高产酵母菌Co-158生理特性研究

对经60Co诱变筛选得到的高产酒精酵母Co-158菌株的耐酒精性、耐糖性、耐酸性、耐盐性进行研究,结果表明,Co-158菌株耐酒精能力强,在含乙醇19%vol的麦芽汁培养基中10h可发酵;耐糖能力高,在葡萄糖浓度达到55%(w/v)时可发酵;耐酸碱能力强,在pH值为2.5～13.0范围内可发酵;耐盐能力强,在11%(w/v)盐溶液中仍然可发酵.     

柿中酿酒酵母的筛选及其耐性研究

为筛选出柿子中的酵母菌,从不同分离源筛选分离得到50多株酵母菌.通过模拟预发酵进行酵母菌的初筛选,并进行复筛、耐性实验,得到了1株酵母菌,编号为Hss-7;对Hss-7菌株的耐性进行了研究,结果表明,Hss-7菌株有很好的耐酒精、糖、盐、酸碱的特性,同时其对几种主要的副产物乳酸、乙酸、甘油都有很好的耐受性.     

几株酒精酵母的发酵性能比较

酵母菌种的好坏直接影响产品质量、设备利用率和产品产量，从而影响企业的经济效益。对1308菌株、1300菌株、安琪超酒酵母、奥特奇酵母产酒精的发酵、耐乙酸、耐乳酸、耐受酒精能力、耐受温度、耐渗透压、耐pH进行了发酵实验比较。结果表明，1308菌株、1300菌株、安琪超酒酵母、奥特奇酵母各有优缺点；菌株1308及安琪超酒酵母生产性能良好。     

基于途径分析的产甘油有孢汉逊酵母菌株的选育

以葡萄汁有孢汉逊酵母（Hanseniaspora uvarum）GF-23为出发菌株,对其甘油的合成代谢途径进行分析并提出育种策略。 对 菌株GF-23进行诱变筛选,最终得到一株耐高渗高产甘油的葡萄汁有孢汉逊酵母突变菌株GY-1。结果表明,突变菌株GY-1的耐氯化 钠质量浓度达到50 g/L,在酵母浸出粉胨葡萄糖（YPD）培养基中培养2 d时,甘油产量为0.44%,是出发菌株的3.33倍;接种在葡萄汁中 发酵6 d后,甘油产量达到0.49%,是出发菌株的4.45倍。 葡萄发酵液中的残糖量为3.03 g/L,酒精度为3.86%vol,说明突变菌株GY-1能 够适用于葡萄酒的发酵。 对突变菌株连续传代5次以上,其遗传性状稳定且甘油产量均无明显变化。     

米根霉产L-乳酸耐温菌株的60Co-γ射线诱变选育

目前产L-乳酸的米根霉菌株的最适发酵温度为32℃,该温度较低,不利于产物分离且易染杂菌。以米根霉As3.819为出发菌株,采用60Co-γ射线进行诱变处理,以正突变率为指标,诱变剂量为400Gy,通过筛选得到耐38℃高温的5号突变株mut-5,经连续传代7次,遗传性状稳定。与出发菌株相比,发酵72h后,mut-5突变株发酵液中的乳酸含量提高了24.15%,乙醇含量降低了9.27%。乳酸脱氢酶(LDH)比活力提高了39.41%,乙醇脱氢酶(ADH)比活力有所下降,而对还原糖的利用速率以及生物量的积累均高于出发菌株。     

不同有机酸碳源对混合菌株产酸的影响

利用从优质窖泥中分离得到的多种菌株进行混合菌株发酵研究。以改良巴克培养基为基础，分别用甲酸、乙酸、丙酸、丁酸、戊酸、乳酸以及不同两种酸的组合为碳源，通过气相色谱分析研究其产酸情况。结果发现以甲酸、戊酸以及甲酸和其他各酸混合作为碳源，只有少量己酸及其他酸产生；乙酸、丙酸、乳酸能很好地被混合菌株利用，以乙酸＋乳酸、乙酸＋丁酸，丙酸＋乳酸，丙酸＋丁酸为碳源，对乙酸的生成有明显的促进作用；混合菌株对底物的     

酱油发酵酱醅中耐盐乳酸菌的分离筛选及产酸特性

对酱油酱醅中耐盐乳酸菌进行分离鉴定,并对分离菌株在不同培养条件下产乳酸能力进行研究。采用加CaCO3和NaCl梯度平板MRS培养基对酱醅中耐盐乳酸菌进行分离、筛选,并结合形态学指标及16SrDNA序列分析对其进行鉴定,研究了分离菌株不同发酵温度、NaCl质量浓度、pH条件下的产乳酸特性。实验结果表明:分离获得的耐盐乳酸菌菌株为德氏乳杆菌保加利亚亚种(Lactobacillus bulgaricus)。该菌株最适发酵温度为38℃,在NaCl质量浓度18 g/dL的条件下,产乳酸量可达22.68 g/L,在中性及偏碱性条件下均能较好地合成乳酸。     

细菌L-乳酸发酵的研究--耐高糖高酸菌株的选育

本文主要研究了L-乳酸发酵中耐高糖高酸菌株的选育及所选菌株的发酵特性情况.结果表明,出发菌株经离子注入诱变后,其生长的临界乳酸和葡萄糖浓度分别为24g/L和150g/L,并经耐高糖高酸的选育和驯化后,得到一株在产酸速率和最终L-乳酸产量方面都比原始对照菌株高的目的菌株LB1-1,其最终L-乳酸产量达到70g/L,出发菌株为43g/L.     

乙醇及有机酸对木醋杆菌合成细菌纤维素的影响

研究了乙醇、草酸、酒石酸、丙酮酸、苹果酸、乳酸、乙酸、柠檬酸、丁二酸对木醋杆菌产细菌纤维素的影响。结果发现:丙酮酸、乳酸、乙酸、乙醇、苹果酸、柠檬酸、丁二酸对木醋杆菌合成细菌纤维素有促进作用;草酸、酒石酸对木醋杆菌合成细菌纤维素有抑制作用;乙醇及各有机酸的最佳添加浓度分别为:丙酮酸0.15%,苹果酸0.1%,乳酸0.3%,乙酸0.4%,柠檬酸0.1%,丁二酸0.2%,乙醇4%;由正交实验得混酸的最适添加配比为:丙酮酸0.1%,苹果酸0.12%,乳酸0.2%,乙酸0.3%,柠檬酸0.12%,丁二酸0.2%,乙醇3%,BC产量达3.012g/L,是空白实验组的2.03倍。     

中和剂对大肠杆菌工程菌HBUT-L16发酵产L-乳酸的影响

该文对前期构建的产高光学纯度L-乳酸的大肠杆菌工程菌HBUT-L进行了耐乳酸钠的驯化,并对驯化前后菌株发酵产L-乳酸的中和剂进行了选择和对比。结果表明,经过28代驯化后的菌株HBUT-L16以Ca（OH）2作中和剂时发酵效果较NaOH为中和剂时效果好,L-乳酸产量、糖酸转化率及生产强度分别提高了6.6%、5.6%、44.4%。与驯化前菌株HBUT-L的发酵结果相比,HBUT-L16以Ca（OH）2为中和剂进行发酵时,乳酸产量提高了4.4%,糖酸转化率提高了2.8%,生产强度增加了26.71%;而以NaOH为中和剂时,对驯化前后菌株的发酵效果影响不大,由此推测耐乳酸钠的驯化主要通过提高工程菌对乳酸根的耐受性而非钠离子的耐受性,来提高L-乳酸的产量。     

Co60诱变原生质体选育高产酒精酵母

将较高产酒精酵母制备成原生质体,经Co^60诱变后,采用四级筛选,得到高产酒精酵母菌株Co-158,其遗传性状稳定。以玉米粉糖化醪为基质发酵72h,成熟醪酒精体积分数为17～％（v／v）,残还原糖为0．0137％。Co-158菌;洙成熟醪酒精体积分数比出发菌株提高了16．34％,比ADY提高了24．48％,残还原糖含量亦远远低于出发菌株和ADY。     

酱香型白酒耐乳酸酵母的筛选及特性研究

该研究从酱香型白酒发酵酒醅中筛选一株高乳酸耐受性的酵母菌进行菌种鉴定,并比较该菌株与模式菌株ATCC6258及用于白酒酿造菌株CICC1926对乳酸的耐受特性,并初步分析该菌株在不同乳酸含量条件下挥发性风味物质的代谢特征。结果表明,获得一株高乳酸耐受特性的菌株MT-Y01,通过形态观察及分子生物学鉴定为库德里阿兹威氏毕赤酵母（Pichia kudriavzevii）;与模式菌株ATCC6258及其用于白酒酿造菌株CICC1926相比,菌株MT-Y01对乳酸的耐受性更强,最高可耐受120 g/L的乳酸;该菌株可在0～120 g/L乳酸含量范围内代谢生成多种酱香型白酒中的风味物质,且产酯能力强,是酱香型白酒发酵过程中一株重要的酵母菌。     

多菌混合发酵鲜枣果醋的工艺研究

采用一株分离得到的植物乳杆菌与酵母协同完成酒精发酵,再接种醋酸菌发酵制作鲜枣发酵醋,减少了枣醋的尖酸感,增加了柔和度,改善了枣醋的风味口感,提高了枣醋的品质。研究得出多菌混合最佳酒精发酵工艺：酵母接种量为2.0%,乳酸菌最佳接种量为2.0%,发酵pH为4.5,发酵温度为28 ℃,初糖为15%,产酒精度为8.4%vol;产乳酸2.13 g/L。最佳醋酸发酵工艺：接种量为12%,发酵温度为34 ℃,搅拌转速 200 r/min,总酸含量达到5.7 g/100 mL。     

Characterization of spoilage yeasts isolated from fermented vegetables and Inhibition by lactic,acetic and propionic acids

Two Saccharomyces sp. yeasts isolated from spoiled fermented vegetables were identified, and the effects of pH, temperature, initial yeast count and organic acids (lactic, acetic or propionic) on their growth in a vegetable juice medium (VJM) was examined. The VJM was fermented by a mixed lactic acid culture to a pH of 3·74, which represented the fermented VJM (VJM-F). A fraction of the VJM-F was neutralized to pH 6·0 with 5 N NaOH, which constituted the fermented and neutralized VJM (VJM-FN). Both yeast strains grew at 4°C in VJM and VJM-FN, and prefermentation by the lactic acid bacteria (LAB) did not affect their subsequent development. In VJM-F at pH 3·74, there were important drops in viable populations with the S. bayanus Y-43 strain during incubations at 4 and 30°C, but not with S. unisporus Y-42. In a broth containing 0·7% lactic acid and having a pH of 3·74, the addition of acetic acid or propionic acid generally inhibited growth of yeast. With S. bayanus Y-43, complete growth inhibition is observed with 0·4% of acetic acid, and propionic acid seemed twice as effective as acetic acid in inhibiting the growth of the Y-43 strain. The S. unisporus Y-42 strain was more resistant to organic acids than S. bayanus Y-43, and complete inhibition was only observed with a mixture of lactic, acetic and propionic acids of 0·7, 0·3 and 0·2%, respectively. Results suggest that acidification with lactic acid alone to pH 3·74 is insufficient to prevent the growth of spoilage yeast in fermented vegetables, and that the presence of other organic acids is desirable in this aim. Furthermore, the inoculation level of the yeast had a significant effect on the time at which visible gas production is observed.     

笃斯越橘恒温自然发酵的主要微生物初步鉴定及应用

以笃斯越橘恒温自然发酵液为研究对象,使用平板分离技术,对发酵液中的微生物组成进行分析。通过形态学鉴定及生理生化鉴定对分离菌株进行分析,结果为:笃斯越橘恒温自然发酵液中微生物主要为乳酸菌、酵母菌、醋酸菌及霉菌;菌株A1、A2为乳酸菌,其中菌株A1为乳杆菌属,菌株A2为链球菌属;菌株B1为酵母菌,菌株B1为克鲁维酵母属。将笃斯越橘恒温自然发酵液作为起始发酵种子接种于已灭菌的人工发酵基质进行发酵,总酚及黄酮含量对比发酵前分别提高了38.10%、5.69%,花色苷及原花青素含量对比发酵前分别降低了30.22%、31.26%,·OH清除率及总抗氧化能力对比发酵前分别提高了3.74%、39.22%,种子发酵液的抗氧化能力显著高于阳性对照组(p0.01)。种子发酵终产物的乙醇含量为0.98%,为低醇发酵物。本试验为笃斯越橘加工提供了一种新的思路。     

葡萄酵素发酵过程中代谢产物的动态变化

为探究葡萄酵素接种发酵过程中物质变化规律,以葡萄为原料,分析了接种酵母菌、醋酸菌以及乳酸菌发酵过程中总酸、有机酸、乙醇体积分数、总酚、主要功效酶（超氧化物歧化酶及β-葡萄糖苷酶）以及香气成分等代谢产物的变化。结果表明：发酵过程中总酸质量浓度呈先上升后下降的趋势,于第34天达到最大值19.37 g/L;在接种酵母菌（0～6 d）发酵过程中有机酸主要以柠檬酸、苹果酸、酒石酸为主,且乙醇主要产生于该阶段;接种醋酸菌后（6～27 d）主要产生乙酸;而后接种乳酸菌后（27～41 d）,乳酸、柠檬酸质量浓度逐渐增加至最大值102.09 mg/L和67.70 mg/L,而苹果酸减少,此时乙醇体积分数降低至最小值0.47%并趋于稳定;总酚含量与β-葡萄糖苷酶活力的变化趋势一致,主要于接种酵母菌（0～6 d）发酵以及接种乳酸菌发酵后期（34～41 d）产生,超氧化物歧化酶活力总体呈波动上升趋势;葡萄酵素发酵过程中产生的挥发性物质主要以醇类、酸类和酯类化合物为主。以上研究结果可为葡萄酵素的精准制备以及品质优化提供理论依据。     

CONTROLLED PRODUCTION OF CIDER BY INDUCTION OF ALCOHOLIC FERMENTATION AND MALOLACTIC CONVERSION

Characterization experiments involving lactic bacteria allowed a strain of Leuconostoc oenos to be selected in terms of growth capacity at variable pH, temperature, ethanol and sulphite concentrations, malic to lactic conversion yield, acetic acid uptake and dextran production capacity. Cider was produced under controlled conditions where the effect of Kloeckera apiculata yeasts on the development of Saccharomyces cerevisiae and production of major non-volatile compounds influencing end product quality was studied. The apiculate yeast was found to produce large amounts of acetic acid and use the other organic acids; also, it hindered fermentation to a certain extent. A study of the effect of the inoculation time with L oenos as an inducer of malolactic fermentation revealed sequential inoculation of the lactic bacterium once most major sugars in the must had been depleted to be the most favourable. Using yeast cell walls boosted fermentation development, as well as degradation of malic acid and synthesis of succinic and acetic acid.     

白酒窖泥中乳酸菌分离鉴定及其发酵产挥发性风味物质比较

从白酒窖泥中分离得到11株乳酸菌,经16S rDNA基因序列同源性分析,鉴定为1株短乳杆菌、1株鼠李糖乳杆菌、2株干酪乳杆菌和7株铅黄肠球菌。分析了11株菌MRS培养基发酵产乳酸性能,结果表明:乳酸产量与菌群生长呈正相关,鼠李糖乳杆菌L9、干酪乳杆菌L10与L11发酵液乳酸含量较高,分别为15.74、15.58、14.74 g/L。4株代表菌相同条件下发酵高粱培养液产挥发性风味组分,共有物质13种,包含了白酒中重要香气成分:乙酸、己酸、乙酸苯乙酯和苯乙醇,且乙酸、己酸相对含量较高。各菌产可挥发性组分差异明显,相对含量较高的化合物种类为:短乳杆菌L5产烷烃类化合物(27.91%),铅黄肠球菌L8产醇类化合物(43.14%),鼠李糖乳杆菌L9产酯类(7.35%)、酮类(3.61%)和吡嗪类(3.3%)化合物,干酪乳杆菌L11产酸类(27.98%)和芳香类(5.96%)化合物。仅有短乳杆菌L5产四甲基吡嗪,短乳杆菌L5和铅黄肠球菌L8可明显产乙醇,鼠李糖乳杆菌L9和干酪乳杆菌L11产3-羟基-2-丁酮。这些物质对白酒风味和口感有重要影响。研究显示,窖泥中各种乳酸菌特征不一,对白酒酿造有不同影响。本研究旨在为进一步挖掘白酒酿造功能微生物、拓展乳酸菌的应用提供理论依据。     

固态发酵食醋生产过程中主要微生物及风味生成的探讨

实验研究了不同时间、不同醋醅层次的微生物分布和数量变化规律,探索影响风味形成的因素。结果表明,发酵前5 d,酵母菌和乳酸菌迅速增殖,第5天酵母菌数达到最高3.4×107 CFU/g,乳酸菌最高为3.2×107 CFU/g,以乳酸为主的不挥发酸同时也生成较快;醋酸菌前3 d增长迅速,之后缓慢增长并以生成挥发性的醋酸为主,第11天醋酸菌数量达到峰值为4.0×107 CFU/g,13 d以后逐渐消亡。醋酸发酵初期,pH值迅速下降,不挥发酸迅速增加,不挥发酸占总酸的比值最大在第7天,为87.22%;总酸在发酵中期的7～13 d增幅最大。乳酸菌的消长影响着不挥发酸的生成,醋酸菌的消长影响着总酸的生成,醋酸发酵过程中控制合适的发酵条件,使两者的相互协调生长,有利于产品口感风味的调和。     

Effects of yeast extract and different amino acids on the dynamics of some components in cabbage juice during fermentation with Bifidobacterium lactis BB-12

Various amino acids and the yeast extract, in amounts of 0.1%(w/v), were separately tested for their influence on the analytical parameters of lactic acid fermentation of cabbage juice with Bifidobacterium animalis subsp. lactis BB-12. Compared with the control, cysteine supplementation led to a decrease of the time to reach pH 5.0 of 6 times and an increase of lactic acid productivity of 1.22 times. After 48 h the ascorbic acid content was by 360.73% higher, the fermented cabbage juices being assigned into a distinct group applying both factor analysis (FA) and cluster analysis (CA). Tryptophan contributed to better values for lactic and acetic acid yield, while lysine and yeast extract especially for acetic acid yield. Valine and leucine were not able to improve the fermentation progress, estimated through the analyzed variables. This work would provide some helpful information for the development of various lacto-fermented vegetable juices using probiotic bacteria.