〈0.05）.No differences were observed in milk composition among dietary treatments（ P〉0.05）. The supplementation of YCWP decreased（P〈0.05） the levels of alanine amino transferase（ALT）, aspartate amino transferase（AST）, while it did not affect（ P〉0.05） alkaline phosphatase（ALP）, total protein（TP）,albumin（ALB）, globulin（GLB）, glucose（GLU）, total cholesterol（TC）, triglyceride（TG） or immunoglobulin G（IgG） in the sow serum. The serum IgG of piglets was increased by the YCWP. The levels of serum ALT and AST were reduced（P〈0.05） for suckling piglets in YCWP treatments. Taken together, the results of current studies might indicate beneficial effects of YCWP supplementation to late gestation and lactation diets on the sow productivity by improving litter weight at weaning, reducing backfat loss, and increasing serum IgG concentrations of piglets.

STUDY ON IMMOBILIZED YEAST CELLS WITH HRDROPHILIC POLYMER CARRIER BY RADIATION - INDUCED COPOLYMERIZATION

In this paper, various kinds of monomers 2-hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate (HPMA) and methoxy polyethylene glycol methylacrylate (M-23G) were eopolymerized by radiation technique at low temperature (-78℃) and several kinds of copolymer carriers were obtained. Yeast cells were immobilized through adhesion and multiplication of yeast cells themselves on these carriers. The etharol productivity of immobilized yeast cells with these carriers was related to the monomer composition and water content of copolymer carriers and the optimum monomer composition was 20%:10% in poly (HEA-M23G). In this case, the ethanol productivity of immobilized yeast cells was 26 mg /( ml·h), which was 4 times as high as that of free cells. In this study, the effect of adding of crosslinking reagent (4G) in copolymer on activity of yeast cells immobilized with the carriers were also studied. It was found that the effect of adding crosslinking reagent (4G) in lower monomer composition of poly(HEA-M23G) on the ethanol productivity of immobilized cells was better than that in higher one in this work.

Inactivation cross section of yeast cells irradiated byheavy ions

Inactivation cross sections for haploid yeast cell strain 211a have beencalculated as 1-hit detector based on the track theory in an extended target mode anda numerical calculation of radial dose distribution. In the calculations, characteristicdose Do is a fitted parameter which is obtained to be 42 Gy, and "radius" of hypothetical target ac is chosen to be 0.spin which is about the size of nucleus of yeastcells for obtaining an overall agreement with experimental cross sections. The resultsof the calculations are in agreement with the experimental data in high LET (linearenergy transfer) including the thindown region.

Micro-environmentally Restricted Yeast Cell Growth within Ca-alginate Microbeads

Micro-environmental restriction effects to yeast cell growth obtained within Ca-alginate microbeads are considered. It is complex phenomenon influenced by: (1) relaxation of expanded polymer network around the cellular clusters, (2) forces generated by cell growth inside the beads and (3) interactions between solvent, network parts and cells. The resulting effects are measured experimentally by estimating volume of microbeads and yeast cell concentration as function of time of cultivation. Comparative analysis of dynamics of cell growth and increase of microbead volume through four regimes indicates that reversible and irreversible local structural changes of Ca-alginate hydrogel induces micro-environmental restrictions to cell growth. The mechanism of restrictions includes both mechanical and electrostatic effects.

Impacts of low level aflatoxin in feed and the use of modified yeast cell wall extract on growth and health of nursery pigs

This study was to investigate the effect of corn naturally contaminated with aflatoxins(AF)under the regulatory level on the growth performance and health of nursery pigs,and the efficiency of yeast cell wall based feed additive(YC)mainly composed ofβ-glucans and mannan oligosaccharide(MOS)(Integral A+,Alltech,Lexington,KY)in prevention of mycotoxicosis.Pigs(60 barrows and 60 gilts at 6.02 ± 0.83kg BW)were randomly allotted to 4 treatments in a randomized complete block design based on a 2×2 factorial arrangement with 10 pens(5 barrow and 5 gilt pens)per treatment and 3 pigs per pen.Pigs were fed experimental diets for 5 wk.First factor was AF(0 or 20 mg/kg in feed)and the second factor was YC(0 or 2 g/kg in feed).Feed intake and body weight were measured weekly,and blood samples were used to measure blood cell counts,immunoglobulin G(Ig G),tumor necrosis factor-a(TNF-a),oxidative damage status,and serological evaluation related to liver health.Aflatoxin decreased(P<0.05)the number of platelet count(247.4 to 193.5×10~3/μL),and it also tended to increase the level of albumin(P=0.055,3.46 to 3.63 g/d L),albumin:globulin ratio(P=0.050,2.09 to 2.37),and Ca(P=0.080,10.79 to 10.97 mg/d L).Yeast cell wall based feed additive increased(P < 0.05)ADG(493 to 524 g/d),and ADFI(796 to 846 g/d)of pigs whereas G:F was not affected,and it also tended to increase(P=0.055)albumin level(3.46 to 3.63 g/d L).Interactions(P < 0.05)on hemoglobin,hematocrit,and platelet count indicated that YC further increased their levels when pigs were eating AF contaminated feed.Interactions(P < 0.05)on urea nitrogen and blood urea N to creatinine ratio indicated that YC further decreased their levels when feed were contaminated with AF.In conclusion,low level of 20 mg AF/kg under the regulatory level had minor effects on hematology without affecting growth performance,however the supplementation of 2 g/kg YC as a source ofβ-glucans and MOS in feed can improve feed intake and therefore the growth of pigs.

Effects of yeast cell wall on growth performance, immune responses and intestinal short chain fatty acid concentrations of broilers in an experimental necrotic enteritis model

Subclinical necrotic enteritis(NE) causes devastating economic losses in the broiler chicken industry,especially in birds raised free of in-feed antibiotics. Prebiotics are potential alternatives to in-feed antibiotics. Yeast cell wall extract(YCW) derived from Saccharomyces cerevisiae is a prebiotic with known immune modulating effects. This study examined the effects of YCW and antibiotics(AB) during subclinical NE on broiler growth performance, intestinal lesions, humoral immune response and gut microflora metabolites. The study employed a 2 × 3 factorial arrangement of treatments. Factors were:NE challenge(yes or no) and feed additive(control, AB, or YCW). Each treatment was replicated in 8 floor pens with 15 birds per pen. Challenged birds had higher feed conversion ratio(FCR) than unchallenged birds on d 35(P < 0.05). Dietary inclusion of AB decreased FCR regardless of challenge(P < 0.05) on d 24 and 35. Inclusion of YCW reduced serum interleukin-1(IL-1) concentration in NE challenged birds(P < 0.01) and increased immunoglobulin(Ig) G(P < 0.05) and Ig M(P < 0.05) levels compared to other dietary treatments regardless of challenge. Yeast cell wall extract increased formic acid concentration in cecal contents during challenge and increased butyric acid concentration in unchallenged birds on d 16.This study indicates YCW suppressed inflammatory response, promoted generation of immunoglobulin and increased short chain fatty acid production suggesting potential benefits to bird health.

Dietary supplementation of yeast cell wall improves the gastrointestinal development of weaned calves

The purpose of this study was to investigate the potential benefits of yeast cell wall(YCW)on the gastrointestinal development of weaned calves.Twenty healthy Holstein male calves(BW=92±8.29 kg and 60±5 d of age)were randomly allocated into 2 groups:CON with no YCW,and YCW(accounted for0.16%of the basal diet).The dietary concentrate-to-roughage ratio was 40:60.All the calves were fed regularly twice a day at 09:00 and 16:00 and had free access to water.The experiment lasted for 60 d.The results showed that calves fed YCW showed higher(P<0.05)length,width,and surface area of papillae in the ventral sac of the rumen as compared to CON.For the dorsal sac of the rumen,the muscularis thickness was thicker(P<0.05)in the YCW group when compared with CON group.The villus height of YCW calves was higher(P<0.05)than that of CON in the ileum.Calves supplemented with YCW also showed a higher(P<0.05)villus height-to-crypt depth ratio in the ileum.The YCW calves exhibited a greater(P<0.05)thickness of the wall in the duodenum and jejunum.Calves supplemented with YCW improved(P<0.05)the claudin 1 mRNA expression in the ileum and occludin mRNA expression in the jejunum and ileum.The YCW increased(P<0.05)the contents of secretory immunoglobulin A in the jejunum and ileum of calves.In conclusion,dietary supplementation with YCW could improve the gastrointestinal development of weaned calves.

Use of dry yeast cells as a cheap nitrogen source for lactic acid production by thermophilic Bacillus coagulans WCPIO-4

Dry yeast cells （DYC） were used as a cheap nitrogen source to replace expensive yeast extract （YE） for L-lactic acid production by thermophilic Bacillus coagulans. Cassava starch （200 g. L1） was converted to L-lactic acid by simultaneous saccharification and fermentation using Bacillus coagulans WCP10-4 at 50℃ in the presence of 20g·L-1 of DYC, giving 148.1 g·L-1 of L- lactic acid at 27 h with a productivity of 5.5 g·L-1·h-1 and a yield of 92%. In contrast, 154.4 g·L-1 of lactic acid was produced at 24 h with a productivity of 6.4 g·L-1. hl and a yield of 96% when equal amount of YE was used under the same conditions. Use of pre-autolyzed DYC at 50℃ for overnight slightly improved the lactic acid titer （154.5g·L-1） and productivity （7.7g·L-1·h-1） but gave the same yield （96%）.

Sequential co-immobilization of β-glucosidase and yeast cells on single polymer support for bioethanol production

Co-immobilization of enzymes and microorganism is an effective way to enable cells to use nonmetabolizable substrates and accelerate reaction rate of overall process. Herein, a facile strategy to separately co-immobilize β-glucosidase(BG) and yeast cells on non-woven fabrics was developed. The BG was firstly in situ entrapped into poly(ethylene glycol)(PEG) network grafted on non-woven fabrics by visible light induced living/controlled graft polymerization. Then re-graft polymerization was performed on the as-formed BG loaded layer by taking advantage of living-grafting polymerization on its surface to in situ encapsulate yeast cells into the second PEG network layer. This layered structure of co-immobilization avoided possible interference between enzyme and cells. Viability assay of yeast cells demonstrated that most of cells were viable after immobilization. While immobilized BG showed decreased V_(max) compared to free BG, indicating that entrapping BG into inner PEG network layer restricted its accessibility with substrates. This co-immobilization sheet could successfully convert cellobiose to ethanol and a maximum of 98.6% bioethanol yield can be obtained after 48 h of simultaneous saccharification and fermentation(SSF). The co-immobilization sheet showed excellent reusability and could still reach more than 60% of original ethanol yield after reusing for 7 batches. Compared with the mixed co-immobilization, the sequential layered immobilization in this system showed better stability and higher ethanol yield.

酵母细胞壁来源、作用机理及在动物养殖中的应用

酵母细胞壁具有吸附病原微生物、调整有益菌落和调节免疫功能等作用,其作为酵母类生物饲料原料的重要组成部分,已经被广泛应用于畜禽养殖的各个环节。本文就酵母细胞壁来源、组成、作用机理及在动物养殖中的应用进行综述,以期为酵母细胞壁在实际生产中的合理应用提供理论参考。

非酿酒酵母与酿酒酵母在米酒混菌发酵中的相互作用机制分析

该研究以传统米酒酿造中常见的两种典型非酿酒酵母,假丝酵母(Candida glabrata,Ca)和扣囊复膜酵母(Saccharomycopsis fibuligera,Sf)为研究对象,利用同时接种和顺序接种两种发酵方式分别与酿酒酵母(Saccharomyces cerevisiae,Sc)进行米酒混菌发酵,探究非酿酒酵母和酿酒酵母间的相互影响及相关作用机制。研究结果表明,虽然2种混菌发酵方式表现出明显不同的发酵特性,但在混菌发酵过程中,当Sc生物量达到一定水平(约107 CFU/mL)后,2株非酿酒酵母的生长均受到显著的抑制,生物量快速下降,而Sc生物量基本未受非酿酒酵母的影响。细胞非接触发酵实验结果表明,一定浓度的Sc与非酿酒酵母的细胞-细胞接触是产生抑制的主要原因。Sc发酵代谢物以及酒精和营养物质含量对非酿酒酵母的生长影响不大。

基于酵母双杂交文库鉴定鸡PGCs形成过程中的关键泛素化修饰酶

试验拟筛选与C2EIP互作的蛋白,构建调节PGCs形成过程的泛素化E3连接酶复合体。通过逆转录和同源重组等方法构建鸡PGCs酵母文库;将C2EIP连入诱饵空载体pGBKT7中,并转化酵母感受态细胞进行诱饵载体(C2EIP-pGBKT7)的毒性和自激活检测;将酵母文库与诱饵载体菌液共培养后,通过涂板筛选阳性克隆并进行测序和生物信息学分析筛选互作蛋白。结果显示:成功构建了鸡PGCs酵母文库,其滴度为3.0×10^(6)cfu/mL,总库容为1.5×10^(7)cfu,且重组率为100%,符合筛库要求。成功构建无毒性和不能自激活的C2EIP-pGBKT7诱饵载体,能够用于后续的文库筛选。C2EIP-pGBKT7诱饵载体菌液与酵母文库共培养后,通过PCR测序与蛋白序列分析后共筛选了36个C2EIP的互作蛋白,其中RCJMBM04和CCDC174蛋白功能域分析发现分别具有典型的RING功能域和PPXY基序,进行的生物信息学分析发现WWP1和WWP2具有典型的WW功能域,能够与CCDC174结合。研究表明,试验成功鉴定了C2EIP/RCJMB04/CCDC174/WWP泛素化E3连接酶复合体,为后续研究泛素化修饰调控鸡PGCs形成机制奠定理论基础。

SSF法培养马克斯克鲁维酵母高产细胞和乙醇的工艺初探

为开发生物能源,使用马克思克鲁维酵母发酵甜菜产生酵母细胞数及乙醇,由系列单因素试验及部分析因试验初步确定发酵条件。结果表明,马克斯克鲁维酵母自身具备纤维素酶和木质素酶活性,在额外添加0.1%纤维素酶、5 g/L氮源尿素,同时采用SSF法和分批补料,摇床速度210.7 r·min^(-1),CaCO_(3)添加量5 g/L,高密度培养的条件下,酵母细胞数和乙醇产量可达到一个平衡的较高值。

合成生物学改造酵母驱动丁二酸绿色生物制造

丁二酸是一种重要的C_(4)平台化合物,采用微生物以可再生生物质资源为原料制造丁二酸具有显著的优势,是当前国内外的研究热点。合成丁二酸的微生物主要包括细菌和酵母两大类,与细菌相比,虽然酵母的丁二酸生产得率低于细菌,但酵母对酸性等逆境的抗性更强,可以在低pH条件下合成丁二酸,不用添加中和剂,从而使丁二酸的下游纯化过程更简单、成本更低。本文综述了近年来利用酵母类微生物合成丁二酸的研究进展,重点介绍以酿酒酵母、解脂耶氏酵母和东方伊萨酵母为代表的酵母类生产菌株的合成生物学改造策略,在此基础上展望通过构建酵母细胞工厂绿色生物制造丁二酸的未来发展方向。

解脂耶氏酵母细胞工厂生产多不饱和脂肪酸的研究进展

多不饱和脂肪酸属直链脂肪酸,是机体生物膜的关键结构组分,它可以调控糖脂代谢及激素代谢,具有促进发育、提高免疫力和预防疾病等多种益生功能,对机体健康具有十分重要的作用。因此,多不饱和脂肪酸在食品、医药和饲料等多个领域均表现出重要的应用价值和广阔的开发前景,市场需求持续上升。与传统的海洋生物提取法相比,微生物合成法具有生产周期短、工艺简单、对环境友好等优势,近年来利用微生物细胞工厂生产多不饱和脂肪酸等微生物油脂逐渐成为科学界和工业界的研究热点和发展趋势。解脂耶氏酵母作为一种非常规产油酵母,因其具备高产油脂和脂肪酸的天然能力,因此成为了代谢工程改造微生物生产多不饱和脂肪酸的首选底盘细胞之一。本文首先介绍了多不饱和脂肪酸的来源及其天然合成途径;然后总结归纳了当前利用代谢工程策略改造解脂耶氏酵母生产多不饱和脂肪酸的研究现状;最后对利用解脂耶氏酵母细胞工厂生产多不饱和脂肪酸存在的主要瓶颈问题和未来发展趋势进行了探讨,期望为未来高效合成多不饱和脂肪酸微生物细胞工厂的构建提供理论支持与思路。

蒲公英提取物及其复合酵母培养物对奶牛隐形乳房炎的药效评价

本研究旨在以患有隐性乳房炎的奶牛为试验对象,评价蒲公英提取物及其复合酵母培养物对奶牛隐性乳房炎的防治效果。试验选取28头同胎次泌乳牛,其中21头患有隐形乳房炎,以体细胞数量为核心指标,采用Excel随机分为A、B、C三个处理组,保证各组隐性乳房炎患病牛的体细胞数无显著性差异;另7头健康奶牛作为阴性对照D组,每组7个重复,每个重复1头奶牛。试验开始,试验A、B两组分别在基础TMR日粮中添加蒲公英提取物40 g/(d·头)、(40 g蒲公英提取物+150 g酵母培养物)/(d·头),试验C、D两组饲喂基础TMR日粮,试验周期为11 d,分别在第0、6、11天采集牛奶和血液样本,检测牛奶体细胞数、血常规及乳品质等相关指标,同时记录每头牛泌乳量。结果显示:(1)体细胞数,试验第6天,与阳性对照C组相比,日粮添加蒲公英提取物以及蒲公英提取物复配酵母培养物组,牛乳中体细胞数分别下降63.2%和40.1%,二者体细胞数均达到阴性对照D组正常奶牛水平,其中蒲公英提取物组达到显著差异水平(P<0.05),而蒲公英提取物复配酵母培养物组表现出下降趋势(0.05<P<0.1)。试验第11天,牛乳中体细胞数结果显示,与阳性对照C组相比,日粮添加蒲公英提取物以及蒲公英提取物复配酵母培养物组,牛乳中体细胞数分别下降68.0%和79.85%,均达到显著差异水平(P<0.05),且与阴性对照D组相比分别下降52.48%和70.1%,达到显著差异水平(P<0.05)。乳脂率,在试验第0天和第6天,各组乳脂率差异均不显著(P>0.05);试验第11天,与阳性对照C组相比,日粮添加蒲公英提取物A组乳脂率差异不显著(P>0.05),而在日粮中添加蒲公英提取物复合酵母培养物B组乳脂率提升25%,表现出上升的趋势(0.05<P<0.1),且与阴性对照D组相比分别上升18.6%和29.3%,A组表现出上升的趋势(0.05<P<0.1),B组达到显著差异水平(P<0.05)。结果表明,日粮添加蒲公英提取物以及蒲公英提取物复合酵母培养物均可以有效降低牛奶中体细胞数,对治疗隐形乳房炎有显著效果;日粮添加蒲公英提取物复合酵母培养物可以提高牛奶的乳脂率;蒲公英提取物和蒲公英提取物复配酵母培养物对泌乳量、血常规指标无显著影响。

Marine Yeasts and Their Applications in Mariculture

The terrestrial yeasts have been receiving great attention in science and industry for over one hundred years because they can produce many kinds of bioactive substances. However, little is known about the bioactive substances of marine yeasts. In recent years, it has been found that marine yeasts have wide applications in mariculture and other fields. Therefore,marine yeasts, the bioactive substances from them and the applications of marine yeasts themselves and the bioactive substances they produced are reviewed in this paper.

Novel functional proteins interact with midkine in hepatic cancer cells

BACKGROUND: Midkine is a heparin-binding growth factor that promotes the proliferation, survival, migration and differentiation of various target cells. Midkine plays an important role in tumorigenesis and tumor progression, and is overexpressed in many human malignant tumors. Patients with high tumor midkine expression frequently have a worse prognosis than those with low expression. The present study was designed to investigate the interaction network of midkine in hepatic cancer cells, and to elucidate its role in hepatocellular carcinoma. METHODS: DNA encoding full-length midkine was cloned into pDBLeu vector to serve as bait in yeast two-hybrid screening to identify interacting proteins. Candidate proteins were examined on SC-Leu-Trp-His+3-AT (20 mmol/L) plates and assayed for X-gal activity, then sequenced and classified according to the GenBank. Finally, identified proteins were expressed by the in vitro expression system pCMVTnT, and protein interactions were confirmed by co-immunoprecipitation. RESULTS: Using the yeast two-hybrid system, we found 6 proteins that interacted with midkine: NK-kappa-B inhibitor alpha (I-κ-B-α), Dvl-binding protein naked cuticle 2, granulin, latent active TGF-β binding protein 3, latent active TGF-β binding protein 4, and phospholipid scramblase 1. In vitro co-immunoprecipitation demonstrated that all identified proteins directly interacted with midkine.CONCLUSION: The identification of midkine-interacting proteins in hepatic cancer cells indicates that midkine is a multifunctional factor that may participate in cell migration, differentiation, and proliferation, and is also associated with the multicellular response feedback during the development of hepatocellular carcinoma.