影响丙酸菌生长和产酸因素的初步研究

研究了培养方式和各种培养条件对丙酸杆菌的生长、丙酸生物量及环境酸度变化的影响,初步确定丙酸杆菌发酵的初步优化培养方式、培养基的始初pH及不同浓度的营养成分对丙酸杆菌的生长和产酸量的影响,初步优化的培养基成分为葡萄糖3.0%,酵母膏2.0%,蛋白胨0.3%,氯化钴6ppm;培养方式静置有氧培养好;灭菌前pH7.0~7.5。     

影响丙酸菌生长和产酸因素的初步研究

研究了培养方式和各种培养条件对丙酸杆菌的生长、丙酸生物量及环境酸度变化的影响，初步确定丙酸杆菌发酵的初步优化培养方式、培养基的始初pH及不同浓度的营养成分对丙酸杆菌的生长和产竣量的影响，初步优化的培养基成分为：葡萄糖30％，酵母膏2．0％，蛋白胨0．3％，氯化钴6ppm；培养方式：静置有氧培养好；灭菌前pH：7．0～7．5。     

培养条件对单增李斯特菌生长的影响

以纯度为99.97%的单增李斯特菌为研究对象,通过测定菌株在各培养条件下菌液的OD600值,分析了不同的NaCl浓度、pH、温度及NaCl浓度为3%～8%(梯度为1%),pH为6～9(梯度为1),温度为0～40℃(梯度为10℃)的交互作用条件下单增李斯特菌的生长状况。结果表明:菌株的对数增长期为8～14h,稳定期为14～18h,18h以后进入衰亡期;菌株在NaCl浓度为0.5%～3.5%范围内生长良好,其最适生长pH为7.5,最适生长温度为37℃。各因素的交互作用通过SPSS软件进行方差分析,得到其p<0.01,即各因素的交互效应极显著。      

不同条件对烟草青枯雷尔氏菌生长的影响

青枯雷尔氏菌（Ralstonia solanacearum）是烟草青枯病的病原菌。为有效防治青枯病,研究了不同培养条件对青枯雷尔氏菌生长的影响;并测定了在不同pH、温度以及在培养基中添加不同浓度的N、P、K、Zn²⁺、Cu²⁺、Ca²⁺、Mg²⁺、HCO₃^-、SO₄^2-对青枯雷尔氏菌生长的影响。结果表明,青枯雷尔氏菌在偏酸和偏碱条件下生长较好,青枯雷尔氏菌最适生长温度为25~45 ℃;高浓度的Zn²⁺和Cu²⁺能够有效抑制青枯雷尔氏菌的生长,其他因素对青枯雷尔氏菌的生长无明显作用。     

窖泥酯化菌的富集筛选及其生长条件研究

以优质老窖泥为研究对象,厌氧条件下富集酯化菌,并对富集条件进行优化。通过传统培养分离法及顶空固相萃取-气相色谱-质谱（HS-SPME-GC-MS）法从优化富集液中筛选酯化菌,通过形态观察、生理生化试验及分子生物学技术对其进行鉴定,并研究其生长条件。结果表明,窖泥富集液培养20 d并富集2次有利于酯化菌的富集,从优化富集液中共筛选出3株产己酸乙酯和丁酸乙酯的厌氧梭菌。经鉴定,菌株Y1、Y2、Y3分别为拜氏梭菌（Clostridium beijerinckii）、Clostridium guangxiense、Clostridium sartagoforme,其中,菌株Y1的最佳生长温度为30 ℃、最适生长pH值为5;菌株Y2的最佳生长温度为34 ℃、最适生长pH值为7;菌株Y3的最佳生长温度为37 ℃,最适生长pH值为5,且3株菌株的最高耐乙醇体积分数达20%。     

硫色镰刀菌（Fusarium sulphureum）体外产毒条件的筛选

对影响硫色镰刀菌（Fusarium sulphureum）体外产生真菌粗毒素的温度、时间、pH值、培养方式及培养基种类进行筛选。结果表明：F. sulphureum的最佳产毒条件是Richard培养基、25 ℃、pH 4.5、振荡培养10 d。在单因素筛选的基础上,以温度、pH值和培养时间为自变量,绿豆种子胚根平均长度为响应值,利用响应面分析法对该菌产毒条件的优化结果表明,22.2 ℃、pH 5.1、振荡培养12 d最有利于体外产毒。     

营养条件对绿僵菌生长特性和抑菌活性的影响

研究了不同培养基、碳、氮营养对金龟子绿僵菌菌落直径、菌丝生物量、分生孢子产生量及其次生代谢产物对植物病原真菌的抑菌活性。发现金龟子绿僵菌的菌丝线性生长以PSA、麦芽糖和酵母最好,以Czapek、甘露醇和脲最差;菌丝生物量以PSA、白砂糖和蛋白胨最大,以Czapek、乳糖和脲最小;分生孢子产生量以PSA、麦芽糖和KNO3最多,以Czapek、甘油和硫酸铵最少。代谢液的抑菌活性实验结果表明,在不同培养基培养的代谢液中,Czapek的抑菌效果最好,SDAY的抑菌效果最差。在不同碳营养培养的代谢液中,白砂糖的抑菌效果最好,乳糖的抑菌效果最差。在不同氮营养培养的代谢液中,蛋白胨的抑菌效果最好,脲的抑菌效果最差。     

弹性蛋白酶产生菌的分离鉴定和发酵条件研究

从污水河的土壤中采集样品,分离得到一株产胞外弹性蛋白酶活性较高且稳定的细菌。经初步鉴定属枯草芽孢杆菌(Bacillus subtilis B1),其酶活力为74.25U/ml。对其进行物理诱变,诱变后的菌株(B9)产酶活性有较大的提高。B9酶活力为120.00U/ml,较原菌株提高了1.62倍。同时研究了其产酶最适条件,产酶最适碳源为蔗糖,最适氮源为干酪素,并对碳源、氮源和生长因子进行了正交试验,研究发现氮源对产酶的影响最大。当蔗糖的用量为4%、干酪素为3%、玉米提取液为0.1%时具有较高的产酶水平。最适发酵初始pH为8.0、300ml最适摇瓶装量为40ml、最适接种量为3%。经发酵条件的优化后,B9酶活达到311.54U/ml、提高了2.59倍;较以往国内报道的酶活要高。     

酵母多糖产生菌的筛选和发酵条件的研究

16种酵母菌通过初筛后，复筛时在培养基中加入磷酸二氢钾、碳源和氮源，筛选出高产多糖的酵母菌种——产脂酵母。确定此产脂酵母最佳发酵条件为：磷酸二氢钾0．6％，蔗糖6％，硝酸铵0．30％，玉米浆0．7％。     

向日葵品种资源对菌核病抗性室内鉴定

利用两种不同的培养基培养核盘菌,用离体叶片接种方法对40个不同向日葵品种进行室内抗性鉴定,结果表明：在Minimal medium培养基上生长的核盘菌和PDA培养基相比,菌丝的生长速度大大降低。菌株经PDA培养基培养接种向日葵叶片后,不同向日葵品种之间抗性水平没有显著差异;而用Minimal medium培养基培养的菌株接种供试的向日葵不同品种叶片后,品种间表现出一定的抗性水平差异。依据接种后不同品种抗性水平的差异将供试向日葵品种划分为三组,即：抗病品种如食葵765、油葵KS7等,共3份;耐病品种如3146、新葵杂5号等,共9份;感病品种如LD1093、新葵杂6号等,共28份。     

向日葵菌核病田间接种方法及品种抗病性研究

为建立有效的向日葵菌核病田间接种鉴定方法,以菌核病菌菌丝体悬浮液和高粱粒菌丝体作为接种物,分别对不同抗感向日葵品种在始花期和盛花期进行人工接种,从而筛选出最佳接菌物类型、浓度及接种时期,并用此方法对52个品种进行抗性评价。试验结果表明：两种接种物均可使向日葵感病品种产生盘腐症状。用菌丝体悬浮液接种时,7．5～15．0 g／L浓度即可区分出向日葵品种间抗感性差异。始花期接种较盛花期可获得更高的发病率及病情指数。同时筛选出5个对盘腐型菌核病表现抗病的向日葵品种。本研究所建立的田间接种方法能够有效地对向日葵进行抗菌核病筛选和鉴定。     

利用微卫星标记分析核盘菌遗传多样性

利用微卫星（SSR）标记,分析来自欧洲和中国的30个核盘菌菌株的遗传多样性和群体结构。结果表明,3对微卫星引物共扩增出21条清晰的谱带,平均每对引物扩增7条谱带,片段长度为158bp～358bp。根据SSR分析结果,30个核盘菌分离物具有较高的遗传相似性。物种水平的Nei遗传多样性指数为0.139 3,Shannon多样性指数为0.248 8。不同菌株群体的Nei遗传距离都较小,为0.009 6～0.049 6。其中俄罗斯群体和奥地利及英国群体之间的遗传距离最大。从30个菌株的UPGMA聚类分析结果看,核盘菌群体结构与地理来源没有明显的直接关系。许多地理来源相同的菌株分散在不同的组里。仅第三组组内的菌株地理来源一致,均来自于中国,且遗传距离比其他菌株的远。群体遗传分析显示,总群体的基因流比较高（2.111 6）,基因分化系数比较低（0.191 5）。     

不同地域和寄主来源的核盘菌遗传多样性分析

为了解核盘菌[Sclerotinia sclerotiorum（Lib.）de Bary]遗传多样性和进化关系,利用SSR分子标记对采自不同地区和寄主来源的32个核盘菌分离物进行分析,17对SSR引物共检测到69个多态性位点,平均每对引物检测到4.06个位点。其中,引物AF377908-1/AF377908-2和AF377922-1/AF377922-2的等位变异数目最多,高达8个,而引物AF377903-1/AF377903-2和AF377925-1/AF377925-2的等位变异数目最少,为2个。17个SSR引物的多态性信息量（PIC）的平均值为0.56,引物AF377922-1/AF377922-2的PIC最高,为0.78。聚类分析显示,32个核盘菌分离物可划分为5个组群,来自同一地区的大部分核盘菌分离物聚在相同或相近的组内,表明核盘菌群体内的SSR遗传背景基本一致,而群体间的遗传变异较大。     

影响荔枝酒发酵过程中挥发酸的因素

目的 探究影响荔枝酒发酵过程中挥发酸的因素.方法 依次通过单因素试验和三因素三水平的正交试验方法对荔枝酒发酵过程中挥发酸含量的关键影响因素进行分析探讨.结果 荔枝酒酿造过程中影响挥发酸含量的关键因素为发酵温度.影响顺序依次为发酵温度、pH值、发酵时间.最适发酵时间为11 d以内,最适pH值为3～5.结论 本研究结果能较...     

Frying stability of high oleic sunflower oils as affected by composition of tocopherol isomers and linoleic acid content

The influence of linoleic acid content and tocopherol isomeric composition on the frying performance of high oleic sunflower oil was evaluated during a 14-day restaurant style frying operation. At equal linoleic acid content, no significant difference was observed between high oleic sunflower oil containing only α-tocopherol and the sample containing a mixture of α-, γ-, and δ-isomers as measured by the amount of total polar components, oligomers, anisidine value, and free fatty acids. On the contrary, at similar tocopherol isomeric composition, high oleic sunflower oil containing lower amount of linoleic acid showed superior frying stability compared to the sample with a higher content of linoleic acid, suggesting that the frying performance of high oleic sunflower oil is dictated primarily by the level of linoleic acid, with the tocopherol isomeric composition of the oil having no significant influence. In all oil samples, the loss of γ-tocopherol was higher than the corresponding loss of α-tocopherol.     

Sterol content in sunflower seeds (Helianthus annuus L.) as affected by genotypes and environmental conditions

Phytosterols play essential roles in many plant cell mechanisms. They are of industrial interest since, as part of the diet, they can reduce low density lipoprotein cholesterol. An increase in plant sterol contents, by improved crop varieties or crop management, could help to answer industrial demands and also to develop environmentally friendly extraction methods. The aim of this study was to evaluate genotypic variability of sterol content in cultivated sunflower and, in particular, effects of sowing date. Results showed large variability among a collection of sixteen sunflower inbred lines and hybrids. Total sterols varied almost twofold between extreme genotypes. A delay of sowing, giving higher temperatures during seed formation, induced a general increase in total sterol concentration by up to 35%, as well as variation in sterol composition according to genotype. These results are considered with an aim of improving sterol content by sunflower breeding programmes.     

At line prediction of PUFA and biohydrogenation intermediates in perirenal and subcutaneous fat from cattle fed sunflower or flaxseed by near infrared spectroscopy

NIRS potential to estimate the proportion of PUFA and their biohydrogenation products in adipose tissues from cattle fed sunflower or flaxseed was tested. Immediately after skinning, perirenal and subcutaneous fat samples from 63 steers were collected, scanned intact at 37 °C and 33 °C, respectively, over a NIR spectral range from 400 to 2498 nm using benchtop equipment and then analyzed for fatty acid composition. NIRS calibrations in perirenal fat showed high predictability for total and major omega − 6 and omega − 3, conjugated linolenic acids, t,t-conjugated linoleic acids (CLA), non-CLA dienes and trans-monounsaturated fatty acids, with R² (RMSECV, %) of 0.88–0.89 (0.16–0.20), 0.89–0.91 (0.07–0.08), 0.86–0.89 (0.01–0.09), 0.82 (0.07), 0.89 (0.46) and 0.86–0.88 (0.87–1.29), respectively. NIRS predictions in subcutaneous fat were less reliable, probably due to lower fatty acid variability. The results show NIRS to be a useful technique for the early, fast and relatively inexpensive estimation of proportions of fatty acids with potential human health effects in cattle perirenal fat.     

Factors affecting conjugated linoleic acid content in milk and meat

Conjugated linoleic acid (CLA) has been recently studied mainly because of its potential in protecting against cancer, atherogenesis, and diabetes. Conjugated linoleic acid (CLA) is a collective term for a series of conjugated dienoic positional and geometrical isomers of linoleic acid, which are found in relative abundance in milk and tissue fat of ruminants compared with other foods. The cis-9, trans-11 isomer is the principle dietary form of CLA found in ruminant products and is produced by partial ruminal biohydrogenation of linoleic acid or by endogenous synthesis in the tissues themselves. The CLA content in milk and meat is affected by several factors, such as animal's breed, age, diet, and management factors related to feed supplements affecting the diet. Conjugated linoleic acid in milk or meat has been shown to be a stable compound under normal cooking and storage conditions. Total CLA content in milk or dairy products ranges from 0.34 to 1.07% of total fat. Total CLA content in raw or processed beef ranges from 0.12 to 0.68% of total fat. It is currently estimated that the average adult consumes only one third to one half of the amount of CLA that has been shown to reduce cancer in animal studies. For this reason, increasing the CLA contents of milk and meat has the potential to raise the nutritive and therapeutic values of dairy products and meat.     

Influence of fatty acid composition on chemical changes in blends of sunflower oils during thermoxidation and frying

The influence of fatty acid composition on formation of new compounds at frying temperatures has been studied in seven samples of sunflower oils widely differing in their fatty acid composition. Thermal oxidation assays as well as frying experiments were carried out and samples were evaluated by measuring the new compounds formed, i.e. polymers, polar compounds and their distribution by molecular weight, and polar fatty acids and their distribution by molecular weight. The levels of all the new compounds analysed strongly depended on the degree of oil unsaturation; the two least unsaturated oils with low content of linoleic acid and high content of palmitic acid behaved exceptionally well. When considering polar compounds or polar fatty acids, the polymers/oxidised monomers ratio increased significantly as the level of degradation increased. The new compounds formed are practically identical when analysed in the used frying oils or in the lipids extracted from the counterpart fried potatoes, independently of the level of degradation.