米曲霉中性蛋白酶钝化大豆胰蛋白酶抑制剂

为了消除大豆饼粕中胰蛋白酶抑制剂的抗营养作用,提高大豆蛋白的利用效率,本文主要从中性蛋白酶加重、酶解温度、Na2SO3加量、不同金属离子和酶解时间等方面考察了米曲霉ZW-06所产中性蛋白酶对豆粕中胰蛋白酶抑制剂的钝化作用.研究结果表明,在豆粕中添加1∶500(质量比)的蛋白酶就能钝化豆粕中40%的胰蛋白酶抑制剂.温度对蛋白酶钝化胰蛋白酶抑制荆的影响很小,金属离子的加入普遍抑制蛋白酶对胰蛋白酶抑制荆的降解,酶解时间在30 min就能达到最大抑制效果.     

Studies on induced Klebsiella mastitis with relationships among N-acetyl-beta-D-glucosaminidase, bacterial and somatic cell counts

Mastitis was induced by infusion of 3,000-7,000 colony-forming units of Klebsiella pneumoniae into the left rear quarter of four primiparous Holstein-Freisians. Greater than 100 organisms were recovered from a quarter milk sample within 2 hr and in 87.5% of the hourly cultures taken after 8 hr. Bacteria, California Mastitis Tests, somatic cell counts and N-acetyl-beta-D-glucosaminidase levels differed significantly from that of control quarters in infused cows after hr 6, 8, 9 and 9 respectively. High correlations were obtained between somatic cell count and N-acetyl-beta-D-glucosaminidase (r = .97) and N-acetyl-beta-D-glucosaminidase and natural log bacterial count (r. = .88). N-acetyl-beta-D-glucosaminidase was related to natural log bacterial counts of samples taken 1, 2, 3, and 4 hr prior to the test (rN-acetyl-beta-D-glucosaminidase and natural log bacterial count (r = .91, .92, .93, and .95).     

微生物混合发酵去除生豆粕中胰蛋白酶抑制剂的研究

利用生物发酵法,对筛选出的对豆粕中胰蛋白酶抑制剂有分解破坏作用的3种微生物菌种进行混合发酵,对发酵条件进行研究,得到最佳的发酵工艺为:基质为豆粕,通气量为60g干料/500ml广口瓶,料水比为1:1,接种量为酵母菌y-0214%、y-0282%、乳酸菌Lc2%,起始pH值自然,起始温度为30℃,发酵72h后豆粕中胰蛋白酶抑制剂被完全分解除去。     

Serologic study of Pasteurella aerogenes sp n.

The antigenic attributes of Pasteurella aerogenes sp n were serologically compared with species of the genera Actinobacillus and Pasteurella. Examination included the tube-agglutination and double-immunodiffusion techniques. The results indicated the possibility of serologically different strains of P aerogenes. Antisera prepared from strains of P aerogenes also reacted well with antigens prepared from Yersinia pseudotuberculosis (P pseudotuberculosis) and P pneumotropica.     

Abortion of a sow caused by Pasteurella aerogenes.

Three strains of the Pasteurella aerogenes complex were isolated as sole pathogens from aborted fetuses of a sow aborted at the 12th week of gestation on a farm of 600 sows. Gross pathology showed no characteristic lesions. The isolates were biochemically identical and resembled P. pneumotropica on the basis of their strong indole and urease positivity but they produced gas, were ornithine decarboxylase negative and fermented mannitol but not trehalose. Only a few differences were apparent in biochemical characteristics between the isolated strains and P. aerogenes. They differed from the type strain of P. aerogenes in ornithine decarboxylase activity, indole production and lactose and mannitol fermentation; however, such strains do occur within this heterogeneous species. At the time of abortion the antibody titre of the aborted sow was 1 in 16 when examined with live bacterial suspension and 1 in 128 if boiled antigen was used. Similar strains could not be isolated from the vaginas of aborted sows or pregnant and newly farrowed sows in the same group. The bacteriological, serological and histological findings support the opinion of other workers on the occasional pathogenic nature of P. aerogenes.     

蟾酥对产气肠杆菌抑制作用的方差分析和相关分析

把采自中华大蟾蜍的蟾酥用蒸馏水稀释成4、6、8、10mg／mL共4种浓度，作为因素A，用LB液体培养基将活化的产气肠杆菌原液按1：10^4和1：10^5稀释，作为因素B，采用二因子（A和B）方差分析观察了蟾酥对产气肠杆菌抑菌圈直径的影响，并分析了蟾酥浓度与抑菌圈直径之间的相关关系。结果显示，蟾酥浓度与抑菌圈直径之间存在显著正相关（r=0．988～0．997）；不同浓度的蟾酥溶液对产气肠杆菌均有抑制作用；且随着蟾酥浓度的升高，抑制作用加强。     

rBmTI-6, a Kunitz-BPTI domain protease inhibitor from the tick Boophilus microplus, its cloning, expression and biochemical characterization

Boophilus microplus is a rich source of trypsin inhibitors, numerous Kunitz-BPTI (bovine pancreatic trypsin inhibitor) inhibitors have been described from larvae and eggs, named BmTIs. Among them, were characterized inhibitors for trypsin, human neutrophil elastase, human plasma kallikrein and plasmin. BmTIs elicited a protective immunological response against B. microplus infestation in cattle. However, only a small amount of purified natural BmTIs can be obtained from larvae and eggs by chromatographic methods, thus if BmTIs are to be used as vaccine antigens (immunogens) the production of recombinant BmTIs (rBmTIs) is essential. In this work we describe the cloning, expression, purification and characterization of rBmTI-6. rBmTI-6 is a three-headed Kunitz-BPTI inhibitor, expressed in the Pichia pastoris system. Although rBmTI-6 was processed by proteases and glycosylated during the expression process, these post-translational modifications did not alter the ability of rBmTI-6 to inhibit protease activity. Purified rBmTI-6 inhibited trypsin and plasmin.     

探究牛源肺炎克雷伯菌bla-SHV耐药基因转移机制

[目的]鉴定分离到牛源肺炎克雷伯杆菌的SHV表型,并通过接合转移实验确定能够水平转移给其他细菌,以探明其耐药基因转移的机制.[方法]对已经分离得到的肺炎克雷伯菌进行药敏试验,检测耐药基因,做水平转移实验.[结果]从分离得到的71株肺炎克雷伯菌中,产超光谱β-内酰胺酶的菌株共有66株,66株中共有7株含SHV基因的肺炎克...     

有效的蛋白酶会有利于环境

农业环境可持续性是指减少农业生产活动对环境的影响,从而可以保护我们生活环境的质量,延长农业土地和其它资源的使用＂寿命＂。酶制剂可以帮助我们实现这一目的。     

乐胺磷对5龄期家蚕肠液蛋白酶活性的影响

乐胺磷是一种兼有触杀作用和胃毒作用的有机磷广谱杀虫剂,在虫害严重的桑田治理中起到较好作用。但由于乐胺磷的作用对象也包括家蚕在内,用药后乐胺磷在桑叶上的残留对家蚕生理生化的影响仍是一个值得探讨的问题。家蚕肠液蛋白酶活性是检测家蚕消化能力的一个标志性酶。本文用紫外吸收法检测了残留量乐胺磷对5龄期家蚕肠液蛋白酶活性的影响。结果显示,在所添食的乐胺磷浓度范围内,乐胺磷添食量与家蚕肠液蛋白酶活性之间呈负相关。在家蚕5龄初期添食乐胺磷引起的肠液蛋白酶活性的下降,至5龄末期已基本消除。     

纳豆芽孢杆菌产蛋白酶固态发酵条件研究

<正>蛋白酶是一种重要的工业用酶,其产量约占酶制剂市场的65%以上[1],广泛应用于食品、药物、皮革制造、蛋白水解和纺织工业等[2-3]。蛋白酶是从动植物组织和微生物代谢物中提取、精制而来的。由于微生物蛋白酶均为胞外酶,与动植物源蛋白酶相比具有相当大的优势,如下游技术处理相对简单、价格低廉、来源广、菌体易于培养、产量高、高产菌株选育简单且快速;此外,微生物蛋白酶还具有动植物源蛋白酶所具有的全部特性和较大的耐热性及一定的酯酶活力,易     

中性蛋白酶对菜粕品质改良的研究

试验研究中性蛋白酶的添加量、酶解料水比、酶解时间及酶解温度对菜粕蛋白品质和硫甙降解的影响,并通过正交试验确定中性蛋白酶最佳酶解条件。结果表明:中性蛋白酶酶解菜粕的最佳条件是酶添加量125U/g、料水比1:1.2、酶解时间48h、酶解温度45℃。在此条件下,菜粕经酶解后,小肽含量从33.54mg/g提高到137.26mg/g,比原菜粕提高了4.09倍;硫甙含量从50.94μmol/g减少到26.31μmol/g,比原菜粕降低了48.34%。     

黑曲霉酸性蛋白酶酶学性质的研究

对黑曲霉菌株ANS1产酸性蛋白酶基本酶学性质的研究表明:酸性蛋白酶适宜反应pH为2.5～4.0,在pH为3.5时,相对酶活力最高;适宜温度为40～50℃,在45℃时,相对酶活力最高;酸性蛋白酶有着较好的热稳定性,曲酶粉在80℃保温5min保留51.4%的相对酶活力,液态酶在80℃恒温水浴中保温60s保留54.6%的相对酶活力,曲酶粉较液态酶有着更好的抗热性;金属离子对酸性蛋白酶活力有一定的影响,在5.0mmol/L的浓度下,Mn2 和Cu2 对酸性蛋白酶有较强的激活作用,Fe3 对该酶表现出明显的抑制作用。