Improving Semi-Dried Brown Rice Noodle Quality via Mixed Fermentation of Lactobacillus and Yeast

To address the coarse texture and poor cooking quality of brown rice flour,we employed fermentation using lactobacillus and yeast in varying proportions.The fermented flour from early indica rice Pear 13 was then processed into semi-dried brown rice noodles.

Effect of β-Glucan (Angel Yeast) Compared to a Placebo on Cold and Flu Incidence and Symptoms in an Adult Population—A Double Blind, Randomised Controlled Trial

Background: 1-3, 1-6 β-glucan derived from Baker’s yeast (Saccharomyces cerevisiae) has been widely studied for its immune stimulatory capabilities and safety. Previous studies found β-glucan to have efficacy at reducing incidence of URTIs as well as being a low risk for negative side effects. The current study aimed to examine the effects of yeast β-glucan (Angel Yeast) on cold and flu incidences and symptoms in healthy adults. Methods: Two hundred and thirty-one males and females aged 18 to 65 years old supplemented with either β-glucan or a placebo for 3-months. Participants completed a general health questionnaire every 4 weeks and in addition, if participants experienced any cold or flu symptoms, these were recorded daily (along with severity) until resolved or up to 2 weeks. Results: Supplementation with β-glucan reduced the self-reported severity of sore throats and improved sleep quality compared to the placebo group. Conclusions: Yeast β-glucan supplementation appears to be able to help reduce certain symptoms experienced during a cold or flu episode and is safe and well tolerated.

Mathematical Modeling of Cell Polarity Establishment of Budding Yeast

The budding yeast Saccharomyces cerevisiae is a powerful model system for studying the cell polarity establishment.The cell polarization process is regulated by signaling molecules,which are initially distributed in the cytoplasm and then recruited to a proper location on the cell membrane in response to spatial cues or spontaneously.Polarization of these signaling molecules involves complex regulation,so the mathematical models become a useful tool to investigate the mechanism behind the process.In this review,we discuss how mathematical modeling has shed light on different regulations in the cell polarization.We also propose future applications for the mathematical modeling of cell polarization and morphogenesis.

Influence of nitrogen status on fermentation performances of non-Saccharomyces yeasts:a review

Nitrogen,one of the most crucial nutrients present in grapes and musts,plays a key role in yeast activities during alcoholic fermentation.Such influences are imposed on yeast growth and fermentation performances including the formation of secondary metabolites.Saccharomyces cerevisiae,the main yeast responsible for fermentation,has been studied extensively regarding nitrogen impacts.On the other hand,a similar study for non-Saccharomyces yeasts,whose contributions to winemaking have gradually been acknowledged,remains to be fully explored,with a few studies being reported.This review starts by discussing nitrogen impacts on non-Saccharomyces yeast growth and fermentation kinetics in different case scenarios,then proceeds to summarize the nitrogen preferences of individual yeast strains with regulation mechanisms elucidated by recent studies.Detailed discussions on the influences on the production of volatile compounds and proposed pathways therein are made,followed by future work suggested as the final section.In summarizing the nitrogen impacts on non-Saccharomyces yeasts throughout alcoholic fermentation,this review will be helpful in obtaining a more comprehensive view on these non-conventional wine yeasts in terms of nutrient requirements and corresponding volatile production.Research gaps will therefore be elucidated for future research.

Impact of Storage Temperature on Microbial Diversity and Probiotic Effect of Liquid Brewers’ Yeast

Using probiotics as animal feed additives instead of antibiotics is gaining momentum to avert adverse negative effects on human health. Liquid brewers yeast (LBY) is an industrial by-product containing probiotic microorganisms and is also used as a protein supplement for dairy animals. Nevertheless, value chain actors lack of appropriate handling practices compromises the by-products quality and safety. This study aimed to determine the effect of variation in temperature on microbial diversity and probiotic effects during the storage time of LBY sampled from distributors and farmers from Githunguri sub-county of Kenya. The samples were stored at 20C, 25C and 30C, then tested on 0, 5, 10, 15 and 20 days. The studys parameters involved determining the pH levels, lactic acid bacteria (LAB), total coliform count (TCC), mould, and yeast in LBY. The rate (k) of the reaction kinetics model was used to extrapolate the expected probiotic shelf life. The LAB and yeast populations were reduced in a first-order reaction at all storage temperatures. The rate of reduction in the numbers of LAB reduced with an increase in temperature (k = 0.019 and 0.023) at 20C and 30C, respectively. Yeasts highest rate of growth reduction was 25C (k = 0.009) and least at 30C (k = 0.043). The minimum effective concentration for probiotics of 106 CFU/mL needed to observe the beneficial physiological impact on farm animals was achieved between 34.9 and 35.5 days at the tested storage temperatures. The study provides insight into the unexploited low-cost probiotic potential of LBY in dairy production. Conversely, handling practices and environmental microbial contamination along the value chain can compromise product quality and safety. There is a need to advocate its use in dairy for improved productivity and sensitize farmers to appropriate hygienic measures along the LBY value chain.

Microbiological Quality of “Rabilé”, a Yeast Used for Fermentation of Dolo, a Local Beer in Dédougou, Burkina Faso

Sorghum beer or dolo is part of the eating habits of part of the population of Dédougou because of its low price compared with industrial beers. Its production is an ancestral tradition that uses traditional equipment and gives dolo organoleptic properties that are not found in industrial beers. The production process involves several stages, including fermentation, which itself comprises natural lactic fermentation followed by alcoholic fermentation using traditional yeasts, which are not controlled in any way. The general aim of this study is to assess the microbiological quality of these fermentative yeasts in the town of Dédougou, in order to contribute to the health safety of the population and the promotion of these local beers. Twenty samples of fermenting yeast were analyzed according to ISO standards, to isolate enterobacteria, total and faecal coliforms according to standard procedures for isolating these micro-organisms. The isolated strains were identified using the API20E gallery. Microbiological analyses revealed the presence of 51.17% enterobacteria, 45.38% total coliforms and 3.45% thermotolerant coliforms. We counted 40% Escherichia coli, 20% Enterobacter cloacae, 20% Klebsiella pneumoniae and 20% Klebsiella spp. All the strains detected are capable of surviving in hostile conditions and could harm the quality of the dolo, consumer health and cause real collective food poisoning in the town of Dédougou. This enabled us to assess the microbial quality of these yeasts and to propose more suitable measures for producing and preserving dolo under hygienic conditions to protect consumer health.

Immobilization techniques for beverage production using yeast cell systems: challenges, types, and future perspectives - a mini review

Yeast immobilization is a process of physical entrapment of yeast cells using different techniques while maintaining their biological activity.Continuous fermentation systems have significant advantages over conventional methods.Research highlights that immobilized yeast cell systems have several benefits as compared to free yeast cells.The immobilized yeast cell systems improve fermentation rates,especially when paired with continuous fermentation and appropriate immobilization techniques.Understanding various immobilization techniques,continuous fermentation processes,yeast metabolic activity related to beverage flavor production,and bioreactor designs is vital for optimizing the use of immobilized yeast cells systems on industrial scale.This review provides an overview of recent basic research on immobilized yeast cell systems,with a focus on continuous beverage fermentation.In this study,different reactor configurations and immobilization techniques are explored.The study focus on the impacts of immobilization on the yeast cells,and discuss the recent advancements in these techniques.The review concludes with a discussion on the practical applications of immobilized yeast cells and continuous fermentation in beverage production.

Yeast hydrolysate attenuates lipopolysaccharide-induced inflammatory responses and intestinal barrier damage in weaned piglets

Background Intestinal inflammation is the main risk factor causing intestinal barrier dysfunction and lipopolysaccharide(LPS)can trigger inflammatory responses in various eukaryotic species.Yeast hydrolysate(YH)possesses multibiological effects and is received remarkable attention as a functional ingredient for improving growth performance and promoting health in animals.However,there is still inconclusive on the protective effects of dietary YH supplementation on intestinal barrier of piglets.This study was conducted to investigate the attenuate effects of YH supplementation on inflammatory responses and intestinal barrier injury in piglets challenged with LPS.Methods Twenty-four piglets(with an average body weight of 7.42±0.34 kg)weaned at 21 days of age were randomly assigned to one of two dietary treatments(12 replications with one pig per pen):a basal diet or a basal diet containing YH(5 g/kg).On the 22nd d,6 piglets in each treatment were intraperitoneally injected with LPS at 150μg/kg BW,and the others were injected with the same amount of sterile normal saline.Four hours later,blood samples of each piglet were collected and then piglets were euthanized.Results Dietary YH supplementation increased average daily feed intake and average daily gain(P<0.01),decreased the ratio of feed intake to gain of piglets(P sponse,evidenced by the increase o=0.048).Lipopolysaccharide(LPS)injection induced systemic inflammatory ref serum concentrations of haptoglobin(HP),adrenocorticotropic hormone(ACTH),cortisol,and interleukin-1β(IL-1β).Furthermore,LPS challenge resulted in inflammatory intestinal damage,by up-regulation of the protein or mRNA abundances of tumor necrosis factor-α(TNF-α),IL-1β,toll-like receptors 4(TLR4)and phosphor-nuclear factor-κB-p65(p-NFκB-p65)(P<0.01),and down-regulation of the jejunal villus height,the protein and mRNA abundances of zonula occludens-1(ZO-1)and occludin(OCC;P<0.05)in jejunal mucosa.Dietary YH supplementation decreased the impaired effects of ACTH,cortisol,HP,IL-1βand diamine oxidase in serum(P<0.05).Moreover,YH supplementation also up-regulated the jejunal villus height,protein and mRNA abundances of ZO-1 and OCC(P<0.05),down-regulated the mRNA expressions of TNF-αand IL-1βand the protein abundances of TNF-α,IL-1β,TLR4 and p-NFκB-p65 in jejunal mucosa in LPS-challenged pigs(P<0.01).Conclusion Yeast hydrolysate could attenuate inflammatory response and intestinal barrier injury in weaned piglets challenged with LPS,which was associated with the inhibition of TLR4/NF-κB signaling pathway activation.

Evaluation and selection of yeasts as potential aroma enhancers for the production of dry-cured ham

Yeasts play a critical role in the flavor formation of dry-cured ham.In this study,41 yeast isolates from the dry-cured ham at different processing stages were evaluated for their technological properties.Debaryomyces hansenii was the most dominant yeast and has been detected at each phase of dry-cured ham,followed by Candida zeylanoides which was mainly detected in salting phase.Yarrowia bubula and Yarrowia alimentaria were found at the first two-phase of dry-cured ham.All isolates of yeast showed enzymatic activities against milk protein and tributyrin,while only 4 strains displayed proteolytic activity on meat protein.Yeast strains were grown in a meat model medium and volatile compounds were identified.The result showed that inoculated yeast strains could promote the production of volatiles and there were significant differences among strains.D.hansenii S25 showed the highest production of volatile compounds,followed by the strain C.zeylanoides C4.D.hansenii S25 was the highest producer of alcohols showing the highest production of benzeneethanol and 3-(methylthio)-1-propanol.Based on OAV and PLS analysis,D.hansenii S25 was strongly correlated with overall flavor and key volatile compounds of dry-cured ham,which could be selected as potential starter cultures.

Dairy Farming Conditions and Utilization Levels of Liquid Brewers’ Yeast in Kenya

Dairy production plays an integral part in supporting smallholder farmers’ livelihoods. The desire to increase the number of dairy cattle is not feasible due to the reduced output of feed resources occasioned by climate change. Consequently, the need to increase productivity per cow is inevitable. Conventional protein supplements are costly;hence, the need to explore affordable nutrientdense alternative feed resources. Liquid brewers’ yeast (LBY), a by-product of the brewing industry, is a rich protein supplement in dairy production. This study aimed to assess the dairy farming conditions and utilization levels of LBY as a feed supplement in Githunguri Sub-county, Kiambu. Semi-structured questionnaires were administered to 457 dairy farmers in a cross-sectional survey. The findings revealed that most farmers (94.2%) fed their cattle on established forage/fodder and crop residues with supplementation. Even though 53.1% of the respondents were aware of the use of LBY, only 30.6% utilized it to supplement dairy cows, most of whom (96.0%) used it fresh without preservation. Membership in farmers’ organizations increased awareness of LBY (r = 0.732). Principal component analysis indicated that the benefits of using LBY outweigh the challenges involved with a loading matrix of 0.891 - 0.954 and 0.681 - 0.807, respectively. The low adoption and use levels of LBY as a source of protein supplements were due to low awareness. There is a need for concerted efforts by stakeholders in the industry to increase farmers’ knowledge base on the utilization and effectiveness of LBY in dairy production.

Growth performance,nutrient digestibility,intestinal morphology,cecal mucosal cytokines and serum antioxidant responses of broiler chickens to dietary enzymatically treated yeast and coccidia challenge

Background There is a growing search for natural feed additives to alleviate the deleterious effects of coccidia infection in poultry production.This study aimed to investigate the effect of enzymatically treated yeast(ETY) on the growth performance,nutrient digestibility,intestinal morphology,antioxidative status,and cecal mucosa cytokines of coccidia-challenged broiler chickens.Methods From d 1 to 14 post hatching,480 broiler chickens were allocated to 3 corn-soybean meal-based experimental diets with increasing concentrations of ETY(0,1,or 2 g/kg).The experiment was designed as a randomized complete block design with body weight(BW) used as a blocking factor.On d 14 post hatching,the birds were re-randomized within each of the 3 experimental diets.Each of the 3 diet groups was split into a challenge or no-challenge group.This resulted in a 3 × 2 factorial arrangement of treatments.The coccidia challenge was administered on d 15 by an oral gavage.Results Dietary ETY improved(P < 0.05) the G:F of birds on d 21 regardless of the challenge state and linearly increased(P < 0.01) the apparent ileal digestibility of dry matter(DM),nitrogen,and gross energy(GE).The coccidia challenge decreased(P < 0.05) BW gain and feed intake of broiler chickens and reduced(P < 0.01) the total tract retention of DM,GE,and nitrogen.The coccidia challenge increased(P < 0.01) the mRNA gene expression of TNFα,IL-1β,IL-10,and IL-6 in the cecal mucosa.There was a tendency(P ne = 0.08) for ETY to linearly reduce IL-1β expression.Additionally,ETY supplementation increased(P < 0.05) the geexpression of OCLN.Serum catalase increased(P < 0.05) with dietary ETY in broiler chickens on d 21.Dietary ETY linearly increased(P < 0.05) the ileal villus height to crypt depth ratio,and ileal goblet cell density in broiler chickens.The ileal and excreta oocyst counts decreased(P < 0.01) with increasing supplementation of dietary ETY in coccidia-challenged broiler chickens on d 21.Conclusions Dietary ETY enhanced nutrient utilization and augmented intestinal development in broiler chickens.However,dietary ETY did not completely attenuate the adverse effects of a coccidia challenge in broiler chickens.

Meta-Analysis Study of the Effects of Yeast Probiotic Supplementation on Milk Production and Energy Corrected Milk of Lactating Dairy Cows

The aim of this study was to use a meta-analytic approach to evaluate the effect of commercially available yeast probiotic “Actisaf®; Sc 47” (Saccharomyces cerevisiae CNCM I-4407) produced and marketed by Phileo by Lesaffre on milk performance in dairy cows. Data from 22 trials including 17 with parallel designs and 5 with cross-over designs were collected, and only data with parallel designs were analyzed. From those trials, 4 are published and 13 are from technical reports. In total, 34 comparisons and 1074 dairy cows met the criteria for inclusion in the final analysis of milk yield (MY). For energy corrected milk (ECM), six trials with 12 comparisons and 476 dairy cows met the criteria for inclusion in the final analysis. Because the data are from different trials with different conditions, the statistical model defined includes the fixed effect of the treatment (with vs. without Actisaf® Sc 47) and the random effect of the trial. The meta-analysis showed a moderate heterogeneity for MY and ECM. The random effect meta-analysis showed an estimated mean difference +1.72 kg/d [95% confidence interval (CI): 1.01 to 2.44] and +2.45 kg/d (95% CI: 1.73 to 3.17) for MY and ECM respectively, in favour of Actisaf® Sc 47. The analysis of data without trials conducted under heat stress conditions showed positive effect of Actisaf® Sc 47. The random effect meta-analysis showed an estimated mean difference of +1.69 kg/d [95% CI: 1.24 to 2.14] and +2.92 kg/d (95% CI: 2.45 to 3.40) for MY and ECM respectively, in favour of Actisaf® Sc 47. These observations provide strong evidence that this commercially available yeast probiotic can significantly improve milk performances of dairy cows under different conditions.

A systematic identification of cold tolerance genes in peanut using yeast functional screening system

Peanut(Arachis hypogaea L.)is a thermophilic crop,and low temperature leads to a significant reduction in annual yields.Despite a few cold tolerant germplasms or cultivars have been discovered and developed,molecular mechanisms governing peanut cold tolerance is poorly understood.Identification of keys genes involved in cold tolerance is the first step to address the underlying mechanism.In this study,we isolated and characterized 157 genes with potentials to confer cold tolerance in peanut by using a yeast functional screening system.GO(Gene ontology)and KEGG(Kyoto encyclopedia of genes and genomes)enrichment analysis of these genes revealed that ribosome and photosynthesis proteins might play essential roles in peanut cold response.Transcriptome results indicated that 60 cold tolerance candidate genes were significantly induced or depressed by low temperature.qRT-PCR analysis demonstrated that several candidate genes could be also regulated by salt or drought stress.Individual overexpression of two UDP-glycosyltransferases(AhUGT2 and AhUGT268)in transgenic yeast cells could enhance their tolerance to multiple abiotic stress.In conclusion,this study advances our understanding of the mechanisms associated with the cold stress responses in peanut,and offers valuable gene resources for genetic improvement of abiotic stress tolerance in crops.

ARTP-ALE Optimized Selection of Low Acetaldehyde Producing Brewer's Yeast and Fermentation Validation

Higher levels of acetaldehyde in beer are one of the major concerns in the current beer industry.Yeast produces acetaldehyde during alcoholic fermentation,and its modification significantly affects beer flavor and quality.A different mutant strain with lower acetaldehyde production and improved ethanol tolerance was constructed using the ARTP-ALE mutagenesis strategy with 4-methylpyrazole-disulfiram.As a result of the mutation,the alcohol dehydrogenase activity of the mutant strain decreased to about 71.22%of that of the wild-type strain.At the same time,the fermentation properties and genetic stability of the newly screened strain showed slight differences from the wild-type strain,and there were no safety concerns regarding industrial use of the mutant strain.

不同酵母发酵的白兰地基酒在蒸馏前后的香气分析

本研究旨在探究以不同酵母(71B、KD、F33、K1、FC9DP、D254、FC9)酿造的新疆产区的白兰地基酒及其新蒸馏白兰地原酒在挥发性风味物质及香气特征的差异。通过对不同样品进行全二维气相色谱-飞行时间质谱分析结合感官定量描述分析。结果显示,添加酵母D254的基酒香气物质总量最高,果香、花香、木质香气特征更突出;在蒸馏后,添加酵母FC9和FC9DP的酒样香气属性更为丰富,其中花香、果香、木质香气属性突出,此外,FC9DP酒样香气化合物相对含量也最高。对比蒸馏前后的基酒,结果显示,除了酚类化合物及内酯类化合物,大部分香气化合物的相对含量皆在蒸馏后有所增加,其中FC9DP样品的酯类、醇类、酸类及萜烯类化合物增加最为明显。此外,经过蒸馏,基酒去除了生青味和酸味的不良气味特征,香气品质有所改善。该研究可为白兰地酿造工艺的进一步改进提供数据参考。

酵母复合微生态制剂对鲤鱼生长性能、免疫指标及抗氧化能力的影响

本试验旨在研究饲料中添加酵母复合微生态制剂对鲤鱼生长性能、免疫指标及抗氧化能力的影响,并确定其适宜的添加量。选用初始体重为(35±0.5)g的鲤鱼540尾,随机分为6组,每组3个重复,每个重复30尾鱼,预饲14 d。以基础日粮为CK组,试验组分别饲喂含0.1‰、0.5‰、1‰、2‰、3‰酵母复合微生态制剂饲料,饲养56 d后采样分析。结果表明:(1)与CK组相比,饲料中添加酵母复合微生态制剂可显著提高鲤鱼的生长性能,2‰、3‰组增重率(WGR)增加了23.01%、24.15%(P<0.05),特定生长率(SGR)增加了13.79%、14.37%(P<0.05),饲料系数(FCR)降低了18.09%、18.59%(P<0.05)。(2)与CK组相比,饲料中添加酵母复合微生态制剂可显著提高鲤鱼的免疫指标,2‰、3‰组溶菌酶(LSZ)提高了47.9%、48.74%(P<0.05),免疫球蛋白M(IgM)提高了48.31%、49.44%(P<0.05),补体C3(C3)提高了39.61%、39.61%(P<0.05),碱性磷酸酶(AKP)提高了17.05%、17.44%(P<0.05),总蛋白(TP)提高了31.03%、30.38%(P<0.05)。(3)与CK组相比,饲料中添加酵母复合微生态制剂可显著提高鲤鱼的抗氧化能力,2‰、3‰组总抗氧化能力(T-AOC)提高了41.69%、41.36%(P<0.05),超氧化物歧化酶(SOD)提高了37.63%、45.71%(P<0.05),过氧化氢酶(CAT)提高了41.69%、41.36%(P<0.05),丙二醛(MDA)降低了22.71%、20.92%(P<0.05)。由此得出,饲料中添加2‰、3‰酵母复合微生态制剂能够显著提高鲤鱼的生长性能、血清免疫指标及肝脏抗氧化能力。基于2‰、3‰添加量组各指标差异不显著,建议酵母复合微生态制剂的最佳添加剂量为2‰。

基于非靶向代谢组学分析两种酵母培养物的成分差异

【目的】比较两种酵母培养物及其代谢成分的差异,为指导酵母培养物的生产及应用提供参考。【方法】材料为1种自研酵母培养物与达农威益康XP酵母培养物,利用非靶标代谢组学UHPLC-QTOF-MS技术,分析比较二者代谢产物成分及差异。【结果】(1)在二级类别注释下,正、负离子模式分别注释到614、497个化合物,主要代谢类别为有机酸,核苷、核苷酸及其衍生物,氨基酸及其衍生物,两种酵母培养物均无特有代谢成分,只在含量上有显著(P<0.05)差异。(2)共237个差异代谢物在正离子模式检出,176个显著(P<0.05)上调表达,61个显著(P<0.05)下调表达;136个差异代谢物在负离子模式检出,64个显著(P<0.05)上调表达,72个显著(P<0.05)下调表达。(3)差异代谢物的KEGG(Kyoto Encyclopedia of Genes and Genomes)富集分析主要集中在丙氨酸、天冬氨酸和谷氨酸等代谢通路。【结论】自研酵母培养物与达农威益康XP的代谢产物含量存在显著差异,但其发酵原料及工艺更简便,并含有多种具药理、生理作用的代谢成分,有潜在应用价值。

利用酵母双杂交筛选菠萝AcSWEET11的互作蛋白

SWEET(sugars will eventually be exported transporter)基因在植物开花过程中具有重要的作用,但AcSWEET11在菠萝成花中的作用机制尚不清楚。通过鉴定成花过程中与AcSWEET11的互作蛋白,为菠萝成花机制的解析奠定基础。本研究利用共转化的方法在菠萝成花过程的cDNA膜文库中筛选AcSWEET11的互作蛋白,分析候选蛋白的表达量。结果表明,pBT3-STE-AcSWEET11+pPR3-N对NMY51酵母细胞无毒性,但有自激活活性。进一步研究结果显示,在TDO/3?AT培养基和QDO培养基上自激活受到抑制。利用该系统筛选到了81个阳性克隆,经测序鉴定出48个与AcSWEET11互作的候选蛋白,包括E3 ubiquitin-protein ligase RING1-like、Trehalose-phosphate synthase 7、Cytochrome P450、TranscriptionfactorLUX等。GO和KEGG分析结果显示,48个蛋白主要分布在细胞进程、代谢过程、刺激反应和催化活性等生物过程,参与脂类代谢、氨基酸代谢和碳水化合物代谢、信号转导和运输与分解代谢等新陈代谢途径。Trehalose-phosphate synthase 7(XP_020105459.1)、Protein TIFY 3-like(XP_020082835.1)、40S ribosomal protein S27(XP_020092770.1)、Heterogeneous nuclear ribonucleoprotein 1-like(XP_020112516.1)等4个基因与AcSWEET11表达趋势一致,在菠萝成花过程中下调表达;Dihydrolipoyl dehydrogenase 2(XP_020113798.1)、Putative lipid-transfer protein DIR1(XP_020086640.1)、clathrin assembly protein At4g32285(XP_020108161.1)等3个基因在菠萝成花过程中上调表达。这些结果表明,AcSWEET11可能通过与Trehalose-phosphatesynthase7等蛋白发生互作,参与菠萝成花过程。本研究进一步丰富了AcSWEET11的蛋白互作网络,为AcSWEET11在菠萝成花中的调控机制的解析奠定基础。

传统酸马奶优势菌群互作及与风味物质的关联性

为研究酸马奶的优势菌群的互作以及菌群与特征风味的关系,对传统酸马奶中分离得到的4株乳酸菌和2株酵母菌进行单菌和混菌发酵,测定14组发酵组酸度,pH值,乳酸菌、酵母菌菌量变化,采用HS-SPME-GC-MS技术分析不同发酵组的挥发性风味物质的差异,并利用Lotka-Volterra模型和偏最小二乘法回归(PLSR)分析酸马奶中乳酸菌和酵母菌的相互作用系数以及优势菌群与特征风味物质形成的关联性。乳酸菌中干酪乳杆菌产酸速率最快,在发酵后期pH值达到3.89;酵母菌中,马克斯克鲁维酵母在发酵后期pH值降至4.16,混菌发酵组的产酸优于单菌发酵组。乳酸菌和单孢酿酒酵母混菌发酵促进单孢酿酒酵母的生长,其中植物乳杆菌、副干酪乳杆菌分别与单孢酿酒酵母混合发酵72 h后,酵母菌菌落数达到1.91×106CFU/mL和1.66×106CFU/mL;并能够促进辛酸、正癸酸等酸类风味物质的产生。而乳酸菌和马克斯克鲁维酵母混菌发酵形成竞争抑制,两者共发酵体系下对酯类物质辛酸乙酯、癸酸乙酯的产生有抑制作用,马克斯克鲁维酵母对产酸速率较快的干酪乳杆菌和副干酪乳杆菌的抑制作用强于瑞士乳杆菌和植物乳杆菌。

橡胶树形成层组织的酵母双杂交cDNA文库构建及HbHDA6互作蛋白筛选

次生乳管是天然橡胶合成和贮存的场所,是由橡胶树树干树皮中维管形成层细胞分裂分化而来。次生乳管的数量与天然橡胶产量直接相关,而这些乳管的数量取决于形成层分化次生乳管的频率(乳管分化能力),是橡胶树产量育种的主要指标。前期研究中,我们发现组蛋白去乙酰化酶(HDA)抑制剂曲古抑菌素A(TSA)能诱导橡胶树乳管分化且组蛋白去乙酰化酶基因(HbHDA6)能够参与橡胶树乳管分化调控。由于组蛋白乙酰化修饰调控橡胶树次生乳管分化的分子机制尚未阐明,因此该文使用冠菌素(COR)诱导橡胶树形成层分化产生次生乳管的实验系统,以分离形成层组织为材料,构建酵母双杂交cDNA文库,以HbHDA6基因为诱饵来筛选酵母双杂交文库,确定与HbHDA6相互作用的蛋白。结果表明:(1)利用Gateway技术构建的均一化COR诱导橡胶树形成层组织的酵母双杂交cDNA文库,初级文库的容量为6.34×10^(6)CFU·mL^(-1),总单克隆数为1.27×10^(7),文库重组率为100%;次级文库的容量为7.72×10^(6)CFU·mL^(-1),总单克隆数为1.54×10^(7),文库重组率为100%。初级文库和次级文库的插入片段平均长度分别为1.1 kb和1.2 kb。(2)成功构建了筛选HbHDA6互作蛋白的pGBKT7-HbHDA6诱饵载体,并确认无自激活活性。(3)使用该诱饵载体对构建的酵母双杂交cDNA文库进行筛选,并通过NCBI_BLAST比对和去除重复以后,获得了22个与HbHDA6发生互作的蛋白,包括CLP1、ERF3、ERF4、HSP82、LARP6a、APT5、PP2A、FBA6等。该研究成果为解析组蛋白乙酰化修饰调控橡胶树次生乳管分化的分子机制提供了理论基础,为转基因改良橡胶树的产胶潜力提供了候选基因,为高性能天然橡胶遗传改良育种提供了新线索。