一株驯化啤酒酵母的分离鉴定及扩大培养条件的优化

为筛选一株驯化啤酒酵母,并对发酵罐扩大培养工艺进行优化,为今后大规模生产提供试验数据。于麦芽汁培养基分离挑选某株具有较好生长力的酵母菌,进行形态学、生化及分子生物学鉴定。应用正交试验设计,从摇瓶温度、pH、取样时间及发酵罐的转速、装液量、接种量等方面进行优化。结果表明,驯化酵母菌株形态学、生化鉴定证明该菌株属于酵母属;发酵罐扩大培养最佳工艺为:转速200r/min,接种量50mL/L,装液量4.5L,此条件下酵母活菌含量为2.8×10~8 CFU/mL。驯化前后表现一致,没有发生变异。优化啤酒酵母菌的发酵罐扩大培养工艺,为下一步规模化生产提供理论参考。     

枯草芽孢杆菌发酵条件的优化

采用单因素及正交实验法对枯草芽孢杆菌的培养基在摇瓶中进行优化,优化后的培养基为葡萄糖15g/L、酵母浸出物5g/L和MgSO45g/L;并通过单因素实验法确定了最佳培养条件为温度35℃,初始pH6.0,接种量3%,装液量20mL/250mL,发酵时间12h。     

饲用硒酵母制备工艺条件的优化

以啤酒酵母为菌种、添加亚硒酸钠的麦芽汁为培养基。从发酵液中硒浓度、发酵培养时间和接种量等方面研究了硒酵母发酵制备的效果。通过正交试验确定的最优工艺条件是:①发酵温度28℃;②接种量10%;③发酵培养基中的硒浓度25μg/ml;④发酵培养时间30h。经测定成品酵母的硒含量可达650mg/kg左右。     

葡萄渣发酵生产高生物量饲料酵母的研究

研究以啤酒酵母为发酵菌种,利用葡萄渣水解液作为发酵培养基的唯一碳源,设计正交试验对高生物量饲料酵母的发酵生产进行了初步研究。结果表明,在发酵液初始pH为6.0,装液量为150 mL/500 mL,接种量为10%,硫酸铵添加量为1.0%,摇床转速为200 r/min,发酵温度为32℃,发酵时间为84 h的最优发酵条件下,酵母的生物量可达22.17 g/L。     

富铬酵母培养条件的优化

研究了富铬酵母的培养方法,采用二苯胺基脲法测定富铬酵母中的铬含量,研究发现,培养基的组成、加铬量、发酵液的pH都对富铬酵母的产量有很大影响,加尿素的麦芽汁培养基能显著提高富铬酵母的产量和铬含量。优化后的富铬酵母培养条件为:麦芽汁加5‰尿素培养基,培养pH为5.0,发酵液中铬浓度为100mg/l,培养时间为24h,培养温度为30℃,接种量为10%。在此条件下,富铬酵母的产量为0.7461g/100ml,铬含量为1673μg/g。     

醇母细胞自溶条件的研究

研究NaCl添加量、pH、温度及时间等条件对酵母培养物液体摇瓶的自溶效果的影响,确定其最佳自溶条件不添加NaCl,pH 5.0,温度50℃,自溶40h,自溶后样品中游离氨基酸含量从初始0提高到1.068g/100mL,可溶性蛋白含量从初始0提高到1.237g/100mL,分别比单因素条件下自溶时提高2.96倍和1.15倍.     

酵母细胞自溶条件的研究

研究NaCl添加量、pH、温度及时间等条件对酵母培养物液体摇瓶的自溶效果的影响,确定其最佳自溶条件：不添加NaCl,pH5.0,温度50℃,自溶40h,自溶后样品中游离氨基酸含量从初始0提高到1.068g/100mL,可溶性蛋白含量从初始0提高到1.237g/100mL,分别比单因素条件下自溶时提高2.96倍和1.15倍。     

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 利用单因素及正交试验法对高产虾青素酵母菌株摇瓶发酵条件进行探索。结果表明,碳源以葡萄糖为宜,氮源以硫酸铵为宜,葡萄糖、硫酸铵、磷酸二氢钾、酵母膏和番茄汁最适添加量分别为4%、0.4%、0.4%、0.6%和0.6%,培养基最适初始pH值为5,最适培养温度为22 ℃,最适装液量以50 mL/500 mL(发酵液体积/三角瓶体积)。     

工程菌产植酸酶摇瓶发酵条件初探

本实验根据毕赤酵母工程菌的特点,在摇瓶中对重组毕赤酵母工程菌株PP-MS-NPm-4-16的发酵条件进行初步研究。确定了60%麦芽-麸皮培养基,40%的蚕蛹培养和190mg/L的酵母营养盐作为高密度发酵的基础培养基,生长阶段和诱导阶段最佳pH分别为5.0和5.5。通过正交实验得到工程菌的最佳摇瓶培养条件为:接种量4%,甲醇浓度40g/L,生长阶段豆油浓度1.3%,诱导阶段豆油浓度3.5%,植酸酶酶活最高可达到192400U/mL。     

重组枯草芽孢杆菌产角蛋白酶的发酵培养基及发酵条件优化

角蛋白是潜在的优良饲用蛋白资源，其中角蛋白酶作为可特异性降解角蛋白的酶类，在角蛋白饲料化领域展现出广泛的应用潜力和价值。本研究以自主构建的重组角蛋白酶工程菌枯草芽孢杆菌WB600-pMA5-kerJY-23为研究对象，利用单因素和二次通用旋转组合设计试验对其摇瓶发酵产角蛋白酶的发酵培养基和发酵条件进行优化。结果表明：该菌株最佳发酵产酶条件为：葡萄糖25 g/L，蔗糖25 g/L，酵母浸膏20 g/L，硫酸铵10 g/L，磷酸氢二钾1.5 g/L，氯化钠0.3 g/L，氯化钙0.025 g/L，硫酸镁0.025 g/L，硫酸亚铁0.015 g/L，氯化锰0.05 g/L，初始pH 8，装液量45 mL/250 mL三角瓶，接种量6%，培养温度37℃，摇床转速200 r/min，发酵周期36 h。在该优化条件下，重组枯草芽孢杆菌WB600发酵产角蛋白酶的酶活达到（2110±15.011）U/mL，较优化前提高了5.10倍（P <0.05），为该酶在角蛋白降解及资源化利用领域的应用提供了理论依据与研究基础。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -