DFCOS-Ⅱ型人工瘤胃模拟活体牛瘤胃发酵的效果评价

以活体为对照,对DFCOS-Ⅱ人工瘤胃模拟活瘤胃发酵效果进行评价.结果表明:该装置模拟瘤胃试验需3-4 d的适应期,4-8 d发酵状态相对稳定,效果较好,且与活体瘤胃值呈一定规律性变化.     

体外产气法研究壳聚糖对山羊瘤胃发酵的影响

应用体外产气法模拟瘤胃发酵,通过测定24 h体外累计产气量、中性洗涤纤维(NDF)的降解率和细菌氮含量,研究添加不同水平壳聚糖对山羊瘤胃发酵的影响.结果表明,壳聚糖可以促进瘤胃发酵,使微生物蛋白合成和纤维分解增加.在本试验条件下,山羊日粮中壳聚糖的最适添加水平为0.09%～0.12%.     

利用体外产气法研究异位酸对山羊瘤胃发酵的影响

应用体外产气法模拟瘤胃发酵,通过测定24 h体外累计产气量、中性洗涤纤维(NDF)的降解率和细菌氮含量,研究添加不同水平异位酸对山羊瘤胃发酵的影响.试验采用单因子设计,异位酸的添加水平分别为0%、0.1%、0.2%、0.4%和0.6%,每个水平4个重复.结果表明,与对照组相比,添加0.2%和0.4%水平的异位酸组能显著提高24 h累计产气量(P＜0.05);NDF降解率显著提高(P＜0.05),其中以0.2%水平的异位酸组NDF降解率最高(P＜0.01);细菌氮含量差异极显著提高(P＜0.01),其中以0.4%水平的异位酸组细菌氮含量最高(P＜0.01).日粮中的异位酸的适宜添加水平为0.2%～0.4%.     

瘤胃微生物体外驯化降解纤维素研究

实验先按照正交表L18(3^7）的设计对瘤胃微生物降解滤纸的营养和环境条件进行研究，发现在C/N为14.2/1、葡萄糖浓度低、乙酸浓度为800mg/L、无丙酸存在，温度为45℃、pH值为6.5的环境条件下，纤维素的降解校为彻底。在以上优化条件的基础上，进行了纤维降解及产酸情况的研究，发现纤维素降解的直接产物葡萄糖不会产生积累而很快就转化为挥发酸，而挥发酸会产生积累。挥发酸主要是乙酸、丙酸和丁酸三种，其中乙酸产量占到86%-93%。在纤维素降解产酸过程中，产气量并不大。     

Regulation of Aflatoxin Biosynthesis: Induction of Aflatoxin Production by Various Carbohydrates

The ability of various compounds to induce aflatoxin biosynthesis by Aspergillus parasiticus was investigated by initially culturing the organism in a peptone basal medium that does not support aflatoxin production, and then transferring the organism to a replacement medium containing the test compound. Ribose, xylose, glucose, fructose, sorbose, mannose, galactose, maltose, sucrose, raffinose, and glycerol induced aflatoxin production. This induction of aflatoxin production was blocked when cycloheximide was incorporated into the replacement medium. Aflatoxin biosynthesis was not induced by lactose, lactic acid, sodium pyruvate, oleic acid, citric acid, sodium acetate, α-methyl-D-glucoside, 3-0-methyl-D-glucoside, cAMP, or cGMP. The results suggest that the synthesis of one or more of the enzymes responsible for aflatoxin formation is regulated by the availability of specific readily-metabolizable carbon sources.     

灌注果寡糖对生长绵羊瘤胃发酵功能的影响

试验采用营养灌注技术研究了果寡糖对生长绵羊瘤胃发酵功能的影响.试验选取6只安装有永久性瘤胃瘘管的内蒙古半细毛羯羊,随机分为两组,试验1组灌注1.00%果寡糖,试验2组灌注2.00%果寡糖.结果表明:灌注果寡糖可以显著(P＜0.05)降低试羊的瘤胃液相pH值和瘤胃内的氨态氮浓度,显著提高(P＜0.05)瘤胃内的挥发性脂肪酸(VFA)含量和瘤胃细菌蛋白(BCP)含量.两个灌注水平都可以提高生长绵羊的瘤胃发酵功能,但2.00%的灌注水平仅在瘤胃氨态氮浓度的降幅方面比1.00%的灌注水平显著增大(P＜0.05),在对瘤胃液相pH值、VFA含量和BCP含量的影响方面两个灌注水平没有显著差异(P＞0.05).     

苹果酸对山羊瘤胃纤维降解率及发酵类型的影响

以4头装有永久性瘤胃瘘管的本地山羊为试验动物,采用4×4拉丁方设计,研究苹果酸(0、5、10和15 g/d)对山羊瘤胃纤维降解率及瘤胃发酵类型的影响。结果表明,日粮中添加苹果酸能够显著提高瘤胃内中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的降解率(P<0.05);瘤胃液中乙酸与丙酸比值显著降低(P<0.05),改变了瘤胃发酵类型;氨态氮浓度显著降低(P<0.05),促进了瘤胃微生物对氨、氮的利用。     

耻垢分枝杆菌产乳酸氧化酶条件的研究

以1株耻垢分枝杆菌(Mycobacterium smegmatis)为出发菌株,对其产乳酸氧化酶的培养基和发酵条件进行研究。结果表明,培养基中添加3%甘油,0.4%蛋白胨,1%DL-乳酸,0.005%VB1,0.05%KH2PO4.H2O,0.05%MgSO4.7H2O,0.01%硫酸亚铁胺有助于产酶;优化培养条件为:250 mL三角瓶中装液量50 mL,起始pH7.2,培养温度37℃,静置培养4 d,乳酸氧化酶平均酶活为65.4 U/mL。     

Effect of Dietary Starch or Micro Algae Supplementation on Rumen Fermentation and Milk Fatty Acid Composition of Dairy Cows

Two experiments with rumen-fistulated dairy cows were conducted to evaluate the effects of feeding docosahexaenoic acid (DHA; C22:6 n-3)-enriched diets or diets provoking a decreased rumen pH on milk fatty acid composition. In the first experiment, dietary treatments were tested during 21-d experimental periods in a 4 × 4 Latin square design. Diets included a control diet, a starch-rich diet, a bicarbonate-buffered starch-rich diet, and a diet supplemented with DHA-enriched micro algae [Schizochytrium sp., 43.0 g/kg of dry matter intake (DMI)]. Algae were supplemented directly through the rumen fistula. The total mixed ration consisted of grass silage, corn silage, soybean meal, and a standard or glucogenic concentrate. The glucogenic and buffered glucogenic diet had no effect on rumen fermentation and milk fatty acid composition because, unexpectedly, no reduced rumen pH was detected. The algae diet had no effect on rumen pH but provoked decreased butyrate and increased isovalerate molar proportions in the rumen. In addition, algae supplementation affected rumen biohydrogenation of linoleic and linolenic acid as reflected in the modified milk fatty acid composition toward increased conjugated linoleic acid (CLA) cis-9 trans-11, CLA trans-9 cis-11, C18:1 trans-10, C18:1 trans-11, and C22:6 n-3 concentrations. Concomitantly, on average, a 45% decrease in DMI and milk yield was observed. Based on these drastic and impractical results, a second animal experiment was performed for 20 d in which 9.35 g/kg of total DMI of algae were incorporated in the concentrate and supplemented to 3 rumen-fistulated cows. Algae concentrate feeding increased rumen pH, which was associated with decreased rumen short-chain fatty acid concentrations. Moreover, a different shift in rumen short-chain fatty acid proportions was observed compared with the first experiment because molar proportions of butyrate, isobutyrate, and isovalerate increased, whereas acetate molar proportion decreased. The milk fatty acid profile changed as in experiment 1. However, the decrease in DMI and milk yield was less pronounced (on average 10%) at this algae supplementation level, whereas milk fat percentage decreased from 47.9 to 22.0 g/kg of milk after algae treatment. In conclusion, an algae supplementation level of about 10 g/kg of DMI proved effective to reduce the milk fat content and to modify the milk fatty acid composition toward increased CLA cis-9 trans-11, C18:1 trans, and DHA concentrations.     

Effect of Fermentation on Soluble Proteins and In Vitro Protein Digestibility of Sorghum, Green Gram and Sorghum-Green Gram Blends

Changes in pH, titratable acidity and proteins of meals of sorghum, green gram and sorghum-green gram blend (70:30, w/w) during fermentation at 25°C up to 5 days were monitored. The pH of fermenting meals decreased sharply with concomitant increase in the titratable acidity within 24 hr. The proteins, free amino acids, soluble proteins and in vitro protein digestibility markedly increased within 24 hr fermentation. Supplementation of green gram with sorghum decreased the acidity and improved the contents of crude protein, soluble proteins and free amino acids of fermented sorghum meal.     

不同载体固定化蒙氏肠球菌发酵蛋壳制备乳酸钙

针对我国每年废弃的大量蛋壳,采用海藻酸钠、海藻酸钠-聚乙烯醇和海藻酸钠-活性炭(sodium alginate-activated carbon,SA-C)3种载体固定化蒙氏肠球菌发酵蛋壳废物生产乳酸钙,考察并比较其机械强度、传质系数、产乳酸钙性能及最佳包埋载体的性质。结果表明,SA-C载体是最适的包埋载体,其乳酸钙产量最高达到101.02 g/L,蛋壳粉转化率为82.43%;在重复发酵18次后仍保持高产率,且在重复发酵10次有缩短发酵周期的趋势。发酵液中蛋壳废物的存在有效维持了固定化细胞的机械稳定性,与游离细胞相比,其细胞操作稳定性、温度、pH值及贮存稳定性在一定范围内都有明显的提高。     

Influence of Pecan Shells and Hulls as a Roughage Source on Milk Production,Rumen Fermentation,and Digestion in Ruminants,

In Experiment 1, 20 lambs (36 kg) were fed five diets containing 0, 5, or 10% pecan shells or hulls to evaluate digestion and nitrogen balance. Digestion was not depressed by diets containing 5% shells. Protein digestibility was not reduced and nitrogen balance was higher for lambs fed 5% hulls than for lambs in other groups. In Experiment 2, 8 Holstein cows (29.3 kg milk/d) were assigned to two diets: basal and basal with 5% shells in the grain mix. Cows fed diets containing shells produced the same amount of milk and milk fat as control cows. In Experiment 3, 12 Holstein cows (27.3 kg milk/d) were assigned to the same two diets used in Experiment 2 and a third treatment received 5% pecan hulls in the grain mix. Cows fed shells or hull diets reduced concentrate intake and milk production. In Experiment 4, 12 Hereford × Angus steers (474.5 kg) were fed diets used in Experiment 3 to examine rumen fermentation, digestion, and passage rates. Steers fed hulls had lower rumen ammonia N and higher rumen pH compared with steers fed the basal diet. Total rumen volatile fatty acid concentration was not different among treatments. Generally, rumen fluid from steers fed hulls had higher proportions of acetate and lower porportions of butyrate. Rumen fluid and particulate passage rates and digestion measurements were not affected by addition of shells or hulls.     

粗壮脉纹孢菌孢子中类胡萝卜素的体外发酵特性

模拟人体消化过程对粗壮脉纹孢菌孢子进行消化,通过酸热法提取消化后孢子粉中的类胡萝卜素,进行体外发酵。采用国标法测定发酵液的产气量、pH、NH3-N,采用气相色谱法测量发酵液中短链脂肪酸的含量。通过16SrRNA高通量测序技术分析志愿者肠道菌群,结果发现消化后的粗壮脉纹孢菌孢子粉中类胡萝卜素经体外发酵,pH值趋于6.0~7.2,与人体肠道pH值接近,产气量较少,不易引起胀气,可产生的乙酸、丙酸、丁酸等有益于人体健康的短链脂肪酸,使拟杆菌减少,变性杆菌增加。粗壮脉纹孢菌孢子粉中类胡萝卜素有利于改善人体肠道菌群,优化肠道菌群中各菌属的比例,有益于人体的肠道健康。     

不同酵母菌发酵产油脂及脂肪酶的研究

通过摇瓶发酵研究了健强地霉、伯顿拟内孢霉、发酵性丝孢酵母油脂积累及脂肪酶活力.考察并比较了不同酵母菌的油脂合成及脂肪酶活力差别,通过酸热法破碎细胞提取油脂,采用橄榄油法测定发酵液和细胞中的脂肪酶活力.     

日粮中添加豆油对肉牛瘤胃发酵及营养物质消化率影响的研究

本试验选用４ 头装有永久瘤胃和真胃瘘管的阉牛,采用４ ×４ 拉丁方设计,对照组牛饲喂基础日粮,３ 个试组在基础日粮中分别添加豆油１５０ｇ 、３００ｇ 及４５０ｇ 。探讨日粮中添加豆油对肉牛瘤胃发酵及营养物质消化率的影响。结果表明,日粮中添加豆油使瘤胃总挥发性脂肪酸（ Ｔ Ｖ Ｆ Ａ） 浓度显著下降,３ 个试验组平均总挥发性脂肪酸（ Ｖ Ｆ Ａ） 浓度比对照组下降２２ ．３７ ％ 。日粮日添加４５０ｇ 豆油使瘤胃内及全消化道干物质和有机物的消化率显著下降（ Ｐ＜ ０ ．０５） 。日粮中补充豆油时,随着添加量的增加瘤胃内及全消化道中性洗涤纤维（ Ｎ Ｄ Ｆ） 消化率呈下降趋势,而对瘤胃后 Ｎ Ｄ Ｆ 消化率无影响。日粮中补充豆油对酸性洗涤纤维（ Ａ Ｄ Ｆ） 消化率的影响与对 Ｎ Ｄ Ｆ 消化率的影响相一致。４ 个组脂肪酸表观消化率分别为６０ ．３７ ％ 、７８ ．６７ ％ 、８５ ．３５ ％ 和８７ ．８３ ％ ,随着豆油添加量的增加脂肪酸表观消化率线性提高。     

不同真菌固体发酵对蕨菜主要活性成分及其体外抗氧化和抗炎症作用的影响

以蕨菜为原料,采用木蹄层孔菌、灵芝和裂褶菌3 种功能真菌进行固体发酵,研究发酵前后蕨菜醇提物中总酚、总黄酮等活性成分的变化,并对发酵前后蕨菜体外抗氧化、抗炎症活性进行评价。结果表明,3 种真菌固体发酵后蕨菜醇提物的总酚含量较发酵前明显下降,而发酵后总黄酮含量较发酵前均显著增加（P＜0.05）。未发酵蕨菜醇提物清除1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl radical,DPPH）自由基和2,2-联氮-二（3-乙基-苯并噻唑-6-磺酸）二铵盐自由基（2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) radical,ABTS＋·）能力均优于固体发酵后的蕨菜醇提物,其中未发酵蕨菜醇提物清除ABTS＋·作用的半数抑制浓度（half-inhibition concentration,IC50）值为（0.51±0.02）mg/mL,而经木蹄层孔菌、灵芝和裂褶菌固体发酵后IC50值分别为（2.69±0.01）、（1.20±0.14）、（0.92±0.01）mg/mL。发酵与未发酵蕨菜醇提物在0～0.2?mg/mL质量浓度条件下,对RAW264.7细胞无毒性作用。发酵与未发酵蕨菜醇提物均能抑制脂多糖（lipopolysaccharides,LPS）诱导的RAW264.7细胞一氧化氮（nitric?oxide,NO）的分泌水平,且呈现量效关系,其中3?种真菌固体发酵后的抑制效果更显著（P＜0.05）。当质量浓度为0.2?mg/mL时,未发酵蕨菜醇提物对LPS诱导的RAW264.7细胞NO释放水平的抑制率为27.09%,而经木蹄层孔菌、灵芝和裂褶菌固体发酵后的抑制率分别为58.61%、63.57%、69.46%。相关性分析表明,发酵前后蕨菜醇提物的总酚含量与其抗氧化能力有较好的相关性,总黄酮含量与抗炎症作用呈显著正相关。     

OPO乳脂粉对肠道微生物体外发酵的影响

为进一步明晰1,3-二油酸-2-棕榈酸甘油三酯（1,3-dioleoyl-2-palmitoyl triglyceride,OPO）乳脂粉的营养机制,扩大OPO的食用范围,以健康大学生粪便为菌源,采用体外厌氧发酵模式,结合传统培养技术和气相色谱法,研究不同含量OPO乳脂粉24 h体外发酵过程中pH值、短链脂肪酸的变化,并分析肠道微生物,计算益生元指数和B/E（Bifidobacterium/Enterobacter）值。结果显示：OPO乳脂粉的添加,能迅速降低发酵液的pH值,下降幅度与OPO含量呈正比;能大幅度增加总短链脂肪酸含量,其中,乙酸和丁酸含量增加明显;能显著促进双歧杆菌和乳酸杆菌的生长,抑制肠杆菌和拟杆菌的生长,提高益生元指数和B/E值,其中OPO含量50 g/kg组在24 h发酵过程中益生元指数最高,在发酵12 h内双歧杆菌增加数量、B/E值均与OPO含量呈正比。因此,综合考虑益生效率,推荐添加组为50 g/kg组。     

发酵条件对纯生啤酒中酸性蛋白酶分泌的影响

发酵条件是影响纯生啤酒发酵过程中酸性蛋白酶分泌的重要因素。研究了发酵温度、培养基pH、酵母接种量和CO2含量等发酵条件对酸性蛋白酶分泌的影响。结果表明,在8℃、pH6.4、接种量5%和不带压发酵的条件下,酸性蛋白酶分泌量少,酶活低,啤酒泡沫稳定性好。     

甜高梁秆固态发酵制取酒精的研究

甜高粱秆液态发酵中，存在着榨汁难，糖分损失严重等问题。采用固态发酵的方式，进行了甜高粱发酵酒精的研究，确定了发酵过程中发酵时间、接种率、初始pH、营养盐等因素的优化方案。将总糖含量为13％，含水量约80％的甜高粱秆直接绞碎至约0．3cm长，在最佳优化条件下35℃固态发酵24h，酒精的理论产率为0．332g乙醇／g甜高粱秆干料，实际得率为0．298g乙醇／g甜高粱秆干料（达到理论产率的89．8％），生产It酒精需要3．01t的甜高粱秆干料。