氮源对酿酒酵母GJ2008不同糖浓度甘蔗汁酒精分批发酵的影响

研究了不同糖浓度下氮源对酿酒酵母GJ2008甘蔗汁酒精发酵的影响,旨在为高浓度甘蔗汁酒精发酵提供研究基础。将2 g/L尿素加入150 g/L、200 g/L、250 g/L、300 g/L和350 g/L总糖质量浓度甘蔗汁培养基中,以对应糖浓度未添加氮源组为对照组,通过分析细胞生长、糖代谢和乙醇生成来探究氮源如何影响甘蔗汁酒精发酵。结果表明：与未添加氮源相比,氮源加快了发酵速度,发酵周期最高缩短为18 h,糖消耗速率和乙醇生成速率最大分别提高了55%和96%;使酒精发酵更彻底,总糖含量最高减少了40.42 g/L;增加了目的产物,乙醇含量最高提升了28.4%。说明氮源有效地促进了甘蔗汁酒精发酵,加强了酵母的无氧呼吸途径。     

补加可同化氮对冰酒发酵的影响

利用初始糖质量浓度426.96 g/L、可同化氮质量浓度为347.49 mg N/L的威代尔冰葡萄汁,补加250mg/L商品氮源,接种0.4 g/L ST酵母,于18~20℃进行冰酒发酵。结果表明:与不补加氮源的冰酒发酵相比,补加可同化氮能加快糖消耗,且消耗量提高3.23%,可同化氮的消耗量降低10.03%,乙酸、乙醇、高级醇和酯类物质产量显著提高,分别提高5.44%、4.65%、9.89%和11.38%,对甘油生成无影响。因此,适量补加可同化氮对发酵过程的参数变化有一定影响,可以显著提高冰酒品质。     

基于柑橘浓缩汁的醋杆菌与酵母发酵特征

以柑橘浓缩汁为唯一原料,研究了葡糖醋杆菌和鲁氏酵母在单一或混合模式下的3种溶氧水平中的发酵特征。结果显示葡糖醋杆菌对糖的利用弱,最低残留总糖和还原糖分别为292.31 mg/m L和74.41 mg/m L,但将乙酸完全消耗。酵母对柑橘汁中的糖和乙酸消耗较彻底,同时乙醇最大积累水平为65.00 g/L(静置模式)。在共酵模式下,溶氧的改善使得糖在72 h~96 h几乎被消耗完,而接种比例的改变将导致发酵终点乙醇最大浓度(35.00 mg/m L)从间歇振荡模式转变为静置模式。只有在单一葡糖醋杆菌条件下,发酵终点的乙偶姻浓度维持在(125.36±13.73)μg/m L。可见,微生物种类、接种比例和溶氧水平对整个发酵过程均产生影响。最佳发酵条件是葡糖醋杆菌与鲁氏酵母混合间歇振荡模式发酵96 h,其总糖和还原糖浓度分别为130.56 mg/m L和37.85 mg/m L,乙醇和乙酸浓度分别为56.00 g/L和33.97μg/m L,乙偶姻浓度为34.02μg/m L。     

高产酸本土非酿酒酵母菌株的筛选及发酵性能研究

以25株本土非酿酒酵母菌为研究对象,采用酵母浸出粉胨葡萄糖（YPD）10培养基及Triple M改良模拟汁初筛,并进行耐受性（乙醇、SO2、糖及pH）测定及葡萄汁发酵,筛选能够有效增加葡萄酒酸度的优良本土非酿酒酵母菌。结果表明,非酿酒酵母菌株LT1及HU4产酸性能较好,具有较好的乙醇、SO2、糖和pH耐受性,其中菌株LT1能耐受乙醇体积分数12%、糖400 g/L及pH 2.75,菌株HU4能耐受乙醇体积分数6%vol、糖250 g/L及pH 2.75。菌株LT1和HU4在葡萄汁中启酵时间较短,发酵旺盛期CO2质量损失速率均＞0.8 g/（L·h）,乳酸产量分别为0.93 g/L、1.14 g/L,乙酸产量分别为0.38 g/L、0.42 g/L,具备酿造增酸葡萄酒的潜力。     

优化有机氮源提高小白链霉菌发酵生产ε-聚赖氨酸效率

ε-聚赖氨酸(ε-poly-L-lysine,ε-PL)是小白链霉菌(Streptomyces albulus)分泌产生的一种同型氨基酸聚合物,具有广泛的抑菌活性,目前被多个国家批准使用,是一种优良天然食品防腐剂。为了进一步提高S. albulus GS114的ε-PL发酵产量,对其发酵培养基中有机氮源的种类及浓度进行了系统优化,并对ε-PL产量提高的原因从氨基酸方面进行了初步解析。研究结果显示,S. albulus GS114的最佳有机氮源为酵母浸粉FM760,最佳添加质量浓度为9.27 g/L,在此条件下,摇瓶自然发酵中ε-PL产量达到(2.60±0.02) g/L,较对照有机氮源提高了22.07%;在pH受控的分批发酵中,ε-PL产量达到(6.41±0.23) g/L,较对照提高42.64%;在补料分批发酵中,ε-PL产量达到62.38 g/L,较对照提高了18.80%,葡萄糖转化率提高了25.77%。同时,通过氨基酸添加实验,初步发现酵母浸粉FM760提高ε-PL产量可能与异亮氨酸、亮氨酸和丙氨酸有关。该研究结果对工业发酵生产ε-PL的有机氮源选择具有重要指导意义。     

Actinobacillus succinogenes NJ113利用豆饼粉为氮源发酵制备丁二酸

考察了不同廉价氮源对A.succinogenes NJ113发酵产酸的影响,结果显示豆饼粉效果较佳。考察A.succi-nogenes NJ113以豆饼粉为氮源发酵制备丁二酸对菌体生长和产酸的影响。结果表明,A.succinogenes NJ113能够利用豆饼粉作氮源发酵制备丁二酸。单独以豆饼粉为氮源时菌体最多能消耗50 g/L初糖。在3 L发酵罐上进行分别以15.53 g/L豆饼粉和10 g/L酵母粉为氮源对A.succinogenes NJ113进行发酵,其中以豆饼粉为氮源时丁二酸产量为35.20 g/L,收率为70.40%,与酵母粉发酵效果相当,副产物甲酸、乙酸浓度分别由9.49 g/L和6.27 g/L降至4.44 g/L和1.14 g/L,乳酸浓度由0.44 g/L增加至2.91 g/L,发酵时间由20 h延长至48 h。以葡萄糖为碳源时,豆饼粉最多能替代6 g/L酵母粉进行发酵,并且最多能消耗100 g/L初糖,丁二酸产量达71.30 g/L。     

树干毕赤酵母CBS5773高浓度木糖发酵乙醇

研究了树干毕赤酵母CBS5773在高浓度木糖条件下发酵乙醇的情况,结果表明,在木糖浓度为200g/L时,树干毕赤酵母仍具有较高产乙醇能力,达0.48mL/10mL。单一添加硫酸铵作为氮源,考察不同pH值、温度、溶解氧对产乙醇的影响,发酵条件为pH4.5、25℃、130r/min时效果最佳。添加不同氮源试验结果表明,添加尿素比添加硫酸铵的效果高出25%,最佳发酵条件为木糖200g/L,蛋白胨0.5g/L,酵母浸膏1.0g/L,CaCl20.25g/L,MgSO40.25g/L,KH2PO42.5g/L,尿素1.0g/L,pH值为4.5,温度30℃,速率150r/min。     

优良本土戴尔有孢圆酵母的筛选及其在冰葡萄酒酿造中的应用

通过测定10株戴尔有孢圆酵母（Torulaspora delbrueckii）（编号为TD1～TD10）对葡萄糖、乙醇、酒石酸、SO2的耐受性能及其产β-葡萄糖苷酶性能,筛选发酵性能良好的戴尔有孢圆酵母,并将筛选菌株与酿酒酵母（Saccharomyces cerevisiae）ST混合发酵冰葡萄汁,最后对冰葡萄酒的基本理化指标进行测定。结果表明,除菌株TD2外,其他菌株均能够耐受葡萄糖500 g/L、乙醇体积分数4%、酒石酸16 g/L及SO2 350 mg/L,其中菌株TD6与TD9产β-葡萄糖苷酶活力较高,为优良本土戴尔有孢圆酵母。将菌株TD6、TD9分别与酿酒酵母ST混合发酵冰葡萄汁时均能在30 d内完成酒精发酵,且冰葡萄酒的基本理化指标均符合国标GB/T 25504—2010《冰葡萄酒》规定。此外,戴尔有孢圆酵母的接种对整个发酵过程的发酵速率与酿酒酵母的生长起到了一定的抑制作用,并且可以降低冰葡萄酒中乙酸和乙醇含量,提高总糖含量。     

海藻糖与赤藓糖醇偶联发酵工艺研究

对陶瓷膜过滤后的海藻糖糖化液进行成分分析，确定主要成分及营养指标。结合成分分析结果，补加氮源进行偶联发酵并对氮源补加量进行优化，在确定的最佳氮源添加量下进行小试工艺的研究与优化。结果表明，偶联发酵最适氮源补加量为酵母浸膏、酵母浸粉各3 g/L；偶联发酵能够实现消耗葡萄糖的目的，发酵72 h，对照组及补氮组残糖分别降至0.09 g/L、0.05 g/L。此外，补充氮源提升了赤藓糖醇得率，但赤藓糖醇水平较低，仅为25.4 g/L，糖醇转化率为30.70%。在补充氮源的基础上，向底料培养基补加葡萄糖至终浓度200 g/L进行发酵，赤藓糖醇得率大幅度提升，发酵液赤藓糖醇浓度提升至104.62 g/L，糖醇转化率50.18%，较优化前分别提升了97.32 g/L,42.26%。该优化偶联发酵工艺降低了下游海藻糖分离纯化的难度，提高了海藻糖的生产效益。本研究为其他稀有糖的生产提供了新的思路。     

活性干酵母活化时间与级数对葡萄酒发酵的影响

研究活性干酵母活化方式对葡萄酒发酵的影响。 分别将活性干酵母进行不同时间（25 min、3 h 15 min、24 h 15 min）和不同级 数（两级和三级）的活化,将等量的酵母种子活化液接种到24 °Bx模拟葡萄汁中,24 ℃条件下发酵18 d。 结果表明,活化3 h 15 min的酿 酒酵母生长代谢能力强,在葡萄汁中生长繁殖迅速,耗糖快;产乙醇较多（60.88 g/L）;产乙酸较少（0.77 g/L）。 进行三级3 h 15 min活化 的酵母活性高,活酵母菌浓度较大（最高4.53×107 个/mL）,不同级数活化的酵母在发酵过程中还原糖含量差异显著（P＜0.05）,CO2生 成量、乙醇和乙酸含量无显著差别（P＞0.05）。     

Fermentation properties of a wine yeast over-expressing the Saccharomyces cerevisiae glycerol 3-phosphate dehydrogenase gene (GPD2)

Wine yeasts efficiently convert sugar into ethanol. The possibility of diverting some of the sugar into compounds other than ethanol by using molecular genetic methods was tested. Over-expression of the yeast glycerol 3-phosphate dehydrogenase gene ( GPD2 ) in a laboratory strain of Saccharomyces cerevisiae led to an approximate two-fold increase in the extracellular glycerol concentration. In the medium fermented with the modified strain, acetic acid concentration also increased approximately two-fold when respiration was blocked. A strain deleted for the GPD2 gene had the opposite phenotype, producing lower amounts of glycerol and acetic acid, with the latter compound only reduced during non-respiratory growth. A commercial wine yeast over-expressing GPD2 produced 16.5 g/L glycerol in a wine fermentation, compared to 7.9 g/L obtained with the parent strain. As seen for the laboratory strain, acetic acid concentrations were also increased when using the genetically modified wine yeast. A panel of wine judges confirmed the increase in volatile acidity of these wines. The altered glycerol biosynthetic pathway sequestered carbon from glycolysis and reduced the production of ethanol by 6 g/L.     

咖啡渣酿酒酵母的筛选及氮源优化营养条件的研究

该文首先对比不同酵母菌酿造咖啡渣酒的产气、产酒精和产香能力,而后探究氮源的种类和浓度对酵母菌酿造咖啡渣酒的影响。结果表明,在备筛的4株酵母菌中,Saccharomyces cerevisiae D254产气能力、产酒精能力和发酵液的感官评分都较佳,适用于酿造咖啡渣酒;氮源的加入能有效解决咖啡渣酒发酵迟缓的问题,提高酵母菌生物量、酒体酒精度,降低残糖含量;其中添加0.20%磷酸氢二铵作氮源时效果最好,生物量由1.21 g/L增加至1.73 g/L,酒精度由7.3%vol增加至9.6%vol,残糖由19.52 g/L降低至5.73 g/L,且所得咖啡渣酒具有咖啡特有的芳香,酒体柔和协调。     

Altered Patterns of Maltose and Glucose Fermentation by Brewing and Wine Yeasts Influenced by the Complexity of Nitrogen Source

Maltose and glucose fermentations by industrial brewing and wine yeasts strains were strongly affected by the structural complexity of the nitrogen source. In this study, four Saccharomyces cerevisiae strains, two brewing and two wine yeasts, were grown in a medium containing maltose or glucose supplemented with a nitrogen source varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Diauxie was observed at low sugar concentration for brewing and wine strains, independent of nitrogen supplementation, and the type of sugar. At high sugar concentrations altered patterns of sugar fermentation were observed, and biomass accumulation and ethanol production depended on the nature of the nitrogen source and were different for brewing and wine strains. In maltose, high biomass production was observed under peptone and casamino acids for the brewing and wine strains, however efficient maltose utilization and high ethanol production was only observed in the presence of casamino acids for one brewing and one wine strain studied. Conversely, peptone and casamino acids induced higher biomass and ethanol production for the two other brewing and wine strains studied. With glucose, in general, peptone induced higher fermentation performance for all strains, and one brewing and wine strain produced the same amount of ethanol with peptone and casamino acids supplementation. Ammonium salts always induced poor yeast performance. The results described in this paper suggest that the complex nitrogen composition of the cultivation medium may create conditions resembling those responsible for inducing sluggish/stuck fermentation, and indicate that the kind and concentration of sugar, the complexity of nitrogen source and the yeast genetic background influence optimal industrial yeast fermentation performance.     

有机酸含量对葡萄酒发酵的影响

为了考察有机酸含量对葡萄酒发酵的影响,在初始有机酸含量分别为4 g/L、7 g/L和10 g/L的模拟葡萄汁中接种酵母,于25 ℃发酵,比较不同初始有机酸含量对葡萄酒发酵过程中酵母生长、降糖、有机酸及挥发性化合物含量的影响。结果表明,初始有机酸含量7 g/L时酵母生长和耗糖最慢,乙醇和乙醛产生量最低;随初始有机酸含量升高,pH值、酒石酸、苹果酸、乳酸、乙酸、总酸、乙酸乙酯和总酯含量呈下降趋势;琥珀酸、正丙醇、异丁醇、异戊醇及总高级醇含量呈上升趋势;但对β-苯乙醇、正丁醇及丁酸乙酯含量影响较小。初始有机酸含量10 g/L的葡萄酒发酵过程酵母生长快、降糖最快,产酸含量适中,同时香气较好。因此,葡萄酒发酵的适宜初始有机酸含量为10 g/L。     

葡糖醋杆菌J2-1静态发酵生产细菌纤维素的培养基优化

为提高葡糖醋杆菌（Gluconacetobacter）J2-1发酵生产细菌纤维素的产量,采用静态发酵方式,利用单因素试验对发酵培养基的碳源、氮源、乙醇、有机酸及无机盐进行优化,并在此基础上选取葡萄糖、MgSO4·7H2O和酵母粉添加量进行正交试验优化。结果表明,发酵培养基最优组分为：葡萄糖80 g/L、酵母粉18 g/L、乙醇2%（V/V）、Na2HPO4·12H2O 3 g/L、乳酸2 g/L、MgSO4·7H2O 0.4 g/L。在此优化发酵培养基条件下,葡糖醋杆菌J2-1静态发酵生产细菌纤维素产量达到9.34 g/L,是优化前的1.89倍。     

有机氮和酵母细胞壁对赤霞珠高糖原料酒精发酵的影响

以高糖度葡萄汁（总糖为286.2 g/L）为发酵原料,对比酵母源有机氮FN502和酵母细胞壁CW101的不同添加时期对葡萄酒酵母酒精发酵速度、乙酸产量、最终酒精度及葡萄糖、果糖残留量的影响。结果表明,在酒精发酵进行1/3时同时添加有机氮FN502和酵母细胞壁CW101（各200 mg/L）,或在酒精发酵进行1/3时添加有机氮FN502（200 mg/L）,进行2/3时添加酵母细胞壁CW101（200 mg/L）,对葡萄酒酵母的酒精发酵速度及果糖消耗促进作用均高于对照及二者分别单独使用,最终酒精度均为16.9%vol,总残糖分别为1.50 g/L和1.58 g/L。有机氮FN502和酵母细胞壁CW101的添加均可显著降低乙酸的产量（P＜0.05）。     

不同洁净度葡萄的葡萄酒发酵效果研究

使用武宣地区3种红曲米作为发酵剂酿造红曲柿酒，分析其理化指标和挥发性风味成分差异，并采用Illumina MiSeq高通量测序技术检测3种红曲米的细菌多样性，以解析不同细菌群落在红曲柿酒发酵过程中的作用。结果表明，不同红曲柿酒总酸和挥发酸含量差异显著（P＜0.05）；挥发性酸类物质组成存在较大差异，其中红曲米样品WX-2制成的红曲柿酒挥发性酸类物质含量最高（10.0%）。从3种红曲米样品共检测出19个细菌门，239个细菌属，共有优势菌门为变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）、拟杆菌门（Bacteroidetes）、放线菌门（Actinobacteria）；共有优势菌属为伯克霍尔德菌属（Burkholderia）、克雷伯氏菌属（Klebsiella），WX-2样品中优势菌属还有醋菌属（Acetobacter）、小球菌属（Pediococcus）、乳酸杆菌属（Lactobacillus），均为产酸菌株。表明红曲米细菌群落结构与红曲柿酒酸类物质的形成紧密相关。     

模拟葡萄汁中可同化氮和还原糖对酵母发酵特性的影响

为研究葡萄汁中可同化氮和还原糖对酵母发酵特性的影响,设计150、240、330、420、500?mg/L可同化氮质量浓度和170、200、230?g/L还原糖质量浓度,共计15?个处理,测定了模拟葡萄汁酒精发酵过程中酵母生长、还原糖消耗和可同化氮消耗的变化。结果表明,模拟汁中可同化氮质量浓度过低（150?mg/L）则不能充分满足酵母生长的需要,同时限制了酵母的还原糖消耗速率,通过提高初始还原糖质量浓度至200?g/L可促进酒精发酵进行;酵母在初始可同化氮质量浓度高于240?mg/L的模拟汁中可以正常生长,此时初始还原糖、可同化氮质量浓度对酵母生长量均无显著影响,还原糖含量最直接影响酿酒酵母菌株的发酵特性,决定发酵时间长短,表现为在初始还原糖质量浓度较低（170?g/L）的模拟汁中,酵母生长速率随着模拟汁初始可同化氮质量浓度的升高而加快,在初始还原糖质量浓度较高（200～230?g/L）的模拟汁中,酵母生长速率不受初始可同化氮质量浓度的影响;当模拟汁初始可同化氮质量浓度高于330?mg/L时,酵母对可同化氮的消耗开始出现剩余,剩余量随着模拟汁初始可同化氮质量浓度的升高而增加,此时可同化氮质量浓度能够充分满足酵母可同化氮代谢的需要,且酵母对可同化氮消耗量随着初始还原糖质量浓度的增加而略有减少。     

Decreasing acetic acid accumulation by a glycerol overproducing strain of Saccharomyces cerevisiae by deleting the ALD6 aldehyde dehydrogenase gene

Glycerol is a major fermentation product of Saccharomyces cerevisiae that contributes to the sensory character of wine. Diverting sugar to glycerol overproduction and away from ethanol production by overexpressing the glycerol 3-phosphate dehydrogenase gene,GPD2, caused S. cerevisiae to produce more than twice as much acetic acid as the wild-type strain (S288C background) in anaerobic cell culture. Deletion of the aldehyde dehydrogenase gene, ALD6, in wild-type and GPD2 overexpressing strains (GPD2-OP) decreased acetic acid production by three- and four-fold, respectively. In conjunction with reduced acetic acid production, the GPD2-OP ald6Delta strain produced more glycerol and less ethanol than the wild-type. The growth rate and fermentation rate were similar for the modified and wild-type strains, although the fermentation rate for the GPD2 ald6Delta strain was slightly less than that of the other strains from 24h onwards. Analysis of the metabolome of the mutants revealed that genetic modification affected the production of some secondary metabolites of fermentation, including acids, esters, aldehydes and higher alcohols, many of which are flavour-active in wine. Modification of GPD2 and ALD6 expression represents an effective strategy to increase the glycerol and decrease the ethanol concentration during fermentation, and alters the chemical composition of the medium such that, potentially, novel flavour diversity is possible. The implications for the use of these modifications in commercial wine production require further investigation in wine yeast strains.