共查询到20条相似文献，搜索用时 174 毫秒
1.
《饲料工业》2021,(8)
以青藏高原冷地早熟禾草地土壤为样品,筛选低温纤维素降解菌株。采用刚果红染色法(水解圈法)和3,5-二硝基水杨酸(DNS)法进行菌株筛选与酶学特性研究,结合形态学与分子生物学方法对其进行鉴定。筛选出一株低温纤维素降解菌株(LD19),经鉴定为钉斑链霉菌(Streptomyces clavifer),同时该菌还具有降解半纤维素的能力。该菌产纤维素酶的最适温度为40℃,最适pH值为6,在30～70℃、pH值4～10时相对酶活力较稳定,Zn~(2+)对酶有抑制作用。该菌产半纤维素酶的最适温度为50℃,最适pH值为6,在30～40℃、pH值4～9时相对酶活力较稳定,Cu~(2+)等对该酶有促进作用。该菌株在培养102 h后两种酶的相对酶活力均达到最高值。菌株LD19可以同时分泌低温纤维素酶和半纤维素酶,在饲用酶制剂的应用中具有较大潜力。 相似文献
2.
采取广西凭祥市原始森林土样为原料,以羧甲基纤维素钠(CMC-Na)为唯一碳源,分离纯化后用刚果红染色法进行初筛,得到两株产纤维素酶能力较强的菌株(PX-10与PX-14)。PX-14有相对较强的产纤维素酶能力,其葡聚糖内切酶活达到5.3 U/mL、滤纸酶活达到5.9 U/mL,根据PX-14菌株形态特征和分子鉴定,鉴定为产黄青霉。对其所产的葡聚糖内切酶的酶学性质进行研究,结果显示,PX-14的葡聚糖内切酶最适温度为50℃,在40～50℃有较高的温度稳定性;最适pH值为8.9,在pH值为8～10之间有较高的pH值稳定性;Co~(2+)、Cu~(2+)对该酶有促进作用,Zn~(2+)、Fe~(2+)等对该酶有抑制作用。该菌具有较强的蔗渣降解能力。 相似文献
3.
对枯草芽孢杆菌B.subtilis Kpg所产纤维素酶的酶学性质进行研究,确定该纤维素酶的最佳温度和最适pH,并进行固体发酵麸皮试验,验证Kpg纤维素酶的实践效果。试验以3,5-二硝基水杨酸酶活测定法为基础,通过改变纤维素酶的反应温度和pH环境,确定最适反应温度和最适pH环境。为研究其实际降解能力,将枯草芽孢杆菌Kpg添加到麸皮中,在37℃环境中发酵6d。结果显示,枯草芽孢杆菌Kpg纤维素酶的最适反应温度为60℃,此时纤维素酶活性最大为108.45U/mL;反应液最适pH值为6.0,此时纤维素酶活性为97.72U/mL;在两者最适条件共同作用下,纤维素酶活性为113.58U/mL。发酵试验结果显示,枯草芽孢杆菌Kpg能够显著降低麸皮中的纤维素含量(P0.05),同时显著提高发酵麸皮中的真蛋白含量(P0.05)。枯草芽孢杆菌Kpg表现出的酶学性质符合发酵微生物选育的标准和特征,为生物饲料的开发和应用提供数据参考。 相似文献
4.
产纤维素酶芽孢杆菌的诱变和酶学性质研究 总被引：1，自引：0，他引：1
为提高芽孢杆菌产纤维素酶的活性,以实验室保存的产纤维素酶枯草芽孢杆菌作为出发菌株,利用紫外线对其进行诱变处理,采用刚果红染色法初筛和3,5-二硝基水杨酸法进行复筛,并对其酶学性质进行初步研究.结果表明:诱变后突变株的纤维素酶活力较出发菌株提高4.476倍.该纤维素酶的最适pH为6.0,且在pH 5.0～7.0酶活力较稳定;该酶的最适酶促反应温度为60 ℃,在无底物保护且水浴30 min的条件下,酶活力在30～65 ℃保持稳定;此外,金属离子K+和Ba2+对酶活力有激活作用,相对酶活分别为108.11％和105.43％,而金属离子Ca2+和Cu2+对酶活性有抑制作用,二者的相对酶活分别为93.80％和89.08 ％. 相似文献
5.
前期从自然界土壤中分离筛选到一株纤维素酶产生菌 Bacillus methylotrophicus SWU6菌株,为提高该菌株发酵产酶能力,本研究采用3,5二硝基水杨酸显色法(DNS)对该菌株产酶所需碳源、氮源、温度、pH 值、装瓶量、接种量等发酵条件进行优化,并比较优化前后等量发酵上清液中 CMCase 酶活大小。结果表明：SWU6菌株产纤维素酶的最适碳源为淀粉,最适氮源为牛肉膏,最适培养温度为50℃,培养基最适初始 pH 值为5.0,最适装瓶量为20%,最适接种量为2%;在最优发酵产酶条件下,SWU6菌株发酵上清液中的 CMCase 酶活达到454.69 U/mL,明显高于优化前利用基础培养基发酵所产的 CMCase 酶活,且酶活提高约3倍。通过发酵条件优化后,SWU6菌株单位体积发酵液显示出了更强的纤维素酶活性。 相似文献
6.
7.
为研究乳酸菌和纤维素酶微贮发酵大豆秸秆过程中pH和主要微生物数量的变化,试验分为8个处理组,每组3个重复,进行乳酸菌和纤维素酶不同组合、不同发酵时间的微贮饲料发酵试验,对发酵饲料pH和乳酸菌、一般细菌、霉菌、酵母菌进行测定。结果表明：添加乳酸菌和纤维素酶发酵大豆秸秆过程中,pH和微生物数量均发生了明显变化,添加乳酸菌和纤维素酶有利于大豆秸秆的微贮,同时添加2种乳酸菌和纤维素酶试验组变化最大,效果最好。 相似文献
8.
本试验旨在构建不同纤维素酶的融合表达系统及探讨融合纤维素酶的酶学性质。利用PCR技术从实验室前期分离的枯草芽孢杆菌中分别扩增2个纤维素酶基因Cel42和Cel22,设计一段柔性接头(GSGGGS),通过酶切连接将2个纤维素酶基因构建在一个开放阅读框(ORF)内,插入到pET32a(+)中构建重组表达载体pET32a(+)-Cel42-Cel22,转化大肠杆菌BL21(DE3)进行诱导表达,并对其酶学性质进行研究。结果表明:本试验成功克隆了2个纤维素酶基因Cel42和Cel22,并构建了重组表达系统BL21(DE3)/pET32a(+)-Cel42-Cel22,十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)估计其分子质量约为101 ku,粗酶液中葡聚糖内切酶活性为57.62 U/mL,葡聚糖外切酶活性为32.57 U/mL。试验所得融合纤维素酶Cel42-Cel22的最适反应温度为50℃,最适反应pH为6.0,温度在30~70℃范围内时可维持70%以上的纤维素酶活性,pH在4.0~9.0范围内时可保持75%以上的纤维素酶活性,除Mn~(2+)外的其他金属离子对纤维素酶的活性均具有一定的抑制作用,其中Hg~(2+)和Cu~(2+)对的抑制作用较明显。由此可见,本试验在大肠杆菌BL21(DE3)中成功表达出了融合纤维素酶Cel42-Cel22,且该酶具有一定的活性,可适应较宽广的温度和pH范围,对金属离子敏感。 相似文献
9.
《黑龙江畜牧兽医》2016,(23)
为了研究桦剥管菌木材纤维素降解机制,试验分别于23℃和28℃培养桦剥管菌,用菌落直径比较生长速度;以白桦木屑、云杉木屑和麦麸为底物诱导培养,以不加木屑的马铃薯液体培养基为对照,测定12 d内桦剥管菌在纤维素外切酶和纤维素内切酶两种纤维素酶活变化;以云杉木屑、白桦木屑、玉米秸秆和麦麸为诱导物,测定15~21 d内木聚糖酶和甘露聚糖酶两种半纤维素酶活变化;检测8种不同金属离子以及金属离子抑制剂EDTA对两种半纤维素酶活性的影响;并对白桦木屑诱导桦剥管菌产半纤维素酶的酶学性质进行了初探。结果表明:桦剥管菌菌丝更适合在28℃培养;纤维素外切酶和纤维素内切酶的最适底物分别为白桦木屑和云杉木屑,木聚糖酶和甘露聚糖酶最适底物分别为麦麸和玉米秸秆;两种半纤维素酶的最适反应温度均为50℃,最适反应pH值分别为5.0和6.0;8种金属离子中,仅Co2+对两种半纤维酶活性均有促进作用,EDTA对两种酶活性均具有较强抑制作用。 相似文献
10.
梅花鹿瘤胃纤维素降解菌的分离鉴定及其酶活力测定 总被引：1，自引：1，他引：0
为获得来源于梅花鹿瘤胃的高效纤维素降解菌,本试验采集了3锯龄健康梅花鹿的新鲜瘤胃液,用羧甲基纤维素钠(CMC-Na)培养基分离筛选纤维素降解菌,综合其形态学、生理生化特征和16SrDNA基因测序等对分离菌株进行分类学鉴定,利用DNS法对菌株的产纤维素酶条件进行初步研究,并探讨以不同物质为底物时的纤维素酶酶学特性,为后期菌株的应用提供理论数据。结果显示,本试验从梅花鹿瘤胃液中分离的菌株N-11是一株高效纤维素降解菌,经鉴定为蜡样芽孢杆菌(Bacillus cereus)。产酶性质研究结果表明,该菌株产纤维素酶活力在30~45℃(最适温度为40℃),pH为6.0~7.0(最适pH 6.0),碳源含量为2%~5%(最佳接种量5%)较高;培养36h时达到产酶高峰,纤维素酶酶活力(CMCA)和滤纸酶酶活力(FPA)分别为12.563、12.414U/mL,在20~50℃或pH 6.0~8.0环境下作用1h,其相对酶活力均保持在80%以上,稳定性较好。以上结果表明,蜡样芽孢杆菌N-11具有较高的纤维素酶活力,在纤维素利用方面具有较高的应用价值。 相似文献
11.
Ontsouka EC Reist M Graber H Blum JW Steiner A Hirsbrunner G 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2004,51(9-10):385-393
Serotoninergic and adrenergic receptors (5-HTR and AR) are involved in the regulation of uterine contractility. The objective of this study was to compare mRNA levels of 5-HTR(1A), 5-HTR(1B), 5-HTR(1D), 5-HTR(1F), 5-HTR(2A), 5-HTR(2B), 5-HTR(2C), 5-HTR(4) and alpha(1A), alpha(1B), alpha(1D), alpha(2AD), alpha(2B), alpha(2C), and beta(1), beta(2), beta(3)-AR in oestrus and dioestrus, and at three uterine locations (tip, middle and base) using quantitative real-time polymerase chain reaction. Uterine specimens consisting of endometrium and myometrium including vessels and serosa were collected from cows in oestrus (n = 10) and dioestrus (n = 15) respectively. Levels of 5-HTR and AR mRNA were expressed relative to the geometric mean of ribosomal RNA (18S), ubiquitin and glyceraldehyde phosphate dehydrogenase by the mean values of geNorm algorithm. 5-HTR(1A), 5-HTR(2C) and beta(3)-AR mRNA could not be detected in uterine tissues. The mRNA levels of 5-HTR(1F) and 5-HTR(2B) were lower (P < 0.05), but of 5-HTR(4) were higher (P < 0.05) in oestrus than in dioestrus. The mRNA levels of alpha(1A)-AR, alpha(2AD)-AR, alpha(2B)-AR were lower (P < 0.05), but of alpha(2C)-AR and beta(2)-AR were higher (P < 0.05) in oestrus than dioestrus. The mRNA levels of 5-HTR(1B) and 5-HTR(1D) (oestrus) and of alpha(2AD)-AR (dioestrus) differed among uterine locations (base > middle > tip; P < 0.05). The mRNA expression of 5-HTR and AR (subtypes) in bovine uterus was associated with cycle activity and varied according to uterine location. Additional studies on protein level will be carried out in order to elucidate the role of these receptor families on uterine contractility, which may then help to clarify clinical relevance. 相似文献
12.
为了研究猪圆环病毒2型(PCV2)核酸疫苗在小鼠攻毒试验中的免疫保护效果,以PCV-2 GXWZ-1株为模板,扩增出ORF2基因及其截短基因8个片段(A(ORF2)、B(51-100aa)、C(101-150aa)、D(181-235aa)、E(151-200aa)、F(51-150aa)、G(101-235aa)、H(51-235aa)),将其插入到pcDNA3.0载体中,构建出真核表达质粒,并将其转染至PK-15细胞,用间接免疫荧光试验检测其瞬时表达情况。将试验小鼠随机分成9组,其中免疫组7组,阴阳性对照各1组,将纯化的真核表达质粒对小鼠进行组合免疫;二免后,用经处理过的PCV-2 GXWZ-2株阳性病料悬液腹腔注射免疫组和非免疫对照组小鼠,阴性对照组用生理盐水腹腔注射;其后进行体重记录、病理切片制作及PCR检测。结果表明:共有6个真核表达质粒成功在PK-15细胞中表达。在攻毒后的3周内,阳性对照组小鼠PCR诊断均为阳性;免疫组中,部分组小鼠在攻毒后第1周或在第2周为阳性,到第3周时各免疫组小鼠全部为阴性;阴性对照组始终为阴性。免疫组在病理保护学方面明显优于非免疫对照组,非免疫对照组的体重增长速率略低于免疫组和阴性对照组。由此可见猪圆环病毒2型核酸疫苗在小鼠攻毒试验中有明显的保护作用。 相似文献
13.
An evaluation of the multiple-breath nitrogen washout as a pulmonary function test in horses. 总被引：1，自引：1，他引：0 
下载免费PDF全文
下载免费PDF全文 Multiple-breath nitrogen washouts (MBNW) were performed with 29 light horses. Seven normal horses were used to examine the reproducibility, and 22, ranging from normal to severely diseased, were used to examine the changes in chronic obstructive pulmonary disease (COPD) and the effect of a bronchodilator, salbutamol, on the distribution of ventilation. The MBNW were analyzed using the functional residual capacity (FRC), end-tidal N2 concentration of the final breath of the MBNW (FETN2,fb), end-tidal N2 concentration when the cumulative expired volume was equal to body weight (FETN2,bw), lung clearance index (LCI), Becklake index (BI), mixing ratio (MR), index of distribution of inspiration (IDI), pulmonary N2 clearance delay (PCD) and ventilatory efficiency (EFF). The LCI, MR, IDI, PCD and EFF were calculated at end-tidal N2 concentrations (FETN2), equal to 3%, 2% and FETN2,fb. The EFF was also calculated at FETN2 = 8%, as was BI. The within day coefficient of variation for most indices of the MBNW was 10-15%. None of the indices varied significantly from day-to-day. The FETN2,fb, FETN2,bw, MR, IDI, PCD, and EFFfb, EFF3% and EFF2% differed between the horses with COPD and the normal horses, and all of the indices, except FRC, were correlated with a histopathological score of the small airways. The FETN2,bw appeared to be the most sensitive index in detecting the horses with COPD. In the horses with COPD, salbutamol caused a decrease in FRC and FETN2,fb indicating increased ventilation of the lung. However, LCI increased suggesting a less efficient distribution of ventilation. 相似文献
14.
Atkins JA Busch DC Bader JF Keisler DH Patterson DJ Lucy MC Smith MF 《Journal of animal science》2008,86(1):83-93
The COSynch protocol has been used to synchronize ovulation and facilitate fixed-time AI in beef cattle. Establishment and maintenance of pregnancy was negatively affected, in previous studies, by GnRH-induced ovulation of small dominant follicles (/=10 mm) and increased ovulatory response after GnRH 2. 相似文献
15.
Davis WC Drbal K Mosaad AE Elbagory AR Tibary A Barrington GM Park YH Hamilton MJ 《Veterinary immunology and immunopathology》2007,119(1-2):123-130
Flow cytometry was used to screen a panel of 320 mAbs, submitted to the Animal Homologues Section of the HLDA8, for mAbs that recognize epitopes conserved on orthologous leukocyte differentiation antigens (LDA) in goats, lamas, and rabbits. Nineteen mAbs specific for CD11a (1), CD14 (3), CD18 (1), CD21 (1), CD29 (2), CD44 (2), CD47 (3), CD49d (1), CD172a (1), CD45RB (1), CD61 (1), RACT48A, and GBSP71A reacted with goat LDA. Twenty three mAbs specific for CD7 (1), CD9 (2), CD11a (1), CD14 (3), CD18 (4), CD29 (1), CD32 (1), CD44 (1), CD47 (4), CD49d (2), CD50 (1), CD80 (1), CD172a (1), and GBSP71A reacted with llama LDA. Eighteen mAbs specific for CD9 (2), CD11a (1), CD14 (2), CD18 (4), CD21 (1), CD44 (2), CD45RB (1), CD49d (1), CD209 (1), RACT48A, and GBSP71A reacted with rabbit LDA. The specificities of two cross reactive mAbs that recognize different conserved epitopes on all leukocytes in two species (RACT48A) and all three species (GBSP71A) have not been determined. The patterns of reactivity of most of the mAbs were consistent with patterns of reactivity noted on human leukocytes. The specificity of some cross reactive mAbs generated in non-human species were validated on human leukocytes. Further studies are needed to verify that CD7, CD32, CD45RB, CD50, and CD209 recognize orthologous molecules in the indicated species. 相似文献
16.
为评价植物种植对土壤化学性质的改良能力,综合运用改良功效系数法、地统计学方法和层次分析法建立了定量化评价体系。对四种植物改良效果进行了评价,结果显示:改良评价值差异最大的指标是碱化度,最高和最低相差将近5000分,改良值相差1000～2000分之间的指标为pH值和Cl-含量,改良值相差最小的是速效P含量(86.7),其他值相差在100～999之间(改良值差值全盐量>CO23-含量>全P含量>Mg2+含量>速效K含量>有机质含量>Na+含量>全K含量>HCO3-含量>全N含量>碱解N含量>Ca2+含量)。籽粒苋改良能力最强的指标为全N含量(403.13)、碱解N含量(419.89)、碱化度(4910.23)、全盐量(986.07)、Na+含量(686.02)、Mg2+含量(950.61)、CO23-含量(929.97);披碱草改良能力最强的指标为全K含量(559.56)、pH值(1908.84)、HCO3-含量(731.40);小叶锦鸡儿改良能力最强的指标为全P含量(822.11)、有机质含量(641.75)、速效K含量(639.65)、速效P含量(89.26)、Ca2+含量(308.86)、Mg2+含量(1020.3)。改良能力综合评价值,籽粒苋(841.15)>披碱草(721.47)>小叶锦鸡儿(180.67)>千屈菜(429.77)。评价体系应用的地统计学方法使评价结果更加准确,区别了指标间权重差异,并综合所有指标的得分,对植物改良能力的评价更符合实际情况。 相似文献
17.
T Nakamura S Yoshino E Iida Y Wakao M Muto M Takahashi 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1990,52(2):285-292
Using adult mongrel dogs, experiments were performed to elucidate the relationship between the changes in the myocardial oxygen tension (PmO2) in anoxia and disturbances of cardiac function. Dogs, forced to inspire 100% N2, suffered from a respiratory arrest after 5 min, and developed acute anoxia. However, by 100% O2 inhalation 2 min after the onset of the respiratory arrest, the anoxia rapidly resolved. The arterial oxygen tension (PaO2), left intra ventricular oxygen tension (PLVO2) and PmO2 showed the most pronounced fall 2 min after the respiratory arrest induced by N2 inhalation. The arterial carbon deoxide tension (PaCO2) decreased until the respiratory arrest, after which it started to rise. When inhalation of 100% O2 was initiated at the anoxia, the PaO2, PLVO2 and PmO2 recovered within 1 min followed by a rise beyond the baseline value. Left ventricular end-diastolic pressure (LVEDP), left atrial mean pressure (LAm), left ventricular systolic pressure (LVSP), aortic mean pressure (Aom), maximum rate of force development by left ventricle (LVmax.dp/dt), total peripheral resistance (TPR), cardiac output (CO) and heart rate (HR) were measured. At the onset of anoxia, these parameters decreased sharply. When inhalation of 100% O2 was initiated within 2 min of the respiratory arrest, these disturbances of cardiac function recovered rapidly. The fall of PmO2 plays an important role in the impairment of cardiac function. 相似文献
18.
Relationship of rumen fluid dilution rate to rumen fermentation and dietary characteristics of beef steers 总被引：1，自引：0，他引：1
Data from seven beef steer trials were compiled and regression analyses used to evaluate relationships among molar proportions of acetate (Ac), propionate (Pr) and butyrate (Bu), total concentration of volatile fatty acids (VFA), rumen ammonia (NH3), rumen pH, rumen fluid dilution rate (FDR), rumen fluid volume (FVOL), body weight (WT), dry matter intake (DMI) and dietary concentration and intake of crude protein (CP and CPI), acid detergent fiber (ADF and ADFI), ash (ASH and ASHI) and metabolizable energy (ME and MEI). Of the six fermentation variables, Pr (negative regression coefficient, beta) and pH (positive beta) were related (P less than .05) to FDR, but only 3 and 12% of the variation in these two variables, respectively, was explained by FDR. When FDR was described by dietary characteristics, ASHI was positively related to FDR (R2 = .16). The best two-variable model for FDR contained DMI (positive beta) and WT (negative beta) and increased R2 to .36. Fluid volume was best described by ME (positive beta; R2 = .20). The two-variable model for FVOL added ASH with a positive partial beta (R2 = .23). When fermentation variables were regressed on dietary characteristics, Ac was best described by ADF (positive beta; R2 = .71). The variable that best described Pr proportion was ADF (negative beta; R2 = .50), and addition of CP (negative beta) and MEI (positive beta) into the Pr model improved R2 to .70. Molar proportion of butyrate was related to CP (positive beta; R2 = .23), and addition of ME (positive beta) to the model improved the R2 to .31. Total VFA concentration was best described by ADFI (positive beta; R2 = .14). An R2 of .29 resulted when ME (positive beta) and CPI (negative beta) were included in the total VFA model. Rumen pH was related to ADF (positive beta; R2 = .45), and addition of CP (positive beta) to the rumen pH model increased R2 to .55. Crude protein concentration was related to ruminal NH3 level (positive beta; R2 = .42), and inclusion of ADFI (positive beta) into the model improved the R2 to .47. 相似文献
19.
20.
为探究青藏高原高寒草甸退化问题,从施肥可以改良草地退化的角度出发,本研究以青海省高寒草甸为研究对象,通过设置不同施肥处理,即对照不施肥（CK）、施加氮肥250 kg·hm-2（N）、磷肥400 kg·hm-2（P）、氮磷肥300 kg·hm-2（NP）、有机肥2 000 kg·hm-2（O）、植物根际促生菌（Plant growth-promoting rhizobacteria,PGPR）菌肥7.5 kg·hm-2（J1）,15 kg·hm-2（J2）,22.5 kg·hm-2（J3）、PGPR菌肥+70%氮肥（J1+N）、PGPR菌肥+70%磷肥（J1+P）,对不同施肥处理高寒草甸的改良效果、PGPR菌肥的适用性以及菌肥替代化肥的效果进行分析。结果表明：NP显著提高地上生物量（P<0.05）,J1+N处理不仅增加了地上生物量,还可缓解施用N肥造成的物种丰富度下降,同时增加土壤水分和全氮含量（P<0.05）,又不会引起盐渍化。综上所述,J1+N处理能够部分替代化肥,减少无机化肥对生态环境的危害,推荐在高寒草甸施用。 相似文献