马克斯克鲁维酵母的中试发酵研究

对马克斯克鲁维酵母（Kluyveromyces marxianus）的细胞积累展开中试发酵,并且在其培养过程中研究菌体的生长情况以及呼吸参数和代谢产物的变化规律。结果表明,通过摇瓶和3 L发酵罐的分批培养,从6株马克斯克鲁维酵母中确定了马克斯克鲁维酵母菌株F#在生长方面更具优势。利用带有尾气分析仪的50 L发酵罐对菌株F#进行分批培养和流加培养,确定了菌株F#存在Crabtree效应。并且通过线上监测呼吸商（RQ）、发酵液pH和溶氧的变化情况,以合适的补料工艺减弱了菌株F#的Crabtree效应,培养12 h后细胞干质量达（54.37±3.3）g/L,实现了细胞的大量积累,对马克斯克鲁维酵母的工业生产具有一定指导意义。     

马克斯克鲁维酵母木薯乙醇发酵工艺研究

通过单因素试验对一株耐高温马克斯克鲁维酵母（Kluyveromyces marxianus）HY32的木薯乙醇发酵工艺进行了研究。结果表明,HY32利用木薯发酵乙醇的最佳工艺条件为料水比1∶5（g∶mL）,发酵时间96 h,接种量11%,发酵温度40 ℃,液化时间1 h,液化温度95 ℃,液化酶添加量为20 U/g淀粉,糖化酶添加量为150 U/g淀粉,硫酸铵添加量6 g/L,初始pH=5.0。在此条件下,HY32发酵木薯酒精度可达8.90%vol,淀粉利用率与淀粉出酒率分别为87.120%和49.48%,残糖量为0.03 g/L。与未优化的初始发酵条件相比,发酵醪的酒精度提高了16.65%。     

马克斯克鲁维酵母固态发酵菊粉酶培养条件的优化

在单因素试验基础上,为进一步提高马克斯克鲁维酵母固态发酵产生的菊粉酶的活力,采用全因子试验设计和中心组合设计对影响的因素进行优化,运用响应面分析模拟得到二次多项式回归方程的预测模型,优化的培养条件为：菊芋粉3．62％,玉米浆干粉2．40％,培养温度28．13℃。模型预测的最大响应值为314．71U／gds,在优化条件下酶活为316．35U／gds,二者基本一致。     

马克斯克鲁维酵母与酿酒酵母混合发酵对液态法黄酒风味的影响

以糯米糖化液为发酵基质,对马克斯克鲁维酵母(Kluyveromyces marxianus)HY32在不同发酵温度、不同通气条件以及与酿酒酵母(Sacchromyces cerevisiae)TRADY混合发酵对黄酒风味物质和感官的影响进行了研究.结果表明,HY32在37℃下发酵的黄酒的乙醇体积分数为7.13％,是28...     

PCRDGGE技术分析混菌发酵乳中马克斯克鲁维酵母与乳酸菌的相互作用

利用变性梯度凝胶电泳(Denaturing Gradient Gel Electrophoresis,DGGE)技术,对混菌发酵及贮藏过程中马克斯克鲁维酵母与乳酸菌之间的相互作用进行分析,进而对整个过程中微生物优势菌群及其稳定性进行跟踪监测。结果表明:混菌发酵及贮藏过程中微生物组成比较稳定,优势菌为嗜热链球菌(Streptococcus thermophilus,ST);发酵过程中,马克斯克鲁维酵母(Kluyveromyces marxianus)的添加对乳酸菌生长起到促进作用,尤其是对保加利亚乳杆菌(Lactobacillus bulgaricus,LB)效果显著,贮藏期间该作用转变为抑制;整个过程乳酸菌的存在对酵母菌的生长具有一定的抑制作用。该研究可为深入探讨乳酸菌与酵母菌共同发酵机理及新型发酵乳制品的开发提供理论基础。      

马克斯克鲁维酵母发酵产β-葡聚糖工艺优化

以马克斯克鲁维酵母为原料,研究马克斯克鲁维酵母发酵产β-葡聚糖的工艺。通过正交试验确定马克斯克鲁维酵母发酵产β-葡聚糖的培养基最佳配比,即葡萄糖用量为3.0%,酵母膏用量为2.5%,蛋白胨用量为1.0%,吐温-80用量为0.3%。以确定的最佳培养基,通过响应面分析法确定马克斯克鲁维酵母产β-葡聚糖的最佳发酵条件,接种量为5.2%,装瓶量31.3%,p H为5.1,发酵温度为31.9℃,β-葡聚糖得率达到6.03%。     

马克斯克鲁维酵母发酵苹果酒的化学成分与抗氧化活性

近年来,由于非酿酒酵母属酵母发酵能够产生更多的风味物质,备受酿酒师的青睐。马克斯克鲁维酵母(Kluyveromyces marxianus)是一种食品安全级的非常规酵母,可用于生产生物酶、木糖醇和芳香化合物等。该研究以Saccharomyces bayanus SAF作为对照,通过发酵苹果酒的化学成分和抗氧化活性对比分析,研究了K.marxianus酿造苹果酒的特征。在25～35℃条件下,K.marxianus能够在96 h内完成乙醇发酵,产量约56.8 g/L。顶空固相微萃取-气相色谱-质谱(head space-solid phase micro-extraction gas chromatography-mass spectrometry, HS-SPME-GC-MS)分析结果表明,K.marxianus发酵产生的乙酸-3-甲基-1-丁酯、辛酸乙酯、己酸乙酯等酯类物质的均高于S.bayanus。2种苹果酒液相色谱-质谱联用仪(liquid chromatograph mass spectrometer, LC-MS)分析鉴定出41种抗氧化成分,其中K.marxianus苹果酒的总...     

马克斯克鲁维酵母与酿酒酵母协同发酵米酒的特性

该文将非酿酒酵母马克斯克鲁维酵母C21(Kluyveromyces marxianus C21)与酿酒酵母1578(Saccharsaccharus cerevisiae 1578)应用于液态发酵米酒中,通过发酵米酒的理化指标、生物量、感官品质及响应面优化试验,研究两株酵母混合液态发酵米酒的特性及其最佳发酵工艺。结果表明：K. marxianus C21发酵米酒在48 h时其生物量及β-葡萄糖苷酶活性最高,与酿酒酵母1578的最佳接种比例为1∶1（质量比）,最佳接种方式为混合顺序接种,该条件下米酒的乙酸乙酯含量及酒精度较优。最佳工艺参数为料液比1∶4(g/mL)、发酵时间74 h、发酵温度25℃,混合酵母添加量0.2%,最终米酒感官评分为98,乙酸乙酯含量为13.06 g/L,酒精度为3.13%vol。综上表明,采用非酿酒酵母和酿酒酵母混合顺序发酵可明显改善米酒的香气及口感。     

马克斯克鲁维酵母高密度发酵条件的优化研究

对影响马克斯克鲁维酵母高密度发酵的培养基营养成分和培养条件展开分析研究。单因素实验发现,YPD作为基础培养基有利于马克斯克鲁维酵母的增殖;培养基成分响应面分析和培养条件正交实验结果表明,当培养基成分为蔗糖67.37 g/L,酵母浸粉29.7 g/L,玉米浆15.61 g/L,KH₂PO₄4.13 g/L,MgSO₄0.3 g/L,初始pH为6.0、发酵温度为30℃、搅拌速度为160 r/min时,发酵培养18 h马克斯克鲁维酵母的生物量最大,为（9.34±0.12）g/L。进一步进行乳饮品发酵实验,优化培养的马克斯克鲁维酵母与乳源培养基培养的马克斯克鲁维酵母,在菌种的生物量和乳饮品的口感风味上无明显差异。因此,优化后的高密度发酵培养基配方和工艺条件适宜于马克斯克鲁维酵母菌的高密度发酵。      

克鲁维酵母固体发酵高产菊粉酶的研究

首次利用固体发酵对筛选得到的一株克鲁维酵母S120高产菊粉酶的发酵工艺进行了初步研究。结果表明：麸皮是菌株S120产酶的最适基质,10％菊芋粉和0．5％硫酸铵有助于产酶;优化培养条件为：在300ml三角瓶中装料量20．0g,含水量为66％（V／W）,起始pH5．7,培养温度34℃,接种量3．9％（V／W）,发酵72h,菊粉酶酶活为118．28U／g（干重）。菌株S120菊粉酶的合成属于延续合成型,在工业生产中具有应用前景。     

发酵豆渣上清液对高脂HepG2细胞糖脂代谢的影响

为减少豆渣资源的浪费,研究发酵豆渣上清液(FOS)的功能活性。以马克斯克鲁维酵母C21为发酵菌株,发酵豆渣制备FOS。在分析FOS活性成分的基础上,评价其抗氧化能力和体外改善糖脂代谢紊乱的效果及机制。结果表明,FOS中可溶性总糖、游离氨基酸和总酚的含量显著升高,相较于未发酵豆渣上清液(NFOS)分别提高了13.52%,507.95%和16.67%,且总抗氧化能力为8.57 μmol Fe2+/mL,比发酵前提升了39.15%。油酸诱导的高脂HepG2细胞试验结果表明,与NFOS相比,FOS的干预显著降低了细胞中的脂滴数量以及甘油三酯(25.39%)和总胆固醇(26.90%)含量,提高了细胞的葡萄糖消耗量(46.77%)和胞内糖原(51.29%)含量。免疫印迹结果显示,400 μg/mL FOS能够显著上调糖脂代谢相关蛋白的表达,PPARα、IRS1和GLUT4与NFOS相比分别上调了30.89%,127.16%和22.84%。结论:FOS能够显著改善油酸诱导的HepG2细胞糖脂代谢紊乱,通过激活PPARα、IRS1和GLUT4蛋白的表达,减少细胞内的脂质蓄积并增强细胞的葡萄糖摄取能力,说明FOS在预防和改善肥胖引起的高脂血症和2型糖尿病方面具有潜在作用。     

马克斯克鲁维酵母菊粉酶的分离纯化和酶学性质研究

马克斯克鲁维酵母产生的孢外菊粉酶经超滤浓缩、DEAE-Cellulose阴离子交换色谱、SephadexG-100凝胶色谱分离纯化,得到两个菊粉酶组分ExoⅠ和ExoⅡ,I/S值分别为0.0249和0.0253,均属外切菊粉酶。ExoⅠ经聚丙烯酰胺凝胶鉴定为均一组分,分子量为85kD。ExoⅠ最适pH值为4.0,最适温度为60℃,Mn2+和Mg2+对酶活力有促进作用,而Cu2+、Fe2+对酶活力有抑制作用,ExoⅠ水解菊粉溶液的产物为果糖和少量葡萄糖。     

Batch kinetics and modelling of ethanolic fermentation of whey

The fermentation of whey by Kluyveromyces marxianus strain MTCC 1288 was studied using varying lactose concentrations at constant temperature and pH. The increase in substrate concentration up to a certain limit was accompanied by an increase in ethanol formation, for example, at a substrate concentration of 10 g L^?1, the production of ethanol was 0.618 g L^?1 whereas at 50 g L^?1 it was 3.98 g L^?1. However, an increase in lactose concentration to 100 g L^?1 led to a drastic decrease in product formation and substrate utilization. The maximum ethanol yield was obtained with an initial lactose concentration of 50 g L^?1. A method of batch kinetics was utilized to formulate a mathematical model using substrate and product inhibition constants. The model successfully simulated the batch kinetics observed at S₀ = 10 and 50 g L^?1 but failed in case of S₀ = 100 g L^?1 because of strong substrate inhibition.     

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。     

低乳糖芒果风味发酵乳制作工艺研究

以生牛乳、芒果泥为原料,通过试验对低乳糖芒果风味发酵乳产品配方及乳化稳定剂的复配方案进行了研究。结果表明:低乳糖芒果风味发酵乳最优配方为白砂糖8.0%、乳清蛋白粉1.0%、芒果泥5.0%、芒果香精0.04%、乳糖酶0.025%;产品最佳稳定剂为羟丙基二淀粉磷酸酯0.4%、明胶0.15%、琼脂0.1%。在该配方及稳定体组合条件下,可获得口感优良,风味合适,货架期质量稳定的低乳糖芒果风味发酵乳。     

Lactose oxidase: A novel activator of the lactoperoxidase system in milk for improved shelf life

The lactoperoxidase system (LS), an antimicrobial system naturally present in milk that is activated by H₂O₂, has been used to inhibit microbial outgrowth in raw milk in areas where refrigeration is not viable. This study evaluated lactose oxidase (LO) as a novel activator of the LS. Lactose oxidase oxidizes lactose and produces H₂O₂ needed for the activation of the LS. The antimicrobial effect of different concentrations of LO with and without components of the LS, thiocyanate (TCN) and lactoperoxidase (LP), was evaluated in model systems and then applied in pasteurized milk and raw milk. In general, an increase in LO caused greater reductions of Pseudomonas fragi in the model systems and treatments were more effective at 6°C than at 21°C. At 6°C, the LO solution at 0.12 and 1.2 g/L showed significantly higher microbial reduction than the control when both added alone and combined with LS components. At 21°C, treatments with 1.2 g/L of LO solution achieved a reduction of >2.93 log cfu/mL in 24 h, but at lower levels there was not a significant reduction from the control. Higher concentrations of TCN led to a greater P. fragi reduction at both temperatures when LO was added alone but not when combined with LP. In pasteurized milk, the LO solution at 0.12 g/L caused a reduction of approximately 1.4 log of P. fragi within 24 h when added alone and a reduction of approximately 2.7 log when combined with LP and TCN. Bacterial counts remained at significantly lower levels than the control during storage, and the TCN-supplemented milk exhibited an approximately 6-log difference from the control by d 7. In raw milk, the total bacterial growth curve showed a longer lag phase when the LS was activated by LO (11.3 ± 1.4 h) compared with the control (4.0 ± 1.0 h), but it was not different from the recommended method (9.4 ± 1.0 h). However, the total bacterial count after 24 h for the sample treated with LO and TCN (5.3 log cfu/mL) was significantly lower compared with the control (7.2 log cfu/mL) and the recommended method (6.1 log cfu/mL). Results from this study suggest that LO is an alternative source of H₂O₂ that enhances the microbial inhibition achieved by the LS. Lactose oxidase could be used to develop enzyme-based preservation technologies for applications where cold chain access is limited. This enzymatic approach to improving the shelf life of dairy products also represents a novel option for clean label spoilage control.     

Assay Conditions Effect on β-Galactosidase Activity from Kluyveromyces lactis

β-galactosidase, derived from Kluyveromyces lactis was assayed for activity using lactose, buffered at pH 6.5 with 0.02M potassium phosphate, and reconstituted nonfat dry milk (NFDM) substrates. Variations in buffer strength, potassium ion concentration and water quality were evaluated. Assay under similar conditions using NFDM and buffered lactose resulted in 4.3 and 6.6 units of activity, respectively. Increasing buffer strength to 0.1M potassium phosphate resulted in a 20% decrease in lactase activity units. Addition of potassium ions, as 0.5M KC1, in the enzyme preparation resulted in an increase in observed activity using both assay systems with a greater impact (160% increase) using NFDM vs buffered lactose (120% increase) as the substrate.